.

.claude/CLAUDE.md

@@ -1,125 +0,0 @@
-(In the following, use `sysctl -n hw.logicalcpu` instead of `nproc` on macOS)
-
-To build Lean you should use `make -j$(nproc) -C build/release`.
-
-## Running Tests
-
-See `tests/README.md` for full documentation. Quick reference:
-
-```bash
-# Full test suite (use after builds to verify correctness)
-CTEST_PARALLEL_LEVEL="$(nproc)" CTEST_OUTPUT_ON_FAILURE=1 \
-make -C build/release -j "$(nproc)" test
-
-# Specific test by name (supports regex via ctest -R)
-CTEST_PARALLEL_LEVEL="$(nproc)" CTEST_OUTPUT_ON_FAILURE=1 \
-make -C build/release -j "$(nproc)" test ARGS='-R grind_ematch'
-
-# Rerun only previously failed tests
-CTEST_PARALLEL_LEVEL="$(nproc)" CTEST_OUTPUT_ON_FAILURE=1 \
-make -C build/release -j "$(nproc)" test ARGS='--rerun-failed'
-
-# Single test from tests/foo/bar/ (quick check during development)
-CTEST_PARALLEL_LEVEL="$(nproc)" CTEST_OUTPUT_ON_FAILURE=1 \
-make -C build/release -j "$(nproc)" test ARGS=-R testname'
-```
-
-## Testing stage 2
-
-When requested to test stage 2, build it as follows:
-```
-make -C build/release stage2 -j$(nproc)
-```
-Stage 2 is *not* automatically invalidated by changes to `src/` which allows for faster iteration
-when fixing a specific file in the stage 2 build but for invalidating any files that already passed
-the stage 2 build as well as for final validation,
-```
-make -C build/release/stage2 clean-stdlib
-```
-must be run manually before building.
-
-## New features
-
-When asked to implement new features:
-* begin by reviewing existing relevant code and tests
-* write comprehensive tests first (expecting that these will initially fail)
-* and then iterate on the implementation until the tests pass.
-
-## Success Criteria
-
-*Never* report success on a task unless you have verified both a clean build without errors, and that the relevant tests pass.
-
-## Build System Safety
-
-**NEVER manually delete build directories** (build/, stage0/, stage1/, etc.) even when builds fail.
-- ONLY use the project's documented build command: `make -j$(nproc) -C build/release`
-- If a build is broken, ask the user before attempting any manual cleanup
-
-## stage0 Is a Copy of src
-
-**Never manually edit files under `stage0/`.** The `stage0/` directory is a snapshot of `src/` produced by `make update-stage0`. To change anything in stage0 (CMakeLists.txt, C++ source, etc.), edit the corresponding file in `src/` and let `update-stage0` propagate it.
-
-## LSP and IDE Diagnostics
-
-After rebuilding, LSP diagnostics may be stale until the user interacts with files. Trust command-line test results over IDE diagnostics.
-
-## Update prompting when the user is frustrated
-
-If the user expresses frustration with you, stop and ask them to help update this `.claude/CLAUDE.md` file with missing guidance.
-
-## Creating pull requests
-
-Follow the commit convention in `doc/dev/commit_convention.md`.
-
-**Title format:** `<type>: <subject>` where type is one of: `feat`, `fix`, `doc`, `style`, `refactor`, `test`, `chore`, `perf`.
-Subject should use imperative present tense ("add" not "added"), no capitalization, no trailing period.
-
-**Body format:** The first paragraph must start with "This PR". This paragraph is automatically incorporated into release notes. Use imperative present tense. Include motivation and contrast with previous behavior when relevant. Do NOT use markdown headings (`## Summary`, `## Test plan`, etc.) in PR bodies.
-
-Example:
-```
-feat: add optional binder limit to `mkPatternFromTheorem`
-
-This PR adds a `num?` parameter to `mkPatternFromTheorem` to control how many
-leading quantifiers are stripped when creating a pattern.
-```
-
-**Changelog labels:** Add one `changelog-*` label to categorize the PR for release notes:
-- `changelog-language` - Language features and metaprograms
-- `changelog-tactics` - User facing tactics
-- `changelog-server` - Language server, widgets, and IDE extensions
-- `changelog-pp` - Pretty printing
-- `changelog-library` - Library
-- `changelog-compiler` - Compiler, runtime, and FFI
-- `changelog-lake` - Lake
-- `changelog-doc` - Documentation
-- `changelog-ffi` - FFI changes
-- `changelog-other` - Other changes
-- `changelog-no` - Do not include this PR in the release changelog
-
-If you're unsure which label applies, it's fine to omit the label and let reviewers add it.
-
-## Module System for `src/` Files
-
-Files in `src/Lean/`, `src/Std/`, and `src/lake/Lake/` must have both `module` and `prelude` (CI enforces `^prelude$` on its own line). With `prelude`, nothing is auto-imported — you must explicitly import `Init.*` modules for standard library features. Check existing files in the same directory for the pattern, e.g.:
-
-```lean
-module
-
-prelude
-import Init.While  -- needed for while/repeat
-import Init.Data.String.TakeDrop  -- needed for String.startsWith
-public import Lean.Compiler.NameMangling  -- public if types are used in public signatures
-```
-
-Files outside these directories (e.g. `tests/`, `script/`) use just `module`.
-
-## CI Log Retrieval
-
-When CI jobs fail, investigate immediately - don't wait for other jobs to complete. Individual job logs are often available even while other jobs are still running. Try `gh run view <run-id> --log` or `gh run view <run-id> --log-failed`, or use `gh run view <run-id> --job=<job-id>` to target the specific failed job. Sleeping is fine when asked to monitor CI and no failures exist yet, but once any job fails, investigate that failure immediately.
-
-## Copyright Headers
-
-New files require a copyright header. To get the year right, always run `date +%Y` rather than relying on memory. The copyright holder should be the author or their current employer — check other recent files by the same author in the repository to determine the correct entity (e.g., "Lean FRO, LLC", "Amazon.com, Inc. or its affiliates").
-
-Test files (in `tests/`) do not need copyright headers.

