test: beta reduction tests for grind

.github/workflows/awaiting-mathlib.yml

@@ -1,20 +0,0 @@
-name: Check awaiting-mathlib label
-
-on:
-  merge_group:
-  pull_request:
-    types: [opened, synchronize, reopened, labeled, unlabeled]
-
-jobs:
-  check-awaiting-mathlib:
-    runs-on: ubuntu-latest
-    steps:
-      - name: Check awaiting-mathlib label
-        if: github.event_name == 'pull_request'
-        uses: actions/github-script@v7
-        with:
-          script: |
-            const { labels } = context.payload.pull_request;
-            if (labels.some(label => label.name == "awaiting-mathlib") && !labels.some(label => label.name == "builds-mathlib")) {
-              core.setFailed('PR is marked "awaiting-mathlib" but "builds-mathlib" label has not been applied yet by the bot');
-            }

.github/workflows/build-template.yml

@@ -1,250 +0,0 @@
-# instantiated by ci.yml
-name: build-template
-on:
-  workflow_call:
-    inputs:
-      check-level:
-        type: string
-        required: true
-      config:
-        type: string
-        required: true
-      nightly:
-        type: string
-        required: true
-      LEAN_VERSION_MAJOR:
-        type: string
-        required: true
-      LEAN_VERSION_MINOR:
-        type: string
-        required: true
-      LEAN_VERSION_PATCH:
-        type: string
-        required: true
-      LEAN_SPECIAL_VERSION_DESC:
-        type: string
-        required: true
-      RELEASE_TAG:
-        type: string
-        required: true
-
-jobs:
-  build:
-    if: github.event_name != 'schedule' || github.repository == 'leanprover/lean4'
-    strategy:
-      matrix:
-        include: ${{fromJson(inputs.config)}}
-      # complete all jobs
-      fail-fast: false
-    runs-on: ${{ matrix.os }}
-    defaults:
-      run:
-        shell: ${{ matrix.shell || 'nix develop -c bash -euxo pipefail {0}' }}
-    name: ${{ matrix.name }}
-    env:
-      # must be inside workspace
-      CCACHE_DIR: ${{ github.workspace }}/.ccache
-      CCACHE_COMPRESS: true
-      # current cache limit
-      CCACHE_MAXSIZE: 400M
-      # squelch error message about missing nixpkgs channel
-      NIX_BUILD_SHELL: bash
-      LSAN_OPTIONS: max_leaks=10
-      # somehow MinGW clang64 (or cmake?) defaults to `g++` even though it doesn't exist
-      CXX: c++
-      MACOSX_DEPLOYMENT_TARGET: 10.15
-    steps:
-      - name: Install Nix
-        uses: DeterminateSystems/nix-installer-action@main
-        if: runner.os == 'Linux' && !matrix.cmultilib
-      - name: Install MSYS2
-        uses: msys2/setup-msys2@v2
-        with:
-          msystem: clang64
-          # `:` means do not prefix with msystem
-          pacboy: "make: python: cmake clang ccache gmp libuv git: zip: unzip: diffutils: binutils: tree: zstd tar:"
-        if: runner.os == 'Windows'
-      - name: Install Brew Packages
-        run: |
-          brew install ccache tree zstd coreutils gmp libuv
-        if: runner.os == 'macOS'
-      - name: Checkout
-        uses: actions/checkout@v4
-        with:
-          # the default is to use a virtual merge commit between the PR and master: just use the PR
-          ref: ${{ github.event.pull_request.head.sha }}
-      - name: Open Nix shell once
-        run: true
-        if: runner.os == 'Linux'
-      # Do check out some CI-relevant files from virtual merge commit to accommodate CI changes on
-      # master (as the workflow files themselves are always taken from the merge)
-      # (needs to be after "Install *" to use the right shell)
-      - name: CI Merge Checkout
-        run: |
-          git fetch --depth=1 origin ${{ github.sha }}
-          git checkout FETCH_HEAD flake.nix flake.lock script/prepare-*
-        if: github.event_name == 'pull_request'
-      # (needs to be after "Checkout" so files don't get overridden)
-      - name: Setup emsdk
-        uses: mymindstorm/setup-emsdk@v14
-        with:
-          version: 3.1.44
-          actions-cache-folder: emsdk
-        if: matrix.wasm
-      - name: Install 32bit c libs
-        run: |
-          sudo dpkg --add-architecture i386
-          sudo apt-get update
-          sudo apt-get install -y gcc-multilib g++-multilib ccache libuv1-dev:i386 pkgconf:i386
-        if: matrix.cmultilib
-      - name: Cache
-        id: restore-cache
-        uses: actions/cache/restore@v4
-        with:
-          # NOTE: must be in sync with `save` below
-          path: |
-            .ccache
-            ${{ matrix.name == 'Linux Lake' && 'build/stage1/**/*.trace
-            build/stage1/**/*.olean
-            build/stage1/**/*.ilean
-            build/stage1/**/*.c
-            build/stage1/**/*.c.o*' || '' }}
-          key: ${{ matrix.name }}-build-v3-${{ github.event.pull_request.head.sha }}
-          # fall back to (latest) previous cache
-          restore-keys: |
-            ${{ matrix.name }}-build-v3
-      # open nix-shell once for initial setup
-      - name: Setup
-        run: |
-          ccache --zero-stats
-        if: runner.os == 'Linux'
-      - name: Set up NPROC
-        run: |
-          echo "NPROC=$(nproc 2>/dev/null || sysctl -n hw.logicalcpu 2>/dev/null || echo 4)" >> $GITHUB_ENV
-      - name: Build
-        run: |
-          ulimit -c unlimited  # coredumps
-          [ -d build ] || mkdir build
-          cd build
-          # arguments passed to `cmake`
-          # this also enables githash embedding into stage 1 library
-          OPTIONS=(-DCHECK_OLEAN_VERSION=ON)
-          OPTIONS+=(-DLEAN_EXTRA_MAKE_OPTS=-DwarningAsError=true)
-          if [[ -n '${{ matrix.cross_target }}' ]]; then
-            # used by `prepare-llvm`
-            export EXTRA_FLAGS=--target=${{ matrix.cross_target }}
-            OPTIONS+=(-DLEAN_PLATFORM_TARGET=${{ matrix.cross_target }})
-          fi
-          if [[ -n '${{ matrix.prepare-llvm }}' ]]; then
-            wget -q ${{ matrix.llvm-url }}
-            PREPARE="$(${{ matrix.prepare-llvm }})"
-            eval "OPTIONS+=($PREPARE)"
-          fi
-          if [[ -n '${{ matrix.release }}' && -n '${{ inputs.nightly }}' ]]; then
-            OPTIONS+=(-DLEAN_SPECIAL_VERSION_DESC=${{ inputs.nightly }})
-          fi
-          if [[ -n '${{ matrix.release }}' && -n '${{ inputs.RELEASE_TAG }}' ]]; then
-            OPTIONS+=(-DLEAN_VERSION_MAJOR=${{ inputs.LEAN_VERSION_MAJOR }})
-            OPTIONS+=(-DLEAN_VERSION_MINOR=${{ inputs.LEAN_VERSION_MINOR }})
-            OPTIONS+=(-DLEAN_VERSION_PATCH=${{ inputs.LEAN_VERSION_PATCH }})
-            OPTIONS+=(-DLEAN_VERSION_IS_RELEASE=1)
-            OPTIONS+=(-DLEAN_SPECIAL_VERSION_DESC=${{ inputs.LEAN_SPECIAL_VERSION_DESC }})
-          fi
-          # contortion to support empty OPTIONS with old macOS bash
-          cmake .. --preset ${{ matrix.CMAKE_PRESET || 'release' }} -B . ${{ matrix.CMAKE_OPTIONS }} ${OPTIONS[@]+"${OPTIONS[@]}"} -DLEAN_INSTALL_PREFIX=$PWD/..
-          time make -j$NPROC
-      - name: Install
-        run: |
-          make -C build install
-      - name: Check Binaries
-        run: ${{ matrix.binary-check }} lean-*/bin/* || true
-      - name: Count binary symbols
-        run: |
-          for f in lean-*/bin/*; do
-            echo "$f: $(nm $f | grep " T " | wc -l) exported symbols"
-          done
-        if: matrix.name == 'Windows'
-      - name: List Install Tree
-        run: |
-          # omit contents of Init/, ...
-          tree --du -h lean-*-* | grep -E ' (Init|Lean|Lake|LICENSE|[a-z])'
-      - name: Pack
-        run: |
-          dir=$(echo lean-*-*)
-          mkdir pack
-          # high-compression tar.zst + zip for release, fast tar.zst otherwise
-          if [[ '${{ startsWith(github.ref, 'refs/tags/') && matrix.release }}' == true || -n '${{ inputs.nightly }}' || -n '${{ inputs.RELEASE_TAG }}' ]]; then
-            ${{ matrix.tar || 'tar' }} cf - $dir | zstd -T0 --no-progress -19 -o pack/$dir.tar.zst
-            zip -rq pack/$dir.zip $dir
-          else
-            ${{ matrix.tar || 'tar' }} cf - $dir | zstd -T0 --no-progress -o pack/$dir.tar.zst
-          fi
-      - uses: actions/upload-artifact@v4
-        if: matrix.release
-        with:
-          name: build-${{ matrix.name }}
-          path: pack/*
-      - name: Lean stats
-        run: |
-          build/stage1/bin/lean --stats src/Lean.lean
-        if: ${{ !matrix.cross }}
-      - name: Test
-        id: test
-        run: |
-          ulimit -c unlimited  # coredumps
-          time ctest --preset ${{ matrix.CMAKE_PRESET || 'release' }} --test-dir build/stage1 -j$NPROC --output-junit test-results.xml ${{ matrix.CTEST_OPTIONS }}
-        if: (matrix.wasm || !matrix.cross) && (inputs.check-level >= 1 || matrix.name == 'Linux release')
-      - name: Test Summary
-        uses: test-summary/action@v2
-        with:
-          paths: build/stage1/test-results.xml
-        # prefix `if` above with `always` so it's run even if tests failed
-        if: always() && steps.test.conclusion != 'skipped'
-      - name: Check Test Binary
-        run: ${{ matrix.binary-check }} tests/compiler/534.lean.out
-        if: (!matrix.cross) && steps.test.conclusion != 'skipped'
-      - name: Build Stage 2
-        run: |
-          make -C build -j$NPROC stage2
-        if: matrix.test-speedcenter
-      - name: Check Stage 3
-        run: |
-          make -C build -j$NPROC check-stage3
-        if: matrix.test-speedcenter
-      - name: Test Speedcenter Benchmarks
-        run: |
-          # Necessary for some timing metrics but does not work on Namespace runners
-          # and we just want to test that the benchmarks run at all here
-          #echo -1 | sudo tee /proc/sys/kernel/perf_event_paranoid
-          export BUILD=$PWD/build PATH=$PWD/build/stage1/bin:$PATH
-          cd tests/bench
-          nix shell .#temci -c temci exec --config speedcenter.yaml --included_blocks fast --runs 1
-        if: matrix.test-speedcenter
-      - name: Check rebootstrap
-        run: |
-          # clean rebuild in case of Makefile changes
-          make -C build update-stage0 && rm -rf build/stage* && make -C build -j$NPROC
-        if: matrix.name == 'Linux' && inputs.check-level >= 1
-      - name: CCache stats
-        if: always()
-        run: ccache -s
-      - name: Show stacktrace for coredumps
-        if: failure() && runner.os == 'Linux'
-        run: |
-          for c in $(find . -name core); do
-            progbin="$(file $c | sed "s/.*execfn: '\([^']*\)'.*/\1/")"
-            echo bt | $GDB/bin/gdb -q $progbin $c || true
-          done
-      - name: Save Cache
-        if: always() && steps.restore-cache.outputs.cache-hit != 'true'
-        uses: actions/cache/save@v4
-        with:
-          # NOTE: must be in sync with `restore` above
-          path: |
-            .ccache
-            ${{ matrix.name == 'Linux Lake' && 'build/stage1/**/*.trace
-            build/stage1/**/*.olean
-            build/stage1/**/*.ilean
-            build/stage1/**/*.c
-            build/stage1/**/*.c.o*' || '' }}
-          key: ${{ steps.restore-cache.outputs.cache-primary-key }}

.github/workflows/check-stage0.yml

@@ -20,7 +20,9 @@ jobs:
 
     - name: Identify stage0 changes
       run: |
-        git diff "${BASE:-HEAD^}..HEAD" --name-only -- stage0/stdlib > "$RUNNER_TEMP/stage0" || true
+        git diff "${BASE:-HEAD^}..HEAD" --name-only -- stage0 |
+          grep -v -x -F $'stage0/src/stdlib_flags.h\nstage0/src/lean.mk.in' \
+          > "$RUNNER_TEMP/stage0" || true
         if test -s "$RUNNER_TEMP/stage0"
         then
           echo "CHANGES=yes" >> "$GITHUB_ENV"

.github/workflows/ci.yml

@@ -36,9 +36,7 @@ jobs:
       # 2: PRs with `release-ci` label, releases (incl. nightlies)
       check-level: ${{ steps.set-level.outputs.check-level }}
       # The build matrix, dynamically generated here
-      matrix: ${{ steps.set-matrix.outputs.matrix }}
-      # secondary build jobs that should not block the CI success/merge queue
-      matrix-secondary: ${{ steps.set-matrix.outputs.matrix-secondary }}
+      matrix: ${{ steps.set-matrix.outputs.result }}
       # Should we make a nightly release? If so, this output contains the lean version string, else it is empty
       nightly: ${{ steps.set-nightly.outputs.nightly }}
       # Should this be the CI for a tagged release?
@@ -137,47 +135,34 @@ jobs:
             console.log(`level: ${level}`);
             // use large runners where available (original repo)
             let large = ${{ github.repository == 'leanprover/lean4' }};
-            const isPr = "${{ github.event_name }}" == "pull_request";
             let matrix = [
-              /* TODO: to be updated to new LLVM
               {
+                // portable release build: use channel with older glibc (2.27)
                 "name": "Linux LLVM",
                 "os": "ubuntu-latest",
                 "release": false,
                 "check-level": 2,
                 "shell": "nix develop .#oldGlibc -c bash -euxo pipefail {0}",
-                "llvm-url": "https://github.com/leanprover/lean-llvm/releases/download/19.1.2/lean-llvm-x86_64-linux-gnu.tar.zst",
+                "llvm-url": "https://github.com/leanprover/lean-llvm/releases/download/15.0.1/lean-llvm-x86_64-linux-gnu.tar.zst",
                 "prepare-llvm": "../script/prepare-llvm-linux.sh lean-llvm*",
                 "binary-check": "ldd -v",
                 // foreign code may be linked against more recent glibc
                 // reverse-ffi needs to be updated to link to LLVM libraries
                 "CTEST_OPTIONS": "-E 'foreign|leanlaketest_reverse-ffi'",
                 "CMAKE_OPTIONS": "-DLLVM=ON -DLLVM_CONFIG=${GITHUB_WORKSPACE}/build/llvm-host/bin/llvm-config"
-              }, */
+              },
               {
-                // portable release build: use channel with older glibc (2.26)
                 "name": "Linux release",
                 "os": large ? "nscloud-ubuntu-22.04-amd64-4x8" : "ubuntu-latest",
                 "release": true,
                 "check-level": 0,
                 "shell": "nix develop .#oldGlibc -c bash -euxo pipefail {0}",
-                "llvm-url": "https://github.com/leanprover/lean-llvm/releases/download/19.1.2/lean-llvm-x86_64-linux-gnu.tar.zst",
+                "llvm-url": "https://github.com/leanprover/lean-llvm/releases/download/15.0.1/lean-llvm-x86_64-linux-gnu.tar.zst",
                 "prepare-llvm": "../script/prepare-llvm-linux.sh lean-llvm*",
                 "binary-check": "ldd -v",
                 // foreign code may be linked against more recent glibc
                 "CTEST_OPTIONS": "-E 'foreign'"
               },
-              {
-                "name": "Linux Lake",
-                "os": large ? "nscloud-ubuntu-22.04-amd64-4x8" : "ubuntu-latest",
-                "check-level": 0,
-                // just a secondary build job for now until false positives can be excluded
-                "secondary": true,
-                "CMAKE_OPTIONS": "-DUSE_LAKE=ON",
-                // TODO: importStructure is not compatible with .olean caching
-                // TODO: why does scopedMacros fail?
-                "CTEST_OPTIONS": "-E 'scopedMacros|importStructure'"
-              },
               {
                 "name": "Linux",
                 "os": large ? "nscloud-ubuntu-22.04-amd64-4x8" : "ubuntu-latest",
@@ -186,12 +171,12 @@ jobs:
                 "check-level": 1,
               },
               {
-                "name": "Linux Reldebug",
+                "name": "Linux Debug",
                 "os": "ubuntu-latest",
                 "check-level": 2,
-                "CMAKE_PRESET": "reldebug",
-                // exclude seriously slow/stackoverflowing tests
-                "CTEST_OPTIONS": "-E 'interactivetest|leanpkgtest|laketest|benchtest|bv_bitblast_stress|3807'"
+                "CMAKE_PRESET": "debug",
+                // exclude seriously slow tests
+                "CTEST_OPTIONS": "-E 'interactivetest|leanpkgtest|laketest|benchtest|bv_bitblast_stress'"
               },
               // TODO: suddenly started failing in CI
               /*{
@@ -209,7 +194,7 @@ jobs:
                 "release": true,
                 "check-level": 2,
                 "shell": "bash -euxo pipefail {0}",
-                "llvm-url": "https://github.com/leanprover/lean-llvm/releases/download/19.1.2/lean-llvm-x86_64-apple-darwin.tar.zst",
+                "llvm-url": "https://github.com/leanprover/lean-llvm/releases/download/15.0.1/lean-llvm-x86_64-apple-darwin.tar.zst",
                 "prepare-llvm": "../script/prepare-llvm-macos.sh lean-llvm*",
                 "binary-check": "otool -L",
                 "tar": "gtar" // https://github.com/actions/runner-images/issues/2619
@@ -219,18 +204,12 @@ jobs:
                 "os": "macos-14",
                 "CMAKE_OPTIONS": "-DLEAN_INSTALL_SUFFIX=-darwin_aarch64",
                 "release": true,
+                "check-level": 0,
                 "shell": "bash -euxo pipefail {0}",
-                "llvm-url": "https://github.com/leanprover/lean-llvm/releases/download/19.1.2/lean-llvm-aarch64-apple-darwin.tar.zst",
+                "llvm-url": "https://github.com/leanprover/lean-llvm/releases/download/15.0.1/lean-llvm-aarch64-apple-darwin.tar.zst",
                 "prepare-llvm": "../script/prepare-llvm-macos.sh lean-llvm*",
                 "binary-check": "otool -L",
-                "tar": "gtar", // https://github.com/actions/runner-images/issues/2619
-                // Special handling for MacOS aarch64, we want:
-                // 1. To run it in PRs so Mac devs get PR toolchains (so secondary is sufficient)
-                // 2. To skip it in merge queues as it takes longer than the Linux build and adds
-                //    little value in the merge queue
-                // 3. To run it in release (obviously)
-                "check-level": isPr ? 0 : 2,
-                "secondary": isPr,
+                "tar": "gtar" // https://github.com/actions/runner-images/issues/2619
               },
               {
                 "name": "Windows",
@@ -241,7 +220,7 @@ jobs:
                 "CMAKE_OPTIONS": "-G \"Unix Makefiles\"",
                 // for reasons unknown, interactivetests are flaky on Windows
                 "CTEST_OPTIONS": "--repeat until-pass:2",
-                "llvm-url": "https://github.com/leanprover/lean-llvm/releases/download/19.1.2/lean-llvm-x86_64-w64-windows-gnu.tar.zst",
+                "llvm-url": "https://github.com/leanprover/lean-llvm/releases/download/15.0.1/lean-llvm-x86_64-w64-windows-gnu.tar.zst",
                 "prepare-llvm": "../script/prepare-llvm-mingw.sh lean-llvm*",
                 "binary-check": "ldd"
               },
@@ -252,21 +231,20 @@ jobs:
                 "release": true,
                 "check-level": 2,
                 "shell": "nix develop .#oldGlibcAArch -c bash -euxo pipefail {0}",
-                "llvm-url": "https://github.com/leanprover/lean-llvm/releases/download/19.1.2/lean-llvm-aarch64-linux-gnu.tar.zst",
+                "llvm-url": "https://github.com/leanprover/lean-llvm/releases/download/15.0.1/lean-llvm-aarch64-linux-gnu.tar.zst",
                 "prepare-llvm": "../script/prepare-llvm-linux.sh lean-llvm*"
               },
-              // Started running out of memory building expensive modules, a 2GB heap is just not that much even before fragmentation
-              //{
-              //  "name": "Linux 32bit",
-              //  "os": "ubuntu-latest",
-              //  // Use 32bit on stage0 and stage1 to keep oleans compatible
-              //  "CMAKE_OPTIONS": "-DSTAGE0_USE_GMP=OFF -DSTAGE0_LEAN_EXTRA_CXX_FLAGS='-m32' -DSTAGE0_LEANC_OPTS='-m32' -DSTAGE0_MMAP=OFF -DUSE_GMP=OFF -DLEAN_EXTRA_CXX_FLAGS='-m32' -DLEANC_OPTS='-m32' -DMMAP=OFF -DLEAN_INSTALL_SUFFIX=-linux_x86 -DCMAKE_LIBRARY_PATH=/usr/lib/i386-linux-gnu/ -DSTAGE0_CMAKE_LIBRARY_PATH=/usr/lib/i386-linux-gnu/ -DPKG_CONFIG_EXECUTABLE=/usr/bin/i386-linux-gnu-pkg-config",
-              //  "cmultilib": true,
-              //  "release": true,
-              //  "check-level": 2,
-              //  "cross": true,
-              //  "shell": "bash -euxo pipefail {0}"
-              //}
+              {
+                "name": "Linux 32bit",
+                "os": "ubuntu-latest",
+                // Use 32bit on stage0 and stage1 to keep oleans compatible
+                "CMAKE_OPTIONS": "-DSTAGE0_USE_GMP=OFF -DSTAGE0_LEAN_EXTRA_CXX_FLAGS='-m32' -DSTAGE0_LEANC_OPTS='-m32' -DSTAGE0_MMAP=OFF -DUSE_GMP=OFF -DLEAN_EXTRA_CXX_FLAGS='-m32' -DLEANC_OPTS='-m32' -DMMAP=OFF -DLEAN_INSTALL_SUFFIX=-linux_x86 -DCMAKE_LIBRARY_PATH=/usr/lib/i386-linux-gnu/ -DSTAGE0_CMAKE_LIBRARY_PATH=/usr/lib/i386-linux-gnu/ -DPKG_CONFIG_EXECUTABLE=/usr/bin/i386-linux-gnu-pkg-config",
+                "cmultilib": true,
+                "release": true,
+                "check-level": 2,
+                "cross": true,
+                "shell": "bash -euxo pipefail {0}"
+              }
               // {
               //   "name": "Web Assembly",
               //   "os": "ubuntu-latest",
@@ -282,41 +260,196 @@ jobs:
               //   "CTEST_OPTIONS": "-R \"leantest_1007\\.lean|leantest_Format\\.lean|leanruntest\\_1037.lean|leanruntest_ac_rfl\\.lean|leanruntest_tempfile.lean\\.|leanruntest_libuv\\.lean\""
               // }
             ];
-            console.log(`matrix:\n${JSON.stringify(matrix, null, 2)}`);
-            matrix = matrix.filter((job) => level >= job["check-level"]);
-            core.setOutput('matrix', matrix.filter((job) => !job["secondary"]));
-            core.setOutput('matrix-secondary', matrix.filter((job) => job["secondary"]));
+            console.log(`matrix:\n${JSON.stringify(matrix, null, 2)}`)
+            return matrix.filter((job) => level >= job["check-level"])
 
   build:
+    needs: [configure]
     if: github.event_name != 'schedule' || github.repository == 'leanprover/lean4'
-    needs: [configure]
-    uses: ./.github/workflows/build-template.yml
-    with:
-      config: ${{needs.configure.outputs.matrix}}
-      check-level: ${{ needs.configure.outputs.check-level }}
-      nightly: ${{ needs.configure.outputs.nightly }}
-      LEAN_VERSION_MAJOR: ${{ needs.configure.outputs.LEAN_VERSION_MAJOR }}
-      LEAN_VERSION_MINOR: ${{ needs.configure.outputs.LEAN_VERSION_MINOR }}
-      LEAN_VERSION_PATCH: ${{ needs.configure.outputs.LEAN_VERSION_PATCH }}
-      LEAN_SPECIAL_VERSION_DESC: ${{ needs.configure.outputs.LEAN_SPECIAL_VERSION_DESC }}
-      RELEASE_TAG: ${{ needs.configure.outputs.RELEASE_TAG }}
-    secrets: inherit
-
-  # build jobs that should not be considered by `all-done` below
-  build-secondary:
-    needs: [configure]
-    if: needs.configure.outputs.matrix-secondary != '[]'
-    uses: ./.github/workflows/build-template.yml
-    with:
-      config: ${{needs.configure.outputs.matrix-secondary}}
-      check-level: ${{ needs.configure.outputs.check-level }}
-      nightly: ${{ needs.configure.outputs.nightly }}
-      LEAN_VERSION_MAJOR: ${{ needs.configure.outputs.LEAN_VERSION_MAJOR }}
-      LEAN_VERSION_MINOR: ${{ needs.configure.outputs.LEAN_VERSION_MINOR }}
-      LEAN_VERSION_PATCH: ${{ needs.configure.outputs.LEAN_VERSION_PATCH }}
-      LEAN_SPECIAL_VERSION_DESC: ${{ needs.configure.outputs.LEAN_SPECIAL_VERSION_DESC }}
-      RELEASE_TAG: ${{ needs.configure.outputs.RELEASE_TAG }}
-    secrets: inherit
+    strategy:
+      matrix:
+        include: ${{fromJson(needs.configure.outputs.matrix)}}
+      # complete all jobs
+      fail-fast: false
+    runs-on: ${{ matrix.os }}
+    defaults:
+      run:
+        shell: ${{ matrix.shell || 'nix develop -c bash -euxo pipefail {0}' }}
+    name: ${{ matrix.name }}
+    env:
+      # must be inside workspace
+      CCACHE_DIR: ${{ github.workspace }}/.ccache
+      CCACHE_COMPRESS: true
+      # current cache limit
+      CCACHE_MAXSIZE: 200M
+      # squelch error message about missing nixpkgs channel
+      NIX_BUILD_SHELL: bash
+      LSAN_OPTIONS: max_leaks=10
+      # somehow MinGW clang64 (or cmake?) defaults to `g++` even though it doesn't exist
+      CXX: c++
+      MACOSX_DEPLOYMENT_TARGET: 10.15
+    steps:
+      - name: Install Nix
+        uses: DeterminateSystems/nix-installer-action@main
+        if: runner.os == 'Linux' && !matrix.cmultilib
+      - name: Install MSYS2
+        uses: msys2/setup-msys2@v2
+        with:
+          msystem: clang64
+          # `:` means do not prefix with msystem
+          pacboy: "make: python: cmake clang ccache gmp libuv git: zip: unzip: diffutils: binutils: tree: zstd tar:"
+        if: runner.os == 'Windows'
+      - name: Install Brew Packages
+        run: |
+          brew install ccache tree zstd coreutils gmp libuv
+        if: runner.os == 'macOS'
+      - name: Checkout
+        uses: actions/checkout@v4
+        with:
+          # the default is to use a virtual merge commit between the PR and master: just use the PR
+          ref: ${{ github.event.pull_request.head.sha }}
+      # Do check out some CI-relevant files from virtual merge commit to accommodate CI changes on
+      # master (as the workflow files themselves are always taken from the merge)
+      # (needs to be after "Install *" to use the right shell)
+      - name: CI Merge Checkout
+        run: |
+          git fetch --depth=1 origin ${{ github.sha }}
+          git checkout FETCH_HEAD flake.nix flake.lock
+        if: github.event_name == 'pull_request'
+      # (needs to be after "Checkout" so files don't get overridden)
+      - name: Setup emsdk
+        uses: mymindstorm/setup-emsdk@v14
+        with:
+          version: 3.1.44
+          actions-cache-folder: emsdk
+        if: matrix.wasm
+      - name: Install 32bit c libs
+        run: |
+          sudo dpkg --add-architecture i386
+          sudo apt-get update
+          sudo apt-get install -y gcc-multilib g++-multilib ccache libuv1-dev:i386 pkgconf:i386
+        if: matrix.cmultilib
+      - name: Cache
+        uses: actions/cache@v4
+        with:
+          path: .ccache
+          key: ${{ matrix.name }}-build-v3-${{ github.event.pull_request.head.sha }}
+          # fall back to (latest) previous cache
+          restore-keys: |
+            ${{ matrix.name }}-build-v3
+          save-always: true
+      # open nix-shell once for initial setup
+      - name: Setup
+        run: |
+          ccache --zero-stats
+        if: runner.os == 'Linux'
+      - name: Set up NPROC
+        run: |
+          echo "NPROC=$(nproc 2>/dev/null || sysctl -n hw.logicalcpu 2>/dev/null || echo 4)" >> $GITHUB_ENV
+      - name: Build
+        run: |
+          mkdir build
+          cd build
+          # arguments passed to `cmake`
+          # this also enables githash embedding into stage 1 library
+          OPTIONS=(-DCHECK_OLEAN_VERSION=ON)
+          OPTIONS+=(-DLEAN_EXTRA_MAKE_OPTS=-DwarningAsError=true)
+          if [[ -n '${{ matrix.cross_target }}' ]]; then
+            # used by `prepare-llvm`
+            export EXTRA_FLAGS=--target=${{ matrix.cross_target }}
+            OPTIONS+=(-DLEAN_PLATFORM_TARGET=${{ matrix.cross_target }})
+          fi
+          if [[ -n '${{ matrix.prepare-llvm }}' ]]; then
+            wget -q ${{ matrix.llvm-url }}
+            PREPARE="$(${{ matrix.prepare-llvm }})"
+            eval "OPTIONS+=($PREPARE)"
+          fi
+          if [[ -n '${{ matrix.release }}' && -n '${{ needs.configure.outputs.nightly }}' ]]; then
+            OPTIONS+=(-DLEAN_SPECIAL_VERSION_DESC=${{ needs.configure.outputs.nightly }})
+          fi
+          if [[ -n '${{ matrix.release }}' && -n '${{ needs.configure.outputs.RELEASE_TAG }}' ]]; then
+            OPTIONS+=(-DLEAN_VERSION_MAJOR=${{ needs.configure.outputs.LEAN_VERSION_MAJOR }})
+            OPTIONS+=(-DLEAN_VERSION_MINOR=${{ needs.configure.outputs.LEAN_VERSION_MINOR }})
+            OPTIONS+=(-DLEAN_VERSION_PATCH=${{ needs.configure.outputs.LEAN_VERSION_PATCH }})
+            OPTIONS+=(-DLEAN_VERSION_IS_RELEASE=1)
+            OPTIONS+=(-DLEAN_SPECIAL_VERSION_DESC=${{ needs.configure.outputs.LEAN_SPECIAL_VERSION_DESC }})
+          fi
+          # contortion to support empty OPTIONS with old macOS bash
+          cmake .. --preset ${{ matrix.CMAKE_PRESET || 'release' }} -B . ${{ matrix.CMAKE_OPTIONS }} ${OPTIONS[@]+"${OPTIONS[@]}"} -DLEAN_INSTALL_PREFIX=$PWD/..
+          time make -j$NPROC
+      - name: Install
+        run: |
+          make -C build install
+      - name: Check Binaries
+        run: ${{ matrix.binary-check }} lean-*/bin/* || true
+      - name: Count binary symbols
+        run: |
+          for f in lean-*/bin/*; do
+            echo "$f: $(nm $f | grep " T " | wc -l) exported symbols"
+          done
+        if: matrix.name == 'Windows'
+      - name: List Install Tree
+        run: |
+          # omit contents of Init/, ...
+          tree --du -h lean-*-* | grep -E ' (Init|Lean|Lake|LICENSE|[a-z])'
+      - name: Pack
+        run: |
+          dir=$(echo lean-*-*)
+          mkdir pack
+          # high-compression tar.zst + zip for release, fast tar.zst otherwise
+          if [[ '${{ startsWith(github.ref, 'refs/tags/') && matrix.release }}' == true || -n '${{ needs.configure.outputs.nightly }}' || -n '${{ needs.configure.outputs.RELEASE_TAG }}' ]]; then
+            ${{ matrix.tar || 'tar' }} cf - $dir | zstd -T0 --no-progress -19 -o pack/$dir.tar.zst
+            zip -rq pack/$dir.zip $dir
+          else
+            ${{ matrix.tar || 'tar' }} cf - $dir | zstd -T0 --no-progress -o pack/$dir.tar.zst
+          fi
+      - uses: actions/upload-artifact@v4
+        if: matrix.release
+        with:
+          name: build-${{ matrix.name }}
+          path: pack/*
+      - name: Lean stats
+        run: |
+          build/stage1/bin/lean --stats src/Lean.lean
+        if: ${{ !matrix.cross }}
+      - name: Test
+        id: test
+        run: |
+          time ctest --preset ${{ matrix.CMAKE_PRESET || 'release' }} --test-dir build/stage1 -j$NPROC --output-junit test-results.xml ${{ matrix.CTEST_OPTIONS }}
+        if: (matrix.wasm || !matrix.cross) && needs.configure.outputs.check-level >= 1
+      - name: Test Summary
+        uses: test-summary/action@v2
+        with:
+          paths: build/stage1/test-results.xml
+        # prefix `if` above with `always` so it's run even if tests failed
+        if: always() && steps.test.conclusion != 'skipped'
+      - name: Check Test Binary
+        run: ${{ matrix.binary-check }} tests/compiler/534.lean.out
+        if: (!matrix.cross) && steps.test.conclusion != 'skipped'
+      - name: Build Stage 2
+        run: |
+          make -C build -j$NPROC stage2
+        if: matrix.test-speedcenter
+      - name: Check Stage 3
+        run: |
+          make -C build -j$NPROC check-stage3
+        if: matrix.test-speedcenter
+      - name: Test Speedcenter Benchmarks
+        run: |
+          # Necessary for some timing metrics but does not work on Namespace runners
+          # and we just want to test that the benchmarks run at all here
+          #echo -1 | sudo tee /proc/sys/kernel/perf_event_paranoid
+          export BUILD=$PWD/build PATH=$PWD/build/stage1/bin:$PATH
+          cd tests/bench
+          nix shell .#temci -c temci exec --config speedcenter.yaml --included_blocks fast --runs 1
+        if: matrix.test-speedcenter
+      - name: Check rebootstrap
+        run: |
+          # clean rebuild in case of Makefile changes
+          make -C build update-stage0 && rm -rf build/stage* && make -C build -j$NPROC
+        if: matrix.name == 'Linux' && needs.configure.outputs.check-level >= 1
+      - name: CCache stats
+        run: ccache -s
 
   # This job collects results from all the matrix jobs
   # This can be made the "required" job, instead of listing each
@@ -348,6 +481,8 @@ jobs:
 
   # This job creates releases from tags
   # (whether they are "unofficial" releases for experiments, or official releases when the tag is "v" followed by a semver string.)
+  # We do not attempt to automatically construct a changelog here:
+  # unofficial releases don't need them, and official release notes will be written by a human.
   release:
     if: startsWith(github.ref, 'refs/tags/')
     runs-on: ubuntu-latest

.github/workflows/nix-ci.yml

@@ -0,0 +1,142 @@
+name: Nix CI
+on:
+  push:
+    branches:
+      - master
+    tags:
+      - '*'
+  pull_request:
+  merge_group:
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  # see ci.yml
+  configure:
+    runs-on: ubuntu-latest
+    outputs:
+      matrix: ${{ steps.set-matrix.outputs.result }}
+    steps:
+      - name: Configure build matrix
+        id: set-matrix
+        uses: actions/github-script@v7
+        with:
+          script: |
+            let large = ${{ github.repository == 'leanprover/lean4' }};
+            let matrix = [
+              {
+                "name": "Nix Linux",
+                "os": large ? "nscloud-ubuntu-22.04-amd64-8x8" : "ubuntu-latest",
+              }
+            ];
+            console.log(`matrix:\n${JSON.stringify(matrix, null, 2)}`);
+            return matrix;
+
+  Build:
+    needs: [configure]
+    runs-on: ${{ matrix.os }}
+    defaults:
+      run:
+        shell: nix run .#ciShell -- bash -euxo pipefail {0}
+    strategy:
+      matrix:
+        include: ${{fromJson(needs.configure.outputs.matrix)}}
+      # complete all jobs
+      fail-fast: false
+    name: ${{ matrix.name }}
+    env:
+      NIX_BUILD_ARGS: --print-build-logs --fallback
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+        with:
+          # the default is to use a virtual merge commit between the PR and master: just use the PR
+          ref: ${{ github.event.pull_request.head.sha }}
+      - name: Set Up Nix Cache
+        uses: actions/cache@v4
+        with:
+          path: nix-store-cache
+          key: ${{ matrix.name }}-nix-store-cache-${{ github.sha }}
+          # fall back to (latest) previous cache
+          restore-keys: |
+            ${{ matrix.name }}-nix-store-cache
+          save-always: true
+      - name: Further Set Up Nix Cache
+        shell: bash -euxo pipefail {0}
+        run: |
+          # Nix seems to mutate the cache, so make a copy
+          cp -r nix-store-cache nix-store-cache-copy || true
+      - name: Install Nix
+        uses: DeterminateSystems/nix-installer-action@main
+        with:
+          extra-conf: |
+            extra-sandbox-paths = /nix/var/cache/ccache?
+            substituters = file://${{ github.workspace }}/nix-store-cache-copy?priority=10&trusted=true https://cache.nixos.org  
+      - name: Prepare CCache Cache
+        run: |
+          sudo mkdir -m0770 -p /nix/var/cache/ccache
+          sudo chown -R $USER /nix/var/cache/ccache
+      - name: Setup CCache Cache
+        uses: actions/cache@v4
+        with:
+          path: /nix/var/cache/ccache
+          key: ${{ matrix.name }}-nix-ccache-${{ github.sha }}
+          # fall back to (latest) previous cache
+          restore-keys: |
+            ${{ matrix.name }}-nix-ccache
+          save-always: true
+      - name: Further Set Up CCache Cache
+        run: |
+          sudo chown -R root:nixbld /nix/var/cache
+          sudo chmod -R 770 /nix/var/cache
+      - name: Build
+        run: |
+          nix build $NIX_BUILD_ARGS .#cacheRoots -o push-build
+      - name: Test
+        run: |
+          nix build --keep-failed $NIX_BUILD_ARGS .#test -o push-test || (ln -s /tmp/nix-build-*/build/source/src/build ./push-test; false)
+      - name: Test Summary
+        uses: test-summary/action@v2
+        with:
+          paths: push-test/test-results.xml
+        if: always()
+        continue-on-error: true
+      - name: Build manual
+        run: |
+          nix build $NIX_BUILD_ARGS --update-input lean --no-write-lock-file ./doc#{lean-mdbook,leanInk,alectryon,inked} -o push-doc
+          nix build $NIX_BUILD_ARGS --update-input lean --no-write-lock-file ./doc
+          # https://github.com/netlify/cli/issues/1809
+          cp -r --dereference ./result ./dist
+        if: matrix.name == 'Nix Linux'
+      - name: Rebuild Nix Store Cache
+        run: |
+          rm -rf nix-store-cache || true
+          nix copy ./push-* --to file://$PWD/nix-store-cache?compression=none
+      - id: deploy-info
+        name: Compute Deployment Metadata
+        run: |
+          set -e
+          python3 -c 'import base64; print("alias="+base64.urlsafe_b64encode(bytes.fromhex("${{github.sha}}")).decode("utf-8").rstrip("="))' >> "$GITHUB_OUTPUT"
+          echo "message=`git log -1 --pretty=format:"%s"`" >> "$GITHUB_OUTPUT"
+      - name: Publish manual to Netlify
+        uses: nwtgck/actions-netlify@v3.0
+        id: publish-manual
+        with:
+          publish-dir: ./dist
+          production-branch: master
+          github-token: ${{ secrets.GITHUB_TOKEN }}
+          deploy-message: |
+            ${{ github.event_name == 'pull_request' && format('pr#{0}: {1}', github.event.number, github.event.pull_request.title) || format('ref/{0}: {1}', github.ref_name, steps.deploy-info.outputs.message) }}
+          alias: ${{ steps.deploy-info.outputs.alias }}
+          enable-commit-comment: false
+          enable-pull-request-comment: false
+          github-deployment-environment: "lean-lang.org/lean4/doc"
+          fails-without-credentials: false
+        env:
+          NETLIFY_AUTH_TOKEN: ${{ secrets.NETLIFY_AUTH_TOKEN }}
+          NETLIFY_SITE_ID: "b8e805d2-7e9b-4f80-91fb-a84d72fc4a68"
+      - name: Fixup CCache Cache
+        run: |
+          sudo chown -R $USER /nix/var/cache

.github/workflows/pr-release.yml

@@ -34,7 +34,7 @@ jobs:
       - name: Download artifact from the previous workflow.
         if: ${{ steps.workflow-info.outputs.pullRequestNumber != '' }}
         id: download-artifact
-        uses: dawidd6/action-download-artifact@v9 # https://github.com/marketplace/actions/download-workflow-artifact
+        uses: dawidd6/action-download-artifact@v7 # https://github.com/marketplace/actions/download-workflow-artifact
         with:
           run_id: ${{ github.event.workflow_run.id }}
           path: artifacts
@@ -111,7 +111,7 @@ jobs:
 
       - name: 'Setup jq'
         if: ${{ steps.workflow-info.outputs.pullRequestNumber != '' }}
-        uses: dcarbone/install-jq-action@v3.1.1
+        uses: dcarbone/install-jq-action@v3.0.1
 
       # Check that the most recently nightly coincides with 'git merge-base HEAD master'
       - name: Check merge-base and nightly-testing-YYYY-MM-DD
@@ -155,20 +155,6 @@ jobs:
           fi
 
           if [[ -n "$MESSAGE" ]]; then
-            # Check if force-mathlib-ci label is present
-            LABELS="$(curl --retry 3 --location --silent \
-                          -H "Authorization: token ${{ secrets.MATHLIB4_COMMENT_BOT }}" \
-                          -H "Accept: application/vnd.github.v3+json" \
-                          "https://api.github.com/repos/leanprover/lean4/issues/${{ steps.workflow-info.outputs.pullRequestNumber }}/labels" \
-                          | jq -r '.[].name')"
-            
-            if echo "$LABELS" | grep -q "^force-mathlib-ci$"; then
-              echo "force-mathlib-ci label detected, forcing CI despite issues"
-              MESSAGE="Forcing Mathlib CI because the \`force-mathlib-ci\` label is present, despite problem: $MESSAGE"
-              FORCE_CI=true
-            else
-              MESSAGE="$MESSAGE You can force Mathlib CI using the \`force-mathlib-ci\` label."
-            fi
 
             echo "Checking existing messages"
 
@@ -215,12 +201,7 @@ jobs:
             else
               echo "The message already exists in the comment body."
             fi
-
-            if [[ "$FORCE_CI" == "true" ]]; then
-              echo "mathlib_ready=true" >> "$GITHUB_OUTPUT"
-            else
-              echo "mathlib_ready=false" >> "$GITHUB_OUTPUT"
-            fi
+            echo "mathlib_ready=false" >> "$GITHUB_OUTPUT"
           else
             echo "mathlib_ready=true" >> "$GITHUB_OUTPUT"
           fi
@@ -271,7 +252,7 @@ jobs:
           if git ls-remote --heads --tags --exit-code origin "nightly-testing-${MOST_RECENT_NIGHTLY}" >/dev/null; then
             BASE="nightly-testing-${MOST_RECENT_NIGHTLY}"
           else
-            echo "Couldn't find a 'nightly-testing-${MOST_RECENT_NIGHTLY}' tag at Batteries. Falling back to 'nightly-testing'."
+            echo "This shouldn't be possible: couldn't find a 'nightly-testing-${MOST_RECENT_NIGHTLY}' tag at Batteries. Falling back to 'nightly-testing'."
             BASE=nightly-testing
           fi
 
@@ -335,7 +316,7 @@ jobs:
           if git ls-remote --heads --tags --exit-code origin "nightly-testing-${MOST_RECENT_NIGHTLY}" >/dev/null; then
             BASE="nightly-testing-${MOST_RECENT_NIGHTLY}"
           else
-            echo "Couldn't find a 'nightly-testing-${MOST_RECENT_NIGHTLY}' branch at Mathlib. Falling back to 'nightly-testing'."
+            echo "This shouldn't be possible: couldn't find a 'nightly-testing-${MOST_RECENT_NIGHTLY}' branch at Mathlib. Falling back to 'nightly-testing'."
             BASE=nightly-testing
           fi
 

.gitignore

@@ -22,7 +22,6 @@ settings.json
 .gdb_history
 .vscode/*
 !.vscode/settings.json
-script/__pycache__
 *.produced.out
 CMakeSettings.json
 CppProperties.json

CMakeLists.txt

@@ -1,30 +1,26 @@
 cmake_minimum_required(VERSION 3.11)
-
-option(USE_MIMALLOC "use mimalloc" ON)
-
 # store all variables passed on the command line into CL_ARGS so we can pass them to the stage builds
 # https://stackoverflow.com/a/48555098/161659
 # MUST be done before call to 'project'
-# Use standard release build (discarding LEAN_EXTRA_CXX_FLAGS etc.) for stage0 by default since it is assumed to be "good", but still pass through CMake platform arguments (compiler, toolchain file, ..).
+# Use standard release build (discarding LEAN_CXX_EXTRA_FLAGS etc.) for stage0 by default since it is assumed to be "good", but still pass through CMake platform arguments (compiler, toolchain file, ..).
 # Use `STAGE0_` prefix to pass variables to stage0 explicitly.
 get_cmake_property(vars CACHE_VARIABLES)
 foreach(var ${vars})
   get_property(currentHelpString CACHE "${var}" PROPERTY HELPSTRING)
   if("${var}" MATCHES "STAGE0_(.*)")
     list(APPEND STAGE0_ARGS "-D${CMAKE_MATCH_1}=${${var}}")
-  elseif("${var}" MATCHES "STAGE1_(.*)")
-    list(APPEND STAGE1_ARGS "-D${CMAKE_MATCH_1}=${${var}}")
   elseif("${currentHelpString}" MATCHES "No help, variable specified on the command line." OR "${currentHelpString}" STREQUAL "")
     list(APPEND CL_ARGS "-D${var}=${${var}}")
     if("${var}" MATCHES "USE_GMP|CHECK_OLEAN_VERSION")
       # must forward options that generate incompatible .olean format
       list(APPEND STAGE0_ARGS "-D${var}=${${var}}")
-    elseif("${var}" MATCHES "LLVM*|PKG_CONFIG|USE_LAKE|USE_MIMALLOC")
+    endif()
+    if("${var}" MATCHES "LLVM*")
+      list(APPEND STAGE0_ARGS "-D${var}=${${var}}")
+    endif()
+    if("${var}" MATCHES "PKG_CONFIG*")
       list(APPEND STAGE0_ARGS "-D${var}=${${var}}")
     endif()
-  elseif("${var}" MATCHES "USE_MIMALLOC")
-    list(APPEND CL_ARGS "-D${var}=${${var}}")
-    list(APPEND STAGE0_ARGS "-D${var}=${${var}}")
   elseif(("${var}" MATCHES "CMAKE_.*") AND NOT ("${var}" MATCHES "CMAKE_BUILD_TYPE") AND NOT ("${var}" MATCHES "CMAKE_HOME_DIRECTORY"))
     list(APPEND PLATFORM_ARGS "-D${var}=${${var}}")
   endif()
@@ -39,14 +35,10 @@ endif()
 
 # Don't do anything with cadical on wasm
 if (NOT ${CMAKE_SYSTEM_NAME} MATCHES "Emscripten")
+  # On CI Linux, we source cadical from Nix instead; see flake.nix
   find_program(CADICAL cadical)
   if(NOT CADICAL)
     set(CADICAL_CXX c++)
-    if (CADICAL_USE_CUSTOM_CXX)
-      set(CADICAL_CXX ${CMAKE_CXX_COMPILER})
-      set(CADICAL_CXXFLAGS "${LEAN_EXTRA_CXX_FLAGS}")
-      set(CADICAL_LDFLAGS "-Wl,-rpath=\\$$ORIGIN/../lib")
-    endif()
     find_program(CCACHE ccache)
     if(CCACHE)
       set(CADICAL_CXX "${CCACHE} ${CADICAL_CXX}")
@@ -55,61 +47,41 @@ if (NOT ${CMAKE_SYSTEM_NAME} MATCHES "Emscripten")
     if(${CMAKE_SYSTEM_NAME} MATCHES "Windows")
       string(APPEND CADICAL_CXXFLAGS " -DNUNLOCKED")
     endif()
-    string(APPEND CADICAL_CXXFLAGS " -DNCLOSEFROM")
     ExternalProject_add(cadical
       PREFIX cadical
       GIT_REPOSITORY https://github.com/arminbiere/cadical
-      GIT_TAG rel-2.1.2
+      GIT_TAG rel-1.9.5
       CONFIGURE_COMMAND ""
-      BUILD_COMMAND $(MAKE) -f ${CMAKE_SOURCE_DIR}/src/cadical.mk
-        CMAKE_EXECUTABLE_SUFFIX=${CMAKE_EXECUTABLE_SUFFIX}
-        CXX=${CADICAL_CXX}
-        CXXFLAGS=${CADICAL_CXXFLAGS}
-        LDFLAGS=${CADICAL_LDFLAGS}
+      # https://github.com/arminbiere/cadical/blob/master/BUILD.md#manual-build
+      BUILD_COMMAND $(MAKE) -f ${CMAKE_SOURCE_DIR}/src/cadical.mk CMAKE_EXECUTABLE_SUFFIX=${CMAKE_EXECUTABLE_SUFFIX} CXX=${CADICAL_CXX} CXXFLAGS=${CADICAL_CXXFLAGS}
       BUILD_IN_SOURCE ON
       INSTALL_COMMAND "")
     set(CADICAL ${CMAKE_BINARY_DIR}/cadical/cadical${CMAKE_EXECUTABLE_SUFFIX} CACHE FILEPATH "path to cadical binary" FORCE)
-    list(APPEND EXTRA_DEPENDS cadical)
+    set(EXTRA_DEPENDS "cadical")
   endif()
   list(APPEND CL_ARGS -DCADICAL=${CADICAL})
 endif()
 
-if (USE_MIMALLOC)
-  ExternalProject_add(mimalloc
-    PREFIX mimalloc
-    GIT_REPOSITORY https://github.com/microsoft/mimalloc
-    GIT_TAG v2.2.3
-    # just download, we compile it as part of each stage as it is small
-    CONFIGURE_COMMAND ""
-    BUILD_COMMAND ""
-    INSTALL_COMMAND "")
-  list(APPEND EXTRA_DEPENDS mimalloc)
-endif()
-
-if (NOT STAGE1_PREV_STAGE)
-  ExternalProject_add(stage0
-    SOURCE_DIR "${LEAN_SOURCE_DIR}/stage0"
-    SOURCE_SUBDIR src
-    BINARY_DIR stage0
-    # do not rebuild stage0 when git hash changes; it's not from this commit anyway
-    # (however, CI will override this as we need to embed the githash into the stage 1 library built
-    # by stage 0)
-    CMAKE_ARGS -DSTAGE=0 -DUSE_GITHASH=OFF ${PLATFORM_ARGS} ${STAGE0_ARGS}
-    BUILD_ALWAYS ON  # cmake doesn't auto-detect changes without a download method
-    INSTALL_COMMAND ""  # skip install
-    DEPENDS ${EXTRA_DEPENDS}
-  )
-  list(APPEND EXTRA_DEPENDS stage0)
-endif()
+ExternalProject_add(stage0
+  SOURCE_DIR "${LEAN_SOURCE_DIR}/stage0"
+  SOURCE_SUBDIR src
+  BINARY_DIR stage0
+  # do not rebuild stage0 when git hash changes; it's not from this commit anyway
+  # (however, `CHECK_OLEAN_VERSION=ON` in CI will override this as we need to
+  # embed the githash into the stage 1 library built by stage 0)
+  CMAKE_ARGS -DSTAGE=0 -DUSE_GITHASH=OFF ${PLATFORM_ARGS} ${STAGE0_ARGS}
+  BUILD_ALWAYS ON  # cmake doesn't auto-detect changes without a download method
+  INSTALL_COMMAND ""  # skip install
+  DEPENDS ${EXTRA_DEPENDS}
+)
 ExternalProject_add(stage1
   SOURCE_DIR "${LEAN_SOURCE_DIR}"
   SOURCE_SUBDIR src
   BINARY_DIR stage1
-  CMAKE_ARGS -DSTAGE=1 -DPREV_STAGE=${CMAKE_BINARY_DIR}/stage0 -DPREV_STAGE_CMAKE_EXECUTABLE_SUFFIX=${STAGE0_CMAKE_EXECUTABLE_SUFFIX} ${CL_ARGS} ${STAGE1_ARGS}
+  CMAKE_ARGS -DSTAGE=1 -DPREV_STAGE=${CMAKE_BINARY_DIR}/stage0 -DPREV_STAGE_CMAKE_EXECUTABLE_SUFFIX=${STAGE0_CMAKE_EXECUTABLE_SUFFIX} ${CL_ARGS}
   BUILD_ALWAYS ON
   INSTALL_COMMAND ""
-  DEPENDS ${EXTRA_DEPENDS}
-  STEP_TARGETS configure
+  DEPENDS stage0
 )
 ExternalProject_add(stage2
   SOURCE_DIR "${LEAN_SOURCE_DIR}"
@@ -120,7 +92,6 @@ ExternalProject_add(stage2
   INSTALL_COMMAND ""
   DEPENDS stage1
   EXCLUDE_FROM_ALL ON
-  STEP_TARGETS configure
 )
 ExternalProject_add(stage3
   SOURCE_DIR "${LEAN_SOURCE_DIR}"

CMakePresets.json

@@ -16,39 +16,26 @@
       "name": "debug",
       "displayName": "Debug build config",
       "cacheVariables": {
-        "LEAN_EXTRA_CXX_FLAGS": "-DLEAN_DEFAULT_THREAD_STACK_SIZE=16*1024*1024",
         "CMAKE_BUILD_TYPE": "Debug"
       },
       "generator": "Unix Makefiles",
       "binaryDir": "${sourceDir}/build/debug"
     },
-    {
-      "name": "reldebug",
-      "displayName": "Release with assertions enabled",
-      "cacheVariables": {
-        "CMAKE_BUILD_TYPE": "RelWithAssert"
-      },
-      "generator": "Unix Makefiles",
-      "binaryDir": "${sourceDir}/build/reldebug"
-    },
     {
       "name": "sanitize",
       "displayName": "Sanitize build config",
       "cacheVariables": {
-        "LEAN_EXTRA_CXX_FLAGS": "-fsanitize=address,undefined -DLEAN_DEFAULT_THREAD_STACK_SIZE=16*1024*1024",
-        "LEANC_EXTRA_CC_FLAGS": "-fsanitize=address,undefined",
-        "LEAN_EXTRA_LINKER_FLAGS": "-fsanitize=address,undefined -fsanitize-link-c++-runtime",
+        "LEAN_EXTRA_CXX_FLAGS": "-fsanitize=address,undefined",
+        "LEANC_EXTRA_FLAGS": "-fsanitize=address,undefined -fsanitize-link-c++-runtime",
         "SMALL_ALLOCATOR": "OFF",
-        "USE_MIMALLOC": "OFF",
-        "BSYMBOLIC": "OFF",
-        "LEAN_TEST_VARS": "MAIN_STACK_SIZE=16000"
+        "BSYMBOLIC": "OFF"
       },
       "generator": "Unix Makefiles",
       "binaryDir": "${sourceDir}/build/sanitize"
     },
     {
       "name": "sandebug",
-      "inherits": ["sanitize", "debug"],
+      "inherits": ["debug", "sanitize"],
       "displayName": "Sanitize+debug build config",
       "binaryDir": "${sourceDir}/build/sandebug"
     }
@@ -62,10 +49,6 @@
       "name": "debug",
       "configurePreset": "debug"
     },
-    {
-      "name": "reldebug",
-      "configurePreset": "reldebug"
-    },
     {
       "name": "sanitize",
       "configurePreset": "sanitize"
@@ -86,11 +69,6 @@
       "configurePreset": "debug",
       "inherits": "release"
     },
-    {
-      "name": "reldebug",
-      "configurePreset": "reldebug",
-      "inherits": "release"
-    },
     {
       "name": "sanitize",
       "configurePreset": "sanitize",

CODEOWNERS

@@ -7,9 +7,8 @@
 /.github/ @kim-em
 /RELEASES.md @kim-em
 /src/kernel/ @leodemoura
-/src/library/compiler/ @zwarich
 /src/lake/ @tydeu
-/src/Lean/Compiler/ @leodemoura @zwarich
+/src/Lean/Compiler/ @leodemoura
 /src/Lean/Data/Lsp/ @mhuisi
 /src/Lean/Elab/Deriving/ @kim-em
 /src/Lean/Elab/Tactic/ @kim-em

README.md

@@ -2,19 +2,20 @@ This is the repository for **Lean 4**.
 
 # About
 
-- [Quickstart](https://lean-lang.org/documentation/setup/)
+- [Quickstart](https://lean-lang.org/lean4/doc/quickstart.html)
 - [Homepage](https://lean-lang.org)
 - [Theorem Proving Tutorial](https://lean-lang.org/theorem_proving_in_lean4/)
 - [Functional Programming in Lean](https://lean-lang.org/functional_programming_in_lean/)
-- [Documentation Overview](https://lean-lang.org/documentation/)
+- [Documentation Overview](https://lean-lang.org/lean4/doc/)
 - [Language Reference](https://lean-lang.org/doc/reference/latest/)
 - [Release notes](RELEASES.md) starting at v4.0.0-m3
-- [Examples](https://lean-lang.org/documentation/examples/)
+- [Examples](https://lean-lang.org/lean4/doc/examples.html)
 - [External Contribution Guidelines](CONTRIBUTING.md)
+- [FAQ](https://lean-lang.org/lean4/doc/faq.html)
 
 # Installation
 
-See [Setting Up Lean](https://lean-lang.org/documentation/setup/).
+See [Setting Up Lean](https://lean-lang.org/lean4/doc/setup.html).
 
 # Contributing
 
@@ -22,4 +23,4 @@ Please read our [Contribution Guidelines](CONTRIBUTING.md) first.
 
 # Building from Source
 
-See [Building Lean](doc/make/index.md).
+See [Building Lean](https://lean-lang.org/lean4/doc/make/index.html) (documentation source: [doc/make/index.md](doc/make/index.md)).

doc/README.md

@@ -1,10 +0,0 @@
-# Developer Documentation and Examples
-
-This directory contains documentation that describes how to work on
-Lean itself, as well as examples that are included in documentation
-that's hosted on the Lean website.  The `make` directory contains
-information on building Lean, and the `dev` directory describes how to
-work on Lean.
-
-The [documentation section](https://lean-lang.org/documentation) has
-links to documentation that describes how to use Lean itself.

doc/SUMMARY.md

@@ -0,0 +1,46 @@
+# Summary
+
+- [What is Lean](./whatIsLean.md)
+- [Tour of Lean](./tour.md)
+- [Setting Up Lean](./quickstart.md)
+  - [Extended Setup Notes](./setup.md)
+- [Theorem Proving in Lean](./tpil.md)
+- [Functional Programming in Lean](fplean.md)
+- [Examples](./examples.md)
+  - [Palindromes](examples/palindromes.lean.md)
+  - [Binary Search Trees](examples/bintree.lean.md)
+  - [A Certified Type Checker](examples/tc.lean.md)
+  - [The Well-Typed Interpreter](examples/interp.lean.md)
+  - [Dependent de Bruijn Indices](examples/deBruijn.lean.md)
+  - [Parametric Higher-Order Abstract Syntax](examples/phoas.lean.md)
+  - [Syntax Examples](./syntax_examples.md)
+    - [Balanced Parentheses](./syntax_example.md)
+    - [Arithmetic DSL](./metaprogramming-arith.md)
+
+# Language Manual
+
+- [The Lean Reference Manual](./reference.md)
+
+# Other
+
+- [Frequently Asked Questions](./faq.md)
+- [Significant Changes from Lean 3](./lean3changes.md)
+- [Syntax Highlighting Lean in LaTeX](./syntax_highlight_in_latex.md)
+- [User Widgets](examples/widgets.lean.md)
+- [Semantic Highlighting](./semantic_highlighting.md)
+
+# Development
+
+- [Development Guide](./dev/index.md)
+- [Building Lean](./make/index.md)
+  - [Ubuntu Setup](./make/ubuntu.md)
+  - [macOS Setup](./make/osx-10.9.md)
+  - [Windows MSYS2 Setup](./make/msys2.md)
+  - [Windows with WSL](./make/wsl.md)
+- [Bootstrapping](./dev/bootstrap.md)
+- [Testing](./dev/testing.md)
+- [Debugging](./dev/debugging.md)
+- [Commit Convention](./dev/commit_convention.md)
+- [Release checklist](./dev/release_checklist.md)
+- [Building This Manual](./dev/mdbook.md)
+- [Foreign Function Interface](./dev/ffi.md)

doc/alectryon.css

@@ -0,0 +1,786 @@
+@charset "UTF-8";
+/*
+Copyright © 2019 Clément Pit-Claudel
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+*/
+
+/*******************************/
+/* CSS reset for .alectryon-io */
+/*******************************/
+
+.content {
+    /*
+    Use `initial` instead of `contents` to avoid a browser bug which removes
+    the element from the accessibility tree.
+    https://developer.mozilla.org/en-US/docs/Web/CSS/display#display_contents
+     */
+    display: initial;
+}
+
+.alectryon-io blockquote {
+    line-height: inherit;
+}
+
+.alectryon-io blockquote:after {
+    display: none;
+}
+
+.alectryon-io label {
+    display: inline;
+    font-size: inherit;
+    margin: 0;
+}
+
+.alectryon-io a {
+    text-decoration: none !important;
+    font-style: oblique !important;
+    color: unset;
+}
+
+/* Undo <small> and <blockquote>, added to improve RSS rendering. */
+
+.alectryon-io small.alectryon-output,
+.alectryon-io small.alectryon-type-info {
+    font-size: inherit;
+}
+
+.alectryon-io blockquote.alectryon-goal,
+.alectryon-io blockquote.alectryon-message {
+    font-weight: normal;
+    font-size: inherit;
+}
+
+/***************/
+/* Main styles */
+/***************/
+
+.alectryon-coqdoc .doc .code,
+.alectryon-coqdoc .doc .comment,
+.alectryon-coqdoc .doc .inlinecode,
+.alectryon-mref,
+.alectryon-block, .alectryon-io,
+.alectryon-toggle-label, .alectryon-banner {
+    font-family: "Source Code Pro", Consolas, "Ubuntu Mono", Menlo, "DejaVu Sans Mono", monospace, monospace !important;
+    font-size: 0.875em;
+    font-feature-settings: "COQX" 1 /* Coq ligatures */, "XV00" 1 /* Legacy */, "calt" 1 /* Fallback */;
+    line-height: initial;
+}
+
+.alectryon-io, .alectryon-block, .alectryon-toggle-label, .alectryon-banner {
+    overflow: visible;
+    overflow-wrap: break-word;
+    position: relative;
+    white-space: pre-wrap;
+}
+
+/*
+CoqIDE doesn't turn off the unicode bidirectional algorithm (and PG simply
+respects the user's `bidi-display-reordering` setting), so don't turn it off
+here either.  But beware unexpected results like `Definition test_אב := 0.`
+
+.alectryon-io span {
+    direction: ltr;
+    unicode-bidi: bidi-override;
+}
+
+In any case, make an exception for comments:
+
+.highlight .c {
+    direction: embed;
+    unicode-bidi: initial;
+}
+*/
+
+.alectryon-mref,
+.alectryon-mref-marker {
+    align-self: center;
+    box-sizing: border-box;
+    display: inline-block;
+    font-size: 80%;
+    font-weight: bold;
+    line-height: 1;
+    box-shadow: 0 0 0 1pt black;
+    padding: 1pt 0.3em;
+    text-decoration: none;
+}
+
+.alectryon-block .alectryon-mref-marker,
+.alectryon-io .alectryon-mref-marker {
+    user-select: none;
+    margin: -0.25em 0 -0.25em 0.5em;
+}
+
+.alectryon-inline .alectryon-mref-marker {
+    margin: -0.25em 0.15em -0.25em 0.625em; /* 625 = 0.5em / 80% */
+}
+
+.alectryon-mref {
+    color: inherit;
+    margin: -0.5em 0.25em;
+}
+
+.alectryon-goal:target .goal-separator .alectryon-mref-marker,
+:target > .alectryon-mref-marker {
+    animation: blink 0.2s step-start 0s 3 normal none;
+    background-color: #fcaf3e;
+    position: relative;
+}
+
+@keyframes blink {
+    50% {
+        box-shadow: 0 0 0 3pt #fcaf3e, 0 0 0 4pt black;
+        z-index: 10;
+    }
+}
+
+.alectryon-toggle,
+.alectryon-io .alectryon-extra-goal-toggle {
+    display: none;
+}
+
+.alectryon-bubble,
+.alectryon-io label,
+.alectryon-toggle-label {
+    cursor: pointer;
+}
+
+.alectryon-toggle-label {
+    display: block;
+    font-size: 0.8em;
+}
+
+.alectryon-io .alectryon-input {
+    padding: 0.1em 0; /* Enlarge the hitbox slightly to fill interline gaps */
+}
+
+.alectryon-io .alectryon-token {
+    white-space: pre-wrap;
+    display: inline;
+}
+
+.alectryon-io .alectryon-sentence.alectryon-target .alectryon-input {
+    /* FIXME if keywords were ‘bolder’ we wouldn't need !important */
+    font-weight: bold !important; /* Use !important to avoid a * selector */
+}
+
+.alectryon-bubble:before,
+.alectryon-toggle-label:before,
+.alectryon-io label.alectryon-input:after,
+.alectryon-io .alectryon-goal > label:before {
+    border: 1px solid #babdb6;
+    border-radius: 1em;
+    box-sizing: border-box;
+    content: '';
+    display: inline-block;
+    font-weight: bold;
+    height: 0.25em;
+    margin-bottom: 0.15em;
+    vertical-align: middle;
+    width: 0.75em;
+}
+
+.alectryon-toggle-label:before,
+.alectryon-io .alectryon-goal > label:before {
+    margin-right: 0.25em;
+}
+
+.alectryon-io .alectryon-goal > label:before {
+    margin-top: 0.125em;
+}
+
+.alectryon-io label.alectryon-input {
+    padding-right: 1em; /* Prevent line wraps before the checkbox bubble */
+}
+
+.alectryon-io label.alectryon-input:after {
+    margin-left: 0.25em;
+    margin-right: -1em; /* Compensate for the anti-wrapping space */
+}
+
+.alectryon-failed {
+    /* Underlines are broken in Chrome (they reset at each element boundary)… */
+    /* text-decoration: red wavy underline; */
+    /* … but it isn't too noticeable with dots */
+    text-decoration: red dotted underline;
+    text-decoration-skip-ink: none;
+    /* Chrome prints background images in low resolution, yielding a blurry underline */
+    /* background: bottom / 0.3em auto repeat-x url(data:image/svg+xml;base64,PHN2ZyB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciIHZpZXdCb3g9IjAgMCAyLjY0NiAxLjg1MiIgaGVpZ2h0PSI4IiB3aWR0aD0iMTAiPjxwYXRoIGQ9Ik0wIC4yNjVjLjc5NCAwIC41MyAxLjMyMiAxLjMyMyAxLjMyMi43OTQgMCAuNTMtMS4zMjIgMS4zMjMtMS4zMjIiIGZpbGw9Im5vbmUiIHN0cm9rZT0icmVkIiBzdHJva2Utd2lkdGg9Ii41MjkiLz48L3N2Zz4=); */
+}
+
+/* Wrapping :hover rules in a media query ensures that tapping a Coq sentence
+   doesn't trigger its :hover state (otherwise, on mobile, tapping a sentence to
+   hide its output causes it to remain visible (its :hover state gets triggered.
+   We only do it for the default style though, since other styles don't put the
+   output over the main text, so showing too much is not an issue. */
+@media (any-hover: hover) {
+    .alectryon-bubble:hover:before,
+    .alectryon-toggle-label:hover:before,
+    .alectryon-io label.alectryon-input:hover:after {
+        background: #eeeeec;
+    }
+
+    .alectryon-io label.alectryon-input:hover {
+        text-decoration: underline dotted #babdb6;
+	    text-shadow: 0 0 1px rgb(46, 52, 54, 0.3); /* #2e3436 + opacity */
+    }
+
+    .alectryon-io .alectryon-sentence:hover .alectryon-output,
+    .alectryon-io .alectryon-token:hover .alectryon-type-info-wrapper,
+    .alectryon-io .alectryon-token:hover .alectryon-type-info-wrapper {
+        z-index: 2; /* Place hovered goals above .alectryon-sentence.alectryon-target ones */
+    }
+}
+
+.alectryon-toggle:checked + .alectryon-toggle-label:before,
+.alectryon-io .alectryon-sentence > .alectryon-toggle:checked + label.alectryon-input:after,
+.alectryon-io .alectryon-extra-goal-toggle:checked + .alectryon-goal > label:before {
+    background-color: #babdb6;
+    border-color: #babdb6;
+}
+
+/* Disable clicks on sentences when the document-wide toggle is set. */
+.alectryon-toggle:checked + label + .alectryon-container label.alectryon-input {
+    cursor: unset;
+    pointer-events: none;
+}
+
+/* Hide individual checkboxes when the document-wide toggle is set. */
+.alectryon-toggle:checked + label + .alectryon-container label.alectryon-input:after {
+    display: none;
+}
+
+/* .alectryon-output is displayed by toggles, :hover, and .alectryon-target rules */
+.alectryon-io .alectryon-output {
+    box-sizing: border-box;
+    display: none;
+    left: 0;
+    right: 0;
+    position: absolute;
+    padding: 0.25em 0;
+    overflow: visible; /* Let box-shadows overflow */
+    z-index: 1; /* Default to an index lower than that used by :hover */
+}
+
+.alectryon-io .alectryon-type-info-wrapper {
+    position: absolute;
+    display: inline-block;
+    width: 100%;
+}
+
+.alectryon-io .alectryon-type-info-wrapper.full-width {
+    left: 0;
+    min-width: 100%;
+    max-width: 100%;
+}
+
+.alectryon-io .alectryon-type-info .goal-separator {
+    height: unset;
+    margin-top: 0em;
+}
+
+.alectryon-io .alectryon-type-info-wrapper .alectryon-type-info {
+    box-sizing: border-box;
+    bottom: 100%;
+    position: absolute;
+    /*padding: 0.25em 0;*/
+    visibility: hidden;
+    overflow: visible; /* Let box-shadows overflow */
+    z-index: 1; /* Default to an index lower than that used by :hover */
+    white-space: pre-wrap !important;
+}
+
+.alectryon-io .alectryon-type-info-wrapper .alectryon-type-info .alectryon-goal.alectryon-docstring {
+    white-space: pre-wrap !important;
+}
+
+@media (any-hover: hover) { /* See note above about this @media query */
+    .alectryon-io .alectryon-sentence:hover .alectryon-output:not(:hover) {
+        display: block;
+    }
+
+    .alectryon-io.output-hidden .alectryon-sentence:hover .alectryon-output:not(:hover) {
+        display: none !important;
+    }
+
+    .alectryon-io.type-info-hidden .alectryon-token:hover .alectryon-type-info-wrapper .alectryon-type-info,
+    .alectryon-io.type-info-hidden .alectryon-token:hover .alectryon-type-info-wrapper .alectryon-type-info {
+        /*visibility: hidden !important;*/
+    }
+
+    .alectryon-io .alectryon-token:hover .alectryon-type-info-wrapper .alectryon-type-info,
+    .alectryon-io .alectryon-token:hover .alectryon-type-info-wrapper .alectryon-type-info {
+        visibility: visible;
+        transition-delay: 0.5s;
+    }
+}
+
+.alectryon-io .alectryon-sentence.alectryon-target .alectryon-output {
+    display: block;
+}
+
+/* Indicate active (hovered or targeted) goals with a shadow. */
+.alectryon-io .alectryon-sentence:hover .alectryon-output:not(:hover) .alectryon-messages,
+.alectryon-io .alectryon-sentence.alectryon-target .alectryon-output  .alectryon-messages,
+.alectryon-io .alectryon-sentence:hover .alectryon-output:not(:hover) .alectryon-goals,
+.alectryon-io .alectryon-sentence.alectryon-target .alectryon-output  .alectryon-goals,
+.alectryon-io .alectryon-token:hover .alectryon-type-info-wrapper .alectryon-type-info {
+    box-shadow: 2px 2px 2px gray;
+}
+
+.alectryon-io .alectryon-extra-goals .alectryon-goal .goal-hyps {
+    display: none;
+}
+
+.alectryon-io .alectryon-extra-goals .alectryon-extra-goal-toggle:not(:checked) + .alectryon-goal label.goal-separator hr {
+    /* Dashes indicate that the hypotheses are hidden */
+    border-top-style: dashed;
+}
+
+
+/* Show just a small preview of the other goals; this is undone by the
+   "extra-goal" toggle and by :hover and .alectryon-target in windowed mode. */
+.alectryon-io .alectryon-extra-goals .alectryon-goal .goal-conclusion {
+    max-height: 5.2em;
+    overflow-y: auto;
+    /* Combining ‘overflow-y: auto’ with ‘display: inline-block’ causes extra space
+       to be added below the box. ‘vertical-align: middle’ gets rid of it. */
+    vertical-align: middle;
+}
+
+.alectryon-io .alectryon-goals,
+.alectryon-io .alectryon-messages {
+    background: #f6f7f6;
+	/*border: thin solid #d3d7cf; /* Convenient when pre's background is already #EEE */
+    display: block;
+    padding: 0.25em;
+}
+
+.alectryon-message::before {
+    content: '';
+    float: right;
+    /* etc/svg/square-bubble-xl.svg */
+    background: url("data:image/svg+xml,%3Csvg width='14' height='14' viewBox='0 0 3.704 3.704' xmlns='http://www.w3.org/2000/svg'%3E%3Cg fill-rule='evenodd' stroke='%23000' stroke-width='.264'%3E%3Cpath d='M.794.934h2.115M.794 1.463h1.455M.794 1.992h1.852'/%3E%3C/g%3E%3Cpath d='M.132.14v2.646h.794v.661l.926-.661h1.72V.14z' fill='none' stroke='%23000' stroke-width='.265'/%3E%3C/svg%3E") top right no-repeat;
+    height: 14px;
+    width: 14px;
+}
+
+.alectryon-toggle:checked + label + .alectryon-container {
+    width: unset;
+}
+
+/* Show goals when a toggle is set */
+.alectryon-toggle:checked + label + .alectryon-container label.alectryon-input + .alectryon-output,
+.alectryon-io .alectryon-sentence > .alectryon-toggle:checked ~ .alectryon-output {
+    display: block;
+    position: static;
+    width: unset;
+    background: unset; /* Override the backgrounds set in floating in windowed mode */
+    padding: 0.25em 0; /* Re-assert so that later :hover rules don't override this padding */
+}
+
+.alectryon-toggle:checked + label + .alectryon-container label.alectryon-input + .alectryon-output .goal-hyps,
+.alectryon-io .alectryon-sentence > .alectryon-toggle:checked ~ .alectryon-output .goal-hyps {
+    /* Overridden back in windowed style */
+    flex-flow: row wrap;
+    justify-content: flex-start;
+}
+
+.alectryon-toggle:checked + label + .alectryon-container .alectryon-sentence .alectryon-output > div,
+.alectryon-io .alectryon-sentence > .alectryon-toggle:checked ~ .alectryon-output > div {
+    display: block;
+}
+
+.alectryon-io .alectryon-extra-goal-toggle:checked + .alectryon-goal .goal-hyps {
+    display: flex;
+}
+
+.alectryon-io .alectryon-extra-goal-toggle:checked + .alectryon-goal .goal-conclusion {
+    max-height: unset;
+    overflow-y: unset;
+}
+
+.alectryon-toggle:checked + label + .alectryon-container .alectryon-sentence > .alectryon-toggle ~ .alectryon-wsp,
+.alectryon-io .alectryon-sentence > .alectryon-toggle:checked ~ .alectryon-wsp {
+    display: none;
+}
+
+.alectryon-io .alectryon-messages,
+.alectryon-io .alectryon-message,
+.alectryon-io .alectryon-goals,
+.alectryon-io .alectryon-goal,
+.alectryon-io .goal-hyps > span,
+.alectryon-io .goal-conclusion {
+    border-radius: 0.15em;
+}
+
+.alectryon-io .alectryon-goal,
+.alectryon-io .alectryon-message {
+    align-items: center;
+    background: #f6f7f6;
+    border: 0em;
+    display: block;
+    flex-direction: column;
+    margin: 0.25em;
+    padding: 0.5em;
+    position: relative;
+}
+
+.alectryon-io .goal-hyps {
+    align-content: space-around;
+    align-items: baseline;
+    display: flex;
+    flex-flow: column nowrap; /* re-stated in windowed mode */
+    justify-content: space-around;
+    /* LATER use a ‘gap’ property instead of margins once supported */
+    margin: -0.15em -0.25em; /* -0.15em to cancel the item spacing */
+    padding-bottom: 0.35em; /* 0.5em-0.15em to cancel the 0.5em of .goal-separator */
+}
+
+.alectryon-io .goal-hyps > br {
+    display: none; /* Only for RSS readers */
+}
+
+.alectryon-io .goal-hyps > span,
+.alectryon-io .goal-conclusion {
+    /*background: #eeeeec;*/
+    display: inline-block;
+    padding: 0.15em 0.35em;
+}
+
+.alectryon-io .goal-hyps > span {
+    align-items: baseline;
+    display: inline-flex;
+    margin: 0.15em 0.25em;
+}
+
+.alectryon-block var,
+.alectryon-inline var,
+.alectryon-io .goal-hyps > span > var {
+    font-weight: 600;
+    font-style: unset;
+}
+
+.alectryon-io .goal-hyps > span > var {
+    /* Shrink the list of names, but let it grow as long as space is available. */
+    flex-basis: min-content;
+    flex-grow: 1;
+}
+
+.alectryon-io .goal-hyps > span b {
+    font-weight: 600;
+    margin: 0 0 0 0.5em;
+    white-space: pre;
+}
+
+.alectryon-io .hyp-body,
+.alectryon-io .hyp-type {
+    display: flex;
+    align-items: baseline;
+}
+
+.alectryon-io .goal-separator {
+    align-items: center;
+    display: flex;
+    flex-direction: row;
+    height: 1em; /* Fixed height to ignore goal name and markers */
+    margin-top: -0.5em; /* Compensated in .goal-hyps when shown */
+}
+
+.alectryon-io .goal-separator hr {
+    border: none;
+    border-top: thin solid #555753;
+    display: block;
+    flex-grow: 1;
+    margin: 0;
+}
+
+.alectryon-io .goal-separator .goal-name {
+    font-size: 0.75em;
+    margin-left: 0.5em;
+}
+
+/**********/
+/* Banner */
+/**********/
+
+.alectryon-banner {
+    background: #eeeeec;
+    border: 1px solid #babcbd;
+    font-size: 0.75em;
+    padding: 0.25em;
+    text-align: center;
+    margin: 1em 0;
+}
+
+.alectryon-banner a {
+    cursor: pointer;
+    text-decoration: underline;
+}
+
+.alectryon-banner kbd {
+    background: #d3d7cf;
+    border-radius: 0.15em;
+    border: 1px solid #babdb6;
+    box-sizing: border-box;
+    display: inline-block;
+    font-family: inherit;
+    font-size: 0.9em;
+    height: 1.3em;
+    line-height: 1.2em;
+    margin: -0.25em 0;
+    padding: 0 0.25em;
+    vertical-align: middle;
+}
+
+/**********/
+/* Toggle */
+/**********/
+
+.alectryon-toggle-label {
+    margin: 1rem 0;
+}
+
+/******************/
+/* Floating style */
+/******************/
+
+/* If there's space, display goals to the right of the code, not below it. */
+@media (min-width: 80rem) {
+    /* Unlike the windowed case, we don't want to move output blocks to the side
+       when they are both :checked and -targeted, since it gets confusing as
+       things jump around; hence the commented-output part of the selector,
+       which would otherwise increase specificity */
+    .alectryon-floating .alectryon-sentence.alectryon-target /* > .alectryon-toggle ~ */ .alectryon-output,
+    .alectryon-floating .alectryon-sentence:hover .alectryon-output {
+        top: 0;
+        left: 100%;
+        right: -100%;
+        padding: 0 0.5em;
+        position:  absolute;
+    }
+
+    .alectryon-floating .alectryon-output {
+        min-height: 100%;
+    }
+
+    .alectryon-floating .alectryon-sentence:hover .alectryon-output {
+        background: white; /* Ensure that short goals hide long ones */
+    }
+
+    /* This odd margin-bottom property prevents the sticky div from bumping
+       against the bottom of its container (.alectryon-output).  The alternative
+       would be enlarging .alectryon-output, but that would cause overflows,
+       enlarging scrollbars and yielding scrolling towards the bottom of the
+       page.  Doing things this way instead makes it possible to restrict
+       .alectryon-output to a reasonable size (100%, through top = bottom = 0).
+       See also https://stackoverflow.com/questions/43909940/. */
+    /* See note on specificity above */
+    .alectryon-floating .alectryon-sentence.alectryon-target /* > .alectryon-toggle ~ */ .alectryon-output > div,
+    .alectryon-floating .alectryon-sentence:hover .alectryon-output > div {
+        margin-bottom: -200%;
+        position: sticky;
+        top: 0;
+    }
+
+    .alectryon-floating .alectryon-toggle:checked + label + .alectryon-container .alectryon-sentence .alectryon-output > div,
+    .alectryon-floating .alectryon-io .alectryon-sentence > .alectryon-toggle:checked ~ .alectryon-output > div {
+        margin-bottom: unset; /* Undo the margin */
+    }
+
+    /* Float underneath the current fragment
+    @media (max-width: 80rem) {
+        .alectryon-floating .alectryon-output {
+            top: 100%;
+        }
+    } */
+}
+
+/********************/
+/* Multi-pane style */
+/********************/
+
+.alectryon-windowed {
+    border: 0 solid #2e3436;
+    box-sizing: border-box;
+}
+
+.alectryon-windowed .alectryon-sentence:hover .alectryon-output {
+    background: white; /* Ensure that short goals hide long ones */
+}
+
+.alectryon-windowed .alectryon-output {
+    position: fixed; /* Overwritten by the ‘:checked’ rules */
+}
+
+/* See note about specificity below */
+.alectryon-windowed .alectryon-sentence:hover .alectryon-output,
+.alectryon-windowed .alectryon-sentence.alectryon-target > .alectryon-toggle ~ .alectryon-output {
+    padding: 0.5em;
+    overflow-y: auto; /* Windowed contents may need to scroll */
+}
+
+.alectryon-windowed .alectryon-io .alectryon-sentence:hover .alectryon-output:not(:hover) .alectryon-messages,
+.alectryon-windowed .alectryon-io .alectryon-sentence.alectryon-target .alectryon-output  .alectryon-messages,
+.alectryon-windowed .alectryon-io .alectryon-sentence:hover .alectryon-output:not(:hover) .alectryon-goals,
+.alectryon-windowed .alectryon-io .alectryon-sentence.alectryon-target .alectryon-output  .alectryon-goals {
+    box-shadow: none; /* A shadow is unnecessary here and incompatible with overflow-y set to auto */
+}
+
+.alectryon-windowed .alectryon-io .alectryon-sentence.alectryon-target .alectryon-output .goal-hyps {
+    /* Restated to override the :checked style */
+    flex-flow: column nowrap;
+    justify-content: space-around;
+}
+
+
+.alectryon-windowed .alectryon-sentence.alectryon-target .alectryon-extra-goals .alectryon-goal .goal-conclusion
+/* Like .alectryon-io .alectryon-extra-goal-toggle:checked + .alectryon-goal .goal-conclusion */ {
+    max-height: unset;
+    overflow-y: unset;
+}
+
+.alectryon-windowed .alectryon-output > div {
+    display: flex; /* Put messages after goals */
+    flex-direction: column-reverse;
+}
+
+/*********************/
+/* Standalone styles */
+/*********************/
+
+.alectryon-standalone {
+    font-family: 'IBM Plex Serif', 'PT Serif', 'Merriweather', 'DejaVu Serif', serif;
+    line-height: 1.5;
+}
+
+@media screen and (min-width: 50rem) {
+    html.alectryon-standalone {
+        /* Prevent flickering when hovering a block causes scrollbars to appear. */
+        margin-left: calc(100vw - 100%);
+        margin-right: 0;
+    }
+}
+
+/* Coqdoc */
+
+.alectryon-coqdoc .doc .code,
+.alectryon-coqdoc .doc .inlinecode,
+.alectryon-coqdoc .doc .comment {
+    display: inline;
+}
+
+.alectryon-coqdoc .doc .comment {
+    color: #eeeeec;
+}
+
+.alectryon-coqdoc .doc .paragraph {
+    height: 0.75em;
+}
+
+/* Centered, Floating */
+
+.alectryon-standalone .alectryon-centered,
+.alectryon-standalone .alectryon-floating {
+    max-width: 50rem;
+    margin: auto;
+}
+
+@media (min-width: 80rem) {
+    .alectryon-standalone .alectryon-floating {
+        max-width: 80rem;
+    }
+
+    .alectryon-standalone .alectryon-floating > * {
+        width: 50%;
+        margin-left: 0;
+    }
+}
+
+/* Windowed */
+
+.alectryon-standalone .alectryon-windowed {
+    display: block;
+    margin: 0;
+    overflow-y: auto;
+    position: absolute;
+    padding: 0 1em;
+}
+
+.alectryon-standalone .alectryon-windowed > * {
+    /* Override properties of docutils_basic.css */
+    margin-left: 0;
+    max-width: unset;
+}
+
+.alectryon-standalone .alectryon-windowed .alectryon-io {
+    box-sizing: border-box;
+    width: 100%;
+}
+
+/* No need to predicate the ‘:hover’ rules below on ‘:not(:checked)’, since ‘left’,
+   ‘right’, ‘top’, and ‘bottom’ will be inactived by the :checked rules setting
+   ‘position’ to ‘static’ */
+
+
+/* Specificity: We want the output to stay inline when hovered while unfolded
+   (:checked), but we want it to move when it's targeted (i.e. when the user
+   is browsing goals one by one using the keyboard, in which case we want to
+   goals to appear in consistent locations).  The selectors below ensure
+   that :hover < :checked < -targeted in terms of specificity. */
+/* LATER: Reimplement this stuff with CSS variables */
+.alectryon-windowed .alectryon-sentence.alectryon-target > .alectryon-toggle ~ .alectryon-output {
+    position: fixed;
+}
+
+@media screen and (min-width: 60rem) {
+    .alectryon-standalone .alectryon-windowed {
+        border-right-width: thin;
+        bottom: 0;
+        left: 0;
+        right: 50%;
+        top: 0;
+    }
+
+    .alectryon-standalone .alectryon-windowed .alectryon-sentence:hover .alectryon-output,
+    .alectryon-standalone .alectryon-windowed .alectryon-sentence.alectryon-target .alectryon-output {
+        bottom: 0;
+        left: 50%;
+        right: 0;
+        top: 0;
+    }
+}
+
+@media screen and (max-width: 60rem) {
+    .alectryon-standalone .alectryon-windowed {
+        border-bottom-width: 1px;
+        bottom: 40%;
+        left: 0;
+        right: 0;
+        top: 0;
+    }
+
+    .alectryon-standalone .alectryon-windowed .alectryon-sentence:hover .alectryon-output,
+    .alectryon-standalone .alectryon-windowed .alectryon-sentence.alectryon-target .alectryon-output {
+        bottom: 0;
+        left: 0;
+        right: 0;
+        top: 60%;
+    }
+}

doc/alectryon.js

@@ -0,0 +1,190 @@
+var Alectryon;
+(function(Alectryon) {
+    (function (slideshow) {
+        function anchor(sentence) { return "#" + sentence.id; }
+
+        function current_sentence() { return slideshow.sentences[slideshow.pos]; }
+
+        function unhighlight() {
+            var sentence = current_sentence();
+            if (sentence) sentence.classList.remove("alectryon-target");
+            slideshow.pos = -1;
+        }
+
+        function highlight(sentence) {
+            sentence.classList.add("alectryon-target");
+        }
+
+        function scroll(sentence) {
+            // Put the top of the current fragment close to the top of the
+            // screen, but scroll it out of view if showing it requires pushing
+            // the sentence past half of the screen.  If sentence is already in
+            // a reasonable position, don't move.
+            var parent = sentence.parentElement;
+            /* We want to scroll the whole document, so start at root… */
+            while (parent && !parent.classList.contains("alectryon-root"))
+                parent = parent.parentElement;
+            /* … and work up from there to find a scrollable element.
+               parent.scrollHeight can be greater than parent.clientHeight
+               without showing scrollbars, so we add a 10px buffer. */
+            while (parent && parent.scrollHeight <= parent.clientHeight + 10)
+                parent = parent.parentElement;
+            /* <body> and <html> elements can have their client rect overflow
+             * the window if their height is unset, so scroll the window
+             * instead */
+            if (parent && (parent.nodeName == "BODY" || parent.nodeName == "HTML"))
+                parent = null;
+
+            var rect = function(e) { return e.getBoundingClientRect(); };
+            var parent_box = parent ? rect(parent) : { y: 0, height: window.innerHeight },
+                sentence_y = rect(sentence).y - parent_box.y,
+                fragment_y = rect(sentence.parentElement).y - parent_box.y;
+
+            // The assertion below sometimes fails for the first element in a block.
+            // console.assert(sentence_y >= fragment_y);
+
+            if (sentence_y < 0.1 * parent_box.height ||
+                sentence_y > 0.7 * parent_box.height) {
+                (parent || window).scrollBy(
+                    0, Math.max(sentence_y - 0.5 * parent_box.height,
+                                fragment_y - 0.1 * parent_box.height));
+            }
+        }
+
+        function highlighted(pos) {
+            return slideshow.pos == pos;
+        }
+
+        function navigate(pos, inhibitScroll) {
+            unhighlight();
+            slideshow.pos = Math.min(Math.max(pos, 0), slideshow.sentences.length - 1);
+            var sentence = current_sentence();
+            highlight(sentence);
+            if (!inhibitScroll)
+                scroll(sentence);
+        }
+
+        var keys = {
+            PAGE_UP: 33,
+            PAGE_DOWN: 34,
+            ARROW_UP: 38,
+            ARROW_DOWN: 40,
+            h: 72, l: 76, p: 80, n: 78
+        };
+
+        function onkeydown(e) {
+            e = e || window.event;
+            if (e.ctrlKey || e.metaKey) {
+                if (e.keyCode == keys.ARROW_UP)
+                    slideshow.previous();
+                else if (e.keyCode == keys.ARROW_DOWN)
+                    slideshow.next();
+                else
+                    return;
+            } else {
+                // if (e.keyCode == keys.PAGE_UP || e.keyCode == keys.p || e.keyCode == keys.h)
+                //     slideshow.previous();
+                // else if (e.keyCode == keys.PAGE_DOWN || e.keyCode == keys.n || e.keyCode == keys.l)
+                //     slideshow.next();
+                // else
+                return;
+            }
+            e.preventDefault();
+        }
+
+        function start() {
+            slideshow.navigate(0);
+        }
+
+        function toggleHighlight(idx) {
+            if (highlighted(idx))
+                unhighlight();
+            else
+                navigate(idx, true);
+        }
+
+        function handleClick(evt) {
+            if (evt.ctrlKey || evt.metaKey) {
+                var sentence = evt.currentTarget;
+
+                // Ensure that the goal is shown on the side, not inline
+                var checkbox = sentence.getElementsByClassName("alectryon-toggle")[0];
+                if (checkbox)
+                    checkbox.checked = false;
+
+                toggleHighlight(sentence.alectryon_index);
+                evt.preventDefault();
+            }
+        }
+
+        function init() {
+            document.onkeydown = onkeydown;
+            slideshow.pos = -1;
+            slideshow.sentences = Array.from(document.getElementsByClassName("alectryon-sentence"));
+            slideshow.sentences.forEach(function (s, idx) {
+                s.addEventListener('click', handleClick, false);
+                s.alectryon_index = idx;
+            });
+        }
+
+        slideshow.start = start;
+        slideshow.end = unhighlight;
+        slideshow.navigate = navigate;
+        slideshow.next = function() { navigate(slideshow.pos + 1); };
+        slideshow.previous = function() { navigate(slideshow.pos + -1); };
+        window.addEventListener('DOMContentLoaded', init);
+    })(Alectryon.slideshow || (Alectryon.slideshow = {}));
+
+    (function (styles) {
+        var styleNames = ["centered", "floating", "windowed"];
+
+        function className(style) {
+            return "alectryon-" + style;
+        }
+
+        function setStyle(style) {
+            var root = document.getElementsByClassName("alectryon-root")[0];
+            styleNames.forEach(function (s) {
+                root.classList.remove(className(s)); });
+            root.classList.add(className(style));
+        }
+
+        function init() {
+            var banner = document.getElementsByClassName("alectryon-banner")[0];
+            if (banner) {
+                banner.append(" Style: ");
+                styleNames.forEach(function (styleName, idx) {
+                    var s = styleName;
+                    var a = document.createElement("a");
+                    a.onclick = function() { setStyle(s); };
+                    a.append(styleName);
+                    if (idx > 0) banner.append("; ");
+                    banner.appendChild(a);
+                });
+                banner.append(".");
+            }
+        }
+
+        window.addEventListener('DOMContentLoaded', init);
+
+        styles.setStyle = setStyle;
+    })(Alectryon.styles || (Alectryon.styles = {}));
+})(Alectryon || (Alectryon = {}));
+
+function setHidden(elements, isVisible, token) {
+    for (let i = 0; i < elements.length; i++) {
+        if (isVisible) {
+            elements[i].classList.remove(token)
+        } else {
+            elements[i].classList.add(token)
+        }
+    }
+}
+
+function toggleShowTypes(checkbox) {
+    setHidden(document.getElementsByClassName("alectryon-io"), checkbox.checked, "type-info-hidden")
+}
+
+function toggleShowGoals(checkbox) {
+    setHidden(document.getElementsByClassName("alectryon-io"), checkbox.checked, "output-hidden")
+}

doc/bin/README.md

@@ -0,0 +1,14 @@
+Lean binary distribution
+------------------------
+
+The binary distribution package contains:
+
+- Lean executable (located in the sub-directory bin)
+- Standard library (located in the sub-directory lib/lean/library)
+
+Assuming you are in the same directory this file is located,
+the following command executes a simple set of examples
+
+% bin/lean examples/ex.lean
+
+For more information on Lean and supported editors, please see https://lean-lang.org/documentation/.

doc/book.toml

@@ -0,0 +1,21 @@
+[book]
+authors = ["Leonardo de Moura", "Sebastian Ullrich"]
+language = "en"
+multilingual = false
+src = "."
+title = "Lean Documentation Overview"
+
+[build]
+build-dir = "out"
+
+[output.html]
+git-repository-url = "https://github.com/leanprover/lean4"
+additional-css = ["alectryon.css", "pygments.css"]
+additional-js = ["alectryon.js"]
+
+[output.html.fold]
+enable = true
+level = 0
+
+[output.html.playground.boring-prefixes]
+lean = "# "