.claude/commands/release.md

@@ -1,166 +0,0 @@
-# Release Management Command
-
-Execute the release process for a given version by running the release checklist and following its instructions.
-
-## Before Starting
-
-**IMPORTANT**: Before beginning the release process, read the in-file documentation:
-- Read `script/release_checklist.py` for what the checklist script does
-- Read `script/release_steps.py` for what the release steps script does
-
-These comments explain the scripts' behavior, which repositories get special handling, and how errors are handled.
-
-## Arguments
-- `version`: The version to release (e.g., v4.24.0)
-
-## Release Notes (Required for -rc1 releases)
-
-For first release candidates (`-rc1`), you must create release notes BEFORE the reference-manual toolchain bump PR can be merged.
-
-**Steps to create release notes:**
-
-1. Generate the release notes:
-   ```bash
-   cd /path/to/lean4
-   python3 script/release_notes.py --since <previous_version> > /tmp/release-notes-<version>.md
-   ```
-   Replace `<previous_version>` with the last stable release (e.g., `v4.27.0` when releasing `v4.28.0-rc1`).
-
-2. Review `/tmp/release-notes-<version>.md` for common issues:
-   - **Unterminated code blocks**: Look for code fences that aren't closed. Fetch original PR with `gh pr view <number>` to repair.
-   - **Truncated descriptions**: Some may end mid-sentence. Complete them from the original PR.
-   - **Markdown issues**: Other syntax problems that could cause parsing errors.
-
-3. Create the release notes file in the reference-manual repository:
-   - File path: `Manual/Releases/v<version>.lean` (e.g., `v4_28_0.lean`)
-   - Use Verso format with proper imports and `#doc (Manual)` block
-   - **Use `#` for headers, not `##`** (Verso uses level 1 for subsections)
-   - **Use plain ` ``` ` not ` ```lean `** (the latter executes code)
-   - **Wrap underscore identifiers in backticks**: `` `bv_decide` `` not `bv_decide`
-
-4. Update `Manual/Releases.lean`:
-   - Add import: `import Manual.Releases.«v4_28_0»`
-   - Add include: `{include 0 Manual.Releases.«v4_28_0»}`
-
-5. Build to verify: `lake build Manual.Releases.v4_28_0`
-
-6. Create a **separate PR** for release notes (not bundled with toolchain bump):
-   ```bash
-   git checkout -b v<version>-release-notes
-   gh pr create --title "doc: add v<version> release notes"
-   ```
-
-For subsequent RCs (`-rc2`, etc.) and stable releases, just update the version number in the existing release notes file title.
-
-See `doc/dev/release_checklist.md` section "Writing the release notes" for full details.
-
-## Process
-
-1. Run `script/release_checklist.py {version}` to check the current status
-2. **CRITICAL: If preliminary lean4 checks fail, STOP immediately and alert the user**
-   - Check for: release branch exists, CMake version correct, tag exists, release page exists, release notes file exists
-   - **IMPORTANT**: The release page is created AUTOMATICALLY by CI after pushing the tag - DO NOT create it manually
-   - **IMPORTANT**: For -rc1 releases, release notes must be created before proceeding
-   - Do NOT create any PRs or proceed with repository updates if these checks fail
-3. Create a todo list tracking all repositories that need updates
-4. **CRITICAL RULE: You can ONLY run `release_steps.py` for a repository if `release_checklist.py` explicitly says to do so**
-   - The checklist output will say "Run `script/release_steps.py {version} {repo_name}` to create it"
-   - If a repository shows "🟡 Dependencies not ready", you CANNOT create a PR for it yet
-   - You MUST rerun `release_checklist.py` before attempting to create PRs for any new repositories
-5. For each repository that the checklist says needs updating:
-   - Run `script/release_steps.py {version} {repo_name}` to create the PR
-   - Mark it complete when the PR is created
-6. After creating PRs, notify the user which PRs need review and merging
-7. **MANDATORY: Rerun `release_checklist.py` to check current status**
-   - Do this after creating each batch of PRs
-   - Do this after the user reports PRs have been merged
-   - NEVER assume a repository is ready without checking the checklist output
-8. As PRs are merged and tagged, dependent repositories will become ready
-9. Continue the cycle: run checklist → create PRs for ready repos → wait for merges → repeat
-10. Continue until all repositories are updated and the release is complete
-
-## Important Notes
-