doc/bool.md

@@ -0,0 +1 @@
+# Booleans

doc/declarations.md

@@ -0,0 +1,884 @@
+# Declarations
+
+-- TODO (fix)
+
+Declaration Names
+=================
+
+A declaration name is a hierarchical [identifier](lexical_structure.md#identifiers) that is interpreted relative to the current namespace as well as (during lookup) to the set of open namespaces.
+
+```lean
+namespace A
+  opaque B.c : Nat
+  #print B.c -- opaque A.B.c : Nat
+end A
+
+#print A.B.c -- opaque A.B.c : Nat
+open A
+#print B.c -- opaque A.B.c : Nat
+```
+
+Declaration names starting with an underscore are reserved for internal use. Names starting with the special atomic name ``_root_`` are interpreted as absolute names.
+
+```lean
+opaque a : Nat
+namespace A
+  opaque a : Int
+  #print _root_.a -- opaque a : Nat
+  #print A.a      -- opaque A.a : Int
+end A
+```
+
+Contexts and Telescopes
+=======================
+
+When processing user input, Lean first parses text to a raw expression format. It then uses background information and type constants to disambiguate overloaded symbols and infer implicit arguments, resulting in a fully-formed expression. This process is known as *elaboration*.
+
+As hinted in [Expression Syntax](expressions.md#expression_syntax),
+expressions are parsed and elaborated with respect to an *environment*
+and a *local context*. Roughly speaking, an environment represents the
+state of Lean at the point where an expression is parsed, including
+previously declared axioms, constants, definitions, and theorems. In a
+given environment, a *local context* consists of a sequence ``(a₁ :
+α₁) (a₂ : α₂) ... (aₙ : αₙ)`` where each ``aᵢ`` is a name denoting a
+local constant and each ``αᵢ`` is an expression of type ``Sort u`` for
+some ``u`` which can involve elements of the environment and the local
+constants ``aⱼ`` for ``j < i``.
+
+Intuitively, a local context is a list of variables that are held constant while an expression is being elaborated. Consider the following
+
+```lean
+def f (a b : Nat) : Nat → Nat := fun c => a + (b + c)
+```
+
+Here the expression ``fun c => a + (b + c)`` is elaborated in the context ``(a : Nat) (b : Nat)`` and the expression ``a + (b + c)`` is elaborated in the context ``(a : Nat) (b : Nat) (c : Nat)``. If you replace the expression ``a + (b + c)`` with an underscore, the error message from Lean will include the current *goal*:
+
+```
+a b c : Nat
+⊢ Nat
+```
+
+Here ``a b c : Nat`` indicates the local context, and the second ``Nat`` indicates the expected type of the result.
+
+A *context* is sometimes called a *telescope*, but the latter is used more generally to include a sequence of declarations occurring relative to a given context. For example, relative to the context ``(a₁ : α₁) (a₂ : α₂) ... (aₙ : αₙ)``, the types ``βᵢ`` in a telescope ``(b₁ : β₁) (b₂ : β₂) ... (bₙ : βₙ)`` can refer to ``a₁, ..., aₙ``. Thus a context can be viewed as a telescope relative to the empty context.
+
+Telescopes are often used to describe a list of arguments, or parameters, to a declaration. In such cases, it is often notationally convenient to let ``(a : α)`` stand for a telescope rather than just a single argument. In general, the annotations described in [Implicit Arguments](expressions.md#implicit_arguments) can be used to mark arguments as implicit.
+
+.. _basic_declarations:
+
+Basic Declarations
+==================
+
+Lean provides ways of adding new objects to the environment. The following provide straightforward ways of declaring new objects:
+
+* ``axiom c : α`` :  declare a constant named ``c`` of type ``α``, it is postulating that `α` is not an empty type.
+* ``def c : α := v`` : defines ``c`` to denote ``v``, which should have type ``α``.
+* ``theorem c : p := v`` : similar to ``def``, but intended to be used when ``p`` is a proposition.
+* ``opaque c : α (:= v)?`` : declares a opaque constant named ``c`` of type ``α``, the optional value `v` is must have type `α`
+  and can be viewed as a certificate that ``α`` is not an empty type. If the value is not provided, Lean tries to find one
+  using a procedure based on type class resolution. The value `v` is hidden from the type checker. You can assume that
+  Lean "forgets" `v` after type checking this kind of declaration.
+
+It is sometimes useful to be able to simulate a definition or theorem without naming it or adding it to the environment.
+
+* ``example : α := t`` : elaborates ``t`` and checks that it has sort ``α`` (often a proposition), without adding it to the environment.
+
+In ``def``, the type (``α`` or ``p``, respectively) can be omitted when it can be inferred by Lean. Constants declared with ``theorem`` are marked as ``irreducible``.
+
+Any of ``def``, ``theorem``, ``axiom``, or ``example`` can take a list of arguments (that is, a context) before the colon. If ``(a : α)`` is a context, the definition ``def foo (a : α) : β := t``
+is interpreted as ``def foo : (a : α) → β := fun a : α => t``. Similarly, a theorem ``theorem foo (a : α) : p := t`` is interpreted as ``theorem foo : ∀ a : α, p := fun a : α => t``.
+
+```lean
+opaque c : Nat
+opaque d : Nat
+axiom cd_eq : c = d
+
+def foo : Nat := 5
+def bar := 6
+def baz (x y : Nat) (s : List Nat) := [x, y] ++ s
+
+theorem foo_eq_five : foo = 5 := rfl
+theorem baz_theorem (x y : Nat) : baz x y [] = [x, y] := rfl
+
+example (x y : Nat) : baz x y [] = [x, y] := rfl
+```
+
+Inductive Types
+===============
+
+Lean's axiomatic foundation allows users to declare arbitrary
+inductive families, following the pattern described by [Dybjer]_. To
+make the presentation more manageable, we first describe inductive
+*types*, and then describe the generalization to inductive *families*
+in the next section. The declaration of an inductive type has the
+following form:
+
+```
+inductive Foo (a : α) where
+  | constructor₁ : (b : β₁) → Foo a
+  | constructor₂ : (b : β₂) → Foo a
+  ...
+  | constructorₙ : (b : βₙ) → Foo a
+```
+
+Here ``(a : α)`` is a context and each ``(b : βᵢ)`` is a telescope in the context ``(a : α)`` together with ``Foo``, subject to the following constraints.
+
+Suppose the telescope ``(b : βᵢ)`` is ``(b₁ : βᵢ₁) ... (bᵤ : βᵢᵤ)``. Each argument in the telescope is either *nonrecursive* or *recursive*.
+
+- An argument ``(bⱼ : βᵢⱼ)`` is *nonrecursive* if ``βᵢⱼ`` does not refer to ``foo,`` the inductive type being defined. In that case, ``βᵢⱼ`` can be any type, so long as it does not refer to any nonrecursive arguments.
+
+- An argument ``(bⱼ : βᵢⱼ)`` is *recursive* if it ``βᵢⱼ`` of the form ``Π (d : δ), foo`` where ``(d : δ)`` is a telescope which does not refer to ``foo`` or any nonrecursive arguments.
+
+The inductive type ``foo`` represents a type that is freely generated by the constructors. Each constructor can take arbitrary data and facts as arguments (the nonrecursive arguments), as well as indexed sequences of elements of ``foo`` that have been previously constructed (the recursive arguments). In set theoretic models, such sets can be represented by well-founded trees labeled by the constructor data, or they can defined using other transfinite or impredicative means.
+
+The declaration of the type ``foo`` as above results in the addition of the following constants to the environment:
+
+- the *type former* ``foo : Π (a : α), Sort u``
+- for each ``i``, the *constructor* ``foo.constructorᵢ : Π (a : α) (b : βᵢ), foo a``
+- the *eliminator* ``foo.rec``, which takes arguments
+
+  + ``(a : α)`` (the parameters)
+  + ``{C : foo a → Type u}`` (the *motive* of the elimination)
+  + for each ``i``, the *minor premise* corresponding to ``constructorᵢ``
+  + ``(x : foo)`` (the *major premise*)
+
+  and returns an element of ``C x``. Here, The ith minor premise is a function which takes
+
+  +  ``(b : βᵢ)`` (the arguments to the constructor)
+  + an argument of type ``Π (d : δ), C (bⱼ d)`` corresponding to each recursive argument ``(bⱼ : βᵢⱼ)``, where ``βᵢⱼ``  is of the form ``Π (d : δ), foo`` (the recursive values of the function being defined)
+
+  and returns an element of ``C (constructorᵢ a b)``, the intended value of the function at ``constructorᵢ a b``.
+
+The eliminator represents a principle of recursion: to construct an element of ``C x`` where ``x : foo a``, it suffices to consider each of the cases where ``x`` is of the form ``constructorᵢ a b`` and to provide an auxiliary construction in each case. In the case where some of the arguments to ``constructorᵢ`` are recursive, we can assume that we have already constructed values of ``C y`` for each value ``y`` constructed at an earlier stage.
+
+Under the propositions-as-type correspondence, when ``C x`` is an element of ``Prop``, the eliminator represents a principle of induction. In order to show ``∀ x, C x``, it suffices to show that ``C`` holds for each constructor, under the inductive hypothesis that it holds for all recursive inputs to the constructor.
+
+The eliminator and constructors satisfy the following identities, in which all the arguments are shown explicitly. Suppose we set ``F := foo.rec a C f₁ ... fₙ``. Then for each constructor, we have the definitional reduction:
+
+```
+F (constructorᵢ a b) = fᵢ b ... (fun d : δᵢⱼ => F (bⱼ d)) ...
+```
+
+where the ellipses include one entry for each recursive argument.
+
+Below are some common examples of inductive types, many of which are defined in the core library.
+
+```lean
+namespace Hide
+universe u v
+
+-- BEGIN
+inductive Empty : Type
+
+inductive Unit : Type
+| unit : Unit
+
+inductive Bool : Type
+| false : Bool
+| true : Bool
+
+inductive Prod (α : Type u) (β : Type v) : Type (max u v)
+| mk : α → β → Prod α β
+
+inductive Sum (α : Type u) (β : Type v)
+| inl : α → Sum α β
+| inr : β → Sum α β
+
+inductive Sigma (α : Type u) (β : α → Type v)
+| mk : (a : α) → β a → Sigma α β
+
+inductive false : Prop
+
+inductive True : Prop
+| trivial : True
+
+inductive And (p q : Prop) : Prop
+| intro : p → q → And p q
+
+inductive Or (p q : Prop) : Prop
+| inl : p → Or p q
+| inr : q → Or p q
+
+inductive Exists (α : Type u) (p : α → Prop) : Prop
+| intro : ∀ x : α, p x → Exists α p
+
+inductive Subtype (α : Type u) (p : α → Prop) : Type u
+| intro : ∀ x : α, p x → Subtype α p
+
+inductive Nat : Type
+| zero : Nat
+| succ : Nat → Nat
+
+inductive List (α : Type u)
+| nil : List α
+| cons : α → List α → List α
+
+-- full binary tree with nodes and leaves labeled from α
+inductive BinTree (α : Type u)
+| leaf : α → BinTree α
+| node : BinTree α → α → BinTree α → BinTree α
+
+-- every internal node has subtrees indexed by Nat
+inductive CBT (α : Type u)
+| leaf : α → CBT α
+| node : (Nat → CBT α) → CBT α
+-- END
+end Hide
+```
+
+Note that in the syntax of the inductive definition ``Foo``, the context ``(a : α)`` is left implicit. In other words, constructors and recursive arguments are written as though they have return type ``Foo`` rather than ``Foo a``.
+
+Elements of the context ``(a : α)`` can be marked implicit as described in [Implicit Arguments](#implicit.md#implicit_arguments). These annotations bear only on the type former, ``Foo``. Lean uses a heuristic to determine which arguments to the constructors should be marked implicit, namely, an argument is marked implicit if it can be inferred from the type of a subsequent argument. If the annotation ``{}`` appears after the constructor, a argument is marked implicit if it can be inferred from the type of a subsequent argument *or the return type*. For example, it is useful to let ``nil`` denote the empty list of any type, since the type can usually be inferred in the context in which it appears. These heuristics are imperfect, and you may sometimes wish to define your own constructors in terms of the default ones. In that case, use the ``[match_pattern]`` [attribute](TODO: missing link) to ensure that these will be used appropriately by the [Equation Compiler](#the-equation-compiler).
+
+There are restrictions on the universe ``u`` in the return type ``Sort u`` of the type former. There are also restrictions on the universe ``u`` in the return type ``Sort u`` of the motive of the eliminator. These will be discussed in the next section in the more general setting of inductive families.
+
+Lean allows some additional syntactic conveniences. You can omit the return type of the type former, ``Sort u``, in which case Lean will infer the minimal possible nonzero value for ``u``. As with function definitions, you can list arguments to the constructors before the colon. In an enumerated type (that is, one where the constructors have no arguments), you can also leave out the return type of the constructors.
+
+```lean
+namespace Hide
+universe u
+
+-- BEGIN
+inductive Weekday
+| sunday | monday | tuesday | wednesday
+| thursday | friday | saturday
+
+inductive Nat
+| zero
+| succ (n : Nat) : Nat
+
+inductive List (α : Type u)
+| nil : List α
+| cons (a : α) (l : List α) : List α
+
+@[match_pattern]
+def List.nil' (α : Type u) : List α := List.nil
+
+def length {α : Type u} : List α → Nat
+| (List.nil' _) => 0
+| (List.cons a l) => 1 + length l
+-- END
+
+end Hide
+```
+
+The type former, constructors, and eliminator are all part of Lean's axiomatic foundation, which is to say, they are part of the trusted kernel. In addition to these axiomatically declared constants, Lean automatically defines some additional objects in terms of these, and adds them to the environment. These include the following:
+
+- ``Foo.recOn`` : a variant of the eliminator, in which the major premise comes first
+- ``Foo.casesOn`` : a restricted version of the eliminator which omits any recursive calls
+- ``Foo.noConfusionType``, ``Foo.noConfusion`` : functions which witness the fact that the inductive type is freely generated, i.e. that the constructors are injective and that distinct constructors produce distinct objects
+- ``Foo.below``, ``Foo.ibelow`` : functions used by the equation compiler to implement structural recursion
+- ``instance : SizeOf Foo`` : a measure which can be used for well-founded recursion
+
+Note that it is common to put definitions and theorems related to a datatype ``foo`` in a namespace of the same name. This makes it possible to use projection notation described in [Structures](struct.md#structures) and [Namespaces](namespaces.md#namespaces).
+
+```lean
+namespace Hide
+universe u
+
+-- BEGIN
+inductive Nat
+| zero
+| succ (n : Nat) : Nat
+
+#check Nat
+#check @Nat.rec
+#check Nat.zero
+#check Nat.succ
+
+#check @Nat.recOn
+#check @Nat.casesOn
+#check @Nat.noConfusionType
+#check @Nat.noConfusion
+#check @Nat.brecOn
+#check Nat.below
+#check Nat.ibelow
+#check Nat._sizeOf_1
+
+-- END
+
+end Hide
+```
+
+.. _inductive_families:
+
+Inductive Families
+==================
+
+In fact, Lean implements a slight generalization of the inductive types described in the previous section, namely, inductive *families*. The declaration of an inductive family in Lean has the following form:
+
+```
+inductive Foo (a : α) : Π (c : γ), Sort u
+| constructor₁ : Π (b : β₁), Foo t₁
+| constructor₂ : Π (b : β₂), Foo t₂
+...
+| constructorₙ : Π (b : βₙ), Foo tₙ
+```
+
+Here ``(a : α)`` is a context, ``(c : γ)`` is a telescope in context ``(a : α)``, each ``(b : βᵢ)`` is a telescope in the context ``(a : α)`` together with ``(Foo : Π (c : γ), Sort u)`` subject to the constraints below, and each ``tᵢ`` is a tuple of terms in the context ``(a : α) (b : βᵢ)`` having the types ``γ``. Instead of defining a single inductive type ``Foo a``, we are now defining a family of types ``Foo a c`` indexed by elements ``c : γ``.  Each constructor, ``constructorᵢ``, places its result in the type ``Foo a tᵢ``, the member of the family with index ``tᵢ``.
+
+The modifications to the scheme in the previous section are straightforward. Suppose the telescope ``(b : βᵢ)`` is ``(b₁ : βᵢ₁) ... (bᵤ : βᵢᵤ)``.
+
+- As before, an argument ``(bⱼ : βᵢⱼ)`` is *nonrecursive* if ``βᵢⱼ`` does not refer to ``Foo,`` the inductive type being defined. In that case, ``βᵢⱼ`` can be any type, so long as it does not refer to any nonrecursive arguments.
+
+- An argument ``(bⱼ : βᵢⱼ)`` is *recursive* if ``βᵢⱼ`` is of the form ``Π (d : δ), Foo s`` where ``(d : δ)`` is a telescope which does not refer to ``Foo`` or any nonrecursive arguments and ``s`` is a tuple of terms in context ``(a : α)`` and the previous nonrecursive ``bⱼ``'s with types ``γ``.
+
+The declaration of the type ``Foo`` as above results in the addition of the following constants to the environment:
+
+- the *type former* ``Foo : Π (a : α) (c : γ), Sort u``
+- for each ``i``, the *constructor* ``Foo.constructorᵢ : Π (a : α) (b : βᵢ), Foo a tᵢ``
+- the *eliminator* ``Foo.rec``, which takes arguments
+
+  + ``(a : α)`` (the parameters)
+  + ``{C : Π (c : γ), Foo a c → Type u}`` (the motive of the elimination)
+  + for each ``i``, the minor premise corresponding to ``constructorᵢ``
+  + ``(x : Foo a)`` (the major premise)
+
+  and returns an element of ``C x``. Here, The ith minor premise is a function which takes
+
+  +  ``(b : βᵢ)`` (the arguments to the constructor)
+  + an argument of type ``Π (d : δ), C s (bⱼ d)`` corresponding to each recursive argument ``(bⱼ : βᵢⱼ)``, where ``βᵢⱼ``  is of the form ``Π (d : δ), Foo s``
+
+  and returns an element of ``C tᵢ (constructorᵢ a b)``.
+
+Suppose we set ``F := Foo.rec a C f₁ ... fₙ``. Then for each constructor, we have the definitional reduction, as before:
+
+```
+F (constructorᵢ a b) = fᵢ b ... (fun d : δᵢⱼ => F (bⱼ d)) ...
+```
+
+where the ellipses include one entry for each recursive argument.
+
+The following are examples of inductive families.
+
+```lean
+namespace Hide
+universe u
+
+-- BEGIN
+inductive Vector (α : Type u) : Nat → Type u
+| nil  : Vector 0
+| succ : Π n, Vector n → Vector (n + 1)
+
+-- 'IsProd s n' means n is a product of elements of s
+inductive IsProd (s : Set Nat) : Nat → Prop
+| base : ∀ n ∈ s, IsProd n
+| step : ∀ m n, IsProd m → IsProd n → IsProd (m * n)
+
+inductive Eq {α : Sort u} (a : α) : α → Prop
+| refl : Eq a
+-- END
+
+end Hide
+```
+
+We can now describe the constraints on the return type of the type former, ``Sort u``. We can always take ``u`` to be ``0``, in which case we are defining an inductive family of propositions. If ``u`` is nonzero, however, it must satisfy the following constraint: for each type ``βᵢⱼ : Sort v`` occurring in the constructors, we must have ``u ≥ v``. In the set-theoretic interpretation, this ensures that the universe in which the resulting type resides is large enough to contain the inductively generated family, given the number of distinctly-labeled constructors. The restriction does not hold for inductively defined propositions, since these contain no data.
+
+Putting an inductive family in ``Prop``, however, does impose a restriction on the eliminator. Generally speaking, for an inductive family in ``Prop``, the motive in the eliminator is required to be in ``Prop``. But there is an exception to this rule: you are allowed to eliminate from an inductively defined ``Prop`` to an arbitrary ``Sort`` when there is only one constructor, and each argument to that constructor is either in ``Prop`` or an index. The intuition is that in this case the elimination does not make use of any information that is not already given by the mere fact that the type of argument is inhabited. This special case is known as *singleton elimination*.
+
+.. _mutual_and_nested_inductive_definitions:
+
+Mutual and Nested Inductive Definitions
+=======================================
+
+Lean supports two generalizations of the inductive families described above, namely, *mutual* and *nested* inductive definitions. These are *not* implemented natively in the kernel. Rather, the definitions are compiled down to the primitive inductive types and families.
+
+The first generalization allows for multiple inductive types to be defined simultaneously.
+
+```
+mutual
+
+inductive Foo (a : α) : Π (c : γ₁), Sort u
+| constructor₁₁ : Π (b : β₁₁), Foo a t₁₁
+| constructor₁₂ : Π (b : β₁₂), Foo a t₁₂
+...
+| constructor₁ₙ : Π (b : β₁ₙ), Foo a t₁ₙ
+
+inductive Bar (a : α) : Π (c : γ₂), Sort u
+| constructor₂₁ : Π (b : β₂₁), Bar a t₂₁
+| constructor₂₂ : Π (b : β₂₂), Bar a t₂₂
+...
+| constructor₂ₘ : Π (b : β₂ₘ), Bar a t₂ₘ
+
+end
+```
+
+Here the syntax is shown for defining two inductive families, ``Foo`` and ``Bar``, but any number is allowed. The restrictions are almost the same as for ordinary inductive families. For example, each ``(b : βᵢⱼ)`` is a telescope relative to the context ``(a : α)``. The difference is that the constructors can now have recursive arguments whose return types are any of the inductive families currently being defined, in this case ``Foo`` and ``Bar``. Note that all of the inductive definitions share the same parameters ``(a : α)``, though they may have different indices.
+
+A mutual inductive definition is compiled down to an ordinary inductive definition using an extra finite-valued index to distinguish the components. The details of the internal construction are meant to be hidden from most users. Lean defines the expected type formers ``Foo`` and ``Bar`` and constructors ``constructorᵢⱼ`` from the internal inductive definition. There is no straightforward elimination principle, however. Instead, Lean defines an appropriate ``sizeOf`` measure, meant for use with well-founded recursion, with the property that the recursive arguments to a constructor are smaller than the constructed value.
+
+The second generalization relaxes the restriction that in the recursive definition of ``Foo``, ``Foo`` can only occur strictly positively in the type of any of its recursive arguments. Specifically, in a nested inductive definition, ``Foo`` can appear as an argument to another inductive type constructor, so long as the corresponding parameter occurs strictly positively in the constructors for *that* inductive type. This process can be iterated, so that additional type constructors can be applied to those, and so on.
+
+A nested inductive definition is compiled down to an ordinary inductive definition using a mutual inductive definition to define copies of all the nested types simultaneously. Lean then constructs isomorphisms between the mutually defined nested types and their independently defined counterparts. Once again, the internal details are not meant to be manipulated by users. Rather, the type former and constructors are made available and work as expected, while an appropriate ``sizeOf`` measure is generated for use with well-founded recursion.
+
+```lean
+universe u
+-- BEGIN
+mutual
+inductive Even : Nat → Prop
+| even_zero : Even 0
+| even_succ : ∀ n, Odd n → Even (n + 1)
+inductive Odd : Nat → Prop
+| odd_succ : ∀ n, Even n → Odd (n + 1)
+end
+
+inductive Tree (α : Type u)
+| mk : α → List (Tree α) → Tree α
+
+inductive DoubleTree (α : Type u)
+| mk : α → List (DoubleTree α) × List (DoubleTree α) → DoubleTree α
+-- END
+```
+
+.. _the_equation_compiler:
+
+The Equation Compiler
+=====================
+
+The equation compiler takes an equational description of a function or proof and tries to define an object meeting that specification. It expects input with the following syntax:
+
+```
+def foo (a : α) : Π (b : β), γ
+| [patterns₁] => t₁
+...
+| [patternsₙ] => tₙ
+```
+
+Here ``(a : α)`` is a telescope, ``(b : β)`` is a telescope in the context ``(a : α)``, and ``γ`` is an expression in the context ``(a : α) (b : β)`` denoting a ``Type`` or a ``Prop``.
+
+Each ``patternsᵢ`` is a sequence of patterns of the same length as ``(b : β)``. A pattern is either:
+
+- a variable, denoting an arbitrary value of the relevant type,
+- an underscore, denoting a *wildcard* or *anonymous variable*,
+- an inaccessible term (see below), or
+- a constructor for the inductive type of the corresponding argument, applied to a sequence of patterns.
+
+In the last case, the pattern must be enclosed in parentheses.
+
+Each term ``tᵢ`` is an expression in the context ``(a : α)`` together with the variables introduced on the left-hand side of the token ``=>``. The term ``tᵢ`` can also include recursive calls to ``foo``, as described below. The equation compiler does case splitting on the variables ``(b : β)`` as necessary to match the patterns, and defines ``foo`` so that it has the value ``tᵢ`` in each of the cases. In ideal circumstances (see below), the equations hold definitionally. Whether they hold definitionally or only propositionally, the equation compiler proves the relevant equations and assigns them internal names. They are accessible by the ``rewrite`` and ``simp`` tactics under the name ``foo`` (see [Rewrite](tactics.md#rewrite) and _[TODO: where is simplifier tactic documented?]_. If some of the patterns overlap, the equation compiler interprets the definition so that the first matching pattern applies in each case. Thus, if the last pattern is a variable, it covers all the remaining cases. If the patterns that are presented do not cover all possible cases, the equation compiler raises an error.
+
+When identifiers are marked with the ``[match_pattern]`` attribute, the equation compiler unfolds them in the hopes of exposing a constructor. For example, this makes it possible to write ``n+1`` and ``0`` instead of ``Nat.succ n`` and ``Nat.zero`` in patterns.
+
+For a nonrecursive definition involving case splits, the defining equations will hold definitionally. With inductive types like ``Char``, ``String``, and ``Fin n``, a case split would produce definitions with an inordinate number of cases. To avoid this, the equation compiler uses ``if ... then ... else`` instead of ``casesOn`` when defining the function. In this case, the defining equations hold definitionally as well.
+
+```lean
+open Nat
+
+def sub2 : Nat → Nat
+| zero          => 0
+| succ zero     => 0
+| succ (succ a) => a
+
+def bar : Nat → List Nat → Bool → Nat
+| 0,   _,      false => 0
+| 0,   b :: _, _     => b
+| 0,   [],     true  => 7
+| a+1, [],     false => a
+| a+1, [],     true  => a + 1
+| a+1, b :: _, _     => a + b
+
+def baz : Char → Nat
+| 'A' => 1
+| 'B' => 2
+| _   => 3
+```
+
+The case where patterns are matched against an argument whose type is an inductive family is known as *dependent pattern matching*. This is more complicated, because the type of the function being defined can impose constraints on the patterns that are matched. In this case, the equation compiler will detect inconsistent cases and rule them out.
+
+```lean
+universe u
+
+inductive Vector (α : Type u) : Nat → Type u
+  | nil  : Vector α 0
+  | cons : α → Vector α n → Vector α (n+1)
+
+namespace Vector
+
+def head : Vector α (n+1) → α
+  | cons h t => h
+
+def tail : Vector α (n+1) → Vector α n
+  | cons h t => t
+
+def map (f : α → β → γ) : Vector α n → Vector β n → Vector γ n
+  | nil, nil => nil
+  | cons a va, cons b vb => cons (f a b) (map f va vb)
+
+end Vector
+```
+
+.. _recursive_functions:
+
+Recursive functions
+===================
+
+Lean must ensure that a recursive function terminates, for which there are two strategies: _structural recursion_, in which all recursive calls are made on smaller parts of the input data, and _well-founded recursion_, in which recursive calls are justified by showing that arguments to recursive calls are smaller according to some other measure.
+
+Structural recursion
+--------------------
+
+If the definition of a function contains recursive calls, Lean first tries to interpret the definition as a structural recursion. In order for that to succeed, the recursive arguments must be subterms of the corresponding arguments on the left-hand side.
+
+The function is then defined using a *course of values* recursion, using automatically generated functions ``below`` and ``brec`` in the namespace corresponding to the inductive type of the recursive argument. In this case the defining equations hold definitionally, possibly with additional case splits.
+
+```lean
+namespace Hide
+
+-- BEGIN
+def fib : Nat → Nat
+| 0     => 1
+| 1     => 1
+| (n+2) => fib (n+1) + fib n
+
+def append {α : Type} : List α → List α → List α
+| [],   l => l
+| h::t, l => h :: append t l
+
+example : append [(1 : Nat), 2, 3] [4, 5] = [1, 2, 3, 4, 5] => rfl
+-- END
+
+end Hide
+```
+
+Well-founded recursion
+---------------------
+
+If structural recursion fails, the equation compiler falls back on well-founded recursion. It tries to infer an instance of ``SizeOf`` for the type of each argument, and then tries to find a permutation of the arguments such that each recursive call is decreasing under the lexicographic order with respect to ``sizeOf`` measures.  Lean uses information in the local context, so you can often provide the relevant proof manually using ``have`` in the body of the definition.
+
+In the case of well-founded recursion, the equation used to declare the function holds only propositionally, but not definitionally, and can be accessed using ``unfold``, ``simp`` and ``rewrite`` with the function name (for example ``unfold foo`` or ``simp [foo]``, where ``foo`` is the function defined with well-founded recursion).
+
+```lean
+namespace Hide
+open Nat
+
+-- BEGIN
+def div : Nat → Nat → Nat
+| x, y =>
+  if h : 0 < y ∧ y ≤ x then
+    have : x - y < x :=
+      sub_lt (Nat.lt_of_lt_of_le h.left h.right) h.left
+    div (x - y) y + 1
+  else
+    0
+
+example (x y : Nat) :
+  div x y = if 0 < y ∧ y ≤ x then div (x - y) y + 1 else 0 :=
+by rw [div]; rfl
+-- END
+
+end Hide
+```
+
+If Lean cannot find a permutation of the arguments for which all recursive calls are decreasing, it will print a table that contains, for every recursive call, which arguments Lean could prove to be decreasing. For example, a function with three recursive calls and four parameters might cause the following message to be printed
+
+```
+example.lean:37:0-43:31: error: Could not find a decreasing measure.
+The arguments relate at each recursive call as follows:
+(<, ≤, =: relation proved, ? all proofs failed, _: no proof attempted)
+           x1 x2 x3 x4
+1) 39:6-27  =  =  _  =
+2) 40:6-25  =  ?  _  <
+3) 41:6-25  <  _  _  _
+Please use `termination_by` to specify a decreasing measure.
+```
+
+This table should be read as follows:
+
+ * In the first recursive call, in line 39, arguments 1, 2 and 4 are equal to the function's parameters.
+ * The second recursive call, in line 40, has an equal first argument, a smaller fourth argument, and nothing could be inferred for the second argument.
+ * The third recursive call, in line 41, has a decreasing first argument.
+ * No other proofs were attempted, either because the parameter has a type without a non-trivial ``WellFounded`` instance (parameter 3), or because it is already clear that no decreasing measure can be found.
+
+
+Lean will print the termination argument it found if ``set_option showInferredTerminationBy true`` is set.
+
+If Lean does not find the termination argument, or if you want to be explicit, you can append a `termination_by` clause to the function definition, after the function's body, but before the `where` clause if present. It is of the form
+```
+termination_by e
+```
+where ``e`` is an expression that depends on the parameters of the function and should be decreasing at each recursive call. The type of `e` should be an instance of the class ``WellFoundedRelation``, which determines how to compare two values of that type.
+
+If ``f`` has parameters “after the ``:``” (for example when defining functions via patterns using `|`), then these can be brought into scope using the syntax
+```
+termination_by a₁ … aₙ => e
+```
+
+By default, Lean uses the tactic ``decreasing_tactic`` when proving that an argument is decreasing; see its documentation for how to globally extend it. You can also choose to use a different tactic for a given function definition with the clause
+```
+decreasing_by <tac>
+```
+which should come after ``termination_by`, if present.
+
+
+Note that recursive definitions can in general require nested recursions, that is, recursion on different arguments of ``foo`` in the template above. The equation compiler handles this by abstracting later arguments, and recursively defining higher-order functions to meet the specification.
+
+Mutual recursion
+----------------
+
+The equation compiler also allows mutual recursive definitions, with a syntax similar to that of [Mutual and Nested Inductive Definitions](#mutual-and-nested-inductive-definitions). Mutual definitions are always compiled using well-founded recursion, and so once again the defining equations hold only propositionally.
+
+```lean
+mutual
+def even : Nat → Bool
+| 0   => true
+| a+1 => odd a
+def odd : Nat → Bool
+| 0   => false
+| a+1 => even a
+end
+
+example (a : Nat) : even (a + 1) = odd a :=
+by simp [even]
+
+example (a : Nat) : odd (a + 1) = even a :=
+by simp [odd]
+```
+
+Well-founded recursion is especially useful with [Mutual and Nested Inductive Definitions](#mutual-and-nested-inductive-definitions), since it provides the canonical way of defining functions on these types.
+
+```lean
+mutual
+inductive Even : Nat → Prop
+| even_zero : Even 0
+| even_succ : ∀ n, Odd n → Even (n + 1)
+inductive Odd : Nat → Prop
+| odd_succ : ∀ n, Even n → Odd (n + 1)
+end
+
+open Even Odd
+
+theorem not_odd_zero : ¬ Odd 0 := fun x => nomatch x
+
+mutual
+theorem even_of_odd_succ : ∀ n, Odd (n + 1) → Even n
+| _, odd_succ n h => h
+theorem odd_of_even_succ : ∀ n, Even (n + 1) → Odd n
+| _, even_succ n h => h
+end
+
+inductive Term
+| const : String → Term
+| app   : String → List Term → Term
+
+open Term
+
+mutual
+def num_consts : Term → Nat
+| .const n  => 1
+| .app n ts => num_consts_lst ts
+def num_consts_lst : List Term → Nat
+| []    => 0
+| t::ts => num_consts t + num_consts_lst ts
+end
+```
+
+In a set of mutually recursive function, either all or no functions must have an explicit termination argument (``termination_by``). A change of the default termination tactic (``decreasing_by``) only affects the proofs about the recursive calls of that function, not the other functions in the group.
+
+```
+mutual
+theorem even_of_odd_succ : ∀ n, Odd (n + 1) → Even n
+| _, odd_succ n h => h
+termination_by n h => h
+decreasing_by decreasing_tactic
+
+theorem odd_of_even_succ : ∀ n, Even (n + 1) → Odd n
+| _, even_succ n h => h
+termination_by n h => h
+end
+```
+
+Another way to express mutual recursion is using local function definitions in ``where`` or ``let rec`` clauses: these can be mutually recursive with each other and their containing function:
+
+```
+theorem even_of_odd_succ : ∀ n, Odd (n + 1) → Even n
+  | _, odd_succ n h => h
+termination_by n h => h
+  where
+    theorem odd_of_even_succ : ∀ n, Even (n + 1) → Odd n
+      | _, even_succ n h => h
+    termination_by n h => h
+```
+
+.. _match_expressions:
+
+Match Expressions
+=================
+
+Lean supports a ``match ... with ...`` construct similar to ones found in most functional programming languages. The syntax is as follows:
+
+```
+match t₁, ..., tₙ with
+| p₁₁, ..., p₁ₙ => s₁
+...
+| pₘ₁, ..., pₘₙ => sₘ
+```
+
+Here ``t₁, ..., tₙ`` are any terms in the context in which the expression appears, the expressions ``pᵢⱼ`` are patterns, and the terms ``sᵢ`` are expressions in the local context together with variables introduced by the patterns on the left-hand side. Each ``sᵢ`` should have the expected type of the entire ``match`` expression.
+
+Any ``match`` expression is interpreted using the equation compiler, which generalizes ``t₁, ..., tₙ``, defines an internal function meeting the specification, and then applies it to ``t₁, ..., tₙ``. In contrast to the definitions in [The Equation Compiler](declarations.md#the-equation-compiler), the terms ``tᵢ`` are arbitrary terms rather than just variables, and the expression can occur anywhere within a Lean expression, not just at the top level of a definition. Note that the syntax here is somewhat different: both the terms ``tᵢ`` and the patterns ``pᵢⱼ`` are separated by commas.
+
+```lean
+def foo (n : Nat) (b c : Bool) :=
+5 + match n - 5, b && c with
+    | 0,   true  => 0
+    | m+1, true  => m + 7
+    | 0,   false => 5
+    | m+1, false => m + 3
+```
+
+When a ``match`` has only one line, Lean provides alternative syntax with a destructuring ``let``, as well as a destructuring lambda abstraction. Thus the following definitions all have the same net effect.
+
+```lean
+def bar₁ : Nat × Nat → Nat
+| (m, n) => m + n
+
+def bar₂ (p : Nat × Nat) : Nat :=
+match p with | (m, n) => m + n
+
+def bar₃ : Nat × Nat → Nat :=
+fun ⟨m, n⟩ => m + n
+
+def bar₄ (p : Nat × Nat) : Nat :=
+let ⟨m, n⟩ := p; m + n
+```
+
+Information about the term being matched can be preserved in each branch using the syntax `match h : t with`. For example, a user may want to match a term `ns ++ ms : List Nat`, while tracking the hypothesis `ns ++ ms = []` or `ns ++ ms= h :: t` in the respective match arm:
+
+```lean
+def foo (ns ms : List Nat) (h1 : ns ++ ms ≠ []) (k : Nat -> Char) : Char :=
+  match h2 : ns ++ ms with
+  -- in this arm, we have the hypothesis `h2 : ns ++ ms = []`
+  | [] => absurd h2 h1
+  -- in this arm, we have the hypothesis `h2 : ns ++ ms = h :: t`
+  | h :: t => k h
+
+-- '7'
+#eval foo [7, 8, 9] [] (by decide) Nat.digitChar
+```
+
+.. _structures_and_records:
+
+Structures and Records
+======================
+
+The ``structure`` command in Lean is used to define an inductive data type with a single constructor and to define its projections at the same time. The syntax is as follows:
+
+```
+structure Foo (a : α) extends Bar, Baz : Sort u :=
+constructor :: (field₁ : β₁) ... (fieldₙ : βₙ)
+```
+
+Here ``(a : α)`` is a telescope, that is, the parameters to the inductive definition. The name ``constructor`` followed by the double colon is optional; if it is not present, the name ``mk`` is used by default. The keyword ``extends`` followed by a list of previously defined structures is also optional; if it is present, an instance of each of these structures is included among the fields to ``Foo``, and the types ``βᵢ`` can refer to their fields as well. The output type, ``Sort u``, can be omitted, in which case Lean infers to smallest non-``Prop`` sort possible. Finally, ``(field₁ : β₁) ... (fieldₙ : βₙ)`` is a telescope relative to ``(a : α)`` and the fields in ``bar`` and ``baz``.
+
+The declaration above is syntactic sugar for an inductive type declaration, and so results in the addition of the following constants to the environment:
+
+- the type former : ``Foo : Π (a : α), Sort u``
+- the single constructor :
+
+```
+Foo.constructor : Π (a : α) (toBar : Bar) (toBaz : Baz)
+  (field₁ : β₁) ... (fieldₙ : βₙ), Foo a
+```
+
+- the eliminator ``Foo.rec`` for the inductive type with that constructor
+
+In addition, Lean defines
+
+- the projections : ``fieldᵢ : Π (a : α) (c : Foo) : βᵢ`` for each ``i``
+
+where any other fields mentioned in ``βᵢ`` are replaced by the relevant projections from ``c``.
+
+Given ``c : Foo``, Lean offers the following convenient syntax for the projection ``Foo.fieldᵢ c``:
+
+- *anonymous projections* : ``c.fieldᵢ``
+- *numbered projections* : ``c.i``
+
+These can be used in any situation where Lean can infer that the type of ``c`` is of the form ``Foo a``. The convention for anonymous projections is extended to any function ``f`` defined in the namespace ``Foo``, as described in [Namespaces](namespaces.md).
+
+Similarly, Lean offers the following convenient syntax for constructing elements of ``Foo``. They are equivalent to ``Foo.constructor b₁ b₂ f₁ f₁ ... fₙ``, where ``b₁ : Bar``, ``b₂ : Baz``, and each ``fᵢ : βᵢ`` :
+
+- *anonymous constructor*: ``⟨ b₁, b₂, f₁, ..., fₙ ⟩``
+- *record notation*:
+
+```
+{ toBar := b₁, toBaz := b₂, field₁ := f₁, ...,
+    fieldₙ := fₙ :  Foo a }
+```
+
+The anonymous constructor can be used in any context where Lean can infer that the expression should have a type of the form ``Foo a``. The unicode brackets are entered as ``\<`` and ``\>`` respectively.
+
+When using record notation, you can omit the annotation ``: Foo a`` when Lean can infer that the expression should have a type of the form ``Foo a``. You can replace either ``toBar`` or ``toBaz`` by assignments to *their* fields as well, essentially acting as though the fields of ``Bar`` and ``Baz`` are simply imported into ``Foo``. Finally, record notation also supports
+
+- *record updates*: ``{ t with ... fieldᵢ := fᵢ ...}``
+
+Here ``t`` is a term of type ``Foo a`` for some ``a``. The notation instructs Lean to take values from ``t`` for any field assignment that is omitted from the list.
+
+Lean also allows you to specify a default value for any field in a structure by writing ``(fieldᵢ : βᵢ := t)``. Here ``t`` specifies the value to use when the field ``fieldᵢ`` is left unspecified in an instance of record notation.
+
+```lean
+universe u v
+
+structure Vec (α : Type u) (n : Nat) :=
+(l : List α) (h : l.length = n)
+
+structure Foo (α : Type u) (β : Nat → Type v) : Type (max u v) :=
+(a : α) (n : Nat) (b : β n)
+
+structure Bar :=
+(c : Nat := 8) (d : Nat)
+
+structure Baz extends Foo Nat (Vec Nat), Bar :=
+(v : Vec Nat n)
+
+#check Foo
+#check @Foo.mk
+#check @Foo.rec
+
+#check Foo.a
+#check Foo.n
+#check Foo.b
+
+#check Baz
+#check @Baz.mk
+#check @Baz.rec
+
+#check Baz.toFoo
+#check Baz.toBar
+#check Baz.v
+
+def bzz := Vec.mk [1, 2, 3] rfl
+
+#check Vec.l bzz
+#check Vec.h bzz
+#check bzz.l
+#check bzz.h
+#check bzz.1
+#check bzz.2
+
+example : Vec Nat 3 := Vec.mk [1, 2, 3] rfl
+example : Vec Nat 3 := ⟨[1, 2, 3], rfl⟩
+example : Vec Nat 3 := { l := [1, 2, 3], h := rfl : Vec Nat 3 }
+example : Vec Nat 3 := { l := [1, 2, 3], h := rfl }
+
+example : Foo Nat (Vec Nat) := ⟨1, 3, bzz⟩
+
+example : Baz := ⟨⟨1, 3, bzz⟩, ⟨5, 7⟩, bzz⟩
+example : Baz := { a := 1, n := 3, b := bzz, c := 5, d := 7, v := bzz}
+def fzz : Foo Nat (Vec Nat) := {a := 1, n := 3, b := bzz}
+
+example : Foo Nat (Vec Nat) := { fzz with a := 7 }
+example : Baz := { fzz with c := 5, d := 7, v := bzz }
+
+example : Bar := { c := 8, d := 9 }
+example : Bar := { d := 9 }  -- uses the default value for c
+```
+
+.. _type_classes:
+
+Type Classes
+============
+
+(Classes and instances. Anonymous instances. Local instances.)
+
+
+.. [Dybjer] Dybjer, Peter, *Inductive Families*. Formal Aspects of Computing 6, 1994, pages 440-465.

doc/definitions.md

@@ -0,0 +1 @@
+# Definitions

doc/dep.md

@@ -0,0 +1,66 @@
+## What makes dependent type theory dependent?
+
+The short explanation is that what makes dependent type theory dependent is that types can depend on parameters.
+You have already seen a nice example of this: the type ``List α`` depends on the argument ``α``, and
+this dependence is what distinguishes ``List Nat`` and ``List Bool``.
+For another example, consider the type ``Vector α n``, the type of vectors of elements of ``α`` of length ``n``.
+This type depends on *two* parameters: the type ``α : Type`` of the elements in the vector and the length ``n : Nat``.
+
+Suppose we wish to write a function ``cons`` which inserts a new element at the head of a list.
+What type should ``cons`` have? Such a function is *polymorphic*: we expect the ``cons`` function for ``Nat``, ``Bool``,
+or an arbitrary type ``α`` to behave the same way.
+So it makes sense to take the type to be the first argument to ``cons``, so that for any type, ``α``, ``cons α``
+is the insertion function for lists of type ``α``. In other words, for every ``α``, ``cons α`` is the function that takes an element ``a : α``
+and a list ``as : List α``, and returns a new list, so we have ``cons α a as : list α``.
+
+It is clear that ``cons α`` should have type ``α → List α → List α``. But what type should ``cons`` have?
+A first guess might be ``Type → α → list α → list α``, but, on reflection, this does not make sense:
+the ``α`` in this expression does not refer to anything, whereas it should refer to the argument of type ``Type``.
+In other words, *assuming* ``α : Type`` is the first argument to the function, the type of the next two elements are ``α`` and ``List α``.
+These types vary depending on the first argument, ``α``.
+
+This is an instance of a *dependent function type*, or *dependent arrow type*. Given ``α : Type`` and ``β : α → Type``,
+think of ``β`` as a family of types over ``α``, that is, a type ``β a`` for each ``a : α``.
+In that case, the type ``(a : α) → β a`` denotes the type of functions ``f`` with the property that,
+for each ``a : α``, ``f a`` is an element of ``β a``. In other words, the type of the value returned by ``f`` depends on its input.
+
+Notice that ``(a : α) → β`` makes sense for any expression ``β : Type``. When the value of ``β`` depends on ``a``
+(as does, for example, the expression ``β a`` in the previous paragraph), ``(a : α) → β`` denotes a dependent function type.
+When ``β`` doesn't depend on ``a``, ``(a : α) → β`` is no different from the type ``α → β``.
+Indeed, in dependent type theory (and in Lean), ``α → β`` is just notation for ``(a : α) → β`` when ``β`` does not depend on ``a``.
+
+Returning to the example of lists, we can use the command `#check` to inspect the type of the following `List` functions
+We will explain the ``@`` symbol and the difference between the round and curly braces momentarily.
+
+```lean
+#check @List.cons    -- {α : Type u_1} → α → List α → List α
+#check @List.nil     -- {α : Type u_1} → List α
+#check @List.length  -- {α : Type u_1} → List α → Nat
+#check @List.append  -- {α : Type u_1} → List α → List α → List α
+```
+
+Just as dependent function types ``(a : α) → β a`` generalize the notion of a function type ``α → β`` by allowing ``β`` to depend on ``α``,
+dependent Cartesian product types ``(a : α) × β a`` generalize the Cartesian product ``α × β`` in the same way. Dependent products are also
+called *sigma* types, and you can also write them as `Σ a : α, β a`. You can use `⟨a, b⟩` or `Sigma.mk a b` to create a dependent pair.
+
+```lean
+universe u v
+
+def f (α : Type u) (β : α → Type v) (a : α) (b : β a) : (a : α) × β a :=
+  ⟨a, b⟩
+
+def g (α : Type u) (β : α → Type v) (a : α) (b : β a) : Σ a : α, β a :=
+  Sigma.mk a b
+
+#reduce f
+#reduce g
+
+#reduce f Type (fun α => α) Nat 10
+#reduce g Type (fun α => α) Nat 10
+
+#reduce (f Type (fun α => α) Nat 10).1 -- Nat
+#reduce (g Type (fun α => α) Nat 10).1 -- Nat
+#reduce (f Type (fun α => α) Nat 10).2 -- 10
+#reduce (g Type (fun α => α) Nat 10).2 -- 10
+```
+The function `f` and `g` above denote the same function.

doc/deptypes.md

@@ -0,0 +1,3 @@
+# Dependent Types
+
+In this section, we introduce simple type theory, types as objects, definitions, and explain what makes dependent type theory *dependent*.

doc/dev/ffi.md

@@ -140,7 +140,7 @@ lean_object * initialize_C(uint8_t builtin, lean_object *);
 ...
 
 lean_initialize_runtime_module();
-//lean_initialize();  // necessary (and replaces `lean_initialize_runtime_module`) if you (indirectly) access the `Lean` package
+//lean_initialize();  // necessary if you (indirectly) access the `Lean` package
 
 lean_object * res;
 // use same default as for Lean executables

doc/dev/mdbook.md

@@ -0,0 +1,109 @@
+# Documentation
+
+The Lean `doc` folder contains the [Lean Manual](https://lean-lang.org/lean4/doc/) and is
+authored in a combination of markdown (`*.md`) files and literate Lean files.  The .lean files are
+preprocessed using a tool called [LeanInk](https://github.com/leanprover/leanink) and
+[Alectryon](https://github.com/Kha/alectryon) which produces a generated markdown file.  We then run
+`mdbook` on the result to generate the html pages.
+
+
+## Settings
+
+We are using the following settings while editing the markdown docs.
+
+```json
+{
+    "files.insertFinalNewline": true,
+    "files.trimTrailingWhitespace": true,
+    "[markdown]": {
+        "rewrap.wrappingColumn": 70
+    }
+}
+```
+
+## Build
+
+### Using Nix
+
+Building the manual using Nix (which is what the CI does) is as easy as
+```bash
+$ nix build --update-input lean ./doc
+```
+You can also open a shell with `mdbook` for running the commands mentioned below with
+`nix develop ./doc#book`. Otherwise, read on.
+
+### Manually
+
+To build and test the book you have to preprocess the .lean files with Alectryon then use our own
+fork of the Rust tool named [mdbook](https://github.com/leanprover/mdbook). We have our own fork of
+mdBook with the following additional features:
+
+* Add support for hiding lines in other languages
+  [#1339](https://github.com/rust-lang/mdBook/pull/1339)
+* Make `mdbook test` call the `lean` compiler to test the snippets.
+* Ability to test a single chapter at a time which is handy when you
+are working on that chapter.  See the `--chapter` option.
+
+So you need to setup these tools before you can run `mdBook`.
+
+1. install [Rust](https://www.rust-lang.org/tools/install)
+which provides you with the `cargo` tool for building rust packages.
+Then run the following:
+    ```bash
+    cargo install --git https://github.com/leanprover/mdBook mdbook
+    ```
+
+1. Clone https://github.com/leanprover/LeanInk.git and run `lake build` then make the resulting
+   binary available to Alectryon using e.g.
+    ```bash
+    # make `leanInk` available in the current shell
+    export PATH=$PWD/build/bin:$PATH
+    ```
+
+1. Create a Python 3.10 environment.
+
+1. Install Alectryon:
+    ```
+    python3 -m pip install git+https://github.com/Kha/alectryon.git@typeid
+    ```
+
+1. Now you are ready to process the `*.lean` files using Alectryon as follows:
+
+    ```
+    cd lean4/doc
+    alectryon --frontend lean4+markup examples/palindromes.lean --backend webpage -o palindromes.lean.md
+    ```
+
+    Repeat this for the other .lean files you care about or write a script to process them all.
+
+1. Now you can build the book using:
+    ```
+    cd lean4/doc
+    mdbook build
+    ```
+
+This will put the HTML in a `out` folder so you can load `out/index.html` in your web browser and
+it should look like https://lean-lang.org/lean4/doc/.
+
+1. It is also handy to use e.g. [`mdbook watch`](https://rust-lang.github.io/mdBook/cli/watch.html)
+   in the `doc/` folder so that it keeps the html up to date while you are editing.
+
+    ```bash
+    mdbook watch --open  # opens the output in `out/` in your default browser
+    ```
+
+## Testing Lean Snippets
+
+You can run the following in the `doc/` folder to test all the lean code snippets.
+
+    ```bash
+    mdbook test
+    ```
+
+and you can use the `--chapter` option to test a specific chapter that you are working on:
+
+    ```bash
+    mdbook test --chapter Array
+    ```
+
+Use chapter name `?` to get a list of all the chapter names.

doc/dev/release_checklist.md

@@ -5,90 +5,124 @@ See below for the checklist for release candidates.
 
 We'll use `v4.6.0` as the intended release version as a running example.
 
-- Run `script/release_checklist.py v4.6.0` to check the status of the release.
-  This script is idempotent, and should be safe to run at any stage of the release process.
-  Note that as of v4.19.0, this script takes some autonomous actions, which can be prevented via `--dry-run`.
 - `git checkout releases/v4.6.0`
   (This branch should already exist, from the release candidates.)
 - `git pull`
 - In `src/CMakeLists.txt`, verify you see
   - `set(LEAN_VERSION_MINOR 6)` (for whichever `6` is appropriate)
   - `set(LEAN_VERSION_IS_RELEASE 1)`
-  - (all of these should already be in place from the release candidates)
+  - (both of these should already be in place from the release candidates)
 - `git tag v4.6.0`
 - `git push $REMOTE v4.6.0`, where `$REMOTE` is the upstream Lean repository (e.g., `origin`, `upstream`)
 - Now wait, while CI runs.
   - You can monitor this at `https://github.com/leanprover/lean4/actions/workflows/ci.yml`,
     looking for the `v4.6.0` tag.
-  - This step can take up to two hours.
+  - This step can take up to an hour.
   - If you are intending to cut the next release candidate on the same day,
     you may want to start on the release candidate checklist now.
-- Next we need to prepare the release notes.
-  - If the stable release is identical to the last release candidate (this should usually be the case),
-    you can reuse the release notes that are already in the Lean Language Reference.
-  - If you want to regenerate the release notes,
-    run `script/release_notes.py --since v4.5.0` on the `releases/v4.6.0` branch,
-    and see the section "Writing the release notes" below for more information.
-  - Release notes live in https://github.com/leanprover/reference-manual, in e.g. `Manual/Releases/v4.6.0.lean`.
-    It's best if you update these at the same time as a you update the `lean-toolchain` for the `reference-manual` repository, see below.
 - Go to https://github.com/leanprover/lean4/releases and verify that the `v4.6.0` release appears.
-  - Verify on Github that "Set as the latest release" is checked.
+  - Edit the release notes on Github to select the "Set as the latest release".
+  - Follow the instructions in creating a release candidate for the "GitHub release notes" step,
+    now that we have a written `RELEASES.md` section.
+    Do a quick sanity check.
 - Next, we will move a curated list of downstream repos to the latest stable release.
-  - In order to have the access rights to push to these repositories and merge PRs,
-    you will need to be a member of the `lean-release-managers` team at both `leanprover-community` and `leanprover`.
-    Contact Kim Morrison (@kim-em) to arrange access.
-  - For each of the repositories listed in `script/release_repos.yml`,
-    - Run `script/release_steps.py v4.6.0 <repo>` (e.g. replacing `<repo>` with `batteries`), which will walk you through the following steps:
-      - Create a new branch off `master`/`main` (as specified in the `branch` field), called `bump_to_v4.6.0`.
-      - Update the contents of `lean-toolchain` to `leanprover/lean4:v4.6.0`.
-      - In the `lakefile.toml` or `lakefile.lean`, if there are dependencies on specific version tags of dependencies, update them to the new tag.
-        If they depend on `main` or `master`, don't change this; you've just updated the dependency, so `lake update` will take care of modifying the manifest.
+  - For each of the repositories listed below:
+    - Make a PR to `master`/`main` changing the toolchain to `v4.6.0`
+      - Update the toolchain file
+      - In the Lakefile, if there are dependencies on specific version tags of dependencies that you've already pushed as part of this process, update them to the new tag.
+        If they depend on `main` or `master`, don't change this; you've just updated the dependency, so it will work and be saved in the manifest
       - Run `lake update`
-      - Commit the changes as `chore: bump toolchain to v4.6.0` and push.
-      - Create a PR with title "chore: bump toolchain to v4.6.0".
+      - The PR title should be "chore: bump toolchain to v4.6.0".
     - Merge the PR once CI completes.
-    - Re-running `script/release_checklist.py` will then create the tag `v4.6.0` from `master`/`main` and push it (unless `toolchain-tag: false` in the `release_repos.yml` file)
-    - `script/release_checklist.py` will then merge the tag `v4.6.0` into the `stable` branch and push it (unless `stable-branch: false` in the `release_repos.yml` file).
-  - Special notes on repositories with exceptional requirements:
-    - `doc-gen4` has addition dependencies which we do not update at each toolchain release, although occasionally these break and need to be updated manually.
-    - `verso`:
-      - The `subverso` dependency is unusual in that it needs to be compatible with _every_ Lean release simultaneously.
-        Usually you don't need to do anything.
-        If you think something is wrong here please contact David Thrane Christiansen (@david-christiansen)
-      - Warnings during `lake update` and `lake build` are expected.
-    - `reference-manual`: the release notes generated by `script/release_notes.py` as described above must be included in
-      `Manual/Releases/v4.6.0.lean`, and `import` and `include` statements adding in `Manual/Releases.lean`. 
-    - `ProofWidgets4` uses a non-standard sequential version tagging scheme, e.g. `v0.0.29`, which does not refer to the toolchain being used.
-      You will need to identify the next available version number from https://github.com/leanprover-community/ProofWidgets4/releases,
-      and push a new tag after merging the PR to `main`.
-    - `mathlib4`:
-      - The `lakefile.toml` should always refer to dependencies via their `main` or `master` branch,
-        not a toolchain tag
-        (with the exception of `ProofWidgets4`, which *must* use a sequential version tag).
-      - Push the PR branch to the main Mathlib repository rather than a fork, or CI may not work reliably
-    - `repl`:
-      There are two copies of `lean-toolchain`/`lakefile.lean`:
-      in the root, and in `test/Mathlib/`. Edit both, and run `lake update` in both directories.
-- An awkward situation that sometimes occurs (e.g. with Verso) is that the `master`/`main` branch has already been moved
-  to a nightly toolchain that comes *after* the stable toolchain we are
-  targeting. In this case it is necessary to create a branch `releases/v4.6.0` from the last commit which was on
-  an earlier toolchain, move that branch to the stable toolchain, and create the toolchain tag from that branch.
-- Run `script/release_checklist.py v4.6.0` one last time to check that everything is in order.
+    - Create the tag `v4.6.0` from `master`/`main` and push it.
+    - Merge the tag `v4.6.0` into the `stable` branch and push it.
+  - We do this for the repositories:
+    - [Batteries](https://github.com/leanprover-community/batteries)
+      - No dependencies
+      - Toolchain bump PR
+      - Create and push the tag
+      - Merge the tag into `stable`
+    - [lean4checker](https://github.com/leanprover/lean4checker)
+      - No dependencies
+      - Toolchain bump PR
+      - Create and push the tag
+      - Merge the tag into `stable`
+    - [doc-gen4](https://github.com/leanprover/doc-gen4)
+      - Dependencies: exist, but they're not part of the release workflow
+      - Toolchain bump PR including updated Lake manifest
+      - Create and push the tag
+      - There is no `stable` branch; skip this step
+    - [Verso](https://github.com/leanprover/verso)
+      - Dependencies: exist, but they're not part of the release workflow
+      - The `SubVerso` dependency should be compatible with _every_ Lean release simultaneously, rather than following this workflow
+      - Toolchain bump PR including updated Lake manifest
+      - Create and push the tag
+      - There is no `stable` branch; skip this step
+    - [Cli](https://github.com/leanprover/lean4-cli)
+      - No dependencies
+      - Toolchain bump PR
+      - Create and push the tag
+      - There is no `stable` branch; skip this step
+    - [ProofWidgets4](https://github.com/leanprover-community/ProofWidgets4)
+      - Dependencies: `Batteries`
+      - Note on versions and branches:
+        - `ProofWidgets` uses a sequential version tagging scheme, e.g. `v0.0.29`,
+          which does not refer to the toolchain being used.
+        - Make a new release in this sequence after merging the toolchain bump PR.
+        - `ProofWidgets` does not maintain a `stable` branch.
+      - Toolchain bump PR
+      - Create and push the tag, following the version convention of the repository
+    - [Aesop](https://github.com/leanprover-community/aesop)
+      - Dependencies: `Batteries`
+      - Toolchain bump PR including updated Lake manifest
+      - Create and push the tag
+      - Merge the tag into `stable`
+    - [import-graph](https://github.com/leanprover-community/import-graph)
+      - Toolchain bump PR including updated Lake manifest
+      - Create and push the tag
+      - There is no `stable` branch; skip this step
+    - [plausible](https://github.com/leanprover-community/plausible)
+      - Toolchain bump PR including updated Lake manifest
+      - Create and push the tag
+      - There is no `stable` branch; skip this step
+    - [Mathlib](https://github.com/leanprover-community/mathlib4)
+      - Dependencies: `Aesop`, `ProofWidgets4`, `lean4checker`, `Batteries`, `doc-gen4`, `import-graph`
+      - Toolchain bump PR notes:
+        - In addition to updating the `lean-toolchain` and `lakefile.lean`,
+          in `.github/workflows/lean4checker.yml` update the line
+          `git checkout v4.6.0` to the appropriate tag.
+        - Push the PR branch to the main Mathlib repository rather than a fork, or CI may not work reliably
+        - Create and push the tag
+        - Create a new branch from the tag, push it, and open a pull request against `stable`.
+          Coordinate with a Mathlib maintainer to get this merged.
+    - [REPL](https://github.com/leanprover-community/repl)
+      - Dependencies: `Mathlib` (for test code)
+      - Note that there are two copies of `lean-toolchain`/`lakefile.lean`:
+        in the root, and in `test/Mathlib/`. Edit both, and run `lake update` in both directories.
+      - Toolchain bump PR including updated Lake manifest
+      - Create and push the tag
+      - Merge the tag into `stable`
+- Run `scripts/release_checklist.py v4.6.0` to check that everything is in order.
+- The `v4.6.0` section of `RELEASES.md` is out of sync between
+  `releases/v4.6.0` and `master`. This should be reconciled:
+  - Replace the `v4.6.0` section on `master` with the `v4.6.0` section on `releases/v4.6.0`
+    and commit this to `master`.
+- Merge the release announcement PR for the Lean website - it will be deployed automatically
 - Finally, make an announcement!
   This should go in https://leanprover.zulipchat.com/#narrow/stream/113486-announce, with topic `v4.6.0`.
   Please see previous announcements for suggested language.
   You will want a few bullet points for main topics from the release notes.
-  If there is a blog post, link to that from the zulip announcement.
+  Link to the blog post from the Zulip announcement.
 - Make sure that whoever is handling social media knows the release is out.
 
-## Time estimates:
-- Initial checks and push the tag: 10 minutes.
-- Waiting for the release: 120 minutes.
-- Preparing release notes: 10 minutes.
-- Bumping toolchains in downstream repositories, up to creating the Mathlib PR: 60 minutes.
+## Optimistic(?) time estimates:
+- Initial checks and push the tag: 30 minutes.
+- Waiting for the release: 60 minutes.
+- Fixing release notes: 10 minutes.
+- Bumping toolchains in downstream repositories, up to creating the Mathlib PR: 30 minutes.
 - Waiting for Mathlib CI and bors: 120 minutes.
-- Finalizing Mathlib tags and stable branch, and updating REPL: 20 minutes.
-- Posting announcement and/or blog post: 30 minutes.
+- Finalizing Mathlib tags and stable branch, and updating REPL: 15 minutes.
+- Posting announcement and/or blog post: 20 minutes.
 
 # Creating a release candidate.
 
@@ -98,10 +132,6 @@ We'll use `v4.7.0-rc1` as the intended release version in this example.
 
 - Decide which nightly release you want to turn into a release candidate.
   We will use `nightly-2024-02-29` in this example.
-- It is essential to choose the nightly that will become the release candidate as early as possible, to avoid confusion.
-- Throughout this process you can use `script/release_checklist.py v4.7.0-rc1` to track progress.
-  This script will also try to do some steps autonomously. It is idempotent and safe to run at any point.
-  You can prevent it taking any actions using `--dry-run`.
 - It is essential that Batteries and Mathlib already have reviewed branches compatible with this nightly.
   - Check that both Batteries and Mathlib's `bump/v4.7.0` branch contain `nightly-2024-02-29`
     in their `lean-toolchain`.
@@ -112,68 +142,76 @@ We'll use `v4.7.0-rc1` as the intended release version in this example.
     git fetch nightly tag nightly-2024-02-29
     git checkout nightly-2024-02-29
     git checkout -b releases/v4.7.0
-    git push --set-upstream origin releases/v4.18.0
     ```
+- In `RELEASES.md` replace `Development in progress` in the `v4.7.0` section with `Release notes to be written.`
+- It is essential to choose the nightly that will become the release candidate as early as possible, to avoid confusion.
 - In `src/CMakeLists.txt`,
   - verify that you see `set(LEAN_VERSION_MINOR 7)` (for whichever `7` is appropriate); this should already have been updated when the development cycle began.
-  - change the `LEAN_VERSION_IS_RELEASE` line to `set(LEAN_VERSION_IS_RELEASE 1)` (this should be a change; on `master` and nightly releases it is always `0`).
+  - `set(LEAN_VERSION_IS_RELEASE 1)` (this should be a change; on `master` and nightly releases it is always `0`).
   - Commit your changes to `src/CMakeLists.txt`, and push.
 - `git tag v4.7.0-rc1`
 - `git push origin v4.7.0-rc1`
 - Now wait, while CI runs.
-  - The CI setup parses the tag to discover the `-rc1` special description, and passes it to `cmake` using a `-D` option. The `-rc1` doesn't need to be placed in the configuration file.
   - You can monitor this at `https://github.com/leanprover/lean4/actions/workflows/ci.yml`, looking for the `v4.7.0-rc1` tag.
-  - This step can take up to two hours.
-- Verify that the release appears at https://github.com/leanprover/lean4/releases/, marked as a prerelease (this should have been done automatically by the CI release job).
-- Next we need to prepare the release notes.
-  - Run `script/release_notes.py --since v4.6.0` on the `releases/v4.7.0` branch,
-    which will report diagnostic messages on `stderr`
-    (including reporting commits that it couldn't associate with a PR, and hence will be omitted)
-    and then a chunk of markdown on `stdout`.
-    See the section "Writing the release notes" below for more information.
-  - Release notes live in https://github.com/leanprover/reference-manual, in e.g. `Manual/Releases/v4.7.0.lean`.
-    It's best if you update these at the same time as a you update the `lean-toolchain` for the `reference-manual` repository, see below. 
+  - This step can take up to an hour.
+- (GitHub release notes) Once the release appears at https://github.com/leanprover/lean4/releases/
+  - Verify that the release is marked as a prerelease (this should have been done automatically by the CI release job).
+  - In the "previous tag" dropdown, select `v4.6.0`, and click "Generate release notes".
+    This will add a list of all the commits since the last stable version.
+    - Delete "update stage0" commits, and anything with a completely inscrutable commit message.
 - Next, we will move a curated list of downstream repos to the release candidate.
   - This assumes that for each repository either:
     * There is already a *reviewed* branch `bump/v4.7.0` containing the required adaptations.
       The preparation of this branch is beyond the scope of this document.
     * The repository does not need any changes to move to the new version.
-    * Note that sometimes there are *unreviewed* but necessary changes on the `nightly-testing` branch of the repository.
-      If so, you will need to merge these into the `bump_to_v4.7.0-rc1` branch manually.
-  - For each of the repositories listed in `script/release_repos.yml`,
-    - Run `script/release_steps.py v4.7.0-rc1 <repo>` (e.g. replacing `<repo>` with `batteries`), which will walk you through the following steps:
-      - Create a new branch off `master`/`main` (as specified in the `branch` field), called `bump_to_v4.7.0-rc1`.
-      - Merge `origin/bump/v4.7.0` if relevant (i.e. `bump-branch: true` appears in `release_repos.yml`).
-      - Otherwise, you *may* need to merge `origin/nightly-testing`.
-      - Note that for `verso` and `reference-manual` development happens on `nightly-testing`, so
-        we will merge that branch into `bump_to_v4.7.0-rc1`, but it is essential in the GitHub interface that we do a rebase merge,
-        in order to preserve the history.
-      - Update the contents of `lean-toolchain` to `leanprover/lean4:v4.7.0-rc1`.
-      - In the `lakefile.toml` or `lakefile.lean`, if there are dependencies on `nightly-testing`, `bump/v4.7.0`, or specific version tags, update them to the new tag.
-        If they depend on `main` or `master`, don't change this; you've just updated the dependency, so `lake update` will take care of modifying the manifest.
-      - Run `lake update`
-      - Run `lake build && if lake check-test; then lake test; fi` to check things are working.
-      - Commit the changes as `chore: bump toolchain to v4.7.0-rc1` and push.
-      - Create a PR with title "chore: bump toolchain to v4.7.0-rc1".
-    - Merge the PR once CI completes. (Recall: for `verso` and `reference-manual` you will need to do a rebase merge.)
-    - Re-running `script/release_checklist.py` will then create the tag `v4.7.0-rc1` from `master`/`main` and push it (unless `toolchain-tag: false` in the `release_repos.yml` file)
-  - We do this for the same list of repositories as for stable releases, see above for notes about special cases.
+  - For each of the target repositories:
+    - If the repository does not need any changes (i.e. `bump/v4.7.0` does not exist) then create
+      a new PR updating `lean-toolchain` to `leanprover/lean4:v4.7.0-rc1` and running `lake update`.
+    - Otherwise:
+      - Checkout the `bump/v4.7.0` branch.
+      - Verify that the `lean-toolchain` is set to the nightly from which the release candidate was created.
+      - `git merge origin/master`
+      - Change the `lean-toolchain` to `leanprover/lean4:v4.7.0-rc1`
+      - In `lakefile.lean`, change any dependencies which were using `nightly-testing` or `bump/v4.7.0` branches
+        back to `master` or `main`, and run `lake update` for those dependencies.
+      - Run `lake build` to ensure that dependencies are found (but it's okay to stop it after a moment).
+      - `git commit`
+      - `git push`
+      - Open a PR from `bump/v4.7.0` to `master`, and either merge it yourself after CI, if appropriate,
+        or notify the maintainers that it is ready to go.
+    - Once the PR has been merged, tag `master` with `v4.7.0-rc1` and push this tag.
+  - We do this for the same list of repositories as for stable releases, see above.
     As above, there are dependencies between these, and so the process above is iterative.
     It greatly helps if you can merge the `bump/v4.7.0` PRs yourself!
-  - It is essential for Mathlib and Batteries CI that you then create the next `bump/v4.8.0` branch
+    It is essential for Mathlib CI that you then create the next `bump/v4.8.0` branch
     for the next development cycle.
     Set the `lean-toolchain` file on this branch to same `nightly` you used for this release.
-- Run `script/release_checklist.py v4.7.0-rc1` one last time to check that everything is in order.
+  - For Batteries/Aesop/Mathlib, which maintain a `nightly-testing` branch, make sure there is a tag
+    `nightly-testing-2024-02-29` with date corresponding to the nightly used for the release
+    (create it if not), and then on the `nightly-testing` branch `git reset --hard master`, and force push.
 - Make an announcement!
   This should go in https://leanprover.zulipchat.com/#narrow/stream/113486-announce, with topic `v4.7.0-rc1`.
   Please see previous announcements for suggested language.
   You will want a few bullet points for main topics from the release notes.
   Please also make sure that whoever is handling social media knows the release is out.
 - Begin the next development cycle (i.e. for `v4.8.0`) on the Lean repository, by making a PR that:
-  - Uses branch name `dev_cycle_v4.8`.
   - Updates `src/CMakeLists.txt` to say `set(LEAN_VERSION_MINOR 8)`
+  - Replaces the "release notes will be copied" text in the `v4.6.0` section of `RELEASES.md` with the
+    finalized release notes from the `releases/v4.6.0` branch.
+  - Replaces the "development in progress" in the `v4.7.0` section of `RELEASES.md` with
+    ```
+    Release candidate, release notes will be copied from the branch `releases/v4.7.0` once completed.
+    ```
+    and inserts the following section before that section:
+    ```
+    v4.8.0
+    ----------
+    Development in progress.
+    ```
+  - Removes all the entries from the `./releases_drafts/` folder.
   - Titled "chore: begin development cycle for v4.8.0"
 
+
 ## Time estimates:
 Slightly longer than the corresponding steps for a stable release.
 Similar process, but more things go wrong.
@@ -214,16 +252,10 @@ Please read https://leanprover-community.github.io/contribute/tags_and_branches.
 
 Release notes are automatically generated from the commit history, using `script/release_notes.py`.
 
-Run this as `script/release_notes.py --since v4.6.0`, where `v4.6.0` is the *previous* release version.
-This script should be run on the `releases/v4.7.0` branch.
-This will generate output for all commits since that tag.
-Note that there is output on both stderr, which should be manually reviewed,
-and on stdout, which should be manually copied into the `reference-manual` repository, in the file `Manual/Releases/v4.7.0.lean`.
-
-The output on stderr should mostly be about commits for which the script could not find an associated PR,
-usually because a PR was rebase-merged because it contained an update to stage0.
-Some judgement is required here: ignore commits which look minor,
-but manually add items to the release notes for significant PRs that were rebase-merged.
+Run this as `script/release_notes.py v4.6.0`, where `v4.6.0` is the *previous* release version. This will generate output
+for all commits since that tag. Note that there is output on both stderr, which should be manually reviewed,
+and on stdout, which should be manually copied to `RELEASES.md`.
 
 There can also be pre-written entries in `./releases_drafts`, which should be all incorporated in the release notes and then deleted from the branch.
-See `./releases_drafts/README.md` for more information.
+  See `./releases_drafts/README.md` for more information.
+

doc/examples.md

@@ -0,0 +1,9 @@
+Examples
+========
+
+- [Palindromes](examples/palindromes.lean.md)
+- [Binary Search Trees](examples/bintree.lean.md)
+- [A Certified Type Checker](examples/tc.lean.md)
+- [The Well-Typed Interpreter](examples/interp.lean.md)
+- [Dependent de Bruijn Indices](examples/deBruijn.lean.md)
+- [Parametric Higher-Order Abstract Syntax](examples/phoas.lean.md)

doc/examples/README.md

@@ -1,4 +0,0 @@
-These examples are checked in Lean's CI to ensure that they continue
-to work. They are included in the documentation section of the Lean
-website via a script that copies the latest version, in order to
-ensure that the website tracks Lean releases rather than `master`.

doc/examples/bintree.lean

@@ -179,7 +179,7 @@ local macro "have_eq " lhs:term:max rhs:term:max : tactic =>
   `(tactic|
     (have h : $lhs = $rhs :=
        -- TODO: replace with linarith
-       by simp +arith at *; apply Nat.le_antisymm <;> assumption
+       by simp_arith at *; apply Nat.le_antisymm <;> assumption
      try subst $lhs))
 
 /-!

doc/examples/bintree.lean.md

@@ -0,0 +1,5 @@
+(this example is rendered by Alectryon in the CI)
+
+```lean
+{{#include bintree.lean}}
+```

doc/examples/deBruijn.lean.md

@@ -0,0 +1,5 @@
+(this example is rendered by Alectryon in the CI)
+
+```lean
+{{#include deBruijn.lean}}
+```

doc/examples/interp.lean.md

@@ -0,0 +1,5 @@
+(this example is rendered by Alectryon in the CI)
+
+```lean
+{{#include interp.lean}}
+```

doc/examples/palindromes.lean.md

@@ -0,0 +1,5 @@
+(this example is rendered by Alectryon in the CI)
+
+```lean
+{{#include palindromes.lean}}
+```

doc/examples/phoas.lean.md

@@ -0,0 +1,5 @@
+(this example is rendered by Alectryon in the CI)
+
+```lean
+{{#include phoas.lean}}
+```

doc/examples/tc.lean.md

@@ -0,0 +1,5 @@
+(this example is rendered by Alectryon in the CI)
+
+```lean
+{{#include tc.lean}}
+```

doc/examples/widgets.lean.md

@@ -0,0 +1,5 @@
+(this chapter is rendered by Alectryon in the CI)
+
+```lean
+{{#include widgets.lean}}
+```

doc/expressions.md

@@ -0,0 +1,550 @@
+Expressions
+===========
+
+Every expression in Lean has a [Type](types.md). Every type is also an
+expression of type `Sort u` for some universe level u. See [Type
+Universes](types.md#type_universes).
+
+Expression Syntax
+=================
+
+The set of expressions in Lean is defined inductively as follows:
+
+* ``Sort u`` : the universe of types at universe level ``u``
+* ``c`` : where ``c`` is an identifier denoting a declared constant or a defined object
+* ``x`` : where ``x`` is a variable in the local context in which the expression is interpreted
+* `m?`  : where `m?` is a metavariable in the metavariable context in which the expression is interpreted,
+  you can view metavariable as a "hole" that still needs to be synthesized
+* ``(x : α) → β`` : the type of functions taking an element ``x`` of ``α`` to an element of ``β``,
+  where ``β`` is an expression whose type is a ``Sort``
+* ``s t`` : the result of applying ``s`` to ``t``, where ``s`` and ``t`` are expressions
+* ``fun x : α => t`` or `λ x : α => t`: the function mapping any value ``x`` of type ``α`` to ``t``, where ``t`` is an expression
+* ``let x := t; s`` : a local definition, denotes the value of ``s`` when ``x`` is replaced by ``t``
+* `s.i`   : a projection, denotes the value of the `i`-th field of `s`
+* `lit`   : a natural number or string literal
+* `mdata k s` : the expression `s` decorated with metadata `k`, where is a key-value map
+
+Every well formed term in Lean has a *type*, which itself is an expression of type ``Sort u`` for some ``u``. The fact that a term ``t`` has type ``α`` is written ``t : α``.
+
+For an expression to be well formed, its components have to satisfy certain typing constraints. These, in turn, determine the type of the resulting term, as follows:
+
+* ``Sort u : Sort (u + 1)``
+* ``c : α``, where ``α`` is the type that ``c`` has been declared or defined to have
+* ``x : α``, where ``α`` is the type that ``x`` has been assigned in the local context where it is interpreted
+* ``?m : α``, where ``α`` is the type that ``?m`` has been declared in the metavariable context where it is interpreted
+* ``(x : α) → β : Sort (imax u v)`` where ``α : Sort u``, and ``β : Sort v`` assuming ``x : α``
+* ``s t : β[t/x]`` where ``s`` has type ``(x : α) → β`` and ``t`` has type ``α``
+* ``(fun x : α => t) : (x : α) → β`` if ``t`` has type ``β`` whenever ``x`` has type ``α``
+* ``(let x := t; s) : β[t/x]`` where ``t`` has type ``α`` and ``s`` has type ``β`` assuming ``x : α``
+* `lit : Nat` if `lit` is a numeral
+* `lit : String` if `lit` is a string literal
+* `mdata k s : α` if `s : α`
+* `s.i : α` if `s : β` and `β` is an inductive datatype with only one constructor, and `i`-th field has type `α`
+
+``Prop`` abbreviates ``Sort 0``, ``Type`` abbreviates ``Sort 1``, and
+``Type u`` abbreviates ``Sort (u + 1)`` when ``u`` is a universe
+variable. We say "``α`` is a type" to express ``α : Type u`` for some
+``u``, and we say "``p`` is a proposition" to express
+``p : Prop``. Using the *propositions as types* correspondence, given
+``p : Prop``, we refer to an expression ``t : p`` as a *proof* of ``p``. In
+contrast, given ``α : Type u`` for some ``u`` and ``t : α``, we
+sometimes refer to ``t`` as *data*.
+
+When the expression ``β`` in ``(x : α) → β`` does not depend on ``x``,
+it can be written ``α → β``. As usual, the variable ``x`` is bound in
+``(x : α) →  β``, ``fun x : α => t``, and ``let x := t; s``. The
+expression ``∀ x : α, β`` is alternative syntax for ``(x : α) →  β``,
+and is intended to be used when ``β`` is a proposition. An underscore
+can be used to generate an internal variable in a binder, as in
+``fun _ : α => t``.
+
+*Metavariables*, that is, temporary placeholders, are used in the
+process of constructing terms. Terms that are added to the
+environment contain neither metavariable nor variables, which is to
+say, they are fully elaborated and make sense in the empty context.
+
+Axioms can be declared using the ``axiom`` keyword.
+Similarly, objects can be defined in various ways, such as using ``def`` and ``theorem`` keywords.
+See [Chapter Declarations](./declarations.md) for more information.
+
+Writing an expression ``(t : α)`` forces Lean to elaborate ``t`` so that it has type ``α`` or report an error if it fails.
+
+Lean supports anonymous constructor notation, anonymous projections,
+and various forms of match syntax, including destructuring ``fun`` and
+``let``. These, as well as notation for common data types (like pairs,
+lists, and so on) are discussed in [Chapter Declarations](./declarations.md)
+in connection with inductive types.
+
+```lean
+universe u
+
+#check Sort 0
+#check Prop
+#check Sort 1
+#check Type
+#check Sort u
+#check Sort (u+1)
+
+#check Nat → Bool
+#check (α : Type u) → List α
+#check (α : Type u) → (β : Type u) → Sum α β
+#check fun x : Nat => x
+#check fun (α : Type u) (x : α) => x
+#check let x := 5; x * 2
+#check "hello"
+#check (fun x => x) true
+```
+
+Implicit Arguments
+==================
+
+When declaring arguments to defined objects in Lean (for example, with
+``def``, ``theorem``, ``axiom``, ``constant``, ``inductive``, or
+``structure``; see [Chapter Declarations](./declarations.md) or when
+declaring variables in sections (see [Other Commands](./other_commands.md)),
+arguments can be annotated as *explicit* or *implicit*.
+This determines how expressions containing the object are interpreted.
+
+* ``(x : α)`` : an explicit argument of type ``α``
+* ``{x : α}`` : an implicit argument, eagerly inserted
+* ``⦃x : α⦄`` or ``{{x : α}}`` : an implicit argument, weakly inserted
+* ``[x : α]`` : an implicit argument that should be inferred by type class resolution
+* ``(x : α := v)`` : an optional argument, with default value ``v``
+* ``(x : α := by tac)`` : an implicit argument, to be synthesized by tactic ``tac``
+
+The name of the variable can be omitted from a class resolution
+argument, in which case an internal name is generated.
+
+When a function has an explicit argument, you can nonetheless ask
+Lean's elaborator to infer the argument automatically, by entering it
+as an underscore (``_``). Conversely, writing ``@foo`` indicates that
+all of the arguments to be ``foo`` are to be given explicitly,
+independent of how ``foo`` was declared.  You can also provide a value
+for an implicit parameter using named arguments.  Named arguments
+enable you to specify an argument for a parameter by matching the
+argument with its name rather than with its position in the parameter
+list.  If you don't remember the order of the parameters but know
+their names, you can send the arguments in any order.  You may also
+provide the value for an implicit parameter whenLean failed to infer
+it. Named arguments also improve the readability of your code by
+identifying what each argument represents.
+
+
+```lean
+def add (x y : Nat) : Nat :=
+  x + y
+
+#check add 2 3 -- Nat
+#eval add 2 3  -- 5
+
+def id1 (α : Type u) (x : α) : α := x
+
+#check id1 Nat 3
+#check id1 _ 3
+
+def id2 {α : Type u} (x : α) : α := x
+
+#check id2 3
+#check @id2 Nat 3
+#check id2 (α := Nat) 3
+#check id2
+#check id2 (α := Nat)
+
+def id3 {{α : Type u}} (x : α) : α := x
+
+#check id3 3
+#check @id3 Nat 3
+#check (id3 : (α : Type) → α → α)
+
+class Cls where
+  val : Nat
+
+instance Cls_five : Cls where
+  val := 5
+
+def ex2 [c : Cls] : Nat := c.val
+
+example : ex2 = 5 := rfl
+
+def ex2a [Cls] : Nat := ex2
+
+example : ex2a = 5 := rfl
+
+def ex3 (x : Nat := 5) := x
+
+#check ex3 2
+#check ex3
+
+example : ex3 = 5 := rfl
+
+def ex4 (x : Nat) (y : Nat := x) : Nat :=
+  x * y
+
+example : ex4 x = x * x :=
+  rfl
+```
+
+Basic Data Types and Assertions
+===============================
+
+The core library contains a number of basic data types, such as the
+natural numbers (`Nat`), the integers (`Int`), the
+booleans (``Bool``), and common operations on these, as well as the
+usual logical quantifiers and connectives. Some example are given
+below. A list of common notations and their precedences can be found
+in a [file](https://github.com/leanprover/lean4/blob/master/src/Init/Notation.lean)
+in the core library. The core library also contains a number of basic
+data type constructors. Definitions can also be found the
+[Data](https://github.com/leanprover/lean4/blob/master/src/Init/Data)
+directory of the core library. For more information, see also [Chapter libraries](./libraries.md).
+
+```
+/- numbers -/
+def f1 (a b c : Nat) : Nat :=
+  a^2 + b^2 + c^2
+
+def p1 (a b c d : Nat) : Prop :=
+  (a + b)^c ≤ d
+
+def p2 (i j k : Int) : Prop :=
+  i % (j * k) = 0
+
+
+/- booleans -/
+
+def f2 (a b c : Bool) : Bool :=
+  a && (b || c)
+
+/- pairs -/
+
+#eval (1, 2)
+
+def p : Nat × Bool := (1, false)
+
+section
+variable (a b c : Nat) (p : Nat × bool)
+
+#check (1, 2)
+#check p.1 * 2
+#check p.2 && tt
+#check ((1, 2, 3) : Nat × Nat × Nat)
+end
+
+/- lists -/
+section
+variable x y z : Nat
+variable xs ys zs : list Nat
+open list
+
+#check (1 :: xs) ++ (y :: zs) ++ [1,2,3]
+#check append (cons 1 xs) (cons y zs)
+#check map (λ x, x^2) [1, 2, 3]
+end
+
+/- sets -/
+section
+variable s t u : set Nat
+
+#check ({1, 2, 3} ∩ s) ∪ ({x | x < 7} ∩ t)
+end
+
+/- strings and characters -/
+#check "hello world"
+#check 'a'
+
+/- assertions -/
+#check ∀ a b c n : Nat,
+  a ≠ 0 ∧ b ≠ 0 ∧ c ≠ 0 ∧ n > 2 → a^n + b^n ≠ c^n
+
+def unbounded (f : Nat → Nat) : Prop := ∀ M, ∃ n, f n ≥ M
+```
+.. _constructors_projections_and_matching:
+
+Constructors, Projections, and Matching
+=======================================
+
+Lean's foundation, the *Calculus of Inductive Constructions*, supports the declaration of *inductive types*. Such types can have any number of *constructors*, and an associated *eliminator* (or *recursor*). Inductive types with one constructor, known as *structures*, have *projections*. The full syntax of inductive types is described in [Declarations](declarations.md), but here we describe some syntactic elements that facilitate their use in expressions.
+
+When Lean can infer the type of an expression and it is an inductive type with one constructor, then one can write ``⟨a1, a2, ..., an⟩`` to apply the constructor without naming it. For example, ``⟨a, b⟩`` denotes ``prod.mk a b`` in a context where the expression can be inferred to be a pair, and ``⟨h₁, h₂⟩`` denotes ``and.intro h₁ h₂`` in a context when the expression can be inferred to be a conjunction. The notation will nest constructions automatically, so ``⟨a1, a2, a3⟩`` is interpreted as ``prod.mk a1 (prod.mk a2 a3)`` when the expression is expected to have a type of the form ``α1 × α2 × α3``. (The latter is interpreted as ``α1 × (α2 × α3)``, since the product associates to the right.)
+
+Similarly, one can use "dot notation" for projections: one can write ``p.fst`` and ``p.snd`` for ``prod.fst p`` and ``prod.snd p`` when Lean can infer that ``p`` is an element of a product, and ``h.left`` and ``h.right`` for ``and.left h`` and ``and.right h`` when ``h`` is a conjunction.
+
+The anonymous projector notation can used more generally for any objects defined in a *namespace* (see [Other Commands](other_commands.md)). For example, if ``l`` has type ``list α`` then ``l.map f`` abbreviates ``list.map f l``, in which ``l`` has been placed at the first argument position where ``list.map`` expects a ``list``.
+
+Finally, for data types with one constructor, one destruct an element by pattern matching using the ``let`` and ``assume`` constructs, as in the examples below. Internally, these are interpreted using the ``match`` construct, which is in turn compiled down for the eliminator for the inductive type, as described in [Declarations](declarations.md).
+
+.. code-block:: lean
+
+    universes u v
+    variable {α : Type u} {β : Type v}
+
+    def p : Nat × ℤ := ⟨1, 2⟩
+    #check p.fst
+    #check p.snd
+
+    def p' : Nat × ℤ × bool := ⟨1, 2, tt⟩
+    #check p'.fst
+    #check p'.snd.fst
+    #check p'.snd.snd
+
+    def swap_pair (p : α × β) : β × α :=
+    ⟨p.snd, p.fst⟩
+
+    theorem swap_conj {a b : Prop} (h : a ∧ b) : b ∧ a :=
+    ⟨h.right, h.left⟩
+
+    #check [1, 2, 3].append [2, 3, 4]
+    #check [1, 2, 3].map (λ x, x^2)
+
+    example (p q : Prop) : p ∧ q → q ∧ p :=
+    λ h, ⟨h.right, h.left⟩
+
+    def swap_pair' (p : α × β) : β × α :=
+    let (x, y) := p in (y, x)
+
+    theorem swap_conj' {a b : Prop} (h : a ∧ b) : b ∧ a :=
+    let ⟨ha, hb⟩ := h in ⟨hb, ha⟩
+
+    def swap_pair'' : α × β → β × α :=
+    λ ⟨x, y⟩, (y, x)
+
+    theorem swap_conj'' {a b : Prop} : a ∧ b → b ∧ a :=
+    assume ⟨ha, hb⟩, ⟨hb, ha⟩
+
+Structured Proofs
+=================
+
+Syntactic sugar is provided for writing structured proof terms:
+
+* ``have h : p := s; t`` is sugar for ``(fun h : p => t) s``
+* ``suffices h : p from s; t`` is sugar for ``(λ h : p => s) t``
+* ``suffices h : p by s; t`` is sugar for ``(suffixes h : p from by s; t)``
+* ``show p from t`` is sugar for ``(have this : p := t; this)``
+* ``show p by tac`` is sugar for ``(show p from by tac)``
+
+Types can be omitted when they can be inferred by Lean. Lean also
+allows ``have : p := t; s``, which gives the assumption the
+name ``this`` in the local context.  Similarly, Lean recognizes the
+variant ``suffices p from s; t``, which use the name ``this`` for the new hypothesis.
+
+The notation ``‹p›`` is notation for ``(by assumption : p)``, and can
+therefore be used to apply hypotheses in the local context.
+
+As noted in [Constructors, Projections and Matching](#constructors_projections_and_matching),
+anonymous constructors and projections and match syntax can be used in proofs just as in expressions that denote data.
+
+.. code-block:: lean
+
+    example (p q r : Prop) : p → (q ∧ r) → p ∧ q :=
+    assume h₁ : p,
+    assume h₂ : q ∧ r,
+    have h₃ : q, from and.left h₂,
+    show p ∧ q, from and.intro h₁ h₃
+
+    example (p q r : Prop) : p → (q ∧ r) → p ∧ q :=
+    assume : p,
+    assume : q ∧ r,
+    have q, from and.left this,
+    show p ∧ q, from and.intro ‹p› this
+
+    example (p q r : Prop) : p → (q ∧ r) → p ∧ q :=
+    assume h₁ : p,
+    assume h₂ : q ∧ r,
+    suffices h₃ : q, from and.intro h₁ h₃,
+    show q, from and.left h₂
+
+Lean also supports a calculational environment, which is introduced with the keyword ``calc``. The syntax is as follows:
+
+.. code-block:: text
+
+    calc
+      <expr>_0  'op_1'  <expr>_1  ':'  <proof>_1
+        '...'   'op_2'  <expr>_2  ':'  <proof>_2
+         ...
+        '...'   'op_n'  <expr>_n  ':'  <proof>_n
+
+Each ``<proof>_i`` is a proof for ``<expr>_{i-1} op_i <expr>_i``.
+
+Here is an example:
+
+.. code-block:: lean
+
+    variable (a b c d e : Nat)
+    variable h1 : a = b
+    variable h2 : b = c + 1
+    variable h3 : c = d
+    variable h4 : e = 1 + d
+
+    theorem T : a = e :=
+    calc
+      a     = b      : h1
+        ... = c + 1  : h2
+        ... = d + 1  : congr_arg _ h3
+        ... = 1 + d  : add_comm d (1 : Nat)
+        ... =  e     : eq.symm h4
+
+The style of writing proofs is most effective when it is used in conjunction with the ``simp`` and ``rewrite`` tactics.
+
+.. _computation:
+
+Computation
+===========
+
+Two expressions that differ up to a renaming of their bound variables are said to be *α-equivalent*, and are treated as syntactically equivalent by Lean.
+
+Every expression in Lean has a natural computational interpretation, unless it involves classical elements that block computation, as described in the next section. The system recognizes the following notions of *reduction*:
+
+* *β-reduction* : An expression ``(λ x, t) s`` β-reduces to ``t[s/x]``, that is, the result of replacing ``x`` by ``s`` in ``t``.
+* *ζ-reduction* : An expression ``let x := s in t`` ζ-reduces to ``t[s/x]``.
+* *δ-reduction* : If ``c`` is a defined constant with definition ``t``, then ``c`` δ-reduces to ``t``.
+* *ι-reduction* : When a function defined by recursion on an inductive type is applied to an element given by an explicit constructor, the result ι-reduces to the specified function value, as described in [Inductive Types](inductive.md).
+
+The reduction relation is transitive, which is to say, is ``s`` reduces to ``s'`` and ``t`` reduces to ``t'``, then ``s t`` reduces to ``s' t'``, ``λ x, s`` reduces to ``λ x, s'``, and so on. If ``s`` and ``t`` reduce to a common term, they are said to be *definitionally equal*. Definitional equality is defined to be the smallest equivalence relation that satisfies all these properties and also includes α-equivalence and the following two relations:
+
+* *η-equivalence* : An expression ``(λx, t x)`` is η-equivalent to ``t``, assuming ``x`` does not occur in ``t``.
+* *proof irrelevance* : If ``p : Prop``, ``s : p``, and ``t : p``, then ``s`` and ``t`` are  considered to be equivalent.
+
+This last fact reflects the intuition that once we have proved a proposition ``p``, we only care that is has been proved; the proof does nothing more than witness the fact that ``p`` is true.
+
+Definitional equality is a strong notion of equality of values. Lean's logical foundations sanction treating definitionally equal terms as being the same when checking that a term is well-typed and/or that it has a given type.
+
+The reduction relation is believed to be strongly normalizing, which is to say, every sequence of reductions applied to a term will eventually terminate. The property guarantees that Lean's type-checking algorithm terminates, at least in principle. The consistency of Lean and its soundness with respect to set-theoretic semantics do not depend on either of these properties.
+
+Lean provides two commands to compute with expressions:
+
+* ``#reduce t`` : use the kernel type-checking procedures to carry out reductions on ``t`` until no more reductions are possible, and show the result
+* ``#eval t`` : evaluate ``t`` using a fast bytecode evaluator, and show the result
+
+Every computable definition in Lean is compiled to bytecode at definition time. Bytecode evaluation is more liberal than kernel evaluation: types and all propositional information are erased, and functions are evaluated using a stack-based virtual machine. As a result, ``#eval`` is more efficient than ``#reduce,`` and can be used to execute complex programs. In contrast, ``#reduce`` is designed to be small and reliable, and to produce type-correct terms at each step. Bytecode is never used in type checking, so as far as soundness and consistency are concerned, only kernel reduction is part of the trusted computing base.
+
+.. code-block:: lean
+
+    #reduce (fun x => x + 3) 5
+    #eval   (fun x => x + 3) 5
+
+    #reduce let x := 5; x + 3
+    #eval   let x := 5; x + 3
+
+    def f x := x + 3
+
+    #reduce f 5
+    #eval   f 5
+
+    #reduce @Nat.rec (λ n => Nat) (0 : Nat)
+                     (λ n recval : Nat => recval + n + 1) (5 : Nat)
+
+    def g : Nat → Nat
+    | 0     => 0
+    | (n+1) => g n + n + 1
+
+    #reduce g 5
+    #eval   g 5
+
+    #eval   g 5000
+
+    example : (fun x => x + 3) 5 = 8 := rfl
+    example : (fun x => f x) = f := rfl
+    example (p : Prop) (h₁ h₂ : p) : h₁ = h₂ := rfl
+
+Note: the combination of proof irrelevance and singleton ``Prop`` elimination in ι-reduction renders the ideal version of definitional equality, as described above, undecidable. Lean's procedure for checking definitional equality is only an approximation to the ideal. It is not transitive, as illustrated by the example below. Once again, this does not compromise the consistency or soundness of Lean; it only means that Lean is more conservative in the terms it recognizes as well typed, and this does not cause problems in practice. Singleton elimination will be discussed in greater detail in [Inductive Types](inductive.md).
+
+.. code-block:: lean
+
+    def R (x y : unit) := false
+    def accrec := @acc.rec unit R (λ_, unit) (λ _ a ih, ()) ()
+    example (h) : accrec h = accrec (acc.intro _ (λ y, acc.inv h)) :=
+                  rfl
+    example (h) : accrec (acc.intro _ (λ y, acc.inv h)) = () := rfl
+    example (h) : accrec h = () := sorry   -- rfl fails
+
+
+Axioms
+======
+
+Lean's foundational framework consists of:
+
+- type universes and dependent function types, as described above
+
+- inductive definitions, as described in [Inductive Types](inductive.md) and
+[Inductive Families](declarations.md#inductive-families).
+
+In addition, the core library defines (and trusts) the following axiomatic extensions:
+
+- propositional extensionality:
+
+  .. code-block:: lean
+
+     namespace hide
+
+     -- BEGIN
+     axiom propext {a b : Prop} : (a ↔ b) → a = b
+     -- END
+
+     end hide
+
+- quotients:
+
+  .. code-block:: lean
+
+     namespace hide
+     -- BEGIN
+     universes u v
+
+     constant quot      : Π {α : Sort u}, (α → α → Prop) → Sort u
+
+     constant quot.mk   : Π {α : Sort u} (r : α → α → Prop),
+                          α → quot r
+
+     axiom    quot.ind  : ∀ {α : Sort u} {r : α → α → Prop}
+                            {β : quot r → Prop},
+                          (∀ a, β (quot.mk r a)) →
+                            ∀ (q : quot r), β q
+
+     constant quot.lift : Π {α : Sort u} {r : α → α → Prop}
+                            {β : Sort u} (f : α → β),
+                          (∀ a b, r a b → f a = f b) → quot r → β
+
+     axiom quot.sound   : ∀ {α : Type u} {r : α → α → Prop}
+                            {a b : α},
+                          r a b → quot.mk r a = quot.mk r b
+     -- END
+     end hide
+
+  ``quot r`` represents the quotient of ``α`` by the smallest equivalence relation containing ``r``. ``quot.mk`` and ``quot.lift`` satisfy the following computation rule:
+
+  .. code-block:: text
+
+     quot.lift f h (quot.mk r a) = f a
+
+- choice:
+
+  .. code-block:: lean
+
+     namespace hide
+     universe u
+
+     -- BEGIN
+     axiom choice {α : Sort u} : nonempty α → α
+     -- END
+
+     end hide
+
+  Here ``nonempty α`` is defined as follows:
+
+  .. code-block:: lean
+
+     namespace hide
+     universe u
+
+     -- BEGIN
+     class inductive nonempty (α : Sort u) : Prop
+     | intro : α → nonempty
+     -- END
+
+     end hide
+
+  It is equivalent to  ``∃ x : α, true``.
+
+The quotient construction implies function extensionality. The ``choice`` principle, in conjunction with the others, makes the axiomatic foundation classical; in particular, it implies the law of the excluded middle and propositional decidability. Functions that make use of ``choice`` to produce data are incompatible with a computational interpretation, and do not produce bytecode. They have to be declared ``noncomputable``.
+
+For metaprogramming purposes, Lean also allows the definition of objects which stand outside the object language. These are denoted with the ``meta`` keyword, as described in [Metaprogramming](metaprogramming.md).

doc/faq.md

@@ -0,0 +1,55 @@
+Frequently Asked Questions
+==========================
+
+### What is Lean?
+
+Lean is a new open source theorem prover being developed at Microsoft Research.
+It is a research project that aims to bridge the gap between interactive and automated theorem proving.
+Lean can be also used as a programming language. Actually, some Lean features are implemented in Lean itself.
+
+### Should I use Lean?
+
+Lean is under heavy development, and we are constantly trying new
+ideas and tweaking the system.  It is a research project and not a product.
+Things change rapidly, and we constantly break backward compatibility.
+Lean comes "as is", you should not expect we will fix bugs and/or add new features for your project.
+We have our own priorities, and will not change them to accommodate your needs.
+Even if you implement a new feature or fix a bug, we may not want to merge it because
+it may conflict with our plans for Lean, it may not be performant, we may not want to maintain it,
+we may be busy, etc. If you really need this new feature or bug fix, we suggest you create your own fork and maintain it yourself.
+
+### Where is the documentation?
+
+This is the Lean 4 manual. It is a work in progress, but it will eventually cover the whole language.
+A public and very active chat room dedicated to Lean is open on [Zulip](https://leanprover.zulipchat.com).
+It is a good place to interact with other Lean users.
+
+### Should I use Lean to teach a course?
+
+Lean has been used to teach courses on logic, type theory and programming languages at CMU and the University of Washington.
+The lecture notes for the CMU course [Logic and Proof](https://lean-lang.org/logic_and_proof) are available online,
+but they are for Lean 3.
+If you decide to teach a course using Lean, we suggest you prepare all material before the beginning of the course, and
+make sure that Lean attends all your needs. You should not expect we will fix bugs and/or add features needed for your course.
+
+### Are there IDEs for Lean?
+
+Yes, see [Setting Up Lean](./setup.md).
+
+### Is Lean sound? How big is the kernel? Should I trust it?
+
+Lean has a relatively small kernel.
+Several independent checkers have been implemented for Lean 3. Two of them are
+[tc](https://github.com/leanprover/tc) and [trepplein](https://github.com/gebner/trepplein).
+We expect similar independent checkers will be built for Lean 4.
+
+### Should I open a new issue?
+
+We use [GitHub](https://github.com/leanprover/lean4/issues) to track bugs and new features.
+Bug reports are always welcome, but nitpicking issues are not (e.g., the error message is confusing).
+See also our [contribution guidelines](https://github.com/leanprover/lean4/blob/master/CONTRIBUTING.md).
+
+### Is it Lean, LEAN, or L∃∀N?
+
+We always use "Lean" in writing.
+When specifying a major version number, we append it together with a single space: Lean 4.

doc/flake.lock

@@ -0,0 +1,151 @@
+{
+  "nodes": {
+    "alectryon": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1654613606,
+        "narHash": "sha256-IGCn1PzTyw8rrwmyWUiw3Jo/dyZVGkMslnHYW7YB8yk=",
+        "owner": "Kha",
+        "repo": "alectryon",
+        "rev": "c3b16f650665745e1da4ddfcc048d3bd639f71d5",
+        "type": "github"
+      },
+      "original": {
+        "owner": "Kha",
+        "ref": "typeid",
+        "repo": "alectryon",
+        "type": "github"
+      }
+    },
+    "flake-utils": {
+      "inputs": {
+        "systems": "systems"
+      },
+      "locked": {
+        "lastModified": 1710146030,
+        "narHash": "sha256-SZ5L6eA7HJ/nmkzGG7/ISclqe6oZdOZTNoesiInkXPQ=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "b1d9ab70662946ef0850d488da1c9019f3a9752a",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    },
+    "lean": {
+      "inputs": {
+        "flake-utils": "flake-utils",
+        "nixpkgs": "nixpkgs",
+        "nixpkgs-old": "nixpkgs-old"
+      },
+      "locked": {
+        "lastModified": 0,
+        "narHash": "sha256-saRAtQ6VautVXKDw1XH35qwP0KEBKTKZbg/TRa4N9Vw=",
+        "path": "../.",
+        "type": "path"
+      },
+      "original": {
+        "path": "../.",
+        "type": "path"
+      }
+    },
+    "leanInk": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1704976501,
+        "narHash": "sha256-FSBUsbX0HxakSnYRYzRBDN2YKmH9EkA0q9p7TSPEJTI=",
+        "owner": "leanprover",
+        "repo": "LeanInk",
+        "rev": "51821e3c2c032c88e4b2956483899d373ec090c4",
+        "type": "github"
+      },
+      "original": {
+        "owner": "leanprover",
+        "ref": "refs/pull/57/merge",
+        "repo": "LeanInk",
+        "type": "github"
+      }
+    },
+    "mdBook": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1660074464,
+        "narHash": "sha256-W30G7AeWBjdJE/CQZJU5vJjaDGZtpmxEKNMEvaYtuF8=",
+        "owner": "leanprover",
+        "repo": "mdBook",
+        "rev": "9321c10c502cd59eea8afc4325a84eab3ddf9391",
+        "type": "github"
+      },
+      "original": {
+        "owner": "leanprover",
+        "repo": "mdBook",
+        "type": "github"
+      }
+    },
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1710889954,
+        "narHash": "sha256-Pr6F5Pmd7JnNEMHHmspZ0qVqIBVxyZ13ik1pJtm2QXk=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "7872526e9c5332274ea5932a0c3270d6e4724f3b",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixpkgs-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "nixpkgs-old": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1581379743,
+        "narHash": "sha256-i1XCn9rKuLjvCdu2UeXKzGLF6IuQePQKFt4hEKRU5oc=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "34c7eb7545d155cc5b6f499b23a7cb1c96ab4d59",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixos-19.03",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "alectryon": "alectryon",
+        "flake-utils": [
+          "lean",
+          "flake-utils"
+        ],
+        "lean": "lean",
+        "leanInk": "leanInk",
+        "mdBook": "mdBook"
+      }
+    },
+    "systems": {
+      "locked": {
+        "lastModified": 1681028828,
+        "narHash": "sha256-Vy1rq5AaRuLzOxct8nz4T6wlgyUR7zLU309k9mBC768=",
+        "owner": "nix-systems",
+        "repo": "default",
+        "rev": "da67096a3b9bf56a91d16901293e51ba5b49a27e",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-systems",
+        "repo": "default",
+        "type": "github"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}

doc/flake.nix

@@ -0,0 +1,93 @@
+{
+  description = "Lean documentation";
+
+  inputs.lean.url = path:../.;
+  inputs.flake-utils.follows = "lean/flake-utils";
+  inputs.mdBook = {
+    url = "github:leanprover/mdBook";
+    flake = false;
+  };
+  inputs.alectryon = {
+    url = "github:Kha/alectryon/typeid";
+    flake = false;
+  };
+  inputs.leanInk = {
+    url = "github:leanprover/LeanInk/refs/pull/57/merge";
+    flake = false;
+  };
+
+  outputs = inputs@{ self, ... }: inputs.flake-utils.lib.eachDefaultSystem (system:
+    with inputs.lean.packages.${system}.deprecated; with nixpkgs;
+    let
+      doc-src = lib.sourceByRegex ../. ["doc.*" "tests(/lean(/beginEndAsMacro.lean)?)?"];
+    in {
+    packages = rec {
+      lean-mdbook = mdbook.overrideAttrs (drv: rec {
+        name = "lean-${mdbook.name}";
+        src = inputs.mdBook;
+        cargoDeps = drv.cargoDeps.overrideAttrs (_: {
+          inherit src;
+          outputHash = "sha256-CO3A9Kpp4sIvkT9X3p+GTidazk7Fn4jf0AP2PINN44A=";
+        });
+        doCheck = false;
+      });
+      book = stdenv.mkDerivation {
+        name ="lean-doc";
+        src = doc-src;
+        buildInputs = [ lean-mdbook ];
+        buildCommand = ''
+          mkdir $out
+          # necessary for `additional-css`...?
+          cp -r --no-preserve=mode $src/doc/* .
+          # overwrite stub .lean.md files
+          cp -r ${inked}/* .
+          mdbook build -d $out
+        '';
+      };
+      leanInk = (buildLeanPackage {
+        name = "Main";
+        src = inputs.leanInk;
+        deps = [ (buildLeanPackage {
+          name = "LeanInk";
+          src = inputs.leanInk;
+        }) ];
+        executableName = "leanInk";
+        linkFlags = ["-rdynamic"];
+      }).executable;
+      alectryon = python3Packages.buildPythonApplication {
+        name = "alectryon";
+        src = inputs.alectryon;
+        propagatedBuildInputs =
+          [ leanInk lean-all ] ++
+          # https://github.com/cpitclaudel/alectryon/blob/master/setup.cfg
+          (with python3Packages; [ pygments dominate beautifulsoup4 docutils ]);
+        doCheck = false;
+      };
+      renderLeanMod = mod: mod.overrideAttrs (final: prev: {
+        name = "${prev.name}.md";
+        buildInputs = prev.buildInputs ++ [ alectryon ];
+        outputs = [ "out" ];
+        buildCommand = ''
+          dir=$(dirname $relpath)
+          mkdir -p $dir out/$dir
+          if [ -d $src ]; then cp -r $src/. $dir/; else cp $src $leanPath; fi
+          alectryon --frontend lean4+markup $leanPath --backend webpage -o $out/$leanPath.md
+        '';
+      });
+      renderPackage = pkg: symlinkJoin {
+        name = "${pkg.name}-mds";
+        paths = map renderLeanMod (lib.attrValues pkg.mods);
+      };
+      literate = buildLeanPackage {
+        name = "literate";
+        src = ./.;
+        roots = [
+          { mod = "examples"; glob = "submodules"; }
+        ];
+      };
+      inked = renderPackage literate;
+      doc = book;
+    };
+    defaultPackage = self.packages.${system}.doc;
+  });
+}

doc/fplean.md

@@ -0,0 +1,7 @@
+Functional Programming in Lean
+=======================
+
+The goal of [this book](https://lean-lang.org/functional_programming_in_lean/) is to be an accessible introduction to using Lean 4 as a programming language.
+It should be useful both to people who want to use Lean as a general-purpose programming language and to mathematicians who want to develop larger-scale proof automation but do not have a background in functional programming.
+It does not assume any background with functional programming, though it's probably not a good first book on programming in general.
+New content will be added once per month until it's done.

doc/funabst.md

@@ -0,0 +1,145 @@
+## Function Abstraction and Evaluation
+
+We have seen that if we have ``m n : Nat``, then we have ``(m, n) : Nat × Nat``.
+This gives us a way of creating pairs of natural numbers.
+Conversely, if we have ``p : Nat × Nat``, then
+we have ``p.1 : Nat`` and ``p.2 : Nat``.
+This gives us a way of "using" a pair, by extracting its two components.
+
+We already know how to "use" a function ``f : α → β``, namely,
+we can apply it to an element ``a : α`` to obtain ``f a : β``.
+But how do we create a function from another expression?
+
+The companion to application is a process known as "lambda abstraction."
+Suppose that giving a variable ``x : α`` we can construct an expression ``t : β``.
+Then the expression ``fun (x : α) => t``, or, equivalently, ``λ (x : α) => t``, is an object of type ``α → β``.
+Think of this as the function from ``α`` to ``β`` which maps any value ``x`` to the value ``t``,
+which may depend on ``x``.
+
+```lean
+#check fun (x : Nat) => x + 5
+#check λ (x : Nat) => x + 5
+#check fun x : Nat => x + 5
+#check λ x : Nat => x + 5
+```
+
+Here are some more examples:
+
+```lean
+constant f : Nat → Nat
+constant h : Nat → Bool → Nat
+
+#check fun x : Nat => fun y : Bool => h (f x) y   -- Nat → Bool → Nat
+#check fun (x : Nat) (y : Bool) => h (f x) y      -- Nat → Bool → Nat
+#check fun x y => h (f x) y                       -- Nat → Bool → Nat
+```
+
+Lean interprets the final three examples as the same expression; in the last expression,
+Lean infers the type of ``x`` and ``y`` from the types of ``f`` and ``h``.
+
+Some mathematically common examples of operations of functions can be described in terms of lambda abstraction:
+
+```lean
+constant f : Nat → String
+constant g : String → Bool
+constant b : Bool
+
+#check fun x : Nat => x        -- Nat → Nat
+#check fun x : Nat => b        -- Nat → Bool
+#check fun x : Nat => g (f x)  -- Nat → Bool
+#check fun x => g (f x)        -- Nat → Bool
+```
+
+Think about what these expressions mean. The expression ``fun x : Nat => x`` denotes the identity function on ``Nat``,
+the expression ``fun x : α => b`` denotes the constant function that always returns ``b``,
+and ``fun x : Nat => g (f x)``, denotes the composition of ``f`` and ``g``.
+We can, in general, leave off the type annotation on a variable and let Lean infer it for us.
+So, for example, we can write ``fun x => g (f x)`` instead of ``fun x : Nat => g (f x)``.
+
+We can abstract over the constants `f` and `g` in the previous definitions:
+
+```lean
+#check fun (g : String → Bool) (f : Nat → String) (x : Nat) => g (f x)
+-- (String → Bool) → (Nat → String) → Nat → Bool
+```
+
+We can also abstract over types:
+
+```lean
+#check fun (α β γ : Type) (g : β → γ) (f : α → β) (x : α) => g (f x)
+```
+The last expression, for example, denotes the function that takes three types, ``α``, ``β``, and ``γ``, and two functions, ``g : β → γ`` and ``f : α → β``, and returns the composition of ``g`` and ``f``. (Making sense of the type of this function requires an understanding of dependent products, which we will explain below.) Within a lambda expression ``fun x : α => t``, the variable ``x`` is a "bound variable": it is really a placeholder, whose "scope" does not extend beyond ``t``.
+For example, the variable ``b`` in the expression ``fun (b : β) (x : α) => b`` has nothing to do with the constant ``b`` declared earlier.
+In fact, the expression denotes the same function as ``fun (u : β) (z : α), u``. Formally, the expressions that are the same up to a renaming of bound variables are called *alpha equivalent*, and are considered "the same." Lean recognizes this equivalence.
+
+Notice that applying a term ``t : α → β`` to a term ``s : α`` yields an expression ``t s : β``.
+Returning to the previous example and renaming bound variables for clarity, notice the types of the following expressions:
+
+```lean
+#check (fun x : Nat => x) 1     -- Nat
+#check (fun x : Nat => true) 1  -- Bool
+
+constant f : Nat → String
+constant g : String → Bool
+
+#check
+  (fun (α β γ : Type) (g : β → γ) (f : α → β) (x : α) => g (f x)) Nat String Bool g f 0
+  -- Bool
+```
+
+As expected, the expression ``(fun x : Nat =>  x) 1`` has type ``Nat``.
+In fact, more should be true: applying the expression ``(fun x : Nat => x)`` to ``1`` should "return" the value ``1``. And, indeed, it does:
+
+```lean
+#reduce (fun x : Nat => x) 1     -- 1
+#reduce (fun x : Nat => true) 1  -- true
+
+constant f : Nat → String
+constant g : String → Bool
+
+#reduce
+  (fun (α β γ : Type) (g : β → γ) (f : α → β) (x : α) => g (f x)) Nat String Bool g f 0
+  -- g (f 0)
+```
+
+The command ``#reduce`` tells Lean to evaluate an expression by *reducing* it to its normal form,
+which is to say, carrying out all the computational reductions that are sanctioned by its kernel.
+The process of simplifying an expression ``(fun x => t) s`` to ``t[s/x]`` -- that is, ``t`` with ``s`` substituted for the variable ``x`` --
+is known as *beta reduction*, and two terms that beta reduce to a common term are called *beta equivalent*.
+But the ``#reduce`` command carries out other forms of reduction as well:
+
+```lean
+constant m : Nat
+constant n : Nat
+constant b : Bool
+
+#reduce (m, n).1        -- m
+#reduce (m, n).2        -- n
+
+#reduce true && false   -- false
+#reduce false && b      -- false
+#reduce b && false      -- Bool.rec false false b
+
+#reduce n + 0           -- n
+#reduce n + 2           -- Nat.succ (Nat.succ n)
+#reduce 2 + 3           -- 5
+```
+
+We explain later how these terms are evaluated.
+For now, we only wish to emphasize that this is an important feature of dependent type theory:
+every term has a computational behavior, and supports a notion of reduction, or *normalization*.
+In principle, two terms that reduce to the same value are called *definitionally equal*.
+They are considered "the same" by Lean's type checker, and Lean does its best to recognize and support these identifications.
+The `#reduce` command is mainly useful to understand why two terms are considered the same.
+
+Lean is also a programming language. It has a compiler to native code and an interpreter.
+You can use the command `#eval` to execute expressions, and it is the preferred way of testing your functions.
+Note that `#eval` and `#reduce` are *not* equivalent. The command `#eval` first compiles Lean expressions
+into an intermediate representation (IR) and then uses an interpreter to execute the generated IR.
+Some builtin types (e.g., `Nat`, `String`, `Array`) have a more efficient representation in the IR.
+The IR has support for using foreign functions that are opaque to Lean.
+
+In contrast, the ``#reduce`` command relies on a reduction engine similar to the one used in Lean's trusted kernel,
+the part of Lean that is responsible for checking and verifying the correctness of expressions and proofs.
+It is less efficient than ``#eval``, and treats all foreign functions as opaque constants.
+We later discuss other differences between the two commands.