-- **NEVER merge PRs autonomously** - always wait for the user to merge PRs themselves
-- The `release_steps.py` script is idempotent - it's safe to rerun
-- The `release_checklist.py` script is idempotent - it's safe to rerun
-- Some repositories depend on others (e.g., mathlib4 depends on batteries, aesop, etc.)
-- Wait for user to merge PRs before dependent repos can be updated
-- Alert user if anything unusual or scary happens
-- Use appropriate timeouts for long-running builds (verso can take 10+ minutes)
-- ProofWidgets4 uses semantic versioning (v0.0.X) - it's okay to create and push the next sequential tag yourself when needed for a release
-
-## PR Status Reporting
-
-Every time you run `release_checklist.py`, you MUST:
-1. Parse the output to identify ALL open PRs mentioned (lines with "✅ PR with title ... exists")
-2. Provide a summary to the user listing ALL open PRs that need review
-3. Group them by status:
-   - PRs for repositories that are blocked by dependencies (show these but note they're blocked)
-   - PRs for repositories that are ready to merge (highlight these)
-4. Format the summary clearly with PR numbers and URLs
-
-This summary should be provided EVERY time you run the checklist, not just after creating new PRs.
-The user needs to see the complete picture of what's waiting for review.
-
-## Checking PR Status When Asked
-
-When the user asks for "status" or you need to report on PRs between checklist runs:
-- **ALWAYS check actual PR state** using `gh pr view <number> --repo <repo> --json state,mergedAt`
-- Do NOT rely on cached CI results or previous checklist output
-- The user may have merged PRs since your last check
-- Report which PRs are MERGED, which are OPEN with CI status, and which are still pending
-- After discovering merged PRs, rerun `release_checklist.py` to advance the release process
-
-## Nightly Infrastructure
-
-The nightly build system uses branches and tags across two repositories:
-
-- `leanprover/lean4` has **branches** `nightly` and `nightly-with-mathlib` tracking the latest nightly builds
-- `leanprover/lean4-nightly` has **dated tags** like `nightly-2026-01-23`
-
-When a nightly succeeds with mathlib, all three should point to the same commit. Don't confuse these: branches are in the main lean4 repo, dated tags are in lean4-nightly.
-
-## CI Failures: Investigate Immediately
-
-**CRITICAL: If the checklist reports `❌ CI: X check(s) failing` for any PR, investigate immediately.**
-
-Do NOT:
-- Report it as "CI in progress" or "some checks pending"
-- Wait for the remaining checks to finish before investigating
-- Assume it's a transient failure without checking
-
-DO:
-1. Run `gh pr checks <number> --repo <owner>/<repo>` to see which specific check failed
-2. Run `gh run view <run-id> --repo <owner>/<repo> --log-failed` to see the failure output
-3. Diagnose the failure and report clearly to the user: what failed and why
-4. Propose a fix if one is obvious (e.g., subverso version mismatch, transient elan install error)
-
-The checklist now distinguishes `❌ X check(s) failing, Y still in progress` from `🔄 Y check(s) in progress`.
-Any `❌` in CI status requires immediate investigation — do not move on.
-
-## Waiting for CI or Merges
-
-Use `gh pr checks --watch` to block until a PR's CI checks complete (no polling needed).
-Run these as background bash commands so you get notified when they finish:
-
-```bash
-# Watch CI, then check merge state
-gh pr checks <number> --repo <owner>/<repo> --watch && gh pr view <number> --repo <owner>/<repo> --json state --jq '.state'
-```
-
-For multiple PRs, launch one background command per PR in parallel. When each completes,
-you'll be notified automatically via a task-notification. Do NOT use sleep-based polling
-loops — `--watch` is event-driven and exits as soon as checks finish.
-
-Note: `gh pr checks --watch` exits as soon as ALL checks complete (pass or fail). If some checks
-fail while others are still running, `--watch` will continue until everything settles, then exit
-with a non-zero code. So a background `--watch` finishing = all checks done; check which failed.
-
-## Error Handling
-
-**CRITICAL**: If something goes wrong or a command fails:
-- **DO NOT** try to manually reproduce the failing steps yourself
-- **DO NOT** try to fix things by running git commands or other manual operations
-- Both scripts are idempotent and designed to handle partial completion gracefully
-- If a script continues to fail after retrying, report the error to the user and wait for instructions