doc/introdef.md

@@ -0,0 +1,66 @@
+## Introducing Definitions
+
+The ``def`` command provides one important way of defining new objects.
+
+```lean
+
+def foo : (Nat → Nat) → Nat :=
+  fun f => f 0
+
+#check foo   -- (Nat → Nat) → Nat
+#print foo
+```
+
+We can omit the type when Lean has enough information to infer it:
+
+```lean
+def foo :=
+  fun (f : Nat → Nat) => f 0
+```
+
+The general form of a definition is ``def foo : α := bar``. Lean can usually infer the type ``α``, but it is often a good idea to write it explicitly.
+This clarifies your intention, and Lean will flag an error if the right-hand side of the definition does not have the right type.
+
+Lean also allows us to use an alternative format that puts the abstracted variables before the colon and omits the lambda:
+```lean
+def double (x : Nat) : Nat :=
+  x + x
+
+#print double
+#check double 3
+#reduce double 3  -- 6
+#eval double 3    -- 6
+
+def square (x : Nat) :=
+  x * x
+
+#print square
+#check square 3
+#reduce square 3  -- 9
+#eval square 3    -- 9
+
+def doTwice (f : Nat → Nat) (x : Nat) : Nat :=
+  f (f x)
+
+#eval doTwice double 2   -- 8
+```
+
+These definitions are equivalent to the following:
+
+```lean
+def double : Nat → Nat :=
+  fun x => x + x
+
+def square : Nat → Nat :=
+  fun x => x * x
+
+def doTwice : (Nat → Nat) → Nat → Nat :=
+  fun f x => f (f x)
+```
+
+We can even use this approach to specify arguments that are types:
+
+```lean
+def compose (α β γ : Type) (g : β → γ) (f : α → β) (x : α) : γ :=
+  g (f x)
+```

doc/lean3changes.md

@@ -0,0 +1,369 @@
+# Significant changes from Lean 3
+
+Lean 4 is not backward compatible with Lean 3.
+We have rewritten most of the system, and took the opportunity to cleanup the syntax,
+metaprogramming framework, and elaborator. In this section, we go over the most significant
+changes.
+
+## Lambda expressions
+
+We do not use `,` anymore to separate the binders from the lambda expression body.
+The Lean 3 syntax for lambda expressions was unconventional, and `,` has been overused in Lean 3.
+For example, we believe a list of lambda expressions is quite confusing in Lean 3, since `,` is used
+to separate the elements of a list, and in the lambda expression itself. We now use `=>` as the separator,
+as an example, `fun x => x` is the identity function. One may still use the symbol `λ` as a shorthand for `fun`.
+The lambda expression notation has many new features that are not supported in Lean 3.
+
+## Pattern matching
+
+In Lean 4, one can easily create new notation that abbreviates commonly used idioms. One of them is a
+`fun` followed by a `match`. In the following examples, we define a few functions using `fun`+`match` notation.
+
+```lean
+# namespace ex1
+def Prod.str : Nat × Nat → String :=
+  fun (a, b) => "(" ++ toString a ++ ", " ++ toString b ++ ")"
+
+structure Point where
+  x : Nat
+  y : Nat
+  z : Nat
+
+def Point.addX : Point → Point → Nat :=
+  fun { x := a, .. } { x := b, .. } =>  a+b
+
+def Sum.str : Option Nat → String :=
+  fun
+    | some a => "some " ++ toString a
+    | none   => "none"
+# end ex1
+```
+
+## Implicit lambdas
+
+In Lean 3 stdlib, we find many [instances](https://github.com/leanprover/lean/blob/master/library/init/category/reader.lean#L39) of the dreadful `@`+`_` idiom.
+It is often used when the expected type is a function type with implicit arguments,
+and we have a constant (`reader_t.pure` in the example) which also takes implicit arguments. In Lean 4, the elaborator automatically introduces lambdas
+for consuming implicit arguments. We are still exploring this feature and analyzing its impact, but the experience so far has been very positive. As an example,
+here is the example in the link above using Lean 4 implicit lambdas.
+
+```lean
+# variable (ρ : Type) (m : Type → Type) [Monad m]
+instance : Monad (ReaderT ρ m) where
+  pure := ReaderT.pure
+  bind := ReaderT.bind
+```
+
+Users can disable the implicit lambda feature by using `@` or writing a lambda expression with `{}` or `[]` binder annotations.
+Here are few examples
+
+```lean
+# namespace ex2
+def id1 : {α : Type} → α → α :=
+  fun x => x
+
+def listId : List ({α : Type} → α → α) :=
+  (fun x => x) :: []
+
+-- In this example, implicit lambda introduction has been disabled because
+-- we use `@` before `fun`
+def id2 : {α : Type} → α → α :=
+  @fun α (x : α) => id1 x
+
+def id3 : {α : Type} → α → α :=
+  @fun α x => id1 x
+
+def id4 : {α : Type} → α → α :=
+  fun x => id1 x
+
+-- In this example, implicit lambda introduction has been disabled
+-- because we used the binder annotation `{...}`
+def id5 : {α : Type} → α → α :=
+  fun {α} x => id1 x
+# end ex2
+```
+
+## Sugar for simple functions
+
+In Lean 3, we can create simple functions from infix operators by using parentheses. For example, `(+1)` is sugar for `fun x, x + 1`. In Lean 4, we generalize this notation using `·` as a placeholder. Here are a few examples:
+
+```lean
+# namespace ex3
+#check (· + 1)
+-- fun a => a + 1
+#check (2 - ·)
+-- fun a => 2 - a
+#eval [1, 2, 3, 4, 5].foldl (·*·) 1
+-- 120
+
+def f (x y z : Nat) :=
+  x + y + z
+
+#check (f · 1 ·)
+-- fun a b => f a 1 b
+
+#eval [(1, 2), (3, 4), (5, 6)].map (·.1)
+-- [1, 3, 5]
+# end ex3
+```
+
+As in Lean 3, the notation is activated using parentheses, and the lambda abstraction is created by collecting the nested `·`s.
+The collection is interrupted by nested parentheses. In the following example, two different lambda expressions are created.
+
+```lean
+#check (Prod.mk · (· + 1))
+-- fun a => (a, fun b => b + 1)
+```
+
+## Function applications
+
+In Lean 4, we have support for named arguments.
+Named arguments enable you to specify an argument for a parameter by matching the argument with
+its name rather than with its position in the parameter list.
+If you don't remember the order of the parameters but know their names,
+you can send the arguments in any order. You may also provide the value for an implicit parameter when
+Lean failed to infer it. Named arguments also improve the readability of your code by identifying what
+each argument represents.
+
+```lean
+def sum (xs : List Nat) :=
+  xs.foldl (init := 0) (·+·)
+
+#eval sum [1, 2, 3, 4]
+-- 10
+
+example {a b : Nat} {p : Nat → Nat → Nat → Prop} (h₁ : p a b b) (h₂ : b = a)
+    : p a a b :=
+  Eq.subst (motive := fun x => p a x b) h₂ h₁
+```
+In the following examples, we illustrate the interaction between named and default arguments.
+
+```lean
+def f (x : Nat) (y : Nat := 1) (w : Nat := 2) (z : Nat) :=
+  x + y + w - z
+
+example (x z : Nat) : f (z := z) x = x + 1 + 2 - z := rfl
+
+example (x z : Nat) : f x (z := z) = x + 1 + 2 - z := rfl
+
+example (x y : Nat) : f x y = fun z => x + y + 2 - z := rfl
+
+example : f = (fun x z => x + 1 + 2 - z) := rfl
+
+example (x : Nat) : f x = fun z => x + 1 + 2 - z := rfl
+
+example (y : Nat) : f (y := 5) = fun x z => x + 5 + 2 - z := rfl
+
+def g {α} [Add α] (a : α) (b? : Option α := none) (c : α) : α :=
+  match b? with
+  | none   => a + c
+  | some b => a + b + c
+
+variable {α} [Add α]
+
+example : g = fun (a c : α) => a + c := rfl
+
+example (x : α) : g (c := x) = fun (a : α) => a + x := rfl
+
+example (x : α) : g (b? := some x) = fun (a c : α) => a + x + c := rfl
+
+example (x : α) : g x = fun (c : α) => x + c := rfl
+
+example (x y : α) : g x y = fun (c : α) => x + y + c := rfl
+```
+
+In Lean 4, we can use `..` to provide missing explicit arguments as `_`.
+This feature combined with named arguments is useful for writing patterns. Here is an example:
+```lean
+inductive Term where
+  | var    (name : String)
+  | num    (val : Nat)
+  | add    (fn : Term) (arg : Term)
+  | lambda (name : String) (type : Term) (body : Term)
+
+def getBinderName : Term → Option String
+  | Term.lambda (name := n) .. => some n
+  | _ => none
+
+def getBinderType : Term → Option Term
+  | Term.lambda (type := t) .. => some t
+  | _ => none
+```
+Ellipsis are also useful when explicit argument can be automatically inferred by Lean, and we want
+to avoid a sequence of `_`s.
+```lean
+example (f : Nat → Nat) (a b c : Nat) : f (a + b + c) = f (a + (b + c)) :=
+  congrArg f (Nat.add_assoc ..)
+```
+
+In Lean 4, writing `f(x)` in place of `f x` is no longer allowed, you must use whitespace between the function and its arguments (e.g., `f (x)`).
+
+## Dependent function types
+
+Given `α : Type` and `β : α → Type`, `(x : α) → β x` denotes the type of functions `f` with the property that,
+for each `a : α`, `f a` is an element of `β a`. In other words, the type of the value returned by `f` depends on its input.
+We say `(x : α) → β x` is a dependent function type. In Lean 3, we write the dependent function type `(x : α) → β x` using
+one of the following three equivalent notations:
+`forall x : α, β x` or `∀ x : α, β x` or `Π x : α, β x`.
+The first two were intended to be used for writing propositions, and the latter for writing code.
+Although the notation `Π x : α, β x` has historical significance, we have removed it from Lean 4 because
+it is awkward to use and often confuses new users. We can still write `forall x : α, β x` and `∀ x : α, β x`.
+
+```lean
+#check forall (α : Type), α → α
+#check ∀ (α : Type), α → α
+#check ∀ α : Type, α → α
+#check ∀ α, α → α
+#check (α : Type) → α → α
+#check {α : Type} → (a : Array α) → (i : Nat) → i < a.size → α
+#check {α : Type} → [ToString α] → α → String
+#check forall {α : Type} (a : Array α) (i : Nat), i < a.size → α
+#check {α β : Type} → α → β → α × β
+```
+
+## The `meta` keyword
+
+In Lean 3, the keyword `meta` is used to mark definitions that can use primitives implemented in C/C++.
+These metadefinitions can also call themselves recursively, relaxing the termination
+restriction imposed by ordinary type theory. Metadefinitions may also use unsafe primitives such as
+`eval_expr (α : Type u) [reflected α] : expr → tactic α`, or primitives that break referential transparency
+`tactic.unsafe_run_io`.
+
+The keyword `meta` has been currently removed from Lean 4. However, we may re-introduce it in the future,
+but with a much more limited purpose: marking meta code that should not be included in the executables produced by Lean.
+
+The keyword `constant` has been deleted in Lean 4, and `axiom` should be used instead. In Lean 4, the new command `opaque` is used to define an opaque definition. Here are two simple examples:
+```lean
+# namespace meta1
+opaque x : Nat := 1
+-- The following example will not type check since `x` is opaque
+-- example : x = 1 := rfl
+
+-- We can evaluate `x`
+#eval x
+-- 1
+
+-- When no value is provided, the elaborator tries to build one automatically for us
+-- using the `Inhabited` type class
+opaque y : Nat
+# end meta1
+```
+
+We can instruct Lean to use a foreign function as the implementation for any definition
+using the attribute `@[extern "foreign_function"]`. It is the user's responsibility to ensure the
+foreign implementation is correct.
+However, a user mistake here will only impact the code generated by Lean, and
+it will **not** compromise the logical soundness of the system.
+That is, you cannot prove `False` using the `@[extern]` attribute.
+We use `@[extern]` with definitions when we want to provide a reference implementation in Lean
+that can be used for reasoning. When we write a definition such as
+```lean
+@[extern "lean_nat_add"]
+def add : Nat → Nat → Nat
+  | a, Nat.zero   => a
+  | a, Nat.succ b => Nat.succ (add a b)
+```
+Lean assumes that the foreign function `lean_nat_add` implements the reference implementation above.
+
+The `unsafe` keyword allows us to define functions using unsafe features such as general recursion,
+and arbitrary type casting. Regular (safe) functions cannot directly use `unsafe` ones since it would
+compromise the logical soundness of the system. As in regular programming languages, programs written
+using unsafe features may crash at runtime. Here are a few unsafe examples:
+```lean
+unsafe def unsound : False :=
+  unsound
+
+#check @unsafeCast
+-- {α : Type _} → {β : Type _} → α → β
+
+unsafe def nat2String (x : Nat) : String :=
+  unsafeCast x
+
+-- The following definition doesn't type check because it is not marked as `unsafe`
+-- def nat2StringSafe (x : Nat) : String :=
+--   unsafeCast x
+```
+
+The `unsafe` keyword is particularly useful when we want to take advantage of an implementation detail of the
+Lean execution runtime. For example, we cannot prove in Lean that arrays have a maximum size, but
+the runtime used to execute Lean programs guarantees that an array cannot have more than 2^64 (2^32) elements
+in a 64-bit (32-bit) machine. We can take advantage of this fact to provide a more efficient implementation for
+array functions. However, the efficient version would not be very useful if it can only be used in
+unsafe code. Thus, Lean 4 provides the attribute `@[implemented_by functionName]`. The idea is to provide
+an unsafe (and potentially more efficient) version of a safe definition or constant. The function `f`
+at the attribute `@[implemented_by f]` is very similar to an extern/foreign function,
+the key difference is that it is implemented in Lean itself. Again, the logical soundness of the system
+cannot be compromised by using the attribute `implemented_by`, but if the implementation is incorrect your
+program may crash at runtime. In the following example, we define `withPtrUnsafe a k h` which
+executes `k` using the memory address where `a` is stored in memory. The argument `h` is proof
+that `k` is a constant function. Then, we "seal" this unsafe implementation at `withPtr`. The proof `h`
+ensures the reference implementation `k 0` is correct. For more information, see the article
+"Sealing Pointer-Based Optimizations Behind Pure Functions".
+```lean
+unsafe
+def withPtrUnsafe {α β : Type} (a : α) (k : USize → β) (h : ∀ u, k u = k 0) : β :=
+  k (ptrAddrUnsafe a)
+
+@[implemented_by withPtrUnsafe]
+def withPtr {α β : Type} (a : α) (k : USize → β) (h : ∀ u, k u = k 0) : β :=
+  k 0
+```
+
+General recursion is very useful in practice, and it would be impossible to implement Lean 4 without it.
+The keyword `partial` implements a very simple and efficient approach for supporting general recursion.
+Simplicity was key here because of the bootstrapping problem. That is, we had to implement Lean in Lean before
+many of its features were implemented (e.g., the tactic framework or support for wellfounded recursion).
+Another requirement for us was performance. Functions tagged with `partial` should be as efficient as the ones implemented in mainstream functional programming
+languages such as OCaml. When the `partial` keyword is used, Lean generates an auxiliary `unsafe` definition that
+uses general recursion, and then defines an opaque constant that is implemented by this auxiliary definition.
+This is very simple, efficient, and is sufficient for users that want to use Lean as a regular programming language.
+A `partial` definition cannot use unsafe features such as `unsafeCast` and `ptrAddrUnsafe`, and it can only be used to
+implement types we already known to be inhabited. Finally, since we "seal" the auxiliary definition using an opaque
+constant, we cannot reason about `partial` definitions.
+
+We are aware that proof assistants such as Isabelle provide a framework for defining partial functions that does not
+prevent users from proving properties about them. This kind of framework can be implemented in Lean 4. Actually,
+it can be implemented by users since Lean 4 is an extensible system. The developers current have no plans to implement
+this kind of support for Lean 4. However, we remark that users can implement it using a function that traverses
+the auxiliary unsafe definition generated by Lean, and produces a safe one using an approach similar to the one used in Isabelle.
+
+```lean
+# namespace partial1
+partial def f (x : Nat) : IO Unit := do
+  IO.println x
+  if x < 100 then
+     f (x+1)
+
+#eval f 98
+# end partial1
+```
+
+## Library changes
+
+These are changes to the library which may trip up Lean 3 users:
+
+- `List` is no longer a monad.
+
+## Style changes
+
+Coding style changes have also been made:
+
+- Term constants and variables are now `lowerCamelCase` rather than `snake_case`
+- Type constants are now `UpperCamelCase`, eg `Nat`, `List`. Type variables are still lower case greek letters. Functors are still lower case latin `(m : Type → Type) [Monad m]`.
+- When defining typeclasses, prefer not to use "has". Eg `ToString` or `Add` instead of `HasToString` or `HasAdd`.
+- Prefer `return` to `pure` in monad expressions.
+- Pipes `<|` are preferred to dollars `$` for function application.
+- Declaration bodies should always be indented:
+  ```lean
+  inductive Hello where
+    | foo
+    | bar
+
+  structure Point where
+    x : Nat
+    y : Nat
+
+  def Point.addX : Point → Point → Nat :=
+    fun { x := a, .. } { x := b, .. } => a + b
+  ```
+- In structures and typeclass definitions, prefer `where` to `:=` and don't surround fields with parentheses. (Shown in `Point` above)

doc/lexical_structure.md

@@ -0,0 +1,180 @@
+Lexical Structure
+=================
+
+This section describes the detailed lexical structure of the Lean
+language.
+
+A Lean program consists of a stream of UTF-8 tokens where each token
+is one of the following:
+
+```
+   token: symbol | command | ident | string | raw_string | char | numeral |
+        : decimal | doc_comment | mod_doc_comment | field_notation
+```
+
+Tokens can be separated by the whitespace characters space, tab, line
+feed, and carriage return, as well as comments. Single-line comments
+start with ``--``, whereas multi-line comments are enclosed by ``/-``
+and ``-/`` and can be nested.
+
+Symbols and Commands
+====================
+
+.. *(TODO: list built-in symbols and command tokens?)*
+
+Symbols are static tokens that are used in term notations and
+commands. They can be both keyword-like (e.g. the `have
+<structured_proofs>` keyword) or use arbitrary Unicode characters.
+
+Command tokens are static tokens that prefix any top-level declaration
+or action. They are usually keyword-like, with transitory commands
+like `#print <instructions>` prefixed by the ``#`` character. The set
+of built-in commands is listed in [Other Commands](./other_commands.md).
+
+Users can dynamically extend the sets of both symbols (via the
+commands listed in [Quoted Symbols](#quoted-symbols) and command
+tokens (via the `[user_command] <attributes>` attribute).
+
+.. _identifiers:
+
+Identifiers
+===========
+
+An *atomic identifier*, or *atomic name*, is (roughly) an alphanumeric
+string that does not begin with a numeral. A (hierarchical)
+*identifier*, or *name*, consists of one or more atomic names
+separated by periods.
+
+Parts of atomic names can be escaped by enclosing them in pairs of French double quotes ``«»``.
+
+```lean
+   def Foo.«bar.baz» := 0  -- name parts ["Foo", "bar.baz"]
+```
+
+```
+   ident: atomic_ident | ident "." atomic_ident
+   atomic_ident: atomic_ident_start atomic_ident_rest*
+   atomic_ident_start: letterlike | "_" | escaped_ident_part
+   letterlike: [a-zA-Z] | greek | coptic | letterlike_symbols
+   greek: <[α-ωΑ-Ωἀ-῾] except for [λΠΣ]>
+   coptic: [ϊ-ϻ]
+   letterlike_symbols: [℀-⅏]
+   escaped_ident_part: "«" [^«»\r\n\t]* "»"
+   atomic_ident_rest: atomic_ident_start | [0-9'ⁿ] | subscript
+   subscript: [₀-₉ₐ-ₜᵢ-ᵪ]
+```
+
+String Literals
+===============
+
+String literals are enclosed by double quotes (``"``). They may contain line breaks, which are conserved in the string value.  Backslash (`\`) is a special escape character which can be used to the following
+special characters:
+- `\\` represents an escaped backslash, so this escape causes one backslash to be included in the string.
+- `\"` puts a double quote in the string.
+- `\'` puts an apostrophe in the string.
+- `\n` puts a new line character in the string.
+- `\t` puts a tab character in the string.
+- `\xHH` puts the character represented by the 2 digit hexadecimal into the string.  For example
+"this \x26 that" which become "this & that".  Values above 0x80 will be interpreted according to the
+[Unicode table](https://unicode-table.com/en/) so "\xA9 Copyright 2021" is "© Copyright 2021".
+- `\uHHHH` puts the character represented by the 4 digit hexadecimal into the string, so the following
+string "\u65e5\u672c" will become "日本" which means "Japan".
+- `\` followed by a newline and then any amount of whitespace is a "gap" that is equivalent to the empty string,
+useful for letting a string literal span across multiple lines. Gaps spanning multiple lines can be confusing,
+so the parser raises an error if the trailing whitespace contains any newlines.
+
+So the complete syntax is:
+
+```
+   string       : '"' string_item '"'
+   string_item  : string_char | char_escape | string_gap
+   string_char  : [^"\\]
+   char_escape  : "\" ("\" | '"' | "'" | "n" | "t" | "x" hex_char{2} | "u" hex_char{4})
+   hex_char     : [0-9a-fA-F]
+   string_gap   : "\" newline whitespace*
+```
+
+Raw String Literals
+===================
+
+Raw string literals are string literals without any escape character processing.
+They begin with `r##...#"` (with zero or more `#` characters) and end with `"#...##` (with the same number of `#` characters).
+The contents of a raw string literal may contain `"##..#` so long as the number of `#` characters
+is less than the number of `#` characters used to begin the raw string literal.
+
+```
+   raw_string          : raw_string_aux(0) | raw_string_aux(1) | raw_string_aux(2) | ...
+   raw_string_aux(n)   : 'r' '#'{n} '"' raw_string_item '"' '#'{n}
+   raw_string_item(n)  : raw_string_char | raw_string_quote(n)
+   raw_string_char     : [^"]
+   raw_string_quote(n) : '"' '#'{0..n-1}
+```
+
+Char Literals
+=============
+
+Char literals are enclosed by single quotes (``'``).
+
+```
+   char      : "'" char_item "'"
+   char_item : char_char | char_escape
+   char_char : [^'\\]
+```
+
+Numeric Literals
+================
+
+Numeric literals can be specified in various bases.
+
+```
+   numeral    : numeral10 | numeral2 | numeral8 | numeral16
+   numeral10  : [0-9]+ ("_"+ [0-9]+)*
+   numeral2   : "0" [bB] ("_"* [0-1]+)+
+   numeral8   : "0" [oO] ("_"* [0-7]+)+
+   numeral16  : "0" [xX] ("_"* hex_char+)+
+```
+
+Floating point literals are also possible with optional exponent:
+
+```
+   float    : numeral10 "." numeral10? [eE[+-]numeral10]
+```
+
+For example:
+
+```
+constant w : Int := 55
+constant x : Nat := 26085
+constant y : Nat := 0x65E5
+constant z : Float := 2.548123e-05
+constant b : Bool := 0b_11_01_10_00
+```
+
+Note: that negative numbers are created by applying the "-" negation prefix operator to the number, for example:
+
+```
+constant w : Int := -55
+```
+
+Doc Comments
+============
+
+A special form of comments, doc comments are used to document modules
+and declarations.
+
+```
+   doc_comment: "/--" ([^-] | "-" [^/])* "-/"
+   mod_doc_comment: "/-!" ([^-] | "-" [^/])* "-/"
+```
+
+Field Notation
+==============
+
+Trailing field notation tokens are used in expressions such as
+``(1+1).to_string``. Note that ``a.toString`` is a single
+[Identifier](#identifiers), but may be interpreted as a field
+notation expression by the parser.
+
+```
+   field_notation: "." ([0-9]+ | atomic_ident)
+```

doc/metaprogramming-arith.md

@@ -0,0 +1,134 @@
+# Arithmetic as an embedded domain-specific language
+
+Let's parse another classic grammar, the grammar of arithmetic expressions with
+addition, multiplication, integers, and variables.  In the process, we'll learn
+how to:
+
+- Convert identifiers such as `x` into strings within a macro.
+- add the ability to "escape" the macro context from within the macro. This is useful to interpret identifiers with their _original_ meaning (predefined values)
+  instead of their new meaning within a macro (treat as a symbol).
+
+Let's begin with the simplest thing possible. We'll define an AST, and use operators `+` and `*` to denote
+building an arithmetic AST.
+
+
+Here's the AST that we will be parsing:
+
+```lean,ignore
+{{#include metaprogramming-arith.lean:1:5}}
+```
+
+We declare a syntax category to describe the grammar that we will be parsing.
+See that we control the precedence of `+` and `*` by writing `syntax:50` for addition and `syntax:60` for multiplication,
+indicating that multiplication binds tighter than addition (higher the number, tighter the binding).
+This allows us to declare _precedence_ when defining new syntax.
+
+```lean,ignore
+{{#include metaprogramming-arith.lean:7:13}}
+```
+
+Further, if we look at `syntax:60  arith:60 "+" arith:61 : arith`, the
+precedence declarations at `arith:60 "+" arith:61` conveys that the left
+argument must have precedence at least `60` or greater, and the right argument
+must have precedence at least`61` or greater.  Note that this forces left
+associativity. To understand this, let's compare two hypothetical parses:
+
+```
+-- syntax:60  arith:60 "+" arith:61 : arith -- Arith.add
+-- a + b + c
+(a:60 + b:61):60 + c
+a + (b:60 + c:61):60
+```
+
+In the parse tree of `a + (b:60 + c:61):60`, we see that the right argument `(b + c)` is given the precedence `60`. However,
+the rule for addition expects the right argument to have a precedence of **at least** 61, as witnessed by the `arith:61` at
+the right-hand-side of `syntax:60 arith:60 "+" arith:61 : arith`. Thus, the rule `syntax:60  arith:60 "+" arith:61 : arith`
+ensures that addition is left associative.
+
+Since addition is declared arguments of precedence `60/61` and multiplication with `70/71`, this causes multiplication to bind
+tighter than addition. Once again, let's compare two hypothetical parses:
+
+```
+-- syntax:60  arith:60 "+" arith:61 : arith -- Arith.add
+-- syntax:70 arith:70 "*" arith:71 : arith -- Arith.mul
+-- a * b + c
+a * (b:60 + c:61):60
+(a:70 * b:71):70 + c
+```
+
+While parsing `a * (b + c)`, `(b + c)` is assigned a precedence `60` by the addition rule. However, multiplication expects
+the right argument to have precedence **at least** 71. Thus, this parse is invalid. In contrast, `(a * b) + c` assigns
+a precedence of `70` to `(a * b)`. This is compatible with addition which expects the left argument to have precedence
+**at least `60` ** (`70` is greater than `60`). Thus, the string `a * b + c` is parsed as `(a * b) + c`.
+For more details, please look at the [Lean manual on syntax extensions](./notation.md#notations-and-precedence).
+
+To go from strings into `Arith`, we define a macro to
+translate the syntax category `arith` into an `Arith` inductive value that
+lives in `term`:
+
+
+```lean,ignore
+{{#include metaprogramming-arith.lean:15:16}}
+```
+
+Our macro rules perform the "obvious" translation:
+
+```lean,ignore
+{{#include metaprogramming-arith.lean:18:23}}
+```
+
+And some examples:
+
+```lean,ignore
+{{#include metaprogramming-arith.lean:25:41}}
+```
+
+Writing variables as strings, such as `"x"`  gets old; wouldn't it be so much
+prettier if we could write `x * y`, and have the macro translate this into `Arith.mul (Arith.Symbol "x") (Arith.mul "y")`?
+We can do this, and this will be our first taste of manipulating macro variables --- we'll use `x.getId` instead of directly evaluating `$x`.
+We also write a macro rule for `Arith|` that translates an identifier into
+a string, using `$(Lean.quote (toString x.getId))`:
+
+```lean,ignore
+{{#include metaprogramming-arith.lean:43:46}}
+```
+
+Let's test and see that we can now write expressions such as `x * y` directly instead of having to write `"x" * "y"`:
+
+```lean,ignore
+{{#include metaprogramming-arith.lean:48:51}}
+```
+
+We now show an unfortunate consequence of the above definitions. Suppose we want to build `(x + y) + z`.
+Since we already have defined `xPlusY` as `x + y`, perhaps we should reuse it! Let's try:
+
+```lean,ignore
+#check `[Arith| xPlusY + z]  -- Arith.add (Arith.symbol "xPlusY") (Arith.symbol "z")
+```
+
+Whoops, that didn't work! What happened? Lean treats `xPlusY` _itself_ as an identifier! So we need to add some syntax
+to be able to "escape" the `Arith|` context. Let's use the syntax `<[ $e:term ]>` to mean: evaluate `$e` as a real term,
+not an identifier. The macro looks like follows:
+
+```lean,ignore
+{{#include metaprogramming-arith.lean:53:56}}
+```
+
+Let's try our previous example:
+
+```lean,ignore
+{{#include metaprogramming-arith.lean:58:58}}
+```
+
+Perfect!
+
+In this tutorial, we expanded on the previous tutorial to parse a more
+realistic grammar with multiple levels of precedence, how to parse identifiers directly
+within a macro, and how to provide an escape from within the macro context.
+
+#### Full code listing
+
+```lean
+{{#include metaprogramming-arith.lean}}
+```
+

doc/mission.md

@@ -0,0 +1,12 @@
+Mission
+=======
+
+Empower software developers to design, develop, and reason about programs.
+Empower mathematicians and scientists to design, develop, and reason about formal models.
+
+How
+---
+
+Lean is an efficient functional programming language based on dependent type theory.
+It is under heavy development, but it already generates very efficient code.
+It also has a powerful meta-programming framework, extensible parser, and IDE support based on LSP.

doc/other_commands.md

@@ -0,0 +1 @@
+# Other Commands

doc/pygments.css

@@ -0,0 +1,83 @@
+/* Pygments stylesheet generated by Alectryon (style=None) */
+td.linenos .normal { color: inherit; background-color: transparent; padding-left: 5px; padding-right: 5px; }
+span.linenos { color: inherit; background-color: transparent; padding-left: 5px; padding-right: 5px; }
+td.linenos .special { color: #000000; background-color: #ffffc0; padding-left: 5px; padding-right: 5px; }
+span.linenos.special { color: #000000; background-color: #ffffc0; padding-left: 5px; padding-right: 5px; }
+.highlight .hll, .code .hll { background-color: #ffffcc }
+.highlight .c, .code .c { color: #555753; font-style: italic } /* Comment */
+.highlight .err, .code .err { color: #a40000; border: 1px solid #cc0000 } /* Error */
+.highlight .g, .code .g { color: #000000 } /* Generic */
+.highlight .k, .code .k { color: #8f5902 } /* Keyword */
+.highlight .l, .code .l { color: #2e3436 } /* Literal */
+.highlight .n, .code .n { color: #000000 } /* Name */
+.highlight .o, .code .o { color: #000000 } /* Operator */
+.highlight .x, .code .x { color: #2e3436 } /* Other */
+.highlight .p, .code .p { color: #000000 } /* Punctuation */
+.highlight .ch, .code .ch { color: #555753; font-weight: bold; font-style: italic } /* Comment.Hashbang */
+.highlight .cm, .code .cm { color: #555753; font-style: italic } /* Comment.Multiline */
+.highlight .cp, .code .cp { color: #3465a4; font-style: italic } /* Comment.Preproc */
+.highlight .cpf, .code .cpf { color: #555753; font-style: italic } /* Comment.PreprocFile */
+.highlight .c1, .code .c1 { color: #555753; font-style: italic } /* Comment.Single */
+.highlight .cs, .code .cs { color: #3465a4; font-weight: bold; font-style: italic } /* Comment.Special */
+.highlight .gd, .code .gd { color: #a40000 } /* Generic.Deleted */
+.highlight .ge, .code .ge { color: #000000; font-style: italic } /* Generic.Emph */
+.highlight .gr, .code .gr { color: #a40000 } /* Generic.Error */
+.highlight .gh, .code .gh { color: #a40000; font-weight: bold } /* Generic.Heading */
+.highlight .gi, .code .gi { color: #4e9a06 } /* Generic.Inserted */
+.highlight .go, .code .go { color: #000000; font-style: italic } /* Generic.Output */
+.highlight .gp, .code .gp { color: #8f5902 } /* Generic.Prompt */
+.highlight .gs, .code .gs { color: #000000; font-weight: bold } /* Generic.Strong */
+.highlight .gu, .code .gu { color: #000000; font-weight: bold } /* Generic.Subheading */
+.highlight .gt, .code .gt { color: #000000; font-style: italic } /* Generic.Traceback */
+.highlight .kc, .code .kc { color: #204a87; font-weight: bold } /* Keyword.Constant */
+.highlight .kd, .code .kd { color: #4e9a06; font-weight: bold } /* Keyword.Declaration */
+.highlight .kn, .code .kn { color: #4e9a06; font-weight: bold } /* Keyword.Namespace */
+.highlight .kp, .code .kp { color: #204a87 } /* Keyword.Pseudo */
+.highlight .kr, .code .kr { color: #8f5902 } /* Keyword.Reserved */
+.highlight .kt, .code .kt { color: #204a87 } /* Keyword.Type */
+.highlight .ld, .code .ld { color: #2e3436 } /* Literal.Date */
+.highlight .m, .code .m { color: #2e3436 } /* Literal.Number */
+.highlight .s, .code .s { color: #ad7fa8 } /* Literal.String */
+.highlight .na, .code .na { color: #c4a000 } /* Name.Attribute */
+.highlight .nb, .code .nb { color: #75507b } /* Name.Builtin */
+.highlight .nc, .code .nc { color: #204a87 } /* Name.Class */
+.highlight .no, .code .no { color: #ce5c00 } /* Name.Constant */
+.highlight .nd, .code .nd { color: #3465a4; font-weight: bold } /* Name.Decorator */
+.highlight .ni, .code .ni { color: #c4a000; text-decoration: underline } /* Name.Entity */
+.highlight .ne, .code .ne { color: #cc0000 } /* Name.Exception */
+.highlight .nf, .code .nf { color: #a40000 } /* Name.Function */
+.highlight .nl, .code .nl { color: #3465a4; font-weight: bold } /* Name.Label */
+.highlight .nn, .code .nn { color: #000000 } /* Name.Namespace */
+.highlight .nx, .code .nx { color: #000000 } /* Name.Other */
+.highlight .py, .code .py { color: #000000 } /* Name.Property */
+.highlight .nt, .code .nt { color: #a40000 } /* Name.Tag */
+.highlight .nv, .code .nv { color: #ce5c00 } /* Name.Variable */
+.highlight .ow, .code .ow { color: #8f5902 } /* Operator.Word */
+.highlight .w, .code .w { color: #d3d7cf; text-decoration: underline } /* Text.Whitespace */
+.highlight .mb, .code .mb { color: #2e3436 } /* Literal.Number.Bin */
+.highlight .mf, .code .mf { color: #2e3436 } /* Literal.Number.Float */
+.highlight .mh, .code .mh { color: #2e3436 } /* Literal.Number.Hex */
+.highlight .mi, .code .mi { color: #2e3436 } /* Literal.Number.Integer */
+.highlight .mo, .code .mo { color: #2e3436 } /* Literal.Number.Oct */
+.highlight .sa, .code .sa { color: #ad7fa8 } /* Literal.String.Affix */
+.highlight .sb, .code .sb { color: #ad7fa8 } /* Literal.String.Backtick */
+.highlight .sc, .code .sc { color: #ad7fa8; font-weight: bold } /* Literal.String.Char */
+.highlight .dl, .code .dl { color: #ad7fa8 } /* Literal.String.Delimiter */
+.highlight .sd, .code .sd { color: #ad7fa8 } /* Literal.String.Doc */
+.highlight .s2, .code .s2 { color: #ad7fa8 } /* Literal.String.Double */
+.highlight .se, .code .se { color: #ad7fa8; font-weight: bold } /* Literal.String.Escape */
+.highlight .sh, .code .sh { color: #ad7fa8; text-decoration: underline } /* Literal.String.Heredoc */
+.highlight .si, .code .si { color: #ce5c00 } /* Literal.String.Interpol */
+.highlight .sx, .code .sx { color: #ad7fa8 } /* Literal.String.Other */
+.highlight .sr, .code .sr { color: #ad7fa8 } /* Literal.String.Regex */
+.highlight .s1, .code .s1 { color: #ad7fa8 } /* Literal.String.Single */
+.highlight .ss, .code .ss { color: #8f5902 } /* Literal.String.Symbol */
+.highlight .bp, .code .bp { color: #5c35cc } /* Name.Builtin.Pseudo */
+.highlight .fm, .code .fm { color: #a40000 } /* Name.Function.Magic */
+.highlight .vc, .code .vc { color: #ce5c00 } /* Name.Variable.Class */
+.highlight .vg, .code .vg { color: #ce5c00; text-decoration: underline } /* Name.Variable.Global */
+.highlight .vi, .code .vi { color: #ce5c00 } /* Name.Variable.Instance */
+.highlight .vm, .code .vm { color: #ce5c00 } /* Name.Variable.Magic */
+.highlight .il, .code .il { color: #2e3436 } /* Literal.Number.Integer.Long */
+.hljs-doctag { color: green  }
+.hljs-comment { color: green  }

doc/quickstart.md

@@ -0,0 +1,23 @@
+# Quickstart
+
+These instructions will walk you through setting up Lean 4 together with VS Code as an editor for Lean 4.
+See [Setup](./setup.md) for supported platforms and other ways to set up Lean 4.
+
+1. Install [VS Code](https://code.visualstudio.com/).
+
+1. Launch VS Code and install the `Lean 4` extension by clicking on the 'Extensions' sidebar entry and searching for 'Lean 4'.
+
+   ![installing the vscode-lean4 extension](images/code-ext.png)
+
+1. Open the Lean 4 setup guide by creating a new text file using 'File > New Text File' (`Ctrl+N` / `Cmd+N`), clicking on the ∀-symbol in the top right and selecting 'Documentation… > Docs: Show Setup Guide'.
+
+   ![show setup guide](images/show-setup-guide.png)
+
+1. Follow the Lean 4 setup guide. It will:
+
+   - walk you through learning resources for Lean,
+   - teach you how to set up Lean's dependencies on your platform,
+   - install Lean 4 for you at the click of a button,
+   - help you set up your first project.
+
+   ![setup guide](images/setup_guide.png)

doc/reference.md

@@ -0,0 +1,3 @@
+# The Lean Reference Manual
+
+The latest version of the Lean reference manual is available [here](https://lean-lang.org/doc/reference/latest).

doc/semantic_highlighting.md

@@ -0,0 +1,23 @@
+Semantic Highlighting
+---------------------
+
+The Lean language server provides semantic highlighting information to editors. In order to benefit from this in VSCode, you may need to activate the "Editor > Semantic Highlighting" option in the preferences (this is translates to `"editor.semanticHighlighting.enabled": true,`
+in `settings.json`). The default option here is to let your color theme decides whether it activates semantic highlighting (the default themes Dark+ and Light+ do activate it for instance).
+
+However this may be insufficient if your color theme does not distinguish enough syntax categories or distinguishes them very subtly. For instance the default Light+ theme uses color `#001080` for variables. This is awfully close to `#000000` that is used as the default text color. This makes it very easy to miss an accidental use of [auto bound implicit arguments](https://lean-lang.org/lean4/doc/autobound.html). For instance in
+```lean
+def my_id (n : nat) := n
+```
+maybe `nat` is a typo and `Nat` was intended. If your color theme is good enough then you should see that `n` and `nat` have the same color since they are both marked as variables by semantic highlighting. If you rather write `(n : Nat)` then `n` keeps its variable color but `Nat` gets the default text color.
+
+If you use such a bad theme, you can fix things by modifying the `Semantic Token Color Customizations` configuration. This cannot be done directly in the preferences dialog but you can click on "Edit in settings.json" to directly edit the settings file. Beware that you must save this file (in the same way you save any file opened in VSCode) before seeing any effect in other tabs or VSCode windows.
+
+In the main config object, you can add something like
+```
+"editor.semanticTokenColorCustomizations": {
+        "[Default Light+]": {"rules": {"function": "#ff0000", "property": "#00ff00", "variable": "#ff00ff"}}
+    },
+```
+The colors in this example are not meant to be nice but to be easy to spot in your file when testing. Of course you need to replace `Default Light+` with the name of your theme, and you can customize several themes if you use several themes. VSCode will display small colored boxes next to the HTML color specifications. Hovering on top of a color specification opens a convenient color picker dialog.
+
+In order to understand what `function`, `property` and `variable` mean in the above example, the easiest path is to open a Lean file and ask VSCode about its classification of various bits of your file. Open the command palette with Ctrl-shift-p (or ⌘-shift-p on a Mac) and search for "Inspect Editor Tokens and Scopes" (typing the word "tokens" should be enough to see it). You can then click on any word in your file and look if there is a "semantic token type" line in the displayed information.

doc/setup.md

@@ -0,0 +1,65 @@
+# Supported Platforms
+
+### Tier 1
+
+Platforms built & tested by our CI, available as binary releases via elan (see below)
+
+* x86-64 Linux with glibc 2.27+
+* x86-64 macOS 10.15+
+* aarch64 (Apple Silicon) macOS 10.15+
+* x86-64 Windows 11 (any version), Windows 10 (version 1903 or higher), Windows Server 2022
+
+### Tier 2
+
+Platforms cross-compiled but not tested by our CI, available as binary releases
+
+Releases may be silently broken due to the lack of automated testing.
+Issue reports and fixes are welcome.
+
+* aarch64 Linux with glibc 2.27+
+* x86 (32-bit) Linux
+* Emscripten Web Assembly
+
+<!--
+### Tier 3
+
+Platforms that are known to work from manual testing, but do not come with CI or official releases
+-->
+
+# Setting Up Lean
+
+See also the [quickstart](./quickstart.md) instructions for a standard setup with VS Code as the editor.
+
+Release builds for all supported platforms are available at <https://github.com/leanprover/lean4/releases>.
+Instead of downloading these and setting up the paths manually, however, it is recommended to use the Lean version manager [`elan`](https://github.com/leanprover/elan) instead:
+```sh
+$ elan self update  # in case you haven't updated elan in a while
+# download & activate latest Lean 4 stable release (https://github.com/leanprover/lean4/releases)
+$ elan default leanprover/lean4:stable
+```
+
+## `lake`
+
+Lean 4 comes with a package manager named `lake`.
+Use `lake init foo` to initialize a Lean package `foo` in the current directory, and `lake build` to typecheck and build it as well as all its dependencies. Use `lake help` to learn about further commands.
+The general directory structure of a package `foo` is
+```sh
+lakefile.lean  # package configuration
+lean-toolchain # specifies the lean version to use
+Foo.lean       # main file, import via `import Foo`
+Foo/
+  A.lean       # further files, import via e.g. `import Foo.A`
+  A/...        # further nesting
+.lake/         # `lake` build output directory
+```
+
+After running `lake build` you will see a binary named `./.lake/build/bin/foo` and when you run it you should see the output:
+```
+Hello, world!
+```
+
+## Editing
+
+Lean implements the [Language Server Protocol](https://microsoft.github.io/language-server-protocol/) that can be used for interactive development in [Emacs](https://github.com/leanprover/lean4-mode), [VS Code](https://github.com/leanprover-community/vscode-lean4), and possibly other editors.
+
+Changes must be saved to be visible in other files, which must then be invalidated using an editor command (see links above).

doc/simptypes.md

@@ -0,0 +1,91 @@
+## Simple Type Theory
+
+"Type theory" gets its name from the fact that every expression has an associated *type*.
+For example, in a given context, ``x + 0`` may denote a natural number and ``f`` may denote a function on the natural numbers.
+For those that don't like math, a Lean natural number is an arbitrary-precision unsigned integer.
+
+Here are some examples of how we can declare objects in Lean and check their types.
+
+```lean
+/- Declare some constants. -/
+
+constant m  : Nat   -- m is a natural number
+constant n  : Nat
+constant b1 : Bool  -- b1 is a Boolean
+constant b2 : Bool
+
+/- Check their types. -/
+
+#check m            -- output: Nat
+#check n
+#check n + 0        -- Nat
+#check m * (n + 0)  -- Nat
+#check b1           -- Bool
+#check b1 && b2     -- "&&" is the Boolean and
+#check b1 || b2     -- Boolean or
+#check true         -- Boolean "true"
+```
+
+Any text between ``/-`` and ``-/`` constitutes a comment block that is ignored by Lean.
+Similarly, two dashes `--` indicate that the rest of the line contains a comment that is also ignored.
+Comment blocks can be nested, making it possible to "comment out" chunks of code, just as in many programming languages.
+
+The ``constant`` command introduce new constant symbols into the working environment.
+The ``#check`` command asks Lean to report their types; in Lean, auxiliary commands that query the system for
+information typically begin with the hash symbol. You should try declaring some constants and type checking
+some expressions on your own. Declaring new objects in this way is a good way to experiment with the system.
+
+What makes simple type theory powerful is that one can build new types out of others.
+For example, if ``a`` and ``b`` are types, ``a -> b`` denotes the type of functions from ``a`` to ``b``,
+and ``a × b`` denotes the type of pairs consisting of an element of ``a``
+paired with an element of ``b``, also known as the *Cartesian product*.
+Note that `×` is a Unicode symbol. We believe that judicious use of Unicode improves legibility,
+and all modern editors have great support for it. In the Lean standard library, we often use
+Greek letters to denote types, and the Unicode symbol `→` as a more compact version of `->`.
+
+```lean
+constant m : Nat
+constant n : Nat
+
+constant f  : Nat → Nat         -- type the arrow as "\to" or "\r"
+constant f' : Nat -> Nat        -- alternative ASCII notation
+constant p  : Nat × Nat         -- type the product as "\times"
+constant q  : Prod Nat Nat      -- alternative notation
+constant g  : Nat → Nat → Nat
+constant g' : Nat → (Nat → Nat) -- has the same type as g!
+constant h  : Nat × Nat → Nat
+constant F  : (Nat → Nat) → Nat -- a "functional"
+
+#check f            -- Nat → Nat
+#check f n          -- Nat
+#check g m n        -- Nat
+#check g m          -- Nat → Nat
+#check (m, n)       -- Nat × Nat
+#check p.1          -- Nat
+#check p.2          -- Nat
+#check (m, n).1     -- Nat
+#check (p.1, n)     -- Nat × Nat
+#check F f          -- Nat
+```
+
+Once again, you should try some examples on your own.
+
+Let us dispense with some basic syntax. You can enter the unicode arrow ``→`` by typing ``\to`` or ``\r``.
+You can also use the ASCII alternative ``->``, so the expressions ``Nat -> Nat`` and ``Nat → Nat`` mean the same thing.
+Both expressions denote the type of functions that take a natural number as input and return a natural number as output.
+The unicode symbol ``×`` for the Cartesian product is entered as ``\times``.
+We will generally use lower-case Greek letters like ``α``, ``β``, and ``γ`` to range over types.
+You can enter these particular ones with ``\a``, ``\b``, and ``\g``.
+
+There are a few more things to notice here. First, the application of a function ``f`` to a value ``x`` is denoted ``f x``.
+Second, when writing type expressions, arrows associate to the *right*; for example, the type of ``g`` is ``Nat → (Nat → Nat)``.
+Thus we can view ``g`` as a function that takes natural numbers and returns another function that takes a natural number and
+returns a natural number.
+In type theory, this is generally more convenient than writing ``g`` as a function that takes a pair of natural numbers as input
+and returns a natural number as output. For example, it allows us to "partially apply" the function ``g``.
+The example above shows that ``g m`` has type ``Nat → Nat``, that is, the function that "waits" for a second argument, ``n``,
+and then returns ``g m n``. Taking a function ``h`` of type ``Nat × Nat → Nat`` and "redefining" it to look like ``g`` is a process
+known as *currying*, something we will come back to below.
+
+By now you may also have guessed that, in Lean, ``(m, n)`` denotes the ordered pair of ``m`` and ``n``,
+and if ``p`` is a pair, ``p.1`` and ``p.2`` denote the two projections.

doc/syntax_example.md

@@ -0,0 +1,80 @@
+# Balanced Parentheses as an Embedded Domain Specific Language
+
+Let's look at how to use macros to extend the Lean 4 parser and embed a language for building _balanced parentheses_.
+This language accepts strings given by the [BNF grammar](https://en.wikipedia.org/wiki/Backus%E2%80%93Naur_form)
+
+```
+Dyck ::=
+  "(" Dyck ")"
+  | "{" Dyck "}"
+  | end
+```
+
+We begin by defining an inductive data type of the grammar we wish to parse:
+
+```lean,ignore
+inductive Dyck : Type where
+  | round : Dyck → Dyck  -- ( <inner> )
+  | curly : Dyck → Dyck  -- { <inner> }
+  | leaf : Dyck
+```
+
+We begin by declaring a _syntax category_ using the `declare_syntax_cat <category>` command.
+This names our grammar and allows us to specify parsing rules associated with our grammar.
+
+```lean,ignore
+declare_syntax_cat brack
+```
+
+Next, we specify the grammar using the `syntax <parse rule>` command:
+
+```lean,ignore
+syntax "end" : brack
+```
+
+The above means that the token "end" lives in syntax category `brack`.
+
+Similarly, we declare the rules `"(" Dyck ")"` and `"{" Dyck "}"` using the rules:
+
+```lean,ignore
+syntax "(" brack ")" : brack
+syntax "{" brack "}" : brack
+```
+
+Finally, we need a way to build _Lean 4 terms_ from this grammar -- that is, we must translate out of this
+grammar into a `Dyck` value, which is a Lean 4 term. For this, we create a new kind of "quotation" that
+consumes syntax in `brack` and produces a `term`.
+
+```lean,ignore
+syntax "`[Dyck| " brack "]" : term
+```
+
+To specify the transformation rules, we use `macro_rules` to declare how the syntax `` `[Dyck| <brack>] ``
+produces terms. This is written using a pattern-matching style syntax, where the left-hand side
+declares the syntax pattern to be matched, and the right-hand side declares the production. Syntax placeholders (antiquotations)
+are introduced via the `$<var-name>` syntax. The right-hand side is
+an arbitrary Lean term that we are producing.
+
+```lean,ignore
+macro_rules
+  | `(`[Dyck| end])    => `(Dyck.leaf)
+  | `(`[Dyck| ($b)]) => `(Dyck.round `[Dyck| $b])  -- recurse
+  | `(`[Dyck| {$b}]) => `(Dyck.curly `[Dyck| $b])  -- recurse
+```
+
+
+```lean,ignore
+#check `[Dyck| end]      -- Dyck.leaf
+#check `[Dyck| {(end)}]  -- Dyck.curl (Dyck.round Dyck.leaf)
+```
+
+In summary, we've seen:
+- How to declare a syntax category for the Dyck grammar.
+- How to specify parse trees of this grammar using `syntax`
+- How to translate out of this grammar into Lean 4 terms using `macro_rules`.
+
+The full program listing is given below:
+
+```lean
+{{#include syntax_example.lean}}
+```

doc/syntax_examples.md

@@ -0,0 +1,4 @@
+# Syntax Metaprogramming Examples
+
+- [Balanced Parentheses](./syntax_example.md)
+- [Arithmetic DSL](./metaprogramming-arith.md)

doc/syntax_highlight_in_latex.md

@@ -0,0 +1,91 @@
+You can copy highlighted code [straight from VS Code](https://code.visualstudio.com/updates/v1_10#_copy-with-syntax-highlighting) to any rich text editor supporting HTML input. For highlighting code in LaTeX, there are two options:
+* [listings](https://ctan.org/pkg/listings), which is a common package and simple to set up, but you may run into some restrictions of it and LaTeX around Unicode
+* [`minted`](https://ctan.org/pkg/minted), a LaTeX package wrapping the [Pygments](https://pygments.org/) syntax highlighting library. It needs a few more steps to set up, but provides unrestricted support for Unicode when combined with XeLaTeX or LuaLaTex.
+
+## Example with `listings`
+
+Save [`lstlean.tex`](https://raw.githubusercontent.com/leanprover/lean4/master/doc/latex/lstlean.tex) into the same directory, or anywhere in your `TEXINPUTS` path, as the following test file:
+```latex
+\documentclass{article}
+\usepackage[T1]{fontenc}
+\usepackage[utf8]{inputenc}
+\usepackage{listings}
+\usepackage{amssymb}
+
+\usepackage{color}
+\definecolor{keywordcolor}{rgb}{0.7, 0.1, 0.1}   % red
+\definecolor{tacticcolor}{rgb}{0.0, 0.1, 0.6}    % blue
+\definecolor{commentcolor}{rgb}{0.4, 0.4, 0.4}   % grey
+\definecolor{symbolcolor}{rgb}{0.0, 0.1, 0.6}    % blue
+\definecolor{sortcolor}{rgb}{0.1, 0.5, 0.1}      % green
+\definecolor{attributecolor}{rgb}{0.7, 0.1, 0.1} % red
+
+\def\lstlanguagefiles{lstlean.tex}
+% set default language
+\lstset{language=lean}
+
+\begin{document}
+\begin{lstlisting}
+theorem funext {f₁ f₂ : ∀ (x : α), β x} (h : ∀ x, f₁ x = f₂ x) : f₁ = f₂ := by
+  show extfunApp (Quotient.mk f₁) = extfunApp (Quotient.mk f₂)
+  apply congrArg
+  apply Quotient.sound
+  exact h
+\end{lstlisting}
+\end{document}
+```
+Compile the file via
+```bash
+$ pdflatex test.tex
+```
+
+* for older LaTeX versions, you might need to use `[utf8x]` instead of `[utf8]` with `inputenc`
+
+## Example with `minted`
+
+First [install Pygments](https://pygments.org/download/) (version 2.18 or newer).
+Then save the following sample LaTeX file `test.tex` into the same directory:
+
+```latex
+\documentclass{article}
+\usepackage{fontspec}
+% switch to a monospace font supporting more Unicode characters
+\setmonofont{FreeMono}
+\usepackage{minted}
+\newmintinline[lean]{lean4}{bgcolor=white}
+\newminted[leancode]{lean4}{fontsize=\footnotesize}
+\usemintedstyle{tango}  % a nice, colorful theme
+
+\begin{document}
+\begin{leancode}
+theorem funext {f₁ f₂ : ∀ (x : α), β x} (h : ∀ x, f₁ x = f₂ x) : f₁ = f₂ := by
+  show extfunApp (Quotient.mk' f₁) = extfunApp (Quotient.mk' f₂)
+  apply congrArg
+  apply Quotient.sound
+  exact h
+\end{leancode}
+\end{document}
+```
+
+You can then compile `test.tex` by executing the following command:
+
+```bash
+xelatex --shell-escape test.tex
+```
+
+Some remarks:
+
+ - either `xelatex` or `lualatex` is required to handle Unicode characters in the code.
+ - `--shell-escape` is needed to allow `xelatex` to execute `pygmentize` in a shell.
+ - If the chosen monospace font is missing some Unicode symbols, you can direct them to be displayed using a fallback font or other replacement LaTeX code.
+   ``` latex
+   \usepackage{newunicodechar}
+   \newfontfamily{\freeserif}{DejaVu Sans}
+   \newunicodechar{✝}{\freeserif{✝}}
+   \newunicodechar{𝓞}{\ensuremath{\mathcal{O}}}
+   ```
+ - If you are using an old version of Pygments, you can copy 
+   [`lean.py`](https://raw.githubusercontent.com/pygments/pygments/master/pygments/lexers/lean.py) into your working directory,
+   and use `lean4.py:Lean4Lexer -x` instead of `lean4` above.
+   If your version of `minted` is v2.7 or newer, but before v3.0,
+   you will additionally need to follow the workaround described in https://github.com/gpoore/minted/issues/360.

doc/tactics.md

@@ -0,0 +1,393 @@
+# Tactics
+
+Tactics are metaprograms, that is, programs that create programs.
+Lean is implemented in Lean, you can import its implementation using `import Lean`.
+The `Lean` package is part of the Lean distribution.
+You can use the functions in the `Lean` package to write your own metaprograms
+that automate repetitive tasks when writing programs and proofs.
+
+We provide the **tactic** domain specific language (DSL) for using the tactic framework.
+The tactic DSL provides commands for creating terms (and proofs). You
+don't need to import the `Lean` package for using the tactic DSL.
+Simple extensions can be implemented using macros. More complex extensions require
+the `Lean` package. Notation used to write Lean terms can be easily lifted to the tactic DSL.
+
+Tactics are instructions that tell Lean how to construct a term or proof.
+Tactics operate on holes also known as goals. Each hole represents a missing
+part of the term you are trying to build. Internally these holes are represented
+as metavariables. They have a type and a local context. The local context contains
+all local variables in scope.
+
+In the following example, we prove the same simple theorem using different tactics.
+The keyword `by` instructs Lean to use the tactic DSL to construct a term.
+Our initial goal is a hole with type `p ∨ q → q ∨ p`. The tactic `intro h`
+fills this hole using the term `fun h => ?m` where `?m` is a new hole we need to solve.
+This hole has type `q ∨ p`, and the local context contains `h : p ∨ q`.
+The tactic `cases` fills the hole using `Or.casesOn h (fun h1 => ?m1) (fun h2 => ?m2)`
+where `?m1` and `?m2` are new holes. The tactic `apply Or.inr` fills the hole `?m1`
+with the application `Or.inr ?m3`, and `exact h1` fills `?m3` with `h1`.
+The tactic `assumption` tries to fill a hole by searching the local context for a term with the same type.
+
+```lean
+theorem ex1 : p ∨ q → q ∨ p := by
+  intro h
+  cases h with
+  | inl h1 =>
+    apply Or.inr
+    exact h1
+  | inr h2 =>
+    apply Or.inl
+    assumption
+
+#print ex1
+/-
+theorem ex1 : {p q : Prop} → p ∨ q → q ∨ p :=
+fun {p q : Prop} (h : p ∨ q) =>
+  Or.casesOn h (fun (h1 : p) => Or.inr h1) fun (h2 : q) => Or.inl h2
+-/
+
+-- You can use `match-with` in tactics.
+theorem ex2 : p ∨ q → q ∨ p := by
+  intro h
+  match h with
+  | Or.inl _  => apply Or.inr; assumption
+  | Or.inr h2 => apply Or.inl; exact h2
+
+-- As we have the `fun+match` syntax sugar for terms,
+-- we have the `intro+match` syntax sugar
+theorem ex3 : p ∨ q → q ∨ p := by
+  intro
+  | Or.inl h1 =>
+    apply Or.inr
+    exact h1
+  | Or.inr h2 =>
+    apply Or.inl
+    assumption
+```
+
+The examples above are all structured, but Lean 4 still supports unstructured
+proofs. Unstructured proofs are useful when creating reusable scripts that may
+discharge different goals.
+Here is an unstructured version of the example above.
+
+```lean
+theorem ex1 : p ∨ q → q ∨ p := by
+  intro h
+  cases h
+  apply Or.inr
+  assumption
+  apply Or.inl
+  assumption
+  done -- fails with an error here if there are unsolvable goals
+
+theorem ex2 : p ∨ q → q ∨ p := by
+  intro h
+  cases h
+  focus -- instructs Lean to `focus` on the first goal,
+    apply Or.inr
+    assumption
+    -- it will fail if there are still unsolvable goals here
+  focus
+    apply Or.inl
+    assumption
+
+theorem ex3 : p ∨ q → q ∨ p := by
+  intro h
+  cases h
+  -- You can still use curly braces and semicolons instead of
+  -- whitespace sensitive notation as in the previous example
+  { apply Or.inr;
+    assumption
+    -- It will fail if there are unsolved goals
+  }
+  { apply Or.inl;
+    assumption
+  }
+
+-- Many tactics tag subgoals. The tactic `cases` tag goals using constructor names.
+-- The tactic `case tag => tactics` instructs Lean to solve the goal
+-- with the matching tag.
+theorem ex4 : p ∨ q → q ∨ p := by
+  intro h
+  cases h
+  case inr =>
+    apply Or.inl
+    assumption
+  case inl =>
+    apply Or.inr
+    assumption
+
+-- Same example for curly braces and semicolons aficionados
+theorem ex5 : p ∨ q → q ∨ p := by {
+  intro h;
+  cases h;
+  case inr => {
+    apply Or.inl;
+    assumption
+  }
+  case inl => {
+    apply Or.inr;
+    assumption
+  }
+}
+```
+
+## Rewrite
+
+TODO
+
+## Pattern matching
+
+As a convenience, pattern-matching has been integrated into tactics such as `intro` and `funext`.
+
+```lean
+theorem ex1 : s ∧ q ∧ r → p ∧ r → q ∧ p := by
+  intro ⟨_, ⟨hq, _⟩⟩ ⟨hp, _⟩
+  exact ⟨hq, hp⟩
+
+theorem ex2 :
+    (fun (x : Nat × Nat) (y : Nat × Nat) => x.1 + y.2)
+    =
+    (fun (x : Nat × Nat) (z : Nat × Nat) => z.2 + x.1) := by
+  funext (a, b) (c, d)
+  show a + d = d + a
+  rw [Nat.add_comm]
+```
+
+## Induction
+
+The `induction` tactic now supports user-defined induction principles with
+multiple targets (aka major premises).
+
+
+```lean
+/-
+theorem Nat.mod.inductionOn
+      {motive : Nat → Nat → Sort u}
+      (x y  : Nat)
+      (ind  : ∀ x y, 0 < y ∧ y ≤ x → motive (x - y) y → motive x y)
+      (base : ∀ x y, ¬(0 < y ∧ y ≤ x) → motive x y)
+      : motive x y :=
+-/
+
+theorem ex (x : Nat) {y : Nat} (h : y > 0) : x % y < y := by
+  induction x, y using Nat.mod.inductionOn with
+  | ind x y h₁ ih =>
+    rw [Nat.mod_eq_sub_mod h₁.2]
+    exact ih h
+  | base x y h₁ =>
+     have : ¬ 0 < y ∨ ¬ y ≤ x := Iff.mp (Decidable.not_and_iff_or_not ..) h₁
+     match this with
+     | Or.inl h₁ => exact absurd h h₁
+     | Or.inr h₁ =>
+       have hgt : y > x := Nat.gt_of_not_le h₁
+       rw [← Nat.mod_eq_of_lt hgt] at hgt
+       assumption
+```
+
+## Cases
+
+TODO
+
+## Injection
+
+TODO
+
+## Split
+
+The `split` tactic can be used to split the cases of an if-then-else or
+match into new subgoals, which can then be discharged individually.
+
+```lean
+def addMoreIfOdd (n : Nat) := if n % 2 = 0 then n + 1 else n + 2
+
+/- Examine each branch of the conditional to show that the result
+   is always positive -/
+example (n : Nat) : 0 < addMoreIfOdd n := by
+  simp only [addMoreIfOdd]
+  split
+  next => exact Nat.zero_lt_succ _
+  next => exact Nat.zero_lt_succ _
+```
+
+```lean
+def binToChar (n : Nat) : Option Char :=
+  match n with
+  | 0 => some '0'
+  | 1 => some '1'
+  | _ => none
+
+example (n : Nat) : (binToChar n).isSome -> n = 0 ∨ n = 1 := by
+  simp only [binToChar]
+  split
+  next => exact fun _ => Or.inl rfl
+  next => exact fun _ => Or.inr rfl
+  next => intro h; cases h
+
+/- Hypotheses about previous cases can be accessed by assigning them a
+   name, like `ne_zero` below. Information about the matched term can also
+   be preserved using the `generalizing` tactic: -/
+example (n : Nat) : (n = 0) -> (binToChar n = some '0') := by
+  simp only [binToChar]
+  split
+  case h_1 => intro _; rfl
+  case h_2 => intro h; cases h
+  /- Here, we can introduce `n ≠ 0` and `n ≠ 1` this case assumes
+     neither of the previous cases matched. -/
+  case h_3 ne_zero _  => intro eq_zero; exact absurd eq_zero ne_zero
+```
+
+## Dependent pattern matching
+
+The `match-with` expression implements dependent pattern matching. You can use it to create concise proofs.
+
+```lean
+inductive Mem : α → List α → Prop where
+  | head (a : α) (as : List α)   : Mem a (a::as)
+  | tail (a b : α) (bs : List α) : Mem a bs → Mem a (b::bs)
+
+infix:50 (priority := high) "∈" => Mem
+
+theorem mem_split {a : α} {as : List α} (h : a ∈ as) : ∃ s t, as = s ++ a :: t :=
+  match a, as, h with
+  | _, _, Mem.head a bs     => ⟨[], ⟨bs, rfl⟩⟩
+  | _, _, Mem.tail a b bs h =>
+    match bs, mem_split h with
+    | _, ⟨s, ⟨t, rfl⟩⟩ => ⟨b::s, ⟨t, List.cons_append .. ▸ rfl⟩⟩
+```
+
+In the tactic DSL, the right-hand-side of each alternative in a `match-with` is a sequence of tactics instead of a term.
+Here is a similar proof using the tactic DSL.
+
+```lean
+# inductive Mem : α → List α → Prop where
+#  | head (a : α) (as : List α)   : Mem a (a::as)
+#  | tail (a b : α) (bs : List α) : Mem a bs → Mem a (b::bs)
+# infix:50 (priority := high) "∈" => Mem
+theorem mem_split {a : α} {as : List α} (h : a ∈ as) : ∃ s t, as = s ++ a :: t := by
+  match a, as, h with
+  | _, _, Mem.head a bs     => exists []; exists bs; rfl
+  | _, _, Mem.tail a b bs h =>
+    match bs, mem_split h with
+    | _, ⟨s, ⟨t, rfl⟩⟩ =>
+      exists b::s; exists t;
+      rw [List.cons_append]
+```
+
+We can use `match-with` nested in tactics.
+Here is a similar proof that uses the `induction` tactic instead of recursion.
+
+```lean
+# inductive Mem : α → List α → Prop where
+#  | head (a : α) (as : List α)   : Mem a (a::as)
+#  | tail (a b : α) (bs : List α) : Mem a bs → Mem a (b::bs)
+# infix:50 (priority := high) "∈" => Mem
+theorem mem_split {a : α} {as : List α} (h : a ∈ as) : ∃ s t, as = s ++ a :: t := by
+  induction as with
+  | nil          => cases h
+  | cons b bs ih => cases h with
+    | head a bs => exact ⟨[], ⟨bs, rfl⟩⟩
+    | tail a b bs h =>
+      match bs, ih h with
+      | _, ⟨s, ⟨t, rfl⟩⟩ =>
+        exists b::s; exists t
+        rw [List.cons_append]
+```
+
+You can create your own notation using existing tactics. In the following example,
+we define a simple `obtain` tactic using macros. We say it is simple because it takes only one
+discriminant. Later, we show how to create more complex automation using macros.
+
+```lean
+# inductive Mem : α → List α → Prop where
+#  | head (a : α) (as : List α)   : Mem a (a::as)
+#  | tail (a b : α) (bs : List α) : Mem a bs → Mem a (b::bs)
+# infix:50 (priority := high) "∈" => Mem
+macro "obtain " p:term " from " d:term : tactic =>
+  `(tactic| match $d:term with | $p:term => ?_)
+
+theorem mem_split {a : α} {as : List α} (h : a ∈ as) : ∃ s t, as = s ++ a :: t := by
+  induction as with
+  | cons b bs ih => cases h with
+    | tail a b bs h =>
+      obtain ⟨s, ⟨t, h⟩⟩ from ih h
+      exists b::s; exists t
+      rw [h, List.cons_append]
+    | head a bs => exact ⟨[], ⟨bs, rfl⟩⟩
+  | nil => cases h
+
+```
+
+## Extensible tactics
+
+In the following example, we define the notation `triv` for the tactic DSL using
+the command `syntax`. Then, we use the command `macro_rules` to specify what should
+be done when `triv` is used. You can provide different expansions, and the tactic DSL
+interpreter will try all of them until one succeeds.
+
+```lean
+-- Define a new notation for the tactic DSL
+syntax "triv" : tactic
+
+macro_rules
+  | `(tactic| triv) => `(tactic| assumption)
+
+theorem ex1 (h : p) : p := by
+  triv
+
+-- You cannot prove the following theorem using `triv`
+-- theorem ex2 (x : α) : x = x := by
+--  triv
+
+-- Let's extend `triv`. The `by` DSL interpreter
+-- tries all possible macro extensions for `triv` until one succeeds
+macro_rules
+  | `(tactic| triv) => `(tactic| rfl)
+
+theorem ex2 (x : α) : x = x := by
+  triv
+
+theorem ex3 (x : α) (h : p) : x = x ∧ p := by
+  apply And.intro <;> triv
+```
+
+# `let-rec`
+
+You can use `let rec` to write local recursive functions. We lifted it to the tactic DSL,
+and you can use it to create proofs by induction.
+
+```lean
+theorem length_replicateTR {α} (n : Nat) (a : α) : (List.replicateTR n a).length = n := by
+  let rec aux (n : Nat) (as : List α)
+      : (List.replicateTR.loop a n as).length = n + as.length := by
+    match n with
+    | 0   => rw [Nat.zero_add]; rfl
+    | n+1 =>
+      show List.length (List.replicateTR.loop a n (a::as)) = Nat.succ n + as.length
+      rw [aux n, List.length_cons, Nat.add_succ, Nat.succ_add]
+  exact aux n []
+```
+
+You can also introduce auxiliary recursive declarations using `where` clause after your definition.
+Lean converts them into a `let rec`.
+
+```lean
+theorem length_replicateTR {α} (n : Nat) (a : α) : (List.replicateTR n a).length = n :=
+  loop n []
+where
+  loop n as : (List.replicateTR.loop a n as).length = n + as.length := by
+    match n with
+    | 0   => rw [Nat.zero_add]; rfl
+    | n+1 =>
+      show List.length (List.replicateTR.loop a n (a::as)) = Nat.succ n + as.length
+      rw [loop n, List.length_cons, Nat.add_succ, Nat.succ_add]
+```
+
+# `begin-end` lovers
+
+If you love Lean 3 `begin ... end` tactic blocks and commas, you can define this notation
+in Lean 4 using macros in a few lines of code.
+
+```lean
+{{#include ../tests/lean/beginEndAsMacro.lean:doc}}
+```

doc/tour.md

@@ -0,0 +1,200 @@
+# Tour of Lean
+
+The best way to learn about Lean is to read and write Lean code.
+This article will act as a tour through some of the key features of the Lean
+language and give you some code snippets that you can execute on your machine.
+To learn about setting up a development environment, check out [Setting Up Lean](./setup.md).
+
+There are two primary concepts in Lean: functions and types.
+This tour will emphasize features of the language which fall into
+these two concepts.
+
+# Functions and Namespaces
+
+The most fundamental pieces of any Lean program are functions organized into namespaces.
+[Functions](./functions.md) perform work on inputs to produce outputs,
+and they are organized under [namespaces](./namespaces.md),
+which are the primary way you group things in Lean.
+They are defined using the `def` command,
+which give the function a name and define its arguments.
+
+```lean
+namespace BasicFunctions
+
+-- The `#eval` command evaluates an expression on the fly and prints the result.
+#eval 2+2
+
+-- You use 'def' to define a function. This one accepts a natural number
+-- and returns a natural number.
+-- Parentheses are optional for function arguments, except for when
+-- you use an explicit type annotation.
+-- Lean can often infer the type of the function's arguments.
+def sampleFunction1 x := x*x + 3
+
+-- Apply the function, naming the function return result using 'def'.
+-- The variable type is inferred from the function return type.
+def result1 := sampleFunction1 4573
+
+-- This line uses an interpolated string to print the result. Expressions inside
+-- braces `{}` are converted into strings using the polymorphic method `toString`
+#eval println! "The result of squaring the integer 4573 and adding 3 is {result1}"
+
+-- When needed, annotate the type of a parameter name using '(argument : type)'.
+def sampleFunction2 (x : Nat) := 2*x*x - x + 3
+
+def result2 := sampleFunction2 (7 + 4)
+
+#eval println! "The result of applying the 2nd sample function to (7 + 4) is {result2}"
+
+-- Conditionals use if/then/else
+def sampleFunction3 (x : Int) :=
+  if x > 100 then
+    2*x*x - x + 3
+  else
+    2*x*x + x - 37
+
+#eval println! "The result of applying sampleFunction3 to 2 is {sampleFunction3 2}"
+
+end BasicFunctions
+```
+
+```lean
+-- Lean has first-class functions.
+-- `twice` takes two arguments `f` and `a` where
+-- `f` is a function from natural numbers to natural numbers, and
+-- `a` is a natural number.
+def twice (f : Nat → Nat) (a : Nat) :=
+  f (f a)
+
+-- `fun` is used to declare anonymous functions
+#eval twice (fun x => x + 2) 10
+
+-- You can prove theorems about your functions.
+-- The following theorem states that for any natural number `a`,
+-- adding 2 twice produces a value equal to `a + 4`.
+theorem twiceAdd2 (a : Nat) : twice (fun x => x + 2) a = a + 4 :=
+  -- The proof is by reflexivity. Lean "symbolically" reduces both sides of the equality
+  -- until they are identical.
+  rfl
+
+-- `(· + 2)` is syntax sugar for `(fun x => x + 2)`. The parentheses + `·` notation
+-- is useful for defining simple anonymous functions.
+#eval twice (· + 2) 10
+
+-- Enumerated types are a special case of inductive types in Lean,
+-- which we will learn about later.
+-- The following command creates a new type `Weekday`.
+inductive Weekday where
+  | sunday    : Weekday
+  | monday    : Weekday
+  | tuesday   : Weekday
+  | wednesday : Weekday
+  | thursday  : Weekday
+  | friday    : Weekday
+  | saturday  : Weekday
+
+-- `Weekday` has 7 constructors/elements.
+-- The constructors live in the `Weekday` namespace.
+-- Think of `sunday`, `monday`, …, `saturday` as being distinct elements of `Weekday`,
+-- with no other distinguishing properties.
+-- The command `#check` prints the type of a term in Lean.
+#check Weekday.sunday
+#check Weekday.monday
+
+-- The `open` command opens a namespace, making all declarations in it accessible without
+-- qualification.
+open Weekday
+#check sunday
+#check tuesday
+
+-- You can define functions by pattern matching.
+-- The following function converts a `Weekday` into a natural number.
+def natOfWeekday (d : Weekday) : Nat :=
+  match d with
+  | sunday    => 1
+  | monday    => 2
+  | tuesday   => 3
+  | wednesday => 4
+  | thursday  => 5
+  | friday    => 6
+  | saturday  => 7
+
+#eval natOfWeekday tuesday
+
+def isMonday : Weekday → Bool :=
+  -- `fun` + `match`  is a common idiom.
+  -- The following expression is syntax sugar for
+  -- `fun d => match d with | monday => true | _ => false`.
+  fun
+    | monday => true
+    | _      => false
+
+#eval isMonday monday
+#eval isMonday sunday
+
+-- Lean has support for type classes and polymorphic methods.
+-- The `toString` method converts a value into a `String`.
+#eval toString 10
+#eval toString (10, 20)
+
+-- The method `toString` converts values of any type that implements
+-- the class `ToString`.
+-- You can implement instances of `ToString` for your own types.
+instance : ToString Weekday where
+  toString (d : Weekday) : String :=
+    match d with
+    | sunday    => "Sunday"
+    | monday    => "Monday"
+    | tuesday   => "Tuesday"
+    | wednesday => "Wednesday"
+    | thursday  => "Thursday"
+    | friday    => "Friday"
+    | saturday  => "Saturday"
+
+#eval toString (sunday, 10)
+
+def Weekday.next (d : Weekday) : Weekday :=
+  match d with
+  | sunday    => monday
+  | monday    => tuesday
+  | tuesday   => wednesday
+  | wednesday => thursday
+  | thursday  => friday
+  | friday    => saturday
+  | saturday  => sunday
+
+#eval Weekday.next Weekday.wednesday
+-- Since the `Weekday` namespace has already been opened, you can also write
+#eval next wednesday
+
+-- Matching on a parameter like in the previous definition
+-- is so common that Lean provides syntax sugar for it. The following
+-- function uses it.
+def Weekday.previous : Weekday -> Weekday
+  | sunday    => saturday
+  | monday    => sunday
+  | tuesday   => monday
+  | wednesday => tuesday
+  | thursday  => wednesday
+  | friday    => thursday
+  | saturday  => friday
+
+#eval next (previous wednesday)
+
+-- We can prove that for any `Weekday` `d`, `next (previous d) = d`
+theorem Weekday.nextOfPrevious (d : Weekday) : next (previous d) = d :=
+  match d with
+  | sunday    => rfl
+  | monday    => rfl
+  | tuesday   => rfl
+  | wednesday => rfl
+  | thursday  => rfl
+  | friday    => rfl
+  | saturday  => rfl
+
+-- You can automate definitions such as `Weekday.nextOfPrevious`
+-- using metaprogramming (or "tactics").
+theorem Weekday.nextOfPrevious' (d : Weekday) : next (previous d) = d := by
+  cases d       -- A proof by case distinction
+  all_goals rfl  -- Each case is solved using `rfl`
+```

doc/tpil.md

@@ -0,0 +1,5 @@
+Theorem Proving in Lean
+=======================
+
+We strongly encourage you to read the book [Theorem Proving in Lean](https://lean-lang.org/theorem_proving_in_lean4/title_page.html).
+Many Lean users consider it to be the Lean Bible.

doc/typeobjs.md

@@ -0,0 +1,129 @@
+## Types as objects
+
+One way in which Lean's dependent type theory extends simple type theory is that types themselves --- entities like ``Nat`` and ``Bool`` ---
+are first-class citizens, which is to say that they themselves are objects. For that to be the case, each of them also has to have a type.
+
+```lean
+#check Nat               -- Type
+#check Bool              -- Type
+#check Nat → Bool        -- Type
+#check Nat × Bool        -- Type
+#check Nat → Nat         -- ...
+#check Nat × Nat → Nat
+#check Nat → Nat → Nat
+#check Nat → (Nat → Nat)
+#check Nat → Nat → Bool
+#check (Nat → Nat) → Nat
+```
+
+We see that each one of the expressions above is an object of type ``Type``. We can also declare new constants and constructors for types:
+
+```lean
+constant α : Type
+constant β : Type
+constant F : Type → Type
+constant G : Type → Type → Type
+
+#check α        -- Type
+#check F α      -- Type
+#check F Nat    -- Type
+#check G α      -- Type → Type
+#check G α β    -- Type
+#check G α Nat  -- Type
+```
+
+Indeed, we have already seen an example of a function of type ``Type → Type → Type``, namely, the Cartesian product.
+
+```lean
+constant α : Type
+constant β : Type
+
+#check Prod α β       -- Type
+#check Prod Nat Nat   -- Type
+```
+
+Here is another example: given any type ``α``, the type ``List α`` denotes the type of lists of elements of type ``α``.
+
+```lean
+constant α : Type
+
+#check List α    -- Type
+#check List Nat  -- Type
+```
+
+Given that every expression in Lean has a type, it is natural to ask: what type does ``Type`` itself have?
+
+```lean
+#check Type      -- Type 1
+```
+
+We have actually come up against one of the most subtle aspects of Lean's typing system.
+Lean's underlying foundation has an infinite hierarchy of types:
+
+```lean
+#check Type     -- Type 1
+#check Type 1   -- Type 2
+#check Type 2   -- Type 3
+#check Type 3   -- Type 4
+#check Type 4   -- Type 5
+```
+
+Think of ``Type 0`` as a universe of "small" or "ordinary" types.
+``Type 1`` is then a larger universe of types, which contains ``Type 0`` as an element,
+and ``Type 2`` is an even larger universe of types, which contains ``Type 1`` as an element.
+The list is indefinite, so that there is a ``Type n`` for every natural number ``n``.
+``Type`` is an abbreviation for ``Type 0``:
+
+```lean
+#check Type
+#check Type 0
+```
+
+There is also another type universe, ``Prop``, which has special properties.
+
+```lean
+#check Prop -- Type
+```
+
+We will discuss ``Prop`` later.
+
+We want some operations, however, to be *polymorphic* over type universes. For example, ``List α`` should
+make sense for any type ``α``, no matter which type universe ``α`` lives in. This explains the type annotation of the function ``List``:
+
+```lean
+#check List    -- Type u_1 → Type u_1
+```
+
+Here ``u_1`` is a variable ranging over type levels. The output of the ``#check`` command means that whenever ``α`` has type ``Type n``, ``List α`` also has type ``Type n``. The function ``Prod`` is similarly polymorphic:
+
+```lean
+#check Prod    -- Type u_1 → Type u_2 → Type (max u_1 u_2)
+```
+
+To define polymorphic constants and variables, Lean allows us to declare universe variables explicitly using the `universe` command:
+
+```lean
+universe u
+constant α : Type u
+#check α
+```
+Equivalently, we can write ``Type _`` to avoid giving the arbitrary universe a name:
+
+```lean
+constant α : Type _
+#check α
+```
+
+Several Lean 3 users use the shorthand `Type*` for `Type _`. The `Type*` notation is not builtin in Lean 4, but you can easily define it using a `macro`.
+```lean
+macro "Type*" : term => `(Type _)
+
+def f (α : Type*) (a : α) := a
+
+def g (α : Type _) (a : α) := a
+
+#check f
+#check g
+```
+
+We explain later how the `macro` command works.

doc/types.md

@@ -0,0 +1,56 @@
+# Types
+
+Every programming language needs a type system and
+Lean has a rich extensible inductive type system.
+
+## Basic Types
+
+Lean has built in support for the following basic types:
+
+- [Bool](bool.md) : a `true` or `false` value.
+- [Int](integers.md) : multiple precision integers (with no overflows!).
+
+- [Nat](integers.md) : natural numbers, or non-negative integers (also with no overflows!).
+- [Float](float.md): floating point numbers.
+- [Char](char.md): a Unicode character.
+- [String](string.md): a UTF-8 encoded string of characters.
+- [Array](array.md): a dynamic (aka growable) array of typed objects.
+- [List](list.md): a linked list of typed objects.
+- TODO: what else?
+
+And Lean allows you to create your own custom types using:
+- [Enumerated Types](enum.md): a special case of inductive types.
+- [Type Classes](typeclasses.md): a way of creating custom polymorphism.
+- [Types as objects](typeobjs.md): a way of manipulating types themselves.
+- [Structures](struct.md): a collection of named and typed fields. A
+  structure is actually special case of inductive datatype.
+- [Inductive Types](inductive.md): TODO: add one liner...
+
+## Universes
+
+Every type in Lean is, by definition, an expression of type `Sort u`
+for some universe level `u`. A universe level is one of the
+following:
+
+* a natural number, `n`
+* a universe variable, `u` (declared with the command `universe` or `universes`)
+* an expression `u + n`, where `u` is a universe level and `n` is a natural number
+* an expression `max u v`, where `u` and `v` are universes
+* an expression `imax u v`, where `u` and `v` are universe levels
+
+The last one denotes the universe level `0` if `v` is `0`, and `max u v` otherwise.
+
+```lean
+universe u v
+
+#check Sort u                       -- Type u
+#check Sort 5                       -- Type 4 : Type 5
+#check Sort (u + 1)                 -- Type u : Type (u + 1)
+#check Sort (u + 3)                 -- Type (u + 2) : Type (u + 3)
+#check Sort (max u v)               -- Sort (max u v) : Type (max u v)
+#check Sort (max (u + 3) v)         -- Sort (max (u + 3) v) : Type (max (u + 3) v)
+#check Sort (imax (u + 3) v)        -- Sort (imax (u + 3) v) : Type (imax (u + 3) v)
+#check Prop                         -- Type
+#check Type                         -- Type 1
+#check Type 1                       -- Type 1 : Type 2
+```

doc/using_lean.md

@@ -0,0 +1 @@
+# Using Lean

doc/whatIsLean.md

@@ -0,0 +1,42 @@
+# What is Lean
+
+Lean is a functional programming language that makes it easy to
+write correct and maintainable code.
+You can also use Lean as an interactive theorem prover.
+
+Lean programming primarily involves defining types and functions.
+This allows your focus to remain on the problem domain and manipulating its data,
+rather than the details of programming.
+
+```lean
+-- Defines a function that takes a name and produces a greeting.
+def getGreeting (name : String) := s!"Hello, {name}! Isn't Lean great?"
+
+-- The `main` function is the entry point of your program.
+-- Its type is `IO Unit` because it can perform `IO` operations (side effects).
+def main : IO Unit :=
+  -- Define a list of names
+  let names := ["Sebastian", "Leo", "Daniel"]
+
+  -- Map each name to a greeting
+  let greetings := names.map getGreeting
+
+  -- Print the list of greetings
+  for greeting in greetings do
+    IO.println greeting
+```
+
+Lean has numerous features, including:
+
+- Type inference
+- First-class functions
+- Powerful data types
+- Pattern matching
+- [Type classes](./typeclass.md)
+- [Monads](./monads/intro.md)
+- [Extensible syntax](./syntax.md)
+- Hygienic macros
+- [Dependent types](https://lean-lang.org/theorem_proving_in_lean4/dependent_type_theory.html)
+- [Metaprogramming](./macro_overview.md)
+- Multithreading
+- Verification: you can prove properties of your functions using Lean itself

flake.lock

@@ -1,49 +1,93 @@
 {
   "nodes": {
-    "nixpkgs": {
+    "flake-utils": {
+      "inputs": {
+        "systems": "systems"
+      },
       "locked": {
-        "lastModified": 1745636243,
-        "narHash": "sha256-kbNvlQZf8wwok3d2X1kM/TlXH/MZ+03ZNv+IPPBx+DM=",
-        "rev": "f771eb401a46846c1aebd20552521b233dd7e18b",
-        "type": "tarball",
-        "url": "https://releases.nixos.org/nixos/unstable/nixos-25.05pre789333.f771eb401a46/nixexprs.tar.xz"
+        "lastModified": 1710146030,
+        "narHash": "sha256-SZ5L6eA7HJ/nmkzGG7/ISclqe6oZdOZTNoesiInkXPQ=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "b1d9ab70662946ef0850d488da1c9019f3a9752a",
+        "type": "github"
       },
       "original": {
-        "type": "tarball",
-        "url": "https://channels.nixos.org/nixos-unstable/nixexprs.tar.xz"
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    },
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1710889954,
+        "narHash": "sha256-Pr6F5Pmd7JnNEMHHmspZ0qVqIBVxyZ13ik1pJtm2QXk=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "7872526e9c5332274ea5932a0c3270d6e4724f3b",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixpkgs-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "nixpkgs-cadical": {
+      "locked": {
+        "lastModified": 1722221733,
+        "narHash": "sha256-sga9SrrPb+pQJxG1ttJfMPheZvDOxApFfwXCFO0H9xw=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "12bf09802d77264e441f48e25459c10c93eada2e",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "12bf09802d77264e441f48e25459c10c93eada2e",
+        "type": "github"
       }
     },
     "nixpkgs-old": {
       "flake": false,
       "locked": {
-        "lastModified": 1582018169,
-        "narHash": "sha256-qv1iK1IchpZKSeWL3NEs4U5Jl5QVyNHDdiMJvLOI4Yc=",
-        "type": "tarball",
-        "url": "https://releases.nixos.org/nixos/19.03/nixos-19.03.173691.34c7eb7545d/nixexprs.tar.xz"
+        "lastModified": 1581379743,
+        "narHash": "sha256-i1XCn9rKuLjvCdu2UeXKzGLF6IuQePQKFt4hEKRU5oc=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "34c7eb7545d155cc5b6f499b23a7cb1c96ab4d59",
+        "type": "github"
       },
       "original": {
-        "type": "tarball",
-        "url": "https://channels.nixos.org/nixos-19.03/nixexprs.tar.xz"
-      }
-    },
-    "nixpkgs-older": {
-      "flake": false,
-      "locked": {
-        "lastModified": 1550657948,
-        "narHash": "sha256-BE0XqzNfzvhhtTXv37LyySyq4moL7z1i1hMvwbFNL/I=",
-        "type": "tarball",
-        "url": "https://releases.nixos.org/nixos/18.03/nixos-18.03.133402.cb0e20d6db9/nixexprs.tar.xz"
-      },
-      "original": {
-        "type": "tarball",
-        "url": "https://channels.nixos.org/nixos-18.03/nixexprs.tar.xz"
+        "owner": "NixOS",
+        "ref": "nixos-19.03",
+        "repo": "nixpkgs",
+        "type": "github"
       }
     },
     "root": {
       "inputs": {
+        "flake-utils": "flake-utils",
         "nixpkgs": "nixpkgs",
-        "nixpkgs-old": "nixpkgs-old",
-        "nixpkgs-older": "nixpkgs-older"
+        "nixpkgs-cadical": "nixpkgs-cadical",
+        "nixpkgs-old": "nixpkgs-old"
+      }
+    },
+    "systems": {
+      "locked": {
+        "lastModified": 1681028828,
+        "narHash": "sha256-Vy1rq5AaRuLzOxct8nz4T6wlgyUR7zLU309k9mBC768=",
+        "owner": "nix-systems",
+        "repo": "default",
+        "rev": "da67096a3b9bf56a91d16901293e51ba5b49a27e",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-systems",
+        "repo": "default",
+        "type": "github"
       }
     }
   },

flake.nix

@@ -1,22 +1,26 @@
 {
   description = "Lean development flake. Not intended for end users.";
 
-  # We use channels so we're not affected by GitHub's rate limits
-  inputs.nixpkgs.url = "https://channels.nixos.org/nixos-unstable/nixexprs.tar.xz";
+  inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";
   # old nixpkgs used for portable release with older glibc (2.27)
-  inputs.nixpkgs-old.url = "https://channels.nixos.org/nixos-19.03/nixexprs.tar.xz";
+  inputs.nixpkgs-old.url = "github:NixOS/nixpkgs/nixos-19.03";
   inputs.nixpkgs-old.flake = false;
-  # old nixpkgs used for portable release with older glibc (2.26)
-  inputs.nixpkgs-older.url = "https://channels.nixos.org/nixos-18.03/nixexprs.tar.xz";
-  inputs.nixpkgs-older.flake = false;
+  # for cadical 1.9.5; sync with CMakeLists.txt
+  inputs.nixpkgs-cadical.url = "github:NixOS/nixpkgs/12bf09802d77264e441f48e25459c10c93eada2e";
+  inputs.flake-utils.url = "github:numtide/flake-utils";
 
-  outputs = inputs: builtins.foldl' inputs.nixpkgs.lib.attrsets.recursiveUpdate {} (builtins.map (system:
+  outputs = { self, nixpkgs, nixpkgs-old, flake-utils, ... }@inputs: flake-utils.lib.eachDefaultSystem (system:
     let
-      pkgs = import inputs.nixpkgs { inherit system; };
+      pkgs = import nixpkgs { inherit system; };
       # An old nixpkgs for creating releases with an old glibc
-      pkgsDist-old = import inputs.nixpkgs-older { inherit system; };
+      pkgsDist-old = import nixpkgs-old { inherit system; };
       # An old nixpkgs for creating releases with an old glibc
-      pkgsDist-old-aarch = import inputs.nixpkgs-old { localSystem.config = "aarch64-unknown-linux-gnu"; };
+      pkgsDist-old-aarch = import nixpkgs-old { localSystem.config = "aarch64-unknown-linux-gnu"; };
+      pkgsCadical = import inputs.nixpkgs-cadical { inherit system; };
+      cadical = if pkgs.stdenv.isLinux then
+        # use statically-linked cadical on Linux to avoid glibc versioning troubles
+        pkgsCadical.pkgsStatic.cadical.overrideAttrs { doCheck = false; }
+      else pkgsCadical.cadical;
 
       lean-packages = pkgs.callPackage (./nix/packages.nix) { src = ./.; };
 
@@ -24,7 +28,7 @@
           stdenv = pkgs.overrideCC pkgs.stdenv lean-packages.llvmPackages.clang;
         } ({
           buildInputs = with pkgs; [
-            cmake gmp libuv ccache pkg-config
+            cmake gmp libuv ccache cadical pkg-config
             lean-packages.llvmPackages.llvm  # llvm-symbolizer for asan/lsan
             gdb
             tree  # for CI
@@ -56,21 +60,18 @@
           GLIBC_DEV = pkgsDist.glibc.dev;
           GCC_LIB = pkgsDist.gcc.cc.lib;
           ZLIB = pkgsDist.zlib;
-          # for CI coredumps
           GDB = pkgsDist.gdb;
         });
     in {
-      packages.${system} = {
+      packages = {
         # to be removed when Nix CI is not needed anymore
         inherit (lean-packages) cacheRoots test update-stage0-commit ciShell;
         deprecated = lean-packages;
       };
 
-      devShells.${system} = {
-        # The default development shell for working on lean itself
-        default = devShellWithDist pkgs;
-        oldGlibc = devShellWithDist pkgsDist-old;
-        oldGlibcAArch = devShellWithDist pkgsDist-old-aarch;
-      };
-    }) ["x86_64-linux" "aarch64-linux"]);
+      # The default development shell for working on lean itself
+      devShells.default = devShellWithDist pkgs;
+      devShells.oldGlibc = devShellWithDist pkgsDist-old;
+      devShells.oldGlibcAArch = devShellWithDist pkgsDist-old-aarch;
+    });
 }

nix/bootstrap.nix

@@ -17,7 +17,7 @@ lib.warn "The Nix-based build is deprecated" rec {
     '';
   } // args // {
     src = args.realSrc or (sourceByRegex args.src [ "[a-z].*" "CMakeLists\.txt" ]);
-    cmakeFlags = ["-DSMALL_ALLOCATOR=ON" "-DUSE_MIMALLOC=OFF"] ++ (args.cmakeFlags or [ "-DSTAGE=1" "-DPREV_STAGE=./faux-prev-stage" "-DUSE_GITHASH=OFF" "-DCADICAL=${cadical}/bin/cadical" ]) ++ (args.extraCMakeFlags or extraCMakeFlags) ++ lib.optional (args.debug or debug) [ "-DCMAKE_BUILD_TYPE=Debug" ];
+    cmakeFlags = (args.cmakeFlags or [ "-DSTAGE=1" "-DPREV_STAGE=./faux-prev-stage" "-DUSE_GITHASH=OFF" "-DCADICAL=${cadical}/bin/cadical" ]) ++ (args.extraCMakeFlags or extraCMakeFlags) ++ lib.optional (args.debug or debug) [ "-DCMAKE_BUILD_TYPE=Debug" ];
     preConfigure = args.preConfigure or "" + ''
       # ignore absence of submodule
       sed -i 's!lake/Lake.lean!!' CMakeLists.txt

nix/buildLeanPackage.nix

@@ -159,7 +159,7 @@ with builtins; let
       dir=$(dirname $relpath)
       mkdir -p $dir $out/$dir $ilean/$dir $c/$dir
       if [ -d $src ]; then cp -r $src/. .; else cp $src $leanPath; fi
-      lean -o $out/$oleanPath -i $out/$ileanPath -c $c/$cPath $leanPath $leanFlags $leanPluginFlags $leanLoadDynlibFlags
+      lean -o $out/$oleanPath -i $ilean/$ileanPath -c $c/$cPath $leanPath $leanFlags $leanPluginFlags $leanLoadDynlibFlags
     '';
   }) // {
     inherit deps;
@@ -194,7 +194,7 @@ with builtins; let
   modCandidates = mapAttrs (mod: header:
     let
       deps = if header.errors == []
-             then map (m: m.module) header.result.imports
+             then map (m: m.module) header.imports
              else abort "errors while parsing imports of ${mod}:\n${lib.concatStringsSep "\n" header.errors}";
     in mkMod mod (map (dep: if modDepsMap ? ${dep} then modCandidates.${dep} else externalModMap.${dep}) deps)) modDepsMap;
   expandGlob = g:
@@ -206,7 +206,7 @@ with builtins; let
   # subset of `modCandidates` that is transitively reachable from `roots`
   mods' = listToAttrs (map (e: { name = e.key; value = modCandidates.${e.key}; }) (genericClosure {
     startSet = map (m: { key = m; }) (concatMap expandGlob roots);
-    operator = e: if modDepsMap ? ${e.key} then map (m: { key = m.module; }) (filter (m: modCandidates ? ${m.module}) modDepsMap.${e.key}.result.imports) else [];
+    operator = e: if modDepsMap ? ${e.key} then map (m: { key = m.module; }) (filter (m: modCandidates ? ${m.module}) modDepsMap.${e.key}.imports) else [];
   }));
   allLinkFlags = lib.foldr (shared: acc: acc ++ [ "-L${shared}" "-l${shared.linkName or shared.name}" ]) linkFlags allNativeSharedLibs;
 

releases_drafts/README.md

@@ -1,19 +1,22 @@
 Draft release notes
 -------------------
 
-This folder contains drafts of release notes for the upcoming version.
+This folder contains drafts of release notes for inclusion in `RELEASES.md`.
 During the process to create a release candidate, we look through all the commits that make up the release
 to prepare the release notes, and in that process we take these drafts into account.
 
 Guidelines:
-- Write good commit messages
-  The first paragraph should briefly explain the impact of a change from a user's point of view.
-  (Recall: the first paragraph, which should begin with "This PR",
-  is automatically incorporated into the release notes by `script/release_notes.py`.
-  See `doc/dev/release_checklist.md` for more details.).
-- This folder is only needed for larger features that span multiple PRs,
+- You should prefer adding release notes to commit messages over adding anything to this folder.
+  A release note should briefly explain the impact of a change from a user's point of view.
+  Please mark these parts out with words such as **release notes** and/or **breaking changes**.
+- It is not necessary to add anything to this folder. It is meant for larger features that span multiple PRs,
   or for anything that would be helpful when preparing the release notes that might be missed
   by someone reading through the change log.
+- If the PR that adds a feature simultaneously adds a draft release note, including the PR number is not required
+  since it can be obtained from the git history for the file.
 
-When notes from this folder are incorporated into the [Lean Language Reference](https://lean-lang.org/doc/reference/latest/releases/#release-notes),
-they should then be deleted from here.
+When release notes are prepared, all the draft release notes are deleted from this folder.
+For release candidates beyond the first one, you can either update `RELEASE.md` directly
+or continue to add drafts.
+
+When a release is finalized, we will copy the completed release notes from `RELEASE.md` to the `master` branch.

releases_drafts/environment.md

@@ -1,6 +0,0 @@
-**Breaking Changes**
-
-* The functions `Lean.Environment.importModules` and `Lean.Environment.finalizeImport` have been extended with a new parameter `loadExts : Bool := false` that enables environment extension state loading.
-  Their previous behavior corresponds to setting the flag to `true` but is only safe to do in combination with `enableInitializersExecution`; see also the `importModules` docstring.
-  The new default value `false` ensures the functions can be used correctly multiple times within the same process when environment extension access is not needed.
-  The wrapper function `Lean.Environment.withImportModules` now always calls `importModules` with `loadExts := false` as it is incompatible with extension loading.

script/benchReelabRss.lean

@@ -1,70 +0,0 @@
-import Lean.Data.Lsp
-import Lean.Elab.Import
-open Lean
-open Lean.Lsp
-open Lean.JsonRpc
-
-/-!
-Tests language server memory use by repeatedly re-elaborate a given file.
-
-NOTE: only works on Linux for now.
--/
-
-def main (args : List String) : IO Unit := do
-  let leanCmd :: file :: iters :: args := args | panic! "usage: script <lean> <file> <#iterations> <server-args>..."
-  let file ← IO.FS.realPath file
-  let uri := s!"file://{file}"
-  Ipc.runWith leanCmd (#["--worker", "-DstderrAsMessages=false"] ++ args ++ #[uri]) do
-  -- for use with heaptrack:
-  --Ipc.runWith "heaptrack" (#[leanCmd, "--worker", "-DstderrAsMessages=false"] ++ args ++ #[uri]) do
-  --  -- heaptrack has no quiet mode??
-  --  let _ ← (← Ipc.stdout).getLine
-  --  let _ ← (← Ipc.stdout).getLine
-    let capabilities := {
-      textDocument? := some {
-        completion? := some {
-          completionItem? := some {
-            insertReplaceSupport? := true
-          }
-        }
-      }
-    }
-    Ipc.writeRequest ⟨0, "initialize", { capabilities : InitializeParams }⟩
-
-    let text ← IO.FS.readFile file
-    let (_, headerEndPos, _) ← Elab.parseImports text
-    let headerEndPos := FileMap.ofString text |>.leanPosToLspPos headerEndPos
-    let mut requestNo : Nat := 1
-    let mut versionNo : Nat := 1
-    Ipc.writeNotification ⟨"textDocument/didOpen", {
-      textDocument := { uri := uri, languageId := "lean", version := 1, text := text } : DidOpenTextDocumentParams }⟩
-    for i in [0:iters.toNat!] do
-      if i > 0 then
-        versionNo := versionNo + 1
-        let params : DidChangeTextDocumentParams := {
-          textDocument := {
-            uri      := uri
-            version? := versionNo
-          }
-          contentChanges := #[TextDocumentContentChangeEvent.rangeChange {
-            start := headerEndPos
-            «end» := headerEndPos
-          } " "]
-        }
-        let params := toJson params
-        Ipc.writeNotification ⟨"textDocument/didChange", params⟩
-        requestNo := requestNo + 1
-
-      let diags ← Ipc.collectDiagnostics requestNo uri versionNo
-      if let some diags := diags then
-        for diag in diags.param.diagnostics do
-          IO.eprintln diag.message
-      requestNo := requestNo + 1
-
-      let status ← IO.FS.readFile s!"/proc/{(← read).pid}/status"
-      for line in status.splitOn "\n" |>.filter (·.startsWith "RssAnon") do
-        IO.eprintln line
-
-    let _ ← Ipc.collectDiagnostics requestNo uri versionNo
-    (← Ipc.stdin).writeLspMessage (Message.notification "exit" none)
-    discard <| Ipc.waitForExit

script/merge_remote.py

@@ -1,157 +0,0 @@
-#!/usr/bin/env python3
-
-"""
-Merge a tag into a branch on a GitHub repository.
-
-This script checks if a specified tag can be merged cleanly into a branch and performs
-the merge if possible. If the merge cannot be done cleanly, it prints a helpful message.
-
-Usage:
-    python3 merge_remote.py <org/repo> <branch> <tag>
-
-Arguments:
-    org/repo: GitHub repository in the format 'organization/repository'
-    branch: The target branch to merge into
-    tag: The tag to merge from
-
-Example:
-    python3 merge_remote.py leanprover/mathlib4 stable v4.6.0
-
-The script uses the GitHub CLI (`gh`), so make sure it's installed and authenticated.
-"""
-
-import argparse
-import subprocess
-import sys
-import tempfile
-import os
-import shutil
-
-
-def run_command(command, check=True, capture_output=True):
-    """Run a shell command and return the result."""
-    try:
-        result = subprocess.run(
-            command,
-            check=check,
-            shell=True,
-            text=True,
-            capture_output=capture_output
-        )
-        return result
-    except subprocess.CalledProcessError as e:
-        if capture_output:
-            print(f"Command failed: {command}")
-            print(f"Error: {e.stderr}")
-        return e
-
-
-def clone_repo(repo, temp_dir):
-    """Clone the repository to a temporary directory."""
-    print(f"Cloning {repo}...")
-    # Remove shallow clone for better merge detection
-    clone_result = run_command(f"gh repo clone {repo} {temp_dir}", check=False)
-    if clone_result.returncode != 0:
-        print(f"Failed to clone repository {repo}.")
-        print(f"Error: {clone_result.stderr}")
-        return False
-    return True
-
-
-def check_and_merge(repo, branch, tag, temp_dir):
-    """Check if tag can be merged into branch and perform the merge if possible."""
-    # Change to the temporary directory
-    os.chdir(temp_dir)
-    
-    # First fetch the specific remote branch with its history
-    print(f"Fetching branch '{branch}'...")
-    fetch_branch = run_command(f"git fetch origin {branch}:refs/remotes/origin/{branch} --update-head-ok")
-    if fetch_branch.returncode != 0:
-        print(f"Error: Failed to fetch branch '{branch}'.")
-        return False
-    
-    # Then fetch the specific tag
-    print(f"Fetching tag '{tag}'...")
-    fetch_tag = run_command(f"git fetch origin tag {tag}")
-    if fetch_tag.returncode != 0:
-        print(f"Error: Failed to fetch tag '{tag}'.")
-        return False
-    
-    # Check if branch exists now that we've fetched it
-    branch_check = run_command(f"git branch -r | grep origin/{branch}")
-    if branch_check.returncode != 0:
-        print(f"Error: Branch '{branch}' does not exist in repository.")
-        return False
-
-    # Check if tag exists
-    tag_check = run_command(f"git tag -l {tag}")
-    if tag_check.returncode != 0 or not tag_check.stdout.strip():
-        print(f"Error: Tag '{tag}' does not exist in repository.")
-        return False
-
-    # Checkout the branch
-    print(f"Checking out branch '{branch}'...")
-    checkout_result = run_command(f"git checkout -b {branch} origin/{branch}")
-    if checkout_result.returncode != 0:
-        return False
-
-    # Try merging the tag directly
-    print(f"Merging {tag} into {branch}...")
-    merge_result = run_command(f"git merge {tag} --no-edit", check=False)
-    
-    if merge_result.returncode != 0:
-        print(f"Cannot merge {tag} cleanly into {branch}.")
-        print("Merge conflicts would occur. Aborting merge.")
-        run_command("git merge --abort")
-        return False
-    
-    print(f"Pushing changes to remote...")
-    push_result = run_command(f"git push origin {branch}")
-    if push_result.returncode != 0:
-        print(f"Failed to push changes to remote.")
-        return False
-    
-    print(f"Successfully merged {tag} into {branch} and pushed to remote.")
-    return True
-
-
-def main():
-    parser = argparse.ArgumentParser(
-        description="Merge a tag into a branch on a GitHub repository.",
-        formatter_class=argparse.RawDescriptionHelpFormatter,
-        epilog="""
-Examples:
-  %(prog)s leanprover/mathlib4 stable v4.6.0    Merge tag v4.6.0 into stable branch
-
-The script will:
-1. Clone the repository
-2. Check if the tag and branch exist
-3. Check if the tag can be merged cleanly into the branch
-4. Perform the merge and push to remote if possible
-        """
-    )
-    parser.add_argument("repo", help="GitHub repository in the format 'organization/repository'")
-    parser.add_argument("branch", help="The target branch to merge into")
-    parser.add_argument("tag", help="The tag to merge from")
-    
-    args = parser.parse_args()
-    
-    # Create a temporary directory for the repository
-    temp_dir = tempfile.mkdtemp()
-    try:
-        # Clone the repository
-        if not clone_repo(args.repo, temp_dir):
-            sys.exit(1)
-        
-        # Check if the tag can be merged and perform the merge
-        if not check_and_merge(args.repo, args.branch, args.tag, temp_dir):
-            sys.exit(1)
-        
-    finally:
-        # Clean up the temporary directory
-        print(f"Cleaning up temporary files...")
-        shutil.rmtree(temp_dir)
-
-
-if __name__ == "__main__":
-    main() 

script/prepare-llvm-linux.sh

@@ -1,5 +1,5 @@
 #!/usr/bin/env bash
-set -euxo pipefail
+set -uo pipefail
 
 # run from root build directory (from inside nix-shell or otherwise defining GLIBC/ZLIB/GMP) as in
 # ```
@@ -14,7 +14,6 @@ set -euxo pipefail
 else
   ln -s llvm llvm-host
 fi
-mkdir -p stage0/lib
 mkdir -p stage1/{bin,lib,lib/glibc,include/clang}
 CP="cp -d"  # preserve symlinks
 # a C compiler!
@@ -26,8 +25,6 @@ cp -L llvm/bin/llvm-ar stage1/bin/
 # dependencies of the above
 $CP llvm/lib/lib{clang-cpp,LLVM}*.so* stage1/lib/
 $CP $ZLIB/lib/libz.so* stage1/lib/
-# also copy USE_LLVM deps into stage 0
-$CP llvm/lib/libLLVM*.so* $ZLIB/lib/libz.so* stage0/lib/
 # general clang++ dependency, breaks cross-library C++ exceptions if linked statically
 $CP $GCC_LIB/lib/libgcc_s.so* stage1/lib/
 # bundle libatomic (referenced by LLVM >= 15, and required by the lean executable to run)
@@ -42,21 +39,20 @@ $CP $GLIBC/lib/*crt* stage1/lib/
 # runtime
 (cd llvm; $CP --parents lib/clang/*/lib/*/{clang_rt.*.o,libclang_rt.builtins*} ../stage1)
 $CP llvm/lib/*/lib{c++,c++abi,unwind}.* $GMP/lib/libgmp.a $LIBUV/lib/libuv.a stage1/lib/
-# LLVM 19 appears to ship the dependencies in 'llvm/lib/<target-triple>/' and 'llvm/include/<target-triple>/'
-# but clang-19 that we use to compile is linked against 'llvm/lib/' and 'llvm/include'
+# LLVM 15 appears to ship the dependencies in 'llvm/lib/<target-triple>/' and 'llvm/include/<target-triple>/'
+# but clang-15 that we use to compile is linked against 'llvm/lib/' and 'llvm/include'
 # https://github.com/llvm/llvm-project/issues/54955
 $CP llvm/lib/*/lib{c++,c++abi,unwind}.* llvm/lib/
 $CP llvm-host/lib/*/lib{c++,c++abi,unwind}.* llvm-host/lib/
 # libc++ headers are looked up in the host compiler's root, so copy over target-specific includes
-$CP -r llvm/include/*-*-* llvm-host/include/ || true
+$CP -r llvm/include/*-*-* llvm-host/include/
 # glibc: use for linking (so Lean programs don't embed newer symbol versions), but not for running (because libc.so, librt.so, and ld.so must be compatible)!
 $CP $GLIBC/lib/libc_nonshared.a stage1/lib/glibc
 # libpthread_nonshared.a must be linked in order to be able to use `pthread_atfork(3)`. LibUV uses this function.
 $CP $GLIBC/lib/libpthread_nonshared.a stage1/lib/glibc
-for f in $GLIBC/lib/{ld,lib{c,dl,m,rt,pthread}}-*; do b=$(basename $f); cp $f stage1/lib/glibc/${b%-*}.so; done
+for f in $GLIBC/lib/lib{c,dl,m,rt,pthread}-*; do b=$(basename $f); cp $f stage1/lib/glibc/${b%-*}.so; done
 OPTIONS=()
-# We build cadical using the custom toolchain on Linux to avoid glibc versioning issues
-echo -n " -DLEAN_STANDALONE=ON -DCADICAL_USE_CUSTOM_CXX=ON"
+echo -n " -DLEAN_STANDALONE=ON"
 echo -n " -DCMAKE_CXX_COMPILER=$PWD/llvm-host/bin/clang++ -DLEAN_CXX_STDLIB='-Wl,-Bstatic -lc++ -lc++abi -Wl,-Bdynamic'"
 echo -n " -DLEAN_EXTRA_CXX_FLAGS='--sysroot $PWD/llvm -idirafter $GLIBC_DEV/include ${EXTRA_FLAGS:-}'"
 # use target compiler directly when not cross-compiling
@@ -68,9 +64,7 @@ fi
 # use `-nostdinc` to make sure headers are not visible by default (in particular, not to `#include_next` in the clang headers),
 # but do not change sysroot so users can still link against system libs
 echo -n " -DLEANC_INTERNAL_FLAGS='--sysroot ROOT -nostdinc -isystem ROOT/include/clang' -DLEANC_CC=ROOT/bin/clang"
-# ld.so is usually included by the libc.so linker script but we discard those. Make sure it is linked to only after `libc.so` like in the original
-# linker script so that no libc symbols are bound to it instead.
-echo -n " -DLEANC_INTERNAL_LINKER_FLAGS='--sysroot ROOT -L ROOT/lib -L ROOT/lib/glibc -lc -lc_nonshared -Wl,--as-needed -l:ld.so -Wl,--no-as-needed -lpthread_nonshared -Wl,--as-needed -Wl,-Bstatic -lgmp -lunwind -luv -Wl,-Bdynamic -Wl,--no-as-needed -fuse-ld=lld'"
+echo -n " -DLEANC_INTERNAL_LINKER_FLAGS='--sysroot ROOT -L ROOT/lib -L ROOT/lib/glibc ROOT/lib/glibc/libc_nonshared.a ROOT/lib/glibc/libpthread_nonshared.a -Wl,--as-needed -Wl,-Bstatic -lgmp -lunwind -luv -Wl,-Bdynamic -Wl,--no-as-needed -fuse-ld=lld'"
 # when not using the above flags, link GMP dynamically/as usual
 echo -n " -DLEAN_EXTRA_LINKER_FLAGS='-Wl,--as-needed -lgmp -luv -lpthread -ldl -lrt -Wl,--no-as-needed'"
 # do not set `LEAN_CC` for tests

script/prepare-llvm-mingw.sh

@@ -25,10 +25,7 @@ cp llvm/lib/clang/*/include/{std*,__std*,limits}.h stage1/include/clang
 echo '
 // https://docs.microsoft.com/en-us/windows/win32/api/errhandlingapi/nf-errhandlingapi-seterrormode
 #define SEM_FAILCRITICALERRORS 0x0001
-__declspec(dllimport) __stdcall unsigned int SetErrorMode(unsigned int uMode);
-// https://docs.microsoft.com/en-us/windows/console/setconsoleoutputcp
-#define CP_UTF8 65001
-__declspec(dllimport) __stdcall int SetConsoleOutputCP(unsigned int wCodePageID);' > stage1/include/clang/windows.h
+__declspec(dllimport) __stdcall unsigned int SetErrorMode(unsigned int uMode);' > stage1/include/clang/windows.h
 # COFF dependencies
 cp /clang64/lib/{crtbegin,crtend,crt2,dllcrt2}.o stage1/lib/
 # runtime

script/release_checklist.py

@@ -7,14 +7,6 @@ import base64
 import subprocess
 import sys
 import os
-import re # Import re module
-# Import run_command from merge_remote.py
-from merge_remote import run_command
-
-def debug(verbose, message):
-    """Print debug message if verbose mode is enabled."""
-    if verbose:
-        print(f"    [DEBUG] {message}")
 
 def parse_repos_config(file_path):
     with open(file_path, "r") as f:
@@ -41,17 +33,10 @@ def branch_exists(repo_url, branch, github_token):
     return response.status_code == 200
 
 def tag_exists(repo_url, tag_name, github_token):
-    # Use /git/matching-refs/tags/ to get all matching tags
-    api_url = repo_url.replace("https://github.com/", "https://api.github.com/repos/") + f"/git/matching-refs/tags/{tag_name}"
+    api_url = repo_url.replace("https://github.com/", "https://api.github.com/repos/") + f"/git/refs/tags/{tag_name}"
     headers = {'Authorization': f'token {github_token}'} if github_token else {}
     response = requests.get(api_url, headers=headers)
-
-    if response.status_code != 200:
-        return False
-
-    # Check if any of the returned refs exactly match our tag
-    matching_tags = response.json()
-    return any(tag["ref"] == f"refs/tags/{tag_name}" for tag in matching_tags)
+    return response.status_code == 200
 
 def release_page_exists(repo_url, tag_name, github_token):
     api_url = repo_url.replace("https://github.com/", "https://api.github.com/repos/") + f"/releases/tags/{tag_name}"
@@ -59,29 +44,13 @@ def release_page_exists(repo_url, tag_name, github_token):
     response = requests.get(api_url, headers=headers)
     return response.status_code == 200
 
-def get_release_notes(tag_name):
-    """Fetch release notes page title from lean-lang.org."""
-    # Strip -rcX suffix if present for the URL
-    base_tag = tag_name.split('-')[0]
-    reference_url = f"https://lean-lang.org/doc/reference/latest/releases/{base_tag}/"
-    try:
-        response = requests.get(reference_url)
-        response.raise_for_status() # Raise HTTPError for bad responses (4xx or 5xx)
-        
-        # Extract title using regex
-        match = re.search(r"<title>(.*?)</title>", response.text, re.IGNORECASE | re.DOTALL)
-        if match:
-            return match.group(1).strip()
-        else:
-            print(f"  ⚠️ Could not find <title> tag in {reference_url}")
-            return None
-            
-    except requests.exceptions.RequestException as e:
-        print(f"  ❌ Error fetching release notes from {reference_url}: {e}")
-        return None
-    except Exception as e:
-        print(f"  ❌ An unexpected error occurred while processing release notes: {e}")
-        return None
+def get_release_notes(repo_url, tag_name, github_token):
+    api_url = repo_url.replace("https://github.com/", "https://api.github.com/repos/") + f"/releases/tags/{tag_name}"
+    headers = {'Authorization': f'token {github_token}'} if github_token else {}
+    response = requests.get(api_url, headers=headers)
+    if response.status_code == 200:
+        return response.json().get("body", "").strip()
+    return None
 
 def get_branch_content(repo_url, branch, file_path, github_token):
     api_url = repo_url.replace("https://github.com/", "https://api.github.com/repos/") + f"/contents/{file_path}?ref={branch}"
@@ -109,12 +78,9 @@ def parse_version(version_str):
 
 def is_version_gte(version1, version2):
     """Check if version1 >= version2, including proper handling of release candidates."""
-    # Check if version1 is a nightly toolchain
-    if version1.startswith("leanprover/lean4:nightly-"):
-        return False
     return parse_version(version1) >= parse_version(version2)
 
-def is_merged_into_stable(repo_url, tag_name, stable_branch, github_token, verbose=False):
+def is_merged_into_stable(repo_url, tag_name, stable_branch, github_token):
     # First get the commit SHA for the tag
     api_base = repo_url.replace("https://github.com/", "https://api.github.com/repos/")
     headers = {'Authorization': f'token {github_token}'} if github_token else {}
@@ -122,57 +88,20 @@ def is_merged_into_stable(repo_url, tag_name, stable_branch, github_token, verbo
     # Get tag's commit SHA
     tag_response = requests.get(f"{api_base}/git/refs/tags/{tag_name}", headers=headers)
     if tag_response.status_code != 200:
-        debug(verbose, f"Could not fetch tag {tag_name}, status code: {tag_response.status_code}")
         return False
-    
-    # Handle both single object and array responses
-    tag_data = tag_response.json()
-    if isinstance(tag_data, list):
-        # Find the exact matching tag in the list
-        matching_tags = [tag for tag in tag_data if tag['ref'] == f'refs/tags/{tag_name}']
-        if not matching_tags:
-            debug(verbose, f"No matching tag found for {tag_name} in response list")
-            return False
-        tag_sha = matching_tags[0]['object']['sha']
-    else:
-        tag_sha = tag_data['object']['sha']
-    
-    # Check if the tag is an annotated tag and get the actual commit SHA
-    if tag_data.get('object', {}).get('type') == 'tag' or (
-        isinstance(tag_data, list) and 
-        matching_tags and 
-        matching_tags[0].get('object', {}).get('type') == 'tag'):
-        
-        # Get the commit that this tag points to
-        tag_obj_response = requests.get(f"{api_base}/git/tags/{tag_sha}", headers=headers)
-        if tag_obj_response.status_code == 200:
-            tag_obj = tag_obj_response.json()
-            if 'object' in tag_obj and tag_obj['object']['type'] == 'commit':
-                commit_sha = tag_obj['object']['sha']
-                debug(verbose, f"Tag is annotated. Resolved commit SHA: {commit_sha}")
-                tag_sha = commit_sha  # Use the actual commit SHA
-    
+    tag_sha = tag_response.json()['object']['sha']
+
     # Get commits on stable branch containing this SHA
     commits_response = requests.get(
         f"{api_base}/commits?sha={stable_branch}&per_page=100",
         headers=headers
     )
     if commits_response.status_code != 200:
-        debug(verbose, f"Could not fetch commits for branch {stable_branch}, status code: {commits_response.status_code}")
         return False
 
     # Check if any commit in stable's history matches our tag's SHA
     stable_commits = [commit['sha'] for commit in commits_response.json()]
-    
-    is_merged = tag_sha in stable_commits
-    
-    debug(verbose, f"Tag SHA: {tag_sha}")
-    debug(verbose, f"First 5 stable commits: {stable_commits[:5]}")
-    debug(verbose, f"Total stable commits fetched: {len(stable_commits)}")
-    if not is_merged:
-        debug(verbose, f"Tag SHA not found in first {len(stable_commits)} commits of stable branch")
-    
-    return is_merged
+    return tag_sha in stable_commits
 
 def is_release_candidate(version):
     return "-rc" in version
@@ -206,110 +135,52 @@ def extract_org_repo_from_url(repo_url):
         return repo_url.replace("https://github.com/", "").rstrip("/")
     return repo_url
 
-def get_next_version(version):
-    """Calculate the next version number, ignoring RC suffix."""
-    # Strip v prefix and RC suffix if present
-    base_version = strip_rc_suffix(version.lstrip('v'))
-    major, minor, patch = map(int, base_version.split('.'))
-    # Next version is always .0
-    return f"v{major}.{minor + 1}.0"
-
-def check_bump_branch_toolchain(url, bump_branch, github_token):
-    """Check if the lean-toolchain file in bump branch starts with either 'leanprover/lean4:nightly-' or the next version."""
-    content = get_branch_content(url, bump_branch, "lean-toolchain", github_token)
-    if content is None:
-        print(f"  ❌ No lean-toolchain file found in {bump_branch} branch")
-        return False
-    
-    # Extract the next version from the bump branch name (bump/v4.X.0)
-    next_version = bump_branch.split('/')[1]
-    
-    if not (content.startswith("leanprover/lean4:nightly-") or 
-            content.startswith(f"leanprover/lean4:{next_version}")):
-        print(f"  ❌ Bump branch toolchain should use either nightly or {next_version}, but found: {content}")
-        return False
-    
-    print(f"  ✅ Bump branch correctly uses toolchain: {content}")
-    return True
-
-def pr_exists_with_title(repo_url, title, github_token):
-    api_url = repo_url.replace("https://github.com/", "https://api.github.com/repos/") + "/pulls"
-    headers = {'Authorization': f'token {github_token}'} if github_token else {}
-    params = {'state': 'open'}
-    response = requests.get(api_url, headers=headers, params=params)
-    if response.status_code != 200:
-        return None
-    pull_requests = response.json()
-    for pr in pull_requests:
-        if pr['title'] == title:
-            return pr['number'], pr['html_url']
-    return None
-
 def main():
-    parser = argparse.ArgumentParser(description="Check release status of Lean4 repositories")
-    parser.add_argument("toolchain", help="The toolchain version to check (e.g., v4.6.0)")
-    parser.add_argument("--verbose", "-v", action="store_true", help="Enable verbose debugging output")
-    parser.add_argument("--dry-run", action="store_true", help="Dry run mode (no actions taken)")
-    args = parser.parse_args()
-
     github_token = get_github_token()
-    toolchain = args.toolchain
-    verbose = args.verbose
-    # dry_run = args.dry_run  # Not used yet but available for future implementation
-    
+
+    if len(sys.argv) != 2:
+        print("Usage: python3 release_checklist.py <toolchain>")
+        sys.exit(1)
+
+    toolchain = sys.argv[1]
     stripped_toolchain = strip_rc_suffix(toolchain)
     lean_repo_url = "https://github.com/leanprover/lean4"
 
-    # Track repository status
-    repo_status = {}  # Will store True for success, False for failure
-
-    # Preliminary checks for lean4 itself
+    # Preliminary checks
     print("\nPerforming preliminary checks...")
-    lean4_success = True
 
     # Check for branch releases/v4.Y.0
     version_major, version_minor, _ = map(int, stripped_toolchain.lstrip('v').split('.'))
     branch_name = f"releases/v{version_major}.{version_minor}.0"
-    if not branch_exists(lean_repo_url, branch_name, github_token):
-        print(f"  ❌ Branch {branch_name} does not exist")
-        print(f"  🟡 After creating the branch, we'll need to check CMake version settings.")
-        lean4_success = False
-    else:
+    if branch_exists(lean_repo_url, branch_name, github_token):
         print(f"  ✅ Branch {branch_name} exists")
+
         # Check CMake version settings
-        if not check_cmake_version(lean_repo_url, branch_name, version_major, version_minor, github_token):
-            lean4_success = False
-
-    # Check for tag and release page
-    if not tag_exists(lean_repo_url, toolchain, github_token):
-        print(f"  ❌ Tag {toolchain} does not exist.")
-        lean4_success = False
+        check_cmake_version(lean_repo_url, branch_name, version_major, version_minor, github_token)
     else:
+        print(f"  ❌ Branch {branch_name} does not exist")
+
+    # Check for tag v4.X.Y(-rcZ)
+    if tag_exists(lean_repo_url, toolchain, github_token):
         print(f"  ✅ Tag {toolchain} exists")
-
-    if not release_page_exists(lean_repo_url, toolchain, github_token):
-        print(f"  ❌ Release page for {toolchain} does not exist")
-        lean4_success = False
     else:
+        print(f"  ❌ Tag {toolchain} does not exist.")
+
+    # Check for release page
+    if release_page_exists(lean_repo_url, toolchain, github_token):
         print(f"  ✅ Release page for {toolchain} exists")
-        
-    # Check the actual release notes page title
-    actual_title = get_release_notes(toolchain)
-    expected_title_prefix = f"Lean {toolchain.lstrip('v')}" # e.g., "Lean 4.19.0" or "Lean 4.19.0-rc1"
 
-    if actual_title is None:
-        # Error already printed by get_release_notes
-        lean4_success = False
-    elif not actual_title.startswith(expected_title_prefix):
-        # Construct URL for the error message (using the base tag)
-        base_tag = toolchain.split('-')[0]
-        check_url = f"https://lean-lang.org/doc/reference/latest/releases/{base_tag}/"
-        print(f"  ❌ Release notes page title mismatch. Expected prefix '{expected_title_prefix}', got '{actual_title}'. Check {check_url}")
-        lean4_success = False
+        # Check the first line of the release notes
+        release_notes = get_release_notes(lean_repo_url, toolchain, github_token)
+        if release_notes and release_notes.splitlines()[0].strip() == toolchain:
+            print(f"  ✅ Release notes look good.")
+        else:
+            previous_minor_version = version_minor - 1
+            previous_stable_branch = f"releases/v{version_major}.{previous_minor_version}.0"
+            previous_release = f"v{version_major}.{previous_minor_version}.0"
+            print(f"  ❌ Release notes not published. Please run `script/release_notes.py {previous_release}` on branch `{previous_stable_branch}`.")
     else:
-        print(f"  ✅ Release notes page title looks good ('{actual_title}').")
-
-    repo_status["lean4"] = lean4_success
+        print(f"  ❌ Release page for {toolchain} does not exist")
 
     # Load repositories and perform further checks
     print("\nChecking repositories...")
@@ -320,141 +191,37 @@ def main():
     for repo in repos:
         name = repo["name"]
         url = repo["url"]
-        org_repo = extract_org_repo_from_url(url)
         branch = repo["branch"]
         check_stable = repo["stable-branch"]
         check_tag = repo.get("toolchain-tag", True)
-        check_bump = repo.get("bump-branch", False)
-        dependencies = repo.get("dependencies", [])
 
         print(f"\nRepository: {name}")
 
-        # Check if any dependencies have failed
-        failed_deps = [dep for dep in dependencies if dep in repo_status and not repo_status[dep]]
-        if failed_deps:
-            print(f"  🟡  Dependencies not ready: {', '.join(failed_deps)}")
-            repo_status[name] = False
-            continue
-
-        # Initialize success flag for this repo
-        success = True
-
         # Check if branch is on at least the target toolchain
         lean_toolchain_content = get_branch_content(url, branch, "lean-toolchain", github_token)
         if lean_toolchain_content is None:
             print(f"  ❌ No lean-toolchain file found in {branch} branch")
-            repo_status[name] = False
             continue
-        
+
         on_target_toolchain = is_version_gte(lean_toolchain_content.strip(), toolchain)
         if not on_target_toolchain:
             print(f"  ❌ Not on target toolchain (needs ≥ {toolchain}, but {branch} is on {lean_toolchain_content.strip()})")
-            pr_title = f"chore: bump toolchain to {toolchain}"
-            pr_info = pr_exists_with_title(url, pr_title, github_token)
-            if pr_info:
-                pr_number, pr_url = pr_info
-                print(f"  ✅ PR with title '{pr_title}' exists: #{pr_number} ({pr_url})")
-            else:
-                print(f"  ❌ PR with title '{pr_title}' does not exist")
-                print(f"     Run `script/release_steps.py {toolchain} {name}` to create it")
-            repo_status[name] = False
             continue
         print(f"  ✅ On compatible toolchain (>= {toolchain})")
 
+        # Only check for tag if toolchain-tag is true
         if check_tag:
-            tag_exists_initially = tag_exists(url, toolchain, github_token)
-            if not tag_exists_initially:                
-                if args.dry_run:
-                    print(f"  ❌ Tag {toolchain} does not exist. Run `script/push_repo_release_tag.py {org_repo} {branch} {toolchain}`.")
-                    repo_status[name] = False
-                    continue
-                else:
-                    print(f"  … Tag {toolchain} does not exist. Running `script/push_repo_release_tag.py {org_repo} {branch} {toolchain}`...")
-                    
-                    # Run the script to create the tag
-                    subprocess.run(["script/push_repo_release_tag.py", org_repo, branch, toolchain])
-                    
-                    # Check again if the tag exists now
-                    if not tag_exists(url, toolchain, github_token):
-                        print(f"  ❌ Manual intervention required.")
-                        repo_status[name] = False
-                        continue
-            
-            # This will print in all successful cases - whether tag existed initially or was created successfully
+            if not tag_exists(url, toolchain, github_token):
+                print(f"  ❌ Tag {toolchain} does not exist. Run `script/push_repo_release_tag.py {extract_org_repo_from_url(url)} {branch} {toolchain}`.")
+                continue
             print(f"  ✅ Tag {toolchain} exists")
 
+        # Only check merging into stable if stable-branch is true and not a release candidate
         if check_stable and not is_release_candidate(toolchain):
-            if not is_merged_into_stable(url, toolchain, "stable", github_token, verbose):
-                org_repo = extract_org_repo_from_url(url)
-                if args.dry_run:
-                    print(f"  ❌ Tag {toolchain} is not merged into stable")
-                    print(f"     Run `script/merge_remote.py {org_repo} stable {toolchain}` to merge it")
-                    repo_status[name] = False
-                    continue
-                else:
-                    print(f"  … Tag {toolchain} is not merged into stable. Running `script/merge_remote.py {org_repo} stable {toolchain}`...")
-                    
-                    # Run the script to merge the tag
-                    subprocess.run(["script/merge_remote.py", org_repo, "stable", toolchain])
-                    
-                    # Check again if the tag is merged now
-                    if not is_merged_into_stable(url, toolchain, "stable", github_token, verbose):
-                        print(f"  ❌ Manual intervention required.")
-                        repo_status[name] = False
-                        continue
-            
-            # This will print in all successful cases - whether tag was merged initially or was merged successfully
-            print(f"  ✅ Tag {toolchain} is merged into stable")
-
-        if check_bump:
-            next_version = get_next_version(toolchain)
-            bump_branch = f"bump/{next_version}"
-            if not branch_exists(url, bump_branch, github_token):
-                if args.dry_run:
-                    print(f"  ❌ Bump branch {bump_branch} does not exist. Run `gh api -X POST /repos/{org_repo}/git/refs -f ref=refs/heads/{bump_branch} -f sha=$(gh api /repos/{org_repo}/git/refs/heads/{branch} --jq .object.sha)` to create it.")
-                    repo_status[name] = False
-                    continue
-                print(f"  … Bump branch {bump_branch} does not exist. Creating it...")
-                result = run_command(f"gh api -X POST /repos/{org_repo}/git/refs -f ref=refs/heads/{bump_branch} -f sha=$(gh api /repos/{org_repo}/git/refs/heads/{branch} --jq .object.sha)", check=False)
-                if result.returncode != 0:
-                    print(f"  ❌ Failed to create bump branch {bump_branch}")
-                    repo_status[name] = False
-                    continue
-            print(f"  ✅ Bump branch {bump_branch} exists")
-            if not check_bump_branch_toolchain(url, bump_branch, github_token):
-                repo_status[name] = False
+            if not is_merged_into_stable(url, toolchain, "stable", github_token):
+                print(f"  ❌ Tag {toolchain} is not merged into stable")
                 continue
-
-        repo_status[name] = success
-
-    # Final check for lean4 master branch
-    print("\nChecking lean4 master branch configuration...")
-    next_version = get_next_version(toolchain)
-    next_minor = int(next_version.split('.')[1])
-    
-    cmake_content = get_branch_content(lean_repo_url, "master", "src/CMakeLists.txt", github_token)
-    if cmake_content is None:
-        print("  ❌ Could not retrieve CMakeLists.txt from master")
-    else:
-        cmake_lines = cmake_content.splitlines()
-        # Find the actual minor version in CMakeLists.txt
-        for line in cmake_lines:
-            if line.strip().startswith("set(LEAN_VERSION_MINOR "):
-                actual_minor = int(line.split()[-1].rstrip(")"))
-                version_minor_correct = actual_minor >= next_minor
-                break
-        else:
-            version_minor_correct = False
-            
-        is_release_correct = any(
-            l.strip().startswith("set(LEAN_VERSION_IS_RELEASE 0)") 
-            for l in cmake_lines
-        )
-        
-        if not (version_minor_correct and is_release_correct):
-            print("  ❌ lean4 needs a \"begin dev cycle\" PR")
-        else:
-            print("  ✅ lean4 master branch is configured for next development cycle")
+            print(f"  ✅ Tag {toolchain} is merged into stable")
 
 if __name__ == "__main__":
     main()

script/release_notes.py

@@ -5,7 +5,6 @@ import re
 import json
 import requests
 import subprocess
-import argparse
 from collections import defaultdict
 from git import Repo
 
@@ -65,39 +64,21 @@ def format_markdown_description(pr_number, description):
     link = f"[#{pr_number}](https://github.com/leanprover/lean4/pull/{pr_number})"
     return f"{link} {description}"
 
-def commit_types():
-    # see doc/dev/commit_convention.md
-    return ['feat', 'fix', 'doc', 'style', 'refactor', 'test', 'chore', 'perf']
-
-def count_commit_types(commits):
-    counts = {
-        'total': len(commits),
-    }
-    for commit_type in commit_types():
-        counts[commit_type] = 0
-    
-    for _, first_line, _ in commits:
-        for commit_type in commit_types():
-            if first_line.startswith(f'{commit_type}:'):
-                counts[commit_type] += 1
-                break
-    
-    return counts
-
 def main():
-    parser = argparse.ArgumentParser(description='Generate release notes from Git commits')
-    parser.add_argument('--since', required=True, help='Git tag to generate release notes since')
-    args = parser.parse_args()
+    if len(sys.argv) != 2:
+        sys.stderr.write("Usage: script.py <git-tag>\n")
+        sys.exit(1)
 
+    tag = sys.argv[1]
     try:
         repo = Repo(".")
     except Exception as e:
         sys.stderr.write(f"Error opening Git repository: {e}\n")
         sys.exit(1)
 
-    commits = get_commits_since_tag(repo, args.since)
+    commits = get_commits_since_tag(repo, tag)
 
-    sys.stderr.write(f"Found {len(commits)} commits since tag {args.since}:\n")
+    sys.stderr.write(f"Found {len(commits)} commits since tag {tag}:\n")
     for commit_hash, first_line, _ in commits:
         sys.stderr.write(f"- {commit_hash}: {first_line}\n")
 
@@ -111,18 +92,14 @@ def main():
         pr_number = check_pr_number(first_line)
 
         if not pr_number:
-            sys.stderr.write(f"No PR number found in commit:\n{commit_hash}\n{first_line}\n")
+            sys.stderr.write(f"No PR number found in {first_line}\n")
             continue
 
         # Remove the first line from the full_message for further processing
         body = full_message[len(first_line):].strip()
 
         paragraphs = body.split('\n\n')
-        description = paragraphs[0] if len(paragraphs) > 0 else ""
-        
-        # If there's a third paragraph and second ends with colon, include it
-        if len(paragraphs) > 1 and description.endswith(':'):
-            description = description + '\n\n' + paragraphs[1]
+        second_paragraph = paragraphs[0] if len(paragraphs) > 0 else ""
 
         labels = fetch_pr_labels(pr_number)
 
@@ -132,7 +109,7 @@ def main():
 
         report_errors = first_line.startswith("feat:") or first_line.startswith("fix:")
 
-        if not description.startswith("This PR "):
+        if not second_paragraph.startswith("This PR "):
             if report_errors:
                 sys.stderr.write(f"No PR description found in commit:\n{commit_hash}\n{first_line}\n{body}\n\n")
                 fallback_description = re.sub(r":$", "", first_line.split(" ", 1)[1]).rsplit(" (#", 1)[0]
@@ -140,7 +117,7 @@ def main():
             else:
                 continue
         else:
-            markdown_description = format_markdown_description(pr_number, description.replace("This PR ", ""))
+            markdown_description = format_markdown_description(pr_number, second_paragraph.replace("This PR ", ""))
 
         changelog_labels = [label for label in labels if label.startswith("changelog-")]
         if len(changelog_labels) > 1:
@@ -155,14 +132,6 @@ def main():
         for label in changelog_labels:
             changelog[label].append((pr_number, markdown_description))
 
-    # Add commit type counting
-    counts = count_commit_types(commits)
-    print(f"For this release, {counts['total']} changes landed. "
-          f"In addition to the {counts['feat']} feature additions and {counts['fix']} fixes listed below "
-          f"there were {counts['refactor']} refactoring changes, {counts['doc']} documentation improvements, "
-          f"{counts['perf']} performance improvements, {counts['test']} improvements to the test suite "
-          f"and {counts['style'] + counts['chore']} other changes.\n")
-
     section_order = sort_sections_order()
     sorted_changelog = sorted(changelog.items(), key=lambda item: section_order.index(format_section_title(item[0])) if format_section_title(item[0]) in section_order else len(section_order))
 
@@ -170,12 +139,7 @@ def main():
         section_title = format_section_title(label) if label != "Uncategorised" else "Uncategorised"
         print(f"## {section_title}\n")
         for _, entry in sorted(entries, key=lambda x: x[0]):
-            # Split entry into lines and indent all lines after the first
-            lines = entry.splitlines()
-            print(f"* {lines[0]}")
-            for line in lines[1:]:
-                print(f"  {line}")
-            print()  # Empty line after each entry
+            print(f"* {entry}\n")
 
 if __name__ == "__main__":
     main()

script/release_repos.yml

@@ -1,10 +1,9 @@
 repositories:
-  - name: batteries
+  - name: Batteries
     url: https://github.com/leanprover-community/batteries
     toolchain-tag: true
     stable-branch: true
     branch: main
-    bump-branch: true
     dependencies: []
 
   - name: lean4checker
@@ -14,40 +13,26 @@ repositories:
     branch: master
     dependencies: []
 
-  - name: quote4
-    url: https://github.com/leanprover-community/quote4
-    toolchain-tag: true
-    stable-branch: true
-    branch: master
-    dependencies: []
-
-  - name: lean4-cli
-    url: https://github.com/leanprover/lean4-cli
-    toolchain-tag: true
-    stable-branch: false
-    branch: main
-    dependencies: []
-
   - name: doc-gen4
     url: https://github.com/leanprover/doc-gen4
     toolchain-tag: true
     stable-branch: false
     branch: main
-    dependencies: [lean4-cli]
+    dependencies: []
 
-  - name: verso
+  - name: Verso
     url: https://github.com/leanprover/verso
     toolchain-tag: true
     stable-branch: false
     branch: main
     dependencies: []
 
-  - name: reference-manual
-    url: https://github.com/leanprover/reference-manual
+  - name: Cli
+    url: https://github.com/leanprover/lean4-cli
     toolchain-tag: true
     stable-branch: false
     branch: main
-    dependencies: [verso]
+    dependencies: []
 
   - name: ProofWidgets4
     url: https://github.com/leanprover-community/ProofWidgets4
@@ -55,24 +40,22 @@ repositories:
     stable-branch: false
     branch: main
     dependencies:
-      - batteries
+      - Batteries
 
-  - name: aesop
+  - name: Aesop
     url: https://github.com/leanprover-community/aesop
     toolchain-tag: true
     stable-branch: true
     branch: master
     dependencies:
-      - batteries
+      - Batteries
 
   - name: import-graph
     url: https://github.com/leanprover-community/import-graph
     toolchain-tag: true
     stable-branch: false
     branch: main
-    dependencies:
-      - lean4-cli
-      - batteries
+    dependencies: []
 
   - name: plausible
     url: https://github.com/leanprover-community/plausible
@@ -81,26 +64,23 @@ repositories:
     branch: main
     dependencies: []
 
-  - name: mathlib4
+  - name: Mathlib
     url: https://github.com/leanprover-community/mathlib4
     toolchain-tag: true
     stable-branch: true
     branch: master
-    bump-branch: true
     dependencies:
-      - aesop
+      - Aesop
       - ProofWidgets4
       - lean4checker
-      - batteries
-      - lean4-cli
+      - Batteries
       - doc-gen4
       - import-graph
-      - plausible
 
-  - name: repl
+  - name: REPL
     url: https://github.com/leanprover-community/repl
     toolchain-tag: true
     stable-branch: true
     branch: master
     dependencies:
-      - mathlib4
+      - Mathlib

script/release_steps.py

@@ -1,149 +0,0 @@
-#!/usr/bin/env python3
-
-"""
-Generate release steps script for Lean4 repositories.
-
-This script helps automate the release process for Lean4 and its dependent repositories
-by generating step-by-step instructions for updating toolchains, creating tags,
-and managing branches.
-
-Usage:
-    python3 release_steps.py <version> <repo>
-
-Arguments:
-    version: The version to set in the lean-toolchain file (e.g., v4.6.0)
-    repo: A substring of the repository name as specified in release_repos.yml
-
-Example:
-    python3 release_steps.py v4.6.0 mathlib
-    python3 release_steps.py v4.6.0 batt
-
-The script reads repository configurations from release_repos.yml in the same directory.
-Each repository may have specific requirements for:
-- Branch management
-- Toolchain updates
-- Dependency updates
-- Tagging conventions
-- Stable branch handling
-"""
-
-import argparse
-import yaml
-import os
-import sys
-import re
-
-def load_repos_config(file_path):
-    with open(file_path, "r") as f:
-        return yaml.safe_load(f)["repositories"]
-
-def find_repo(repo_substring, config):
-    pattern = re.compile(re.escape(repo_substring), re.IGNORECASE)
-    matching_repos = [r for r in config if pattern.search(r["name"])]
-    if not matching_repos:
-        print(f"Error: No repository matching '{repo_substring}' found in configuration.")
-        sys.exit(1)
-    if len(matching_repos) > 1:
-        print(f"Error: Multiple repositories matching '{repo_substring}' found in configuration: {', '.join(r['name'] for r in matching_repos)}")
-        sys.exit(1)
-    return matching_repos[0]
-
-def generate_script(repo, version, config):
-    repo_config = find_repo(repo, config)
-    repo_name = repo_config['name']
-    repo_url = repo_config['url']
-    # Extract the last component of the URL, removing the .git extension if present
-    repo_dir = repo_url.split('/')[-1].replace('.git', '')
-    default_branch = repo_config.get("branch", "main")
-    dependencies = repo_config.get("dependencies", [])
-    requires_tagging = repo_config.get("toolchain-tag", True)
-    has_stable_branch = repo_config.get("stable-branch", True)
-
-    script_lines = [
-        f"cd {repo_dir}",
-        "git fetch",
-        f"git checkout {default_branch} && git pull",
-        f"git checkout -b bump_to_{version}",
-        f"echo leanprover/lean4:{version} > lean-toolchain",
-    ]
-
-    # Special cases for specific repositories
-    if repo_name == "repl":
-        script_lines.extend([
-            "lake update",
-            "cd test/Mathlib",
-            f"perl -pi -e 's/rev = \"v\\d+\\.\\d+\\.\\d+(-rc\\d+)?\"/rev = \"{version}\"/g' lakefile.toml",
-            f"echo leanprover/lean4:{version} > lean-toolchain",
-            "lake update",
-            "cd ../..",
-            "./test.sh"
-        ])
-    elif dependencies:
-        script_lines.append('perl -pi -e \'s/"v4\\.[0-9]+(\\.[0-9]+)?(-rc[0-9]+)?"/"' + version + '"/g\' lakefile.*')
-        script_lines.append("lake update")
-
-    script_lines.append("")
-
-    script_lines.extend([
-        f'git commit -am "chore: bump toolchain to {version}"',
-        ""
-    ])
-
-    if re.search(r'rc\d+$', version) and repo_name in ["batteries", "mathlib4"]:
-        script_lines.extend([
-            "echo 'This repo has nightly-testing infrastructure'",
-            f"git merge origin/bump/{version.split('-rc')[0]}",
-            "echo 'Please resolve any conflicts.'",
-            ""
-        ])
-    if re.search(r'rc\d+$', version) and repo_name in ["verso", "reference-manual"]:
-        script_lines.extend([
-            "echo 'This repo does development on nightly-testing: remember to rebase merge the PR.'",
-            f"git merge origin/nightly-testing",
-            "echo 'Please resolve any conflicts.'",
-            ""
-        ])
-    if repo_name != "Mathlib":
-        script_lines.extend([
-            "lake build && if lake check-test; then lake test; fi",
-            ""
-        ])
-
-    script_lines.extend([
-        'gh pr create --title "chore: bump toolchain to ' + version + '" --body ""',
-        "echo 'Please review the PR and merge or rebase it.'",
-        ""
-    ])
-
-    return "\n".join(script_lines)
-
-def main():
-    parser = argparse.ArgumentParser(
-        description="Generate release steps script for Lean4 repositories.",
-        formatter_class=argparse.RawDescriptionHelpFormatter,
-        epilog="""
-Examples:
-  %(prog)s v4.6.0 mathlib    Generate steps for updating Mathlib to v4.6.0
-  %(prog)s v4.6.0 batt       Generate steps for updating Batteries to v4.6.0
-  
-The script will generate shell commands to:
-1. Update the lean-toolchain file
-2. Create appropriate branches and commits
-3. Create pull requests
-
-(Note that the steps of creating toolchain version tags, and merging these into `stable` branches,
-are handled by `script/release_checklist.py`.)
-"""
-    )
-    parser.add_argument("version", help="The version to set in the lean-toolchain file (e.g., v4.6.0)")
-    parser.add_argument("repo", help="A substring of the repository name as specified in release_repos.yml")
-    args = parser.parse_args()
-
-    config_path = os.path.join(os.path.dirname(__file__), "release_repos.yml")
-    config = load_repos_config(config_path)
-
-    script = generate_script(args.repo, args.version, config)
-    print(script)
-
-if __name__ == "__main__":
-    main()

src/CMakeLists.txt

@@ -10,7 +10,7 @@ endif()
 include(ExternalProject)
 project(LEAN CXX C)
 set(LEAN_VERSION_MAJOR 4)
-set(LEAN_VERSION_MINOR 21)
+set(LEAN_VERSION_MINOR 16)
 set(LEAN_VERSION_PATCH 0)
 set(LEAN_VERSION_IS_RELEASE 0)  # This number is 1 in the release revision, and 0 otherwise.
 set(LEAN_SPECIAL_VERSION_DESC "" CACHE STRING "Additional version description like 'nightly-2018-03-11'")
@@ -20,11 +20,6 @@ if (LEAN_SPECIAL_VERSION_DESC)
 elseif (NOT LEAN_VERSION_IS_RELEASE)
   string(APPEND LEAN_VERSION_STRING "-pre")
 endif()
-if (LEAN_VERSION_IS_RELEASE)
-  set(LEAN_MANUAL_ROOT "https://lean-lang.org/doc/reference/${LEAN_VERSION_STRING}/")
-else()
-  set(LEAN_MANUAL_ROOT "")
-endif()
 
 set(LEAN_PLATFORM_TARGET "" CACHE STRING "LLVM triple of the target platform")
 if (NOT LEAN_PLATFORM_TARGET)
@@ -74,13 +69,12 @@ option(TRACK_LIVE_EXPRS    "TRACK_LIVE_EXPRS" OFF)
 option(CUSTOM_ALLOCATORS   "CUSTOM_ALLOCATORS" ON)
 option(SAVE_SNAPSHOT       "SAVE_SNAPSHOT" ON)
 option(SAVE_INFO           "SAVE_INFO" ON)
-option(SMALL_ALLOCATOR     "SMALL_ALLOCATOR" OFF)
+option(SMALL_ALLOCATOR     "SMALL_ALLOCATOR" ON)
 option(MMAP                "MMAP" ON)
 option(LAZY_RC             "LAZY_RC" OFF)
 option(RUNTIME_STATS       "RUNTIME_STATS" OFF)
 option(BSYMBOLIC "Link with -Bsymbolic to reduce call overhead in shared libraries (Linux)" ON)
 option(USE_GMP "USE_GMP" ON)
-option(USE_MIMALLOC "use mimalloc" ON)
 
 # development-specific options
 option(CHECK_OLEAN_VERSION "Only load .olean files compiled with the current version of Lean" OFF)
@@ -93,11 +87,6 @@ if ("${LAZY_RC}" MATCHES "ON")
   set(LEAN_LAZY_RC "#define LEAN_LAZY_RC")
 endif()
 
-if (USE_MIMALLOC)
-  set(SMALL_ALLOCATOR OFF)
-  set(LEAN_MIMALLOC "#define LEAN_MIMALLOC")
-endif()
-
 if ("${SMALL_ALLOCATOR}" MATCHES "ON")
   set(LEAN_SMALL_ALLOCATOR "#define LEAN_SMALL_ALLOCATOR")
 endif()
@@ -155,12 +144,11 @@ if(${CMAKE_SYSTEM_NAME} MATCHES "Windows")
   # do not import the world from windows.h using appropriately named flag
   string(APPEND LEAN_EXTRA_CXX_FLAGS " -D WIN32_LEAN_AND_MEAN")
   # DLLs must go next to executables on Windows
-  set(CMAKE_RELATIVE_LIBRARY_OUTPUT_DIRECTORY "bin")
+  set(CMAKE_LIBRARY_OUTPUT_DIRECTORY "${CMAKE_BINARY_DIR}/bin")
 else()
-  set(CMAKE_RELATIVE_LIBRARY_OUTPUT_DIRECTORY "lib/lean")
+  set(CMAKE_LIBRARY_OUTPUT_DIRECTORY "${CMAKE_BINARY_DIR}/lib/lean")
 endif()
 
-set(CMAKE_LIBRARY_OUTPUT_DIRECTORY "${CMAKE_BINARY_DIR}/${CMAKE_RELATIVE_LIBRARY_OUTPUT_DIRECTORY}")
 set(CMAKE_ARCHIVE_OUTPUT_DIRECTORY "${CMAKE_BINARY_DIR}/lib/lean")
 
 # OSX default thread stack size is very small. Moreover, in Debug mode, each new stack frame consumes a lot of extra memory.
@@ -191,11 +179,10 @@ set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} "${CMAKE_SOURCE_DIR}/cmake/Modules")
 
 # Initialize CXXFLAGS.
 set(CMAKE_CXX_FLAGS                "${LEAN_EXTRA_CXX_FLAGS} -DLEAN_BUILD_TYPE=\"${CMAKE_BUILD_TYPE}\" -DLEAN_EXPORTING")
-set(CMAKE_CXX_FLAGS_DEBUG          "-DLEAN_DEBUG")
+set(CMAKE_CXX_FLAGS_DEBUG          "-DLEAN_DEBUG -DLEAN_TRACE")
 set(CMAKE_CXX_FLAGS_MINSIZEREL     "-DNDEBUG")
 set(CMAKE_CXX_FLAGS_RELEASE        "-DNDEBUG")
 set(CMAKE_CXX_FLAGS_RELWITHDEBINFO "-DNDEBUG")
-set(CMAKE_CXX_FLAGS_RELWITHASSERT  "-DLEAN_DEBUG")
 
 # SPLIT_STACK
 if (SPLIT_STACK)
@@ -222,7 +209,6 @@ elseif (MSVC)
     set(CMAKE_CXX_FLAGS_DEBUG          "/Od /Zi ${CMAKE_CXX_FLAGS_DEBUG}")
     set(CMAKE_CXX_FLAGS_MINSIZEREL     "/Os /Zc:inline ${CMAKE_CXX_FLAGS_MINSIZEREL}")
     set(CMAKE_CXX_FLAGS_RELEASE        "/O2 /Oi /Oy /Zc:inline ${CMAKE_CXX_FLAGS_RELEASE}")
-    set(CMAKE_CXX_FLAGS_RELWITHASSERT  "/O2 /Oi /Oy /Zc:inline ${CMAKE_CXX_FLAGS_RELWITHASSERT}")
     set(CMAKE_CXX_FLAGS_RELWITHDEBINFO "/O2 /Oi /Zi ${CMAKE_CXX_FLAGS_RELWITHDEBINFO}")
     set(LEAN_EXTRA_LINKER_FLAGS        "/LTCG:INCREMENTAL ${LEAN_EXTRA_LINKER_FLAGS}")
     set(CMAKE_STATIC_LINKER_FLAGS      "${CMAKE_STATIC_LINKER_FLAGS} ${LEAN_EXTRA_LINKER_FLAGS}")
@@ -242,13 +228,11 @@ if (NOT MSVC)
       set(CMAKE_CXX_FLAGS_MINSIZEREL     "-Os ${CMAKE_CXX_FLAGS_MINSIZEREL}")
     endif ()
     set(CMAKE_CXX_FLAGS_RELEASE        "-O3 ${CMAKE_CXX_FLAGS_RELEASE}")
-    set(CMAKE_CXX_FLAGS_RELWITHASSERT  "-O3 ${CMAKE_CXX_FLAGS_RELWITHASSERT}")
     set(CMAKE_CXX_FLAGS_RELWITHDEBINFO "-O2 -g3 -fno-omit-frame-pointer ${CMAKE_CXX_FLAGS_RELWITHDEBINFO}")
 elseif (MULTI_THREAD)
     set(CMAKE_CXX_FLAGS_DEBUG          "/MTd ${CMAKE_CXX_FLAGS_DEBUG}")
     set(CMAKE_CXX_FLAGS_MINSIZEREL     "/MT ${CMAKE_CXX_FLAGS_MINSIZEREL}")
     set(CMAKE_CXX_FLAGS_RELEASE        "/MT ${CMAKE_CXX_FLAGS_RELEASE}")
-    set(CMAKE_CXX_FLAGS_RELWITHASSERT  "/MT ${CMAKE_CXX_FLAGS_RELWITHASSERT}")
     set(CMAKE_CXX_FLAGS_RELWITHDEBINFO "/MT ${CMAKE_CXX_FLAGS_RELWITHDEBINFO}")
 endif ()
 
@@ -369,8 +353,8 @@ if(LLVM)
   execute_process(COMMAND ${LLVM_CONFIG} --version COMMAND_ERROR_IS_FATAL ANY OUTPUT_VARIABLE LLVM_CONFIG_VERSION ECHO_OUTPUT_VARIABLE OUTPUT_STRIP_TRAILING_WHITESPACE)
   string(REGEX MATCH "^[0-9]*" LLVM_CONFIG_MAJOR_VERSION ${LLVM_CONFIG_VERSION})
   message(STATUS "Found 'llvm-config' at '${LLVM_CONFIG}' with version '${LLVM_CONFIG_VERSION}', major version '${LLVM_CONFIG_MAJOR_VERSION}'")
-  if (NOT LLVM_CONFIG_MAJOR_VERSION STREQUAL "19")
-    message(FATAL_ERROR "Unable to find llvm-config version 19. Found invalid version '${LLVM_CONFIG_MAJOR_VERSION}'")
+  if (NOT LLVM_CONFIG_MAJOR_VERSION STREQUAL "15")
+    message(FATAL_ERROR "Unable to find llvm-config version 15. Found invalid version '${LLVM_CONFIG_MAJOR_VERSION}'")
   endif()
   # -DLEAN_LLVM is used to conditionally compile Lean features that depend on LLVM
   string(APPEND CMAKE_CXX_FLAGS " -D LEAN_LLVM")
@@ -470,20 +454,20 @@ if(${CMAKE_SYSTEM_NAME} MATCHES "Linux")
   string(APPEND CMAKE_CXX_FLAGS " -fPIC -ftls-model=initial-exec")
   string(APPEND LEANC_EXTRA_CC_FLAGS " -fPIC")
   string(APPEND TOOLCHAIN_SHARED_LINKER_FLAGS " -Wl,-rpath=\\$$ORIGIN/..:\\$$ORIGIN")
-  string(APPEND LAKESHARED_LINKER_FLAGS " -Wl,--whole-archive ${CMAKE_BINARY_DIR}/lib/lean/libLake.a.export -Wl,--no-whole-archive")
-  string(APPEND CMAKE_EXE_LINKER_FLAGS " -Wl,-rpath=$ORIGIN/../lib:$ORIGIN/../lib/lean")
+  string(APPEND LAKESHARED_LINKER_FLAGS " -Wl,--whole-archive ${CMAKE_BINARY_DIR}/lib/temp/libLake.a.export -Wl,--no-whole-archive")
+  string(APPEND CMAKE_EXE_LINKER_FLAGS " -Wl,-rpath=\\\$ORIGIN/../lib:\\\$ORIGIN/../lib/lean")
 elseif(${CMAKE_SYSTEM_NAME} MATCHES "Darwin")
   string(APPEND CMAKE_CXX_FLAGS " -ftls-model=initial-exec")
   string(APPEND INIT_SHARED_LINKER_FLAGS " -install_name @rpath/libInit_shared.dylib")
   string(APPEND LEANSHARED_1_LINKER_FLAGS " -install_name @rpath/libleanshared_1.dylib")
   string(APPEND LEANSHARED_LINKER_FLAGS " -install_name @rpath/libleanshared.dylib")
-  string(APPEND LAKESHARED_LINKER_FLAGS " -Wl,-force_load,${CMAKE_BINARY_DIR}/lib/lean/libLake.a.export -install_name @rpath/libLake_shared.dylib")
+  string(APPEND LAKESHARED_LINKER_FLAGS " -Wl,-force_load,${CMAKE_BINARY_DIR}/lib/temp/libLake.a.export -install_name @rpath/libLake_shared.dylib")
   string(APPEND CMAKE_EXE_LINKER_FLAGS " -Wl,-rpath,@executable_path/../lib -Wl,-rpath,@executable_path/../lib/lean")
 elseif(${CMAKE_SYSTEM_NAME} MATCHES "Emscripten")
   string(APPEND CMAKE_CXX_FLAGS " -fPIC")
   string(APPEND LEANC_EXTRA_CC_FLAGS " -fPIC")
 elseif(${CMAKE_SYSTEM_NAME} MATCHES "Windows")
-  string(APPEND LAKESHARED_LINKER_FLAGS " -Wl,--out-implib,${CMAKE_BINARY_DIR}/lib/lean/libLake_shared.dll.a -Wl,--whole-archive ${CMAKE_BINARY_DIR}/lib/lean/libLake.a.export -Wl,--no-whole-archive")
+  string(APPEND LAKESHARED_LINKER_FLAGS " -Wl,--out-implib,${CMAKE_BINARY_DIR}/lib/lean/libLake_shared.dll.a -Wl,--whole-archive ${CMAKE_BINARY_DIR}/lib/temp/libLake.a.export -Wl,--no-whole-archive")
 endif()
 
 if(${CMAKE_SYSTEM_NAME} MATCHES "Linux")
@@ -511,10 +495,7 @@ if(${CMAKE_SYSTEM_NAME} MATCHES "Windows")
   # import libraries created by the stdlib.make targets
   string(APPEND LEANC_SHARED_LINKER_FLAGS " -lInit_shared -lleanshared_1 -lleanshared")
 elseif("${CMAKE_SYSTEM_NAME}" MATCHES "Darwin")
-  # The second flag is necessary to even *load* dylibs without resolved symbols, as can happen
-  # if a Lake `extern_lib` depends on a symbols defined by the Lean library but is loaded even
-  # before definition.
-  string(APPEND LEANC_SHARED_LINKER_FLAGS " -Wl,-undefined,dynamic_lookup -Wl,-no_fixup_chains")
+  string(APPEND LEANC_SHARED_LINKER_FLAGS " -Wl,-undefined,dynamic_lookup")
 endif()
 # Linux ignores undefined symbols in shared libraries by default
 
@@ -533,16 +514,7 @@ if(USE_GITHASH)
     message(STATUS "git commit sha1: ${GIT_SHA1}")
   endif()
 else()
-  if(USE_LAKE AND ${STAGE} EQUAL 0)
-    # we need to embed *some* hash for Lake to invalidate stage 1 on stage 0 changes
-    execute_process(
-        COMMAND git ls-tree HEAD "${CMAKE_CURRENT_SOURCE_DIR}/../../stage0" --object-only
-        OUTPUT_VARIABLE GIT_SHA1
-        OUTPUT_STRIP_TRAILING_WHITESPACE)
-    message(STATUS "stage0 sha1: ${GIT_SHA1}")
-  else()
-    set(GIT_SHA1 "")
-  endif()
+  set(GIT_SHA1 "")
 endif()
 configure_file("${LEAN_SOURCE_DIR}/githash.h.in" "${LEAN_BINARY_DIR}/githash.h")
 
@@ -561,9 +533,6 @@ else()
   set(LEAN_IS_STAGE0 "#define LEAN_IS_STAGE0 0")
 endif()
 configure_file("${LEAN_SOURCE_DIR}/config.h.in" "${LEAN_BINARY_DIR}/include/lean/config.h")
-if (USE_MIMALLOC)
-  file(COPY "${LEAN_BINARY_DIR}/../mimalloc/src/mimalloc/include/mimalloc.h" DESTINATION "${LEAN_BINARY_DIR}/include/lean")
-endif()
 install(DIRECTORY ${LEAN_BINARY_DIR}/include/ DESTINATION include)
 configure_file(${LEAN_SOURCE_DIR}/lean.mk.in ${LEAN_BINARY_DIR}/share/lean/lean.mk)
 install(DIRECTORY ${LEAN_BINARY_DIR}/share/ DESTINATION share)
@@ -572,9 +541,6 @@ include_directories(${LEAN_SOURCE_DIR})
 include_directories(${CMAKE_BINARY_DIR})  # version.h etc., "private" headers
 include_directories(${CMAKE_BINARY_DIR}/include)  # config.h etc., "public" headers
 
-# Lean code only needs this one include
-string(APPEND LEANC_OPTS " -I${CMAKE_BINARY_DIR}/include")
-
 # Use CMake profile C++ flags for building Lean libraries, but do not embed in `leanc`
 string(TOUPPER "${CMAKE_BUILD_TYPE}" uppercase_CMAKE_BUILD_TYPE)
 string(APPEND LEANC_OPTS " ${CMAKE_CXX_FLAGS_${uppercase_CMAKE_BUILD_TYPE}}")
@@ -689,7 +655,7 @@ add_custom_target(make_stdlib ALL
   # The actual rule is in a separate makefile because we want to prefix it with '+' to use the Make job server
   # for a parallelized nested build, but CMake doesn't let us do that.
   # We use `lean` from the previous stage, but `leanc`, headers, etc. from the current stage
-  COMMAND $(MAKE) -f ${CMAKE_BINARY_DIR}/stdlib.make Init Std Lean Leanc
+  COMMAND $(MAKE) -f ${CMAKE_BINARY_DIR}/stdlib.make Init Std Lean
   VERBATIM)
 
 # if we have LLVM enabled, then build `lean.h.bc` which has the LLVM bitcode
@@ -768,7 +734,7 @@ if(${STAGE} GREATER 0 AND EXISTS ${LEAN_SOURCE_DIR}/Leanc.lean AND NOT ${CMAKE_S
   add_custom_target(leanc ALL
     WORKING_DIRECTORY ${CMAKE_BINARY_DIR}/leanc
     DEPENDS leanshared
-    COMMAND $(MAKE) -f ${CMAKE_BINARY_DIR}/stdlib.make leanc
+    COMMAND $(MAKE) -f ${CMAKE_BINARY_DIR}/stdlib.make Leanc
     VERBATIM)
 endif()
 
@@ -787,11 +753,7 @@ add_custom_target(clean-olean
   DEPENDS clean-stdlib)
 
 install(DIRECTORY "${CMAKE_BINARY_DIR}/lib/" DESTINATION lib
-  PATTERN temp EXCLUDE
-  PATTERN "*.export" EXCLUDE
-  PATTERN "*.hash" EXCLUDE
-  PATTERN "*.trace" EXCLUDE
-  PATTERN "*.rsp" EXCLUDE)
+  PATTERN temp EXCLUDE)
 
 # symlink source into expected installation location for go-to-definition, if file system allows it
 file(MAKE_DIRECTORY ${CMAKE_BINARY_DIR}/src)
@@ -822,31 +784,12 @@ if(LEAN_INSTALL_PREFIX)
 endif()
 
 # Escape for `make`. Yes, twice.
-string(REPLACE "$" "\\\$$" CMAKE_EXE_LINKER_FLAGS_MAKE "${CMAKE_EXE_LINKER_FLAGS}")
+string(REPLACE "$" "$$" CMAKE_EXE_LINKER_FLAGS_MAKE "${CMAKE_EXE_LINKER_FLAGS}")
+string(REPLACE "$" "$$" CMAKE_EXE_LINKER_FLAGS_MAKE_MAKE "${CMAKE_EXE_LINKER_FLAGS_MAKE}")
 configure_file(${LEAN_SOURCE_DIR}/stdlib.make.in ${CMAKE_BINARY_DIR}/stdlib.make)
 
-# hacky
-function(toml_escape IN OUTVAR)
-  if(IN)
-    string(STRIP "${IN}" OUT)
-    string(REPLACE " " "\", \"" OUT "${OUT}")
-    set(${OUTVAR} "\"${OUT}\"" PARENT_SCOPE)
-  endif()
-endfunction()
-string(REPLACE "ROOT" "${CMAKE_BINARY_DIR}" LEANC_CC "${LEANC_CC}")
-string(REPLACE "ROOT" "${CMAKE_BINARY_DIR}" LEANC_INTERNAL_FLAGS "${LEANC_INTERNAL_FLAGS}")
-string(REPLACE "ROOT" "${CMAKE_BINARY_DIR}" LEANC_INTERNAL_LINKER_FLAGS "${LEANC_INTERNAL_LINKER_FLAGS}")
-set(LEANC_OPTS_TOML "${LEANC_OPTS} ${LEANC_EXTRA_CC_FLAGS} ${LEANC_INTERNAL_FLAGS}")
-set(LINK_OPTS_TOML "${LEANC_INTERNAL_LINKER_FLAGS} -L${CMAKE_BINARY_DIR}/lib/lean ${LEAN_EXTRA_LINKER_FLAGS}")
-
-toml_escape("${LEAN_EXTRA_MAKE_OPTS}" LEAN_EXTRA_OPTS_TOML)
-toml_escape("${LEANC_OPTS_TOML}" LEANC_OPTS_TOML)
-toml_escape("${LINK_OPTS_TOML}" LINK_OPTS_TOML)
-
-if(${CMAKE_SYSTEM_NAME} MATCHES "Windows")
-  set(LAKE_LIB_PREFIX "lib")
-endif()
-
 if(USE_LAKE AND STAGE EQUAL 1)
   configure_file(${LEAN_SOURCE_DIR}/lakefile.toml.in ${LEAN_SOURCE_DIR}/lakefile.toml)
+  configure_file(${LEAN_SOURCE_DIR}/lakefile.toml.in ${LEAN_SOURCE_DIR}/../tests/lakefile.toml)
+  configure_file(${LEAN_SOURCE_DIR}/lakefile.toml.in ${LEAN_SOURCE_DIR}/../lakefile.toml)
 endif()

src/Init.lean

@@ -3,8 +3,6 @@ Copyright (c) 2014 Microsoft Corporation. All rights reserved.
 Released under Apache 2.0 license as described in the file LICENSE.
 Authors: Leonardo de Moura
 -/
-module
-
 prelude
 import Init.Prelude
 import Init.Notation
@@ -40,6 +38,3 @@ import Init.Grind
 import Init.While
 import Init.Syntax
 import Init.Internal
-import Init.Try
-import Init.BinderNameHint
-import Init.Task

src/Init/BinderNameHint.lean

@@ -1,44 +0,0 @@
-/-
-Copyright (c) 2025 Lean FRO, LLC. All rights reserved.
-Released under Apache 2.0 license as described in the file LICENSE.
-Authors: Joachim Breitner
--/
-
-module
-
-prelude
-import Init.Prelude
-import Init.Tactics
-
-set_option linter.unusedVariables false in
-/--
-The expression `binderNameHint v binder e` defined to be `e`.
-
-If it is used on the right-hand side of an equation that is used for rewriting by `rw` or `simp`,
-and `v` is a local variable, and `binder` is an expression that (after beta-reduction) is a binder
-(`fun w => …` or `∀ w, …`), then it will rename `v` to the name used in that binder, and remove
-the `binderNameHint`.
-
-A typical use of this gadget would be as follows; the gadget ensures that after rewriting, the local
-variable is still `name`, and not `x`:
-```
-theorem all_eq_not_any_not (l : List α) (p : α → Bool) :
-    l.all p = !l.any fun x => binderNameHint x p (!p x) := sorry
-
-example (names : List String) : names.all (fun name => "Waldo".isPrefixOf name) = true := by
-  rw [all_eq_not_any_not]
-  -- ⊢ (!names.any fun name => !"Waldo".isPrefixOf name) = true
-```
-
-If `binder` is not a binder, then the name of `v` attains a macro scope. This only matters when the
-resulting term is used in a non-hygienic way, e.g. in termination proofs for well-founded recursion.
-
-This gadget is supported by
-* `simp`, `dsimp` and `rw` in the right-hand-side of an equation
-* `simp` in the assumptions of congruence rules
-
-It is ineffective in other positions (hyptheses of rewrite rules) or when used by other tactics
-(e.g. `apply`).
--/
-@[simp ↓, expose]
-def binderNameHint {α : Sort u} {β : Sort v} {γ : Sort w} (v : α) (binder : β) (e : γ) : γ := e

src/Init/BinderPredicates.lean

@@ -3,8 +3,6 @@ Copyright (c) 2021 Microsoft Corporation. All rights reserved.
 Released under Apache 2.0 license as described in the file LICENSE.
 Authors: Gabriel Ebner
 -/
-module
-
 prelude
 import Init.NotationExtra
 

src/Init/ByCases.lean

@@ -3,8 +3,6 @@ Copyright (c) 2024 Lean FRO, LLC. All rights reserved.
 Released under Apache 2.0 license as described in the file LICENSE.
 Authors: Leonardo de Moura, Mario Carneiro
 -/
-module
-
 prelude
 import Init.Classical
 
@@ -40,5 +38,25 @@ theorem apply_ite (f : α → β) (P : Prop) [Decidable P] (x y : α) :
   apply_dite f P (fun _ => x) (fun _ => y)
 
 /-- A `dite` whose results do not actually depend on the condition may be reduced to an `ite`. -/
-@[simp] theorem dite_eq_ite [Decidable P] :
-  (dite P (fun _ => a) (fun _ => b)) = ite P a b := rfl
+@[simp] theorem dite_eq_ite [Decidable P] : (dite P (fun _ => a) fun _ => b) = ite P a b := rfl
+
+@[deprecated "Use `ite_eq_right_iff`" (since := "2024-09-18")]
+theorem ite_some_none_eq_none [Decidable P] :
+    (if P then some x else none) = none ↔ ¬ P := by
+  simp only [ite_eq_right_iff, reduceCtorEq]
+  rfl
+
+@[deprecated "Use `Option.ite_none_right_eq_some`" (since := "2024-09-18")]
+theorem ite_some_none_eq_some [Decidable P] :
+    (if P then some x else none) = some y ↔ P ∧ x = y := by
+  split <;> simp_all
+
+@[deprecated "Use `dite_eq_right_iff" (since := "2024-09-18")]
+theorem dite_some_none_eq_none [Decidable P] {x : P → α} :
+    (if h : P then some (x h) else none) = none ↔ ¬P := by
+  simp
+
+@[deprecated "Use `Option.dite_none_right_eq_some`" (since := "2024-09-18")]
+theorem dite_some_none_eq_some [Decidable P] {x : P → α} {y : α} :
+    (if h : P then some (x h) else none) = some y ↔ ∃ h : P, x h = y := by
+  by_cases h : P <;> simp [h]

src/Init/Classical.lean

@@ -3,8 +3,6 @@ Copyright (c) 2020 Microsoft Corporation. All rights reserved.
 Released under Apache 2.0 license as described in the file LICENSE.
 Authors: Leonardo de Moura, Mario Carneiro
 -/
-module
-
 prelude
 import Init.PropLemmas
 
@@ -177,10 +175,7 @@ theorem or_iff_not_imp_right : a ∨ b ↔ (¬b → a) := Decidable.or_iff_not_i
 
 theorem not_imp_iff_and_not : ¬(a → b) ↔ a ∧ ¬b := Decidable.not_imp_iff_and_not
 
-theorem not_and_iff_not_or_not : ¬(a ∧ b) ↔ ¬a ∨ ¬b := Decidable.not_and_iff_not_or_not
-
-@[deprecated not_and_iff_not_or_not (since := "2025-03-18")]
-abbrev not_and_iff_or_not_not := @not_and_iff_not_or_not
+theorem not_and_iff_or_not_not : ¬(a ∧ b) ↔ ¬a ∨ ¬b := Decidable.not_and_iff_or_not_not
 
 theorem not_iff : ¬(a ↔ b) ↔ (¬a ↔ b) := Decidable.not_iff
 
@@ -200,7 +195,7 @@ end Classical
 /- Export for Mathlib compat. -/
 export Classical (imp_iff_right_iff imp_and_neg_imp_iff and_or_imp not_imp)
 
-/-- Extract an element from an existential statement, using `Classical.choose`. -/
+/-- Extract an element from a existential statement, using `Classical.choose`. -/
 -- This enables projection notation.
 @[reducible] noncomputable def Exists.choose {p : α → Prop} (P : ∃ a, p a) : α := Classical.choose P
 

src/Init/Coe.lean

@@ -3,8 +3,6 @@ Copyright (c) 2020 Microsoft Corporation. All rights reserved.
 Released under Apache 2.0 license as described in the file LICENSE.
 Authors: Leonardo de Moura, Mario Carneiro
 -/
-module
-
 prelude
 import Init.Prelude
 set_option linter.missingDocs true -- keep it documented
@@ -309,6 +307,9 @@ instance boolToSort : CoeSort Bool Prop where
 instance decPropToBool (p : Prop) [Decidable p] : CoeDep Prop p Bool where
   coe := decide p
 
+instance optionCoe {α : Type u} : Coe α (Option α) where
+  coe := some
+
 instance subtypeCoe {α : Sort u} {p : α → Prop} : CoeOut (Subtype p) α where
   coe v := v.val
 

src/Init/Control.lean

@@ -3,8 +3,6 @@ Copyright (c) 2016 Microsoft Corporation. All rights reserved.
 Released under Apache 2.0 license as described in the file LICENSE.
 Authors: Leonardo de Moura
 -/
-module
-
 prelude
 import Init.Control.Basic
 import Init.Control.State

src/Init/Control/Basic.lean

@@ -3,11 +3,8 @@ Copyright (c) 2020 Microsoft Corporation. All rights reserved.
 Released under Apache 2.0 license as described in the file LICENSE.
 Author: Leonardo de Moura, Sebastian Ullrich
 -/
-module
-
 prelude
 import Init.Core
-import Init.BinderNameHint
 
 universe u v w
 
@@ -38,17 +35,7 @@ instance (priority := 500) instForInOfForIn' [ForIn' m ρ α d] : ForIn m ρ α
   simp [h]
   rfl
 
-@[wf_preprocess] theorem forIn_eq_forIn' [d : Membership α ρ] [ForIn' m ρ α d] {β} [Monad m]
-    (x : ρ) (b : β) (f : (a : α) → β → m (ForInStep β)) :
-    forIn x b f = forIn' x b (fun x h => binderNameHint x f <| binderNameHint h () <| f x) := by
-  rfl
-
-@[deprecated forIn_eq_forIn' (since := "2025-04-04")]
-abbrev forIn_eq_forin' := @forIn_eq_forIn'
-
-/--
-Extracts the value from a `ForInStep`, ignoring whether it is `ForInStep.done` or `ForInStep.yield`.
--/
+/-- Extract the value from a `ForInStep`, ignoring whether it is `done` or `yield`. -/
 def ForInStep.value (x : ForInStep α) : α :=
   match x with
   | ForInStep.done b => b
@@ -57,28 +44,12 @@ def ForInStep.value (x : ForInStep α) : α :=
 @[simp] theorem ForInStep.value_done (b : β) : (ForInStep.done b).value = b := rfl
 @[simp] theorem ForInStep.value_yield (b : β) : (ForInStep.yield b).value = b := rfl
 
-/--
-Maps a function over a functor, with parameters swapped so that the function comes last.
-
-This function is `Functor.map` with the parameters reversed, typically used via the `<&>` operator.
--/
 @[reducible]
 def Functor.mapRev {f : Type u → Type v} [Functor f] {α β : Type u} : f α → (α → β) → f β :=
   fun a f => f <$> a
 
-@[inherit_doc Functor.mapRev]
 infixr:100 " <&> " => Functor.mapRev
 
-recommended_spelling "mapRev" for "<&>" in [Functor.mapRev, «term_<&>_»]
-
-/--
-Discards the value in a functor, retaining the functor's structure.
-
-Discarding values is especially useful when using `Applicative` functors or `Monad`s to implement
-effects, and some operation should be carried out only for its effects. In `do`-notation, statements
-whose values are discarded must return `Unit`, and `discard` can be used to explicitly discard their
-values.
--/
 @[always_inline, inline]
 def Functor.discard {f : Type u → Type v} {α : Type u} [Functor f] (x : f α) : f PUnit :=
   Functor.mapConst PUnit.unit x
@@ -98,7 +69,7 @@ Error recovery and state can interact subtly. For example, the implementation of
 -/
 -- NB: List instance is in mathlib. Once upstreamed, add
 -- * `List`, where `failure` is the empty list and `<|>` concatenates.
-class Alternative (f : Type u → Type v) : Type (max (u+1) v) extends Applicative f where
+class Alternative (f : Type u → Type v) extends Applicative f : Type (max (u+1) v) where
   /--
   Produces an empty collection or recoverable failure.  The `<|>` operator collects values or recovers
   from failures. See `Alternative` for more details.
@@ -141,13 +112,6 @@ instance : ToBool Bool where
   | true  => t
   | false => f
 
-/--
-Converts the result of the monadic action `x` to a `Bool`. If it is `true`, returns it and ignores
-`y`; otherwise, runs `y` and returns its result.
-
-This a monadic counterpart to the short-circuiting `||` operator, usually accessed via the `<||>`
-operator.
--/
 @[macro_inline] def orM {m : Type u → Type v} {β : Type u} [Monad m] [ToBool β] (x y : m β) : m β := do
   let b ← x
   match toBool b with
@@ -156,15 +120,6 @@ operator.
 
 infixr:30 " <||> " => orM
 
-recommended_spelling "orM" for "<||>" in [orM, «term_<||>_»]
-
-/--
-Converts the result of the monadic action `x` to a `Bool`. If it is `true`, returns `y`; otherwise,
-returns the original result of `x`.
-
-This a monadic counterpart to the short-circuiting `&&` operator, usually accessed via the `<&&>`
-operator.
--/
 @[macro_inline] def andM {m : Type u → Type v} {β : Type u} [Monad m] [ToBool β] (x y : m β) : m β := do
   let b ← x
   match toBool b with
@@ -173,12 +128,7 @@ operator.
 
 infixr:35 " <&&> " => andM
 
-recommended_spelling "andM" for "<&&>" in [andM, «term_<&&>_»]
-
-/--
-Runs a monadic action and returns the negation of its result.
--/
-@[macro_inline] def notM {m : Type → Type v} [Functor m] (x : m Bool) : m Bool :=
+@[macro_inline] def notM {m : Type → Type v} [Applicative m] (x : m Bool) : m Bool :=
   not <$> x
 
 /-!
@@ -293,61 +243,21 @@ Using `control` means that `runInBase` can be used multiple times.
 -/
 
 
-/--
-A way to lift a computation from one monad to another while providing the lifted computation with a
-means of interpreting computations from the outer monad. This provides a means of lifting
-higher-order operations automatically.
+/-- MonadControl is a way of stating that the monad `m` can be 'run inside' the monad `n`.
+
+This is the same as [`MonadBaseControl`](https://hackage.haskell.org/package/monad-control-1.0.3.1/docs/Control-Monad-Trans-Control.html#t:MonadBaseControl) in Haskell.
+To learn about `MonadControl`, see the comment above this docstring.
 
-Clients should typically use `control` or `controlAt`, which request an instance of `MonadControlT`:
-the reflexive, transitive closure of `MonadControl`. New instances should be defined for
-`MonadControl` itself.
 -/
--- This is the same as
--- [`MonadBaseControl`](https://hackage.haskell.org/package/monad-control-1.0.3.1/docs/Control-Monad-Trans-Control.html#t:MonadBaseControl)
--- in Haskell.
 class MonadControl (m : semiOutParam (Type u → Type v)) (n : Type u → Type w) where
-  /--
-  A type that can be used to reconstruct both a returned value and any state used by the outer
-  monad.
-  -/
   stM      : Type u → Type u
-  /--
-  Lifts an action from the inner monad `m` to the outer monad `n`. The inner monad has access to a
-  reverse lifting operator that can run an `n` action, returning a value and state together.
-  -/
   liftWith : {α : Type u} → (({β : Type u} → n β → m (stM β)) → m α) → n α
-  /--
-  Lifts a monadic action that returns a state and a value in the inner monad to an action in the
-  outer monad. The extra state information is used to restore the results of effects from the
-  reverse lift passed to `liftWith`'s parameter.
-  -/
   restoreM : {α : Type u} → m (stM α) → n α
 
-/--
-A way to lift a computation from one monad to another while providing the lifted computation with a
-means of interpreting computations from the outer monad. This provides a means of lifting
-higher-order operations automatically.
-
-Clients should typically use `control` or `controlAt`, which request an instance of `MonadControlT`:
-the reflexive, transitive closure of `MonadControl`. New instances should be defined for
-`MonadControl` itself.
--/
+/-- Transitive closure of MonadControl. -/
 class MonadControlT (m : Type u → Type v) (n : Type u → Type w) where
-  /--
-  A type that can be used to reconstruct both a returned value and any state used by the outer
-  monad.
-  -/
   stM      : Type u → Type u
-  /--
-  Lifts an action from the inner monad `m` to the outer monad `n`. The inner monad has access to a
-  reverse lifting operator that can run an `n` action, returning a value and state together.
-  -/
   liftWith : {α : Type u} → (({β : Type u} → n β → m (stM β)) → m α) → n α
-  /--
-  Lifts a monadic action that returns a state and a value in the inner monad to an action in the
-  outer monad. The extra state information is used to restore the results of effects from the
-  reverse lift passed to `liftWith`'s parameter.
-  -/
   restoreM {α : Type u} : stM α → n α
 
 export MonadControlT (stM liftWith restoreM)
@@ -363,48 +273,25 @@ instance (m : Type u → Type v) [Pure m] : MonadControlT m m where
   liftWith f := f fun x => x
   restoreM x := pure x
 
-/--
-Lifts an operation from an inner monad to an outer monad, providing it with a reverse lifting
-operator that allows outer monad computations to be run in the inner monad. The lifted operation is
-required to return extra information that is required in order to reconstruct the reverse lift's
-effects in the outer monad; this extra information is determined by `stM`.
-
-This function takes the inner monad as an explicit parameter. Use `control` to infer the monad.
--/
 @[always_inline, inline]
 def controlAt (m : Type u → Type v) {n : Type u → Type w} [MonadControlT m n] [Bind n] {α : Type u}
     (f : ({β : Type u} → n β → m (stM m n β)) → m (stM m n α)) : n α :=
   liftWith f >>= restoreM
 
-/--
-Lifts an operation from an inner monad to an outer monad, providing it with a reverse lifting
-operator that allows outer monad computations to be run in the inner monad. The lifted operation is
-required to return extra information that is required in order to reconstruct the reverse lift's
-effects in the outer monad; this extra information is determined by `stM`.
-
-This function takes the inner monad as an implicit parameter. Use `controlAt` to specify it
-explicitly.
--/
 @[always_inline, inline]
 def control {m : Type u → Type v} {n : Type u → Type w} [MonadControlT m n] [Bind n] {α : Type u}
     (f : ({β : Type u} → n β → m (stM m n β)) → m (stM m n α)) : n α :=
   controlAt m f
 
 /--
-Overloaded monadic iteration over some container type.
-
-An instance of `ForM m γ α` describes how to iterate a monadic operator over a container of type `γ`
-with elements of type `α` in the monad `m`. The element type should be uniquely determined by the
-monad and the container.
-
-Use `ForM.forIn` to construct a `ForIn` instance from a `ForM` instance, thus enabling the use of
-the `for` operator in `do`-notation.
+  Typeclass for the polymorphic `forM` operation described in the "do unchained" paper.
+  Remark:
+  - `γ` is a "container" type of elements of type `α`.
+  - `α` is treated as an output parameter by the typeclass resolution procedure.
+    That is, it tries to find an instance using only `m` and `γ`.
 -/
 class ForM (m : Type u → Type v) (γ : Type w₁) (α : outParam (Type w₂)) where
-  /--
-  Runs the monadic action `f` on each element of the collection `coll`.
-  -/
-  forM [Monad m] (coll : γ) (f : α → m PUnit) : m PUnit
+  forM [Monad m] : γ → (α → m PUnit) → m PUnit
 
 export ForM (forM)
 
@@ -428,7 +315,3 @@ def Bind.bindLeft [Bind m] (f : α → m β) (ma : m α) : m β :=
 @[inherit_doc] infixr:55 " >=> " => Bind.kleisliRight
 @[inherit_doc] infixr:55 " <=< " => Bind.kleisliLeft
 @[inherit_doc] infixr:55 " =<< " => Bind.bindLeft
-
-recommended_spelling "kleisliRight" for ">=>" in [Bind.kleisliRight, «term_>=>_»]
-recommended_spelling "kleisliLeft" for "<=<" in [Bind.kleisliLeft, «term_<=<_»]
-recommended_spelling "bindLeft" for "=<<" in [Bind.bindLeft, «term_=<<_»]

src/Init/Control/EState.lean

@@ -3,8 +3,6 @@ Copyright (c) 2019 Microsoft Corporation. All rights reserved.
 Released under Apache 2.0 license as described in the file LICENSE.
 Authors: Leonardo de Moura
 -/
-module
-
 prelude
 import Init.Control.State
 import Init.Control.Except
@@ -31,11 +29,8 @@ namespace EStateM
 
 variable {ε σ α β : Type u}
 
-/--
-Alternative orElse operator that allows callers to select which exception should be used when both
-operations fail. The default is to use the first exception since the standard `orElse` uses the
-second.
--/
+/-- Alternative orElse operator that allows to select which exception should be used.
+    The default is to use the first exception since the standard `orElse` uses the second. -/
 @[always_inline, inline]
 protected def orElse' {δ} [Backtrackable δ σ] (x₁ x₂ : EStateM ε σ α) (useFirstEx := true) : EStateM ε σ α := fun s =>
   let d := Backtrackable.save s;
@@ -59,11 +54,6 @@ instance : MonadFinally (EStateM ε σ) := {
       | Result.error e₂ s => Result.error e₂ s
 }
 
-/--
-Converts a state monad action into a state monad action with exceptions.
-
-The resulting action does not throw an exception.
--/
 @[always_inline, inline] def fromStateM {ε σ α : Type} (x : StateM σ α) : EStateM ε σ α := fun s =>
   match x.run s with
   | (a, s') => EStateM.Result.ok a s'

src/Init/Control/Except.lean

@@ -5,8 +5,6 @@ Authors: Jared Roesch, Sebastian Ullrich
 
 The Except monad transformer.
 -/
-module
-
 prelude
 import Init.Control.Basic
 import Init.Control.Id
@@ -15,20 +13,10 @@ import Init.Coe
 namespace Except
 variable {ε : Type u}
 
-/--
-A successful computation in the `Except ε` monad: `a` is returned, and no exception is thrown.
--/
 @[always_inline, inline]
 protected def pure (a : α) : Except ε α :=
   Except.ok a
 
-/--
-Transforms a successful result with a function, doing nothing when an exception is thrown.
-
-Examples:
- * `(pure 2 : Except String Nat).map toString = pure 2`
- * `(throw "Error" : Except String Nat).map toString = throw "Error"`
--/
 @[always_inline, inline]
 protected def map (f : α → β) : Except ε α → Except ε β
   | Except.error err => Except.error err
@@ -39,78 +27,36 @@ protected def map (f : α → β) : Except ε α → Except ε β
   intro e
   simp [Except.map]; cases e <;> rfl
 
-/--
-Transforms exceptions with a function, doing nothing on successful results.
-
-Examples:
- * `(pure 2 : Except String Nat).mapError (·.length) = pure 2`
- * `(throw "Error" : Except String Nat).mapError (·.length) = throw 5`
--/
 @[always_inline, inline]
 protected def mapError (f : ε → ε') : Except ε α → Except ε' α
   | Except.error err => Except.error <| f err
   | Except.ok v      => Except.ok v
 
-/--
-Sequences two operations that may throw exceptions, allowing the second to depend on the value
-returned by the first.
-
-If the first operation throws an exception, then it is the result of the computation. If the first
-succeeds but the second throws an exception, then that exception is the result. If both succeed,
-then the result is the result of the second computation.
-
-This is the implementation of the `>>=` operator for `Except ε`.
--/
 @[always_inline, inline]
 protected def bind (ma : Except ε α) (f : α → Except ε β) : Except ε β :=
   match ma with
   | Except.error err => Except.error err
   | Except.ok v      => f v
 
-/-- Returns `true` if the value is `Except.ok`, `false` otherwise. -/
+/-- Returns true if the value is `Except.ok`, false otherwise. -/
 @[always_inline, inline]
 protected def toBool : Except ε α → Bool
   | Except.ok _    => true
   | Except.error _ => false
 
-@[inherit_doc Except.toBool]
 abbrev isOk : Except ε α → Bool := Except.toBool
 
-/--
-Returns `none` if an exception was thrown, or `some` around the value on success.
-
-Examples:
- * `(pure 10 : Except String Nat).toOption = some 10`
- * `(throw "Failure" : Except String Nat).toOption = none`
--/
 @[always_inline, inline]
 protected def toOption : Except ε α → Option α
   | Except.ok a    => some a
   | Except.error _ => none
 
-/--
-Handles exceptions thrown in the `Except ε` monad.
-
-If `ma` is successful, its result is returned. If it throws an exception, then `handle` is invoked
-on the exception's value.
-
-Examples:
- * `(pure 2 : Except String Nat).tryCatch (pure ·.length) = pure 2`
- * `(throw "Error" : Except String Nat).tryCatch (pure ·.length) = pure 5`
- * `(throw "Error" : Except String Nat).tryCatch (fun x => throw ("E: " ++ x)) = throw "E: Error"`
--/
 @[always_inline, inline]
 protected def tryCatch (ma : Except ε α) (handle : ε → Except ε α) : Except ε α :=
   match ma with
   | Except.ok a    => Except.ok a
   | Except.error e => handle e
 
-/--
-Recovers from exceptions thrown in the `Except ε` monad. Typically used via the `<|>` operator.
-
-`Except.tryCatch` is a related operator that allows the recovery procedure to depend on _which_
-exception was thrown.
--/
 def orElseLazy (x : Except ε α) (y : Unit → Except ε α) : Except ε α :=
   match x with
   | Except.ok a    => Except.ok a
@@ -124,26 +70,12 @@ instance : Monad (Except ε) where
 
 end Except
 
-/--
-Adds exceptions of type `ε` to a monad `m`.
--/
-@[expose] def ExceptT (ε : Type u) (m : Type u → Type v) (α : Type u) : Type v :=
+def ExceptT (ε : Type u) (m : Type u → Type v) (α : Type u) : Type v :=
   m (Except ε α)
 
-/--
-Use a monadic action that may return an exception's value as an action in the transformed monad that
-may throw the corresponding exception.
-
-This is the inverse of `ExceptT.run`.
--/
 @[always_inline, inline]
 def ExceptT.mk {ε : Type u} {m : Type u → Type v} {α : Type u} (x : m (Except ε α)) : ExceptT ε m α := x
 
-/--
-Use a monadic action that may throw an exception as an action that may return an exception's value.
-
-This is the inverse of `ExceptT.mk`.
--/
 @[always_inline, inline]
 def ExceptT.run {ε : Type u} {m : Type u → Type v} {α : Type u} (x : ExceptT ε m α) : m (Except ε α) := x
 
@@ -151,41 +83,25 @@ namespace ExceptT
 
 variable {ε : Type u} {m : Type u → Type v} [Monad m]
 
-/--
-Returns the value `a` without throwing exceptions or having any other effect.
--/
 @[always_inline, inline]
 protected def pure {α : Type u} (a : α) : ExceptT ε m α :=
   ExceptT.mk <| pure (Except.ok a)
 
-/--
-Handles exceptions thrown by an action that can have no effects _other_ than throwing exceptions.
--/
 @[always_inline, inline]
 protected def bindCont {α β : Type u} (f : α → ExceptT ε m β) : Except ε α → m (Except ε β)
   | Except.ok a    => f a
   | Except.error e => pure (Except.error e)
 
-/--
-Sequences two actions that may throw exceptions. Typically used via `do`-notation or the `>>=`
-operator.
--/
 @[always_inline, inline]
 protected def bind {α β : Type u} (ma : ExceptT ε m α) (f : α → ExceptT ε m β) : ExceptT ε m β :=
   ExceptT.mk <| ma >>= ExceptT.bindCont f
 
-/--
-Transforms a successful computation's value using `f`. Typically used via the `<$>` operator.
--/
 @[always_inline, inline]
 protected def map {α β : Type u} (f : α → β) (x : ExceptT ε m α) : ExceptT ε m β :=
   ExceptT.mk <| x >>= fun a => match a with
     | (Except.ok a)    => pure <| Except.ok (f a)
     | (Except.error e) => pure <| Except.error e
 
-/--
-Runs a computation from an underlying monad in the transformed monad with exceptions.
--/
 @[always_inline, inline]
 protected def lift {α : Type u} (t : m α) : ExceptT ε m α :=
   ExceptT.mk <| Except.ok <$> t
@@ -194,9 +110,6 @@ protected def lift {α : Type u} (t : m α) : ExceptT ε m α :=
 instance : MonadLift (Except ε) (ExceptT ε m) := ⟨fun e => ExceptT.mk <| pure e⟩
 instance : MonadLift m (ExceptT ε m) := ⟨ExceptT.lift⟩
 
-/--
-Handles exceptions produced in the `ExceptT ε` transformer.
--/
 @[always_inline, inline]
 protected def tryCatch {α : Type u} (ma : ExceptT ε m α) (handle : ε → ExceptT ε m α) : ExceptT ε m α :=
   ExceptT.mk <| ma >>= fun res => match res with
@@ -211,11 +124,6 @@ instance : Monad (ExceptT ε m) where
   bind := ExceptT.bind
   map  := ExceptT.map
 
-/--
-Transforms exceptions using the function `f`.
-
-This is the `ExceptT` version of `Except.mapError`.
--/
 @[always_inline, inline]
 protected def adapt {ε' α : Type u} (f : ε → ε') : ExceptT ε m α → ExceptT ε' m α := fun x =>
   ExceptT.mk <| Except.mapError f <$> x
@@ -242,12 +150,8 @@ instance (ε) : MonadExceptOf ε (Except ε) where
 namespace MonadExcept
 variable {ε : Type u} {m : Type v → Type w}
 
-/--
-An alternative unconditional error recovery operator that allows callers to specify which exception
-to throw in cases where both operations throw exceptions.
-
-By default, the first is thrown, because the `<|>` operator throws the second.
--/
+/-- Alternative orelse operator that allows to select which exception should be used.
+    The default is to use the first exception since the standard `orelse` uses the second. -/
 @[always_inline, inline]
 def orelse' [MonadExcept ε m] {α : Type v} (t₁ t₂ : m α) (useFirstEx := true) : m α :=
   tryCatch t₁ fun e₁ => tryCatch t₂ fun e₂ => throw (if useFirstEx then e₁ else e₂)
@@ -267,24 +171,13 @@ instance (ε : Type u) (m : Type u → Type v) [Monad m] : MonadControl m (Excep
   liftWith f := liftM <| f fun x => x.run
   restoreM x := x
 
-/--
-Monads that provide the ability to ensure an action happens, regardless of exceptions or other
-failures.
-
-`MonadFinally.tryFinally'` is used to desugar `try ... finally ...` syntax.
--/
 class MonadFinally (m : Type u → Type v) where
-  /--
-  Runs an action, ensuring that some other action always happens afterward.
-
-  More specifically, `tryFinally' x f` runs `x` and then the “finally” computation `f`. If `x`
-  succeeds with some value `a : α`, `f (some a)` is returned. If `x` fails for `m`'s definition of
-  failure, `f none` is returned.
-
-  `tryFinally'` can be thought of as performing the same role as a `finally` block in an imperative
-  programming language.
-  -/
-  tryFinally' {α β} : (x : m α) → (f : Option α → m β) → m (α × β)
+  /-- `tryFinally' x f` runs `x` and then the "finally" computation `f`.
+  When `x` succeeds with `a : α`, `f (some a)` is returned. If `x` fails
+  for `m`'s definition of failure, `f none` is returned. Hence `tryFinally'`
+  can be thought of as performing the same role as a `finally` block in
+  an imperative programming language. -/
+  tryFinally' {α β} : m α → (Option α → m β) → m (α × β)
 
 export MonadFinally (tryFinally')
 

src/Init/Control/ExceptCps.lean

@@ -3,8 +3,6 @@ Copyright (c) 2021 Microsoft Corporation. All rights reserved.
 Released under Apache 2.0 license as described in the file LICENSE.
 Authors: Leonardo de Moura
 -/
-module
-
 prelude
 import Init.Control.Lawful.Basic
 
@@ -12,37 +10,19 @@ import Init.Control.Lawful.Basic
 The Exception monad transformer using CPS style.
 -/
 
-/--
-Adds exceptions of type `ε` to a monad `m`.
-
-Instead of using `Except ε` to model exceptions, this implementation uses continuation passing
-style. This has different performance characteristics from `ExceptT ε`.
--/
-@[expose] def ExceptCpsT (ε : Type u) (m : Type u → Type v) (α : Type u) := (β : Type u) → (α → m β) → (ε → m β) → m β
+def ExceptCpsT (ε : Type u) (m : Type u → Type v) (α : Type u) := (β : Type u) → (α → m β) → (ε → m β) → m β
 
 namespace ExceptCpsT
 
-/--
-Use a monadic action that may throw an exception as an action that may return an exception's value.
--/
 @[always_inline, inline]
 def run {ε α : Type u} [Monad m] (x : ExceptCpsT ε m α) : m (Except ε α) :=
   x _ (fun a => pure (Except.ok a)) (fun e => pure (Except.error e))
 
 set_option linter.unusedVariables false in  -- `s` unused
-/--
-Use a monadic action that may throw an exception by providing explicit success and failure
-continuations.
--/
 @[always_inline, inline]
 def runK {ε α : Type u} (x : ExceptCpsT ε m α) (s : ε) (ok : α → m β) (error : ε → m β) : m β :=
   x _ ok error
 
-/--
-Returns the value of a computation, forgetting whether it was an exception or a success.
-
-This corresponds to early return.
--/
 @[always_inline, inline]
 def runCatch [Monad m] (x : ExceptCpsT α m α) : m α :=
   x α pure pure
@@ -60,9 +40,6 @@ instance : MonadExceptOf ε (ExceptCpsT ε m) where
   throw e  := fun _ _ k => k e
   tryCatch x handle := fun _ k₁ k₂ => x _ k₁ (fun e => handle e _ k₁ k₂)
 
-/--
-Run an action from the transformed monad in the exception monad.
--/
 @[always_inline, inline]
 def lift [Monad m] (x : m α) : ExceptCpsT ε m α :=
   fun _ k _ => x >>= k

src/Init/Control/Id.lean

@@ -5,36 +5,12 @@ Authors: Sebastian Ullrich
 
 The identity Monad.
 -/
-module
-
 prelude
 import Init.Core
 
 universe u
 
-/--
-The identity function on types, used primarily for its `Monad` instance.
-
-The identity monad is useful together with monad transformers to construct monads for particular
-purposes. Additionally, it can be used with `do`-notation in order to use control structures such as
-local mutability, `for`-loops, and early returns in code that does not otherwise use monads.
-
-Examples:
-```lean example
-def containsFive (xs : List Nat) : Bool := Id.run do
-  for x in xs do
-    if x == 5 then return true
-  return false
-```
-
-```lean example
-#eval containsFive [1, 3, 5, 7]
-```
-```output
-true
-```
--/
-@[expose] def Id (type : Type u) : Type u := type
+def Id (type : Type u) : Type u := type
 
 namespace Id
 
@@ -44,19 +20,10 @@ instance : Monad Id where
   bind x f := f x
   map f x := f x
 
-/--
-The identity monad has a `bind` operator.
--/
 def hasBind : Bind Id :=
   inferInstance
 
-/--
-Runs a computation in the identity monad.
-
-This function is the identity function. Because its parameter has type `Id α`, it causes
-`do`-notation in its arguments to use the `Monad Id` instance.
--/
-@[always_inline, inline, expose]
+@[always_inline, inline]
 protected def run (x : Id α) : α := x
 
 instance [OfNat α n] : OfNat (Id α) n :=

src/Init/Control/Lawful.lean

@@ -3,9 +3,6 @@ Copyright (c) 2021 Microsoft Corporation. All rights reserved.
 Released under Apache 2.0 license as described in the file LICENSE.
 Authors: Sebastian Ullrich, Leonardo de Moura, Mario Carneiro
 -/
-module
-
 prelude
 import Init.Control.Lawful.Basic
 import Init.Control.Lawful.Instances
-import Init.Control.Lawful.Lemmas

src/Init/Control/Lawful/Basic.lean

@@ -3,8 +3,6 @@ Copyright (c) 2021 Microsoft Corporation. All rights reserved.
 Released under Apache 2.0 license as described in the file LICENSE.
 Authors: Sebastian Ullrich, Leonardo de Moura, Mario Carneiro
 -/
-module
-
 prelude
 import Init.SimpLemmas
 import Init.Meta
@@ -15,85 +13,46 @@ open Function
   rfl
 
 /--
-A functor satisfies the functor laws.
-
-The `Functor` class contains the operations of a functor, but does not require that instances
-prove they satisfy the laws of a functor. A `LawfulFunctor` instance includes proofs that the laws
-are satisfied. Because `Functor` instances may provide optimized implementations of `mapConst`,
-`LawfulFunctor` instances must also prove that the optimized implementation is equivalent to the
-standard implementation.
+The `Functor` typeclass only contains the operations of a functor.
+`LawfulFunctor` further asserts that these operations satisfy the laws of a functor,
+including the preservation of the identity and composition laws:
+```
+id <$> x = x
+(h ∘ g) <$> x = h <$> g <$> x
+```
 -/
 class LawfulFunctor (f : Type u → Type v) [Functor f] : Prop where
-  /--
-  The `mapConst` implementation is equivalent to the default implementation.
-  -/
   map_const          : (Functor.mapConst : α → f β → f α) = Functor.map ∘ const β
-  /--
-  The `map` implementation preserves identity.
-  -/
   id_map   (x : f α) : id <$> x = x
-  /--
-  The `map` implementation preserves function composition.
-  -/
   comp_map (g : α → β) (h : β → γ) (x : f α) : (h ∘ g) <$> x = h <$> g <$> x
 
 export LawfulFunctor (map_const id_map comp_map)
 
 attribute [simp] id_map
 
-@[simp] theorem id_map' [Functor f] [LawfulFunctor f] (x : f α) : (fun a => a) <$> x = x :=
+@[simp] theorem id_map' [Functor m] [LawfulFunctor m] (x : m α) : (fun a => a) <$> x = x :=
   id_map x
 
 @[simp] theorem Functor.map_map [Functor f] [LawfulFunctor f] (m : α → β) (g : β → γ) (x : f α) :
     g <$> m <$> x = (fun a => g (m a)) <$> x :=
   (comp_map _ _ _).symm
 
-theorem Functor.map_unit [Functor f] [LawfulFunctor f] {a : f PUnit} : (fun _ => PUnit.unit) <$> a = a := by
-  simp [map]
-
 /--
-An applicative functor satisfies the laws of an applicative functor.
-
-The `Applicative` class contains the operations of an applicative functor, but does not require that
-instances prove they satisfy the laws of an applicative functor. A `LawfulApplicative` instance
-includes proofs that the laws are satisfied.
-
-Because `Applicative` instances may provide optimized implementations of `seqLeft` and `seqRight`,
-`LawfulApplicative` instances must also prove that the optimized implementation is equivalent to the
-standard implementation.
+The `Applicative` typeclass only contains the operations of an applicative functor.
+`LawfulApplicative` further asserts that these operations satisfy the laws of an applicative functor:
+```
+pure id <*> v = v
+pure (·∘·) <*> u <*> v <*> w = u <*> (v <*> w)
+pure f <*> pure x = pure (f x)
+u <*> pure y = pure (· y) <*> u
+```
 -/
-class LawfulApplicative (f : Type u → Type v) [Applicative f] : Prop extends LawfulFunctor f where
-  /-- `seqLeft` is equivalent to the default implementation. -/
+class LawfulApplicative (f : Type u → Type v) [Applicative f] extends LawfulFunctor f : Prop where
   seqLeft_eq  (x : f α) (y : f β)     : x <* y = const β <$> x <*> y
-  /-- `seqRight` is equivalent to the default implementation. -/
   seqRight_eq (x : f α) (y : f β)     : x *> y = const α id <$> x <*> y
-  /--
-  `pure` before `seq` is equivalent to `Functor.map`.
-
-  This means that `pure` really is pure when occurring immediately prior to `seq`.
-   -/
   pure_seq    (g : α → β) (x : f α)   : pure g <*> x = g <$> x
-
-  /--
-  Mapping a function over the result of `pure` is equivalent to applying the function under `pure`.
-
-  This means that `pure` really is pure with respect to `Functor.map`.
-  -/
   map_pure    (g : α → β) (x : α)     : g <$> (pure x : f α) = pure (g x)
-
-  /--
-  `pure` after `seq` is equivalent to `Functor.map`.
-
-  This means that `pure` really is pure when occurring just after `seq`.
-  -/
   seq_pure    {α β : Type u} (g : f (α → β)) (x : α) : g <*> pure x = (fun h => h x) <$> g
-
-  /--
-  `seq` is associative.
-
-  Changing the nesting of `seq` calls while maintaining the order of computations results in an
-  equivalent computation. This means that `seq` is not doing any more than sequencing.
-  -/
   seq_assoc   {α β γ : Type u} (x : f α) (g : f (α → β)) (h : f (β → γ)) : h <*> (g <*> x) = ((@comp α β γ) <$> h) <*> g <*> x
   comp_map g h x := (by
     repeat rw [← pure_seq]
@@ -107,36 +66,21 @@ attribute [simp] map_pure seq_pure
   simp [pure_seq]
 
 /--
-Lawful monads are those that satisfy a certain behavioral specification. While all instances of
-`Monad` should satisfy these laws, not all implementations are required to prove this.
+The `Monad` typeclass only contains the operations of a monad.
+`LawfulMonad` further asserts that these operations satisfy the laws of a monad,
+including associativity and identity laws for `bind`:
+```
+pure x >>= f = f x
+x >>= pure = x
+x >>= f >>= g = x >>= (fun x => f x >>= g)
+```
 
-`LawfulMonad.mk'` is an alternative constructor that contains useful defaults for many fields.
+`LawfulMonad.mk'` is an alternative constructor containing useful defaults for many fields.
 -/
-class LawfulMonad (m : Type u → Type v) [Monad m] : Prop extends LawfulApplicative m where
-  /--
-  A `bind` followed by `pure` composed with a function is equivalent to a functorial map.
-
-  This means that `pure` really is pure after a `bind` and has no effects.
-  -/
+class LawfulMonad (m : Type u → Type v) [Monad m] extends LawfulApplicative m : Prop where
   bind_pure_comp (f : α → β) (x : m α) : x >>= (fun a => pure (f a)) = f <$> x
-  /--
-  A `bind` followed by a functorial map is equivalent to `Applicative` sequencing.
-
-  This means that the effect sequencing from `Monad` and `Applicative` are the same.
-  -/
   bind_map       {α β : Type u} (f : m (α → β)) (x : m α) : f >>= (. <$> x) = f <*> x
-  /--
-  `pure` followed by `bind` is equivalent to function application.
-
-  This means that `pure` really is pure before a `bind` and has no effects.
-  -/
   pure_bind      (x : α) (f : α → m β) : pure x >>= f = f x
-  /--
-  `bind` is associative.
-
-  Changing the nesting of `bind` calls while maintaining the order of computations results in an
-  equivalent computation. This means that `bind` is not doing more than data-dependent sequencing.
-  -/
   bind_assoc     (x : m α) (f : α → m β) (g : β → m γ) : x >>= f >>= g = x >>= fun x => f x >>= g
   map_pure g x    := (by rw [← bind_pure_comp, pure_bind])
   seq_pure g x    := (by rw [← bind_map]; simp [map_pure, bind_pure_comp])
@@ -144,7 +88,6 @@ class LawfulMonad (m : Type u → Type v) [Monad m] : Prop extends LawfulApplica
 
 export LawfulMonad (bind_pure_comp bind_map pure_bind bind_assoc)
 attribute [simp] pure_bind bind_assoc bind_pure_comp
-attribute [grind] pure_bind
 
 @[simp] theorem bind_pure [Monad m] [LawfulMonad m] (x : m α) : x >>= pure = x := by
   show x >>= (fun a => pure (id a)) = x
@@ -190,22 +133,8 @@ theorem seqLeft_eq_bind [Monad m] [LawfulMonad m] (x : m α) (y : m β) : x <* y
   rw [← bind_pure_comp]
   simp only [bind_assoc, pure_bind]
 
-/--
-This is just a duplicate of `LawfulApplicative.map_pure`,
-but sometimes applies when that doesn't.
-
-It is named with a prime to avoid conflict with the inherited field `LawfulMonad.map_pure`.
--/
-@[simp] theorem LawfulMonad.map_pure' [Monad m] [LawfulMonad m] {a : α} :
-    (f <$> pure a : m β) = pure (f a) := by
-  simp only [map_pure]
-
-/--
-This is just a duplicate of `Functor.map_map`, but sometimes applies when that doesn't.
--/
-@[simp] theorem LawfulMonad.map_map {m} [Monad m] [LawfulMonad m] {x : m α} :
-    g <$> f <$> x = (fun a => g (f a)) <$> x := by
-  simp only [Functor.map_map]
+theorem Functor.map_unit [Monad m] [LawfulMonad m] {a : m PUnit} : (fun _ => PUnit.unit) <$> a = a := by
+  simp [map]
 
 /--
 An alternative constructor for `LawfulMonad` which has more

src/Init/Control/Lawful/Instances.lean

@@ -3,12 +3,9 @@ Copyright (c) 2021 Microsoft Corporation. All rights reserved.
 Released under Apache 2.0 license as described in the file LICENSE.
 Authors: Sebastian Ullrich, Leonardo de Moura, Mario Carneiro
 -/
-module
-
 prelude
 import Init.Control.Lawful.Basic
-import all Init.Control.Except
-import all Init.Control.State
+import Init.Control.Except
 import Init.Control.StateRef
 import Init.Ext
 
@@ -99,7 +96,7 @@ end ExceptT
 
 instance : LawfulMonad (Except ε) := LawfulMonad.mk'
   (id_map := fun x => by cases x <;> rfl)
-  (pure_bind := fun _ _ => by rfl)
+  (pure_bind := fun _ _ => rfl)
   (bind_assoc := fun a _ _ => by cases a <;> rfl)
 
 instance : LawfulApplicative (Except ε) := inferInstance
@@ -127,7 +124,7 @@ namespace ReaderT
 @[simp] theorem run_monadLift [MonadLiftT n m] (x : n α) (ctx : ρ)
     : (monadLift x : ReaderT ρ m α).run ctx = (monadLift x : m α) := rfl
 
-@[simp] theorem run_monadMap [MonadFunctorT n m] (f : {β : Type u} → n β → n β) (x : ReaderT ρ m α) (ctx : ρ)
+@[simp] theorem run_monadMap [MonadFunctor n m] (f : {β : Type u} → n β → n β) (x : ReaderT ρ m α) (ctx : ρ)
     : (monadMap @f x : ReaderT ρ m α).run ctx = monadMap @f (x.run ctx) := rfl
 
 @[simp] theorem run_read [Monad m] (ctx : ρ) : (ReaderT.read : ReaderT ρ m ρ).run ctx = pure ctx := rfl
@@ -202,7 +199,7 @@ theorem run_bind_lift {α σ : Type u} [Monad m] [LawfulMonad m] (x : m α) (f :
 
 @[simp] theorem run_monadLift {α σ : Type u} [Monad m] [MonadLiftT n m] (x : n α) (s : σ) : (monadLift x : StateT σ m α).run s = (monadLift x : m α) >>= fun a => pure (a, s) := rfl
 
-@[simp] theorem run_monadMap [MonadFunctorT n m] (f : {β : Type u} → n β → n β) (x : StateT σ m α) (s : σ) :
+@[simp] theorem run_monadMap [MonadFunctor n m] (f : {β : Type u} → n β → n β) (x : StateT σ m α) (s : σ) :
     (monadMap @f x : StateT σ m α).run s = monadMap @f (x.run s) := rfl
 
 @[simp] theorem run_seq {α β σ : Type u} [Monad m] [LawfulMonad m] (f : StateT σ m (α → β)) (x : StateT σ m α) (s : σ) : (f <*> x).run s = (f.run s >>= fun fs => (fun (p : α × σ) => (fs.1 p.1, p.2)) <$> x.run fs.2) := by
@@ -248,7 +245,7 @@ instance : LawfulMonad (EStateM ε σ) := .mk'
     match x s with
     | .ok _ _ => rfl
     | .error _ _ => rfl)
-  (pure_bind := fun _ _ => by rfl)
+  (pure_bind := fun _ _ => rfl)
   (bind_assoc := fun x _ _ => funext <| fun s => by
     dsimp only [EStateM.instMonad, EStateM.bind]
     match x s with

src/Init/Control/Lawful/Lemmas.lean

@@ -1,59 +0,0 @@
-/-
-Copyright (c) 2025 Lean FRO, LLC. All rights reserved.
-Released under Apache 2.0 license as described in the file LICENSE.
-Authors: Kim Morrison
--/
-module
-
-prelude
-import Init.Control.Lawful.Basic
-import Init.RCases
-import Init.ByCases
-
--- Mapping by a function with a left inverse is injective.
-theorem map_inj_of_left_inverse [Functor m] [LawfulFunctor m] {f : α → β}
-    (w : ∃ g : β → α, ∀ x, g (f x) = x) {x y : m α} :
-    f <$> x = f <$> y ↔ x = y := by
-  constructor
-  · intro h
-    rcases w with ⟨g, w⟩
-    replace h := congrArg (g <$> ·) h
-    simpa [w] using h
-  · rintro rfl
-    rfl
-
--- Mapping by an injective function is injective, as long as the domain is nonempty.
-@[simp] theorem map_inj_right_of_nonempty [Functor m] [LawfulFunctor m] [Nonempty α] {f : α → β}
-    (w : ∀ {x y}, f x = f y → x = y) {x y : m α} :
-    f <$> x = f <$> y ↔ x = y := by
-  constructor
-  · intro h
-    apply (map_inj_of_left_inverse ?_).mp h
-    let ⟨a⟩ := ‹Nonempty α›
-    refine ⟨?_, ?_⟩
-    · intro b
-      by_cases p : ∃ a, f a = b
-      · exact Exists.choose p
-      · exact a
-    · intro b
-      simp only [exists_apply_eq_apply, ↓reduceDIte]
-      apply w
-      apply Exists.choose_spec (p := fun a => f a = f b)
-  · rintro rfl
-    rfl
-
-@[simp] theorem map_inj_right [Monad m] [LawfulMonad m]
-    {f : α → β} (h : ∀ {x y : α}, f x = f y → x = y) {x y : m α} :
-    f <$> x = f <$> y ↔ x = y := by
-  by_cases hempty : Nonempty α
-  · exact map_inj_right_of_nonempty h
-  · constructor
-    · intro h'
-      have (z : m α) : z = (do let a ← z; let b ← pure (f a); x) := by
-        conv => lhs; rw [← bind_pure z]
-        congr; funext a
-        exact (hempty ⟨a⟩).elim
-      rw [this x, this y]
-      rw [← bind_assoc, ← map_eq_pure_bind, h', map_eq_pure_bind, bind_assoc]
-    · intro h'
-      rw [h']

src/Init/Control/Option.lean

@@ -3,29 +3,18 @@ Copyright (c) 2017 Microsoft Corporation. All rights reserved.
 Released under Apache 2.0 license as described in the file LICENSE.
 Authors: Leonardo de Moura, Sebastian Ullrich
 -/
-module
-
 prelude
 import Init.Data.Option.Basic
 import Init.Control.Basic
 import Init.Control.Except
 
-set_option linter.missingDocs true
-
 universe u v
 
 instance : ToBool (Option α) := ⟨Option.isSome⟩
 
-/--
-Adds the ability to fail to a monad. Unlike ordinary exceptions, there is no way to signal why a
-failure occurred.
--/
-@[expose] def OptionT (m : Type u → Type v) (α : Type u) : Type v :=
+def OptionT (m : Type u → Type v) (α : Type u) : Type v :=
   m (Option α)
 
-/--
-Executes an action that might fail in the underlying monad `m`, returning `none` in case of failure.
--/
 @[always_inline, inline]
 def OptionT.run {m : Type u → Type v} {α : Type u} (x : OptionT m α) : m (Option α) :=
   x
@@ -33,25 +22,15 @@ def OptionT.run {m : Type u → Type v} {α : Type u} (x : OptionT m α) : m (Op
 namespace OptionT
 variable {m : Type u → Type v} [Monad m] {α β : Type u}
 
-/--
-Converts an action that returns an `Option` into one that might fail, with `none` indicating
-failure.
--/
 protected def mk (x : m (Option α)) : OptionT m α :=
   x
 
-/--
-Sequences two potentially-failing actions. The second action is run only if the first succeeds.
--/
 @[always_inline, inline]
 protected def bind (x : OptionT m α) (f : α → OptionT m β) : OptionT m β := OptionT.mk do
   match (← x) with
   | some a => f a
   | none   => pure none
 
-/--
-Succeeds with the provided value.
--/
 @[always_inline, inline]
 protected def pure (a : α) : OptionT m α := OptionT.mk do
   pure (some a)
@@ -61,20 +40,11 @@ instance : Monad (OptionT m) where
   pure := OptionT.pure
   bind := OptionT.bind
 
-instance {m : Type u → Type v} [Pure m] : Inhabited (OptionT m α) where
-  default := pure (f:=m) default
-
-/--
-Recovers from failures. Typically used via the `<|>` operator.
--/
 @[always_inline, inline] protected def orElse (x : OptionT m α) (y : Unit → OptionT m α) : OptionT m α := OptionT.mk do
   match (← x) with
   | some a => pure (some a)
   | _      => y ()
 
-/--
-A recoverable failure.
--/
 @[always_inline, inline] protected def fail : OptionT m α := OptionT.mk do
   pure none
 
@@ -82,12 +52,6 @@ instance : Alternative (OptionT m) where
   failure := OptionT.fail
   orElse  := OptionT.orElse
 
-/--
-Converts a computation from the underlying monad into one that could fail, even though it does not.
-
-This function is typically implicitly accessed via a `MonadLiftT` instance as part of [automatic
-lifting](lean-manual://section/monad-lifting).
--/
 @[always_inline, inline] protected def lift (x : m α) : OptionT m α := OptionT.mk do
   return some (← x)
 
@@ -95,12 +59,9 @@ instance : MonadLift m (OptionT m) := ⟨OptionT.lift⟩
 
 instance : MonadFunctor m (OptionT m) := ⟨fun f x => f x⟩
 
-/--
-Handles failures by treating them as exceptions of type `Unit`.
--/
 @[always_inline, inline] protected def tryCatch (x : OptionT m α) (handle : Unit → OptionT m α) : OptionT m α := OptionT.mk do
   let some a ← x | handle ()
-  pure <| some a
+  pure a
 
 instance : MonadExceptOf Unit (OptionT m) where
   throw    := fun _ => OptionT.fail

src/Init/Control/Reader.lean

@@ -5,28 +5,17 @@ Authors: Sebastian Ullrich
 
 The Reader monad transformer for passing immutable State.
 -/
-module
-
 prelude
 import Init.Control.Basic
 import Init.Control.Id
 import Init.Control.Except
 
-set_option linter.missingDocs true
-
 namespace ReaderT
 
-/--
-Recovers from errors. The same local value is provided to both branches. Typically used via the
-`<|>` operator.
--/
 @[always_inline, inline]
 protected def orElse [Alternative m] (x₁ : ReaderT ρ m α) (x₂ : Unit → ReaderT ρ m α) : ReaderT ρ m α :=
   fun s => x₁ s <|> x₂ () s
 
-/--
-Fails with a recoverable error.
--/
 @[always_inline, inline]
 protected def failure [Alternative m] : ReaderT ρ m α :=
   fun _ => failure
@@ -46,8 +35,4 @@ instance : MonadControl m (ReaderT ρ m) where
 instance ReaderT.tryFinally [MonadFinally m] : MonadFinally (ReaderT ρ m) where
   tryFinally' x h ctx := tryFinally' (x ctx) (fun a? => h a? ctx)
 
-/--
-A monad with access to a read-only value of type `ρ`. The value can be locally overridden by
-`withReader`, but it cannot be mutated.
--/
 @[reducible] def ReaderM (ρ : Type u) := ReaderT ρ Id

src/Init/Control/State.lean

@@ -5,49 +5,24 @@ Authors: Leonardo de Moura, Sebastian Ullrich
 
 The State monad transformer.
 -/
-module
-
 prelude
 import Init.Control.Basic
 import Init.Control.Id
 import Init.Control.Except
-
-set_option linter.missingDocs true
-
 universe u v w
 
-/--
-Adds a mutable state of type `σ` to a monad.
-
-Actions in the resulting monad are functions that take an initial state and return, in `m`, a tuple
-of a value and a state.
--/
-@[expose] def StateT (σ : Type u) (m : Type u → Type v) (α : Type u) : Type (max u v) :=
+def StateT (σ : Type u) (m : Type u → Type v) (α : Type u) : Type (max u v) :=
   σ → m (α × σ)
 
-/--
-Executes an action from a monad with added state in the underlying monad `m`. Given an initial
-state, it returns a value paired with the final state.
--/
 @[always_inline, inline]
 def StateT.run {σ : Type u} {m : Type u → Type v} {α : Type u} (x : StateT σ m α) (s : σ) : m (α × σ) :=
   x s
 
-/--
-Executes an action from a monad with added state in the underlying monad `m`. Given an initial
-state, it returns a value, discarding the final state.
--/
 @[always_inline, inline]
 def StateT.run' {σ : Type u} {m : Type u → Type v} [Functor m] {α : Type u} (x : StateT σ m α) (s : σ) : m α :=
   (·.1) <$> x s
 
-/--
-A tuple-based state monad.
-
-Actions in `StateM σ` are functions that take an initial state and return a value paired with a
-final state.
--/
-@[expose, reducible]
+@[reducible]
 def StateM (σ α : Type u) : Type u := StateT σ Id α
 
 instance {σ α} [Subsingleton σ] [Subsingleton α] : Subsingleton (StateM σ α) where
@@ -63,23 +38,14 @@ section
 variable {σ : Type u} {m : Type u → Type v}
 variable [Monad m] {α β : Type u}
 
-/--
-Returns the given value without modifying the state. Typically used via `Pure.pure`.
--/
 @[always_inline, inline]
 protected def pure (a : α) : StateT σ m α :=
   fun s => pure (a, s)
 
-/--
-Sequences two actions. Typically used via the `>>=` operator.
--/
 @[always_inline, inline]
 protected def bind (x : StateT σ m α) (f : α → StateT σ m β) : StateT σ m β :=
   fun s => do let (a, s) ← x s; f a s
 
-/--
-Modifies the value returned by a computation. Typically used via the `<$>` operator.
--/
 @[always_inline, inline]
 protected def map (f : α → β) (x : StateT σ m α) : StateT σ m β :=
   fun s => do let (a, s) ← x s; pure (f a, s)
@@ -90,17 +56,10 @@ instance : Monad (StateT σ m) where
   bind := StateT.bind
   map  := StateT.map
 
-/--
-Recovers from errors. The state is rolled back on error recovery. Typically used via the `<|>`
-operator.
--/
 @[always_inline, inline]
 protected def orElse [Alternative m] {α : Type u} (x₁ : StateT σ m α) (x₂ : Unit → StateT σ m α) : StateT σ m α :=
   fun s => x₁ s <|> x₂ () s
 
-/--
-Fails with a recoverable error. The state is rolled back on error recovery.
--/
 @[always_inline, inline]
 protected def failure [Alternative m] {α : Type u} : StateT σ m α :=
   fun _ => failure
@@ -109,40 +68,18 @@ instance [Alternative m] : Alternative (StateT σ m) where
   failure := StateT.failure
   orElse  := StateT.orElse
 
-/--
-Retrieves the current value of the monad's mutable state.
-
-This increments the reference count of the state, which may inhibit in-place updates.
--/
 @[always_inline, inline]
 protected def get : StateT σ m σ :=
   fun s => pure (s, s)
 
-/--
-Replaces the mutable state with a new value.
--/
 @[always_inline, inline]
 protected def set : σ → StateT σ m PUnit :=
   fun s' _ => pure (⟨⟩, s')
 
-/--
-Applies a function to the current state that both computes a new state and a value. The new state
-replaces the current state, and the value is returned.
-
-It is equivalent to `do let (a, s) := f (← StateT.get); StateT.set s; pure a`. However, using
-`StateT.modifyGet` may lead to better performance because it doesn't add a new reference to the
-state value, and additional references can inhibit in-place updates of data.
--/
 @[always_inline, inline]
 protected def modifyGet (f : σ → α × σ) : StateT σ m α :=
   fun s => pure (f s)
 
-/--
-Runs an action from the underlying monad in the monad with state. The state is not modified.
-
-This function is typically implicitly accessed via a `MonadLiftT` instance as part of [automatic
-lifting](lean-manual://section/monad-lifting).
--/
 @[always_inline, inline]
 protected def lift {α : Type u} (t : m α) : StateT σ m α :=
   fun s => do let a ← t; pure (a, s)
@@ -161,9 +98,7 @@ instance (ε) [MonadExceptOf ε m] : MonadExceptOf ε (StateT σ m) := {
 end
 end StateT
 
-/--
-Creates a suitable implementation of `ForIn.forIn` from a `ForM` instance.
--/
+/-- Adapter to create a ForIn instance from a ForM instance -/
 @[always_inline, inline]
 def ForM.forIn [Monad m] [ForM (StateT β (ExceptT β m)) ρ α]
     (x : ρ) (b : β) (f : α → β → m (ForInStep β)) : m β := do