.claude/settings.json

@@ -1,13 +0,0 @@
-{
-  "extraKnownMarketplaces": {
-    "leanprover": {
-      "source": {
-        "source": "github",
-        "repo": "leanprover/skills"
-      }
-    }
-  },
-  "enabledPlugins": {
-    "lean@leanprover": true
-  }
-}

.claude/skills/profiling/SKILL.md

@@ -1,26 +0,0 @@
----
-name: profiling
-description: Profile Lean programs with demangled names using samply and Firefox Profiler. Use when the user asks to profile a Lean binary or investigate performance.
-allowed-tools: Bash, Read, Glob, Grep
----
-
-# Profiling Lean Programs
-
-Full documentation: `script/PROFILER_README.md`.
-
-## Quick Start
-
-```bash
-script/lean_profile.sh ./build/release/stage1/bin/lean some_file.lean
-```
-
-Requires `samply` (`cargo install samply`) and `python3`.
-
-## Agent Notes
-
-- The pipeline is interactive (serves to browser at the end). When running non-interactively, run the steps manually instead of using the wrapper script.
-- The three steps are: `samply record --save-only`, `symbolicate_profile.py`, then `serve_profile.py`.
-- `lean_demangle.py` works standalone as a stdin filter (like `c++filt`) for quick name lookups.
-- The `--raw` flag on `lean_demangle.py` gives exact demangled names without postprocessing (keeps `._redArg`, `._lam_0` suffixes as-is).
-- Use `PROFILE_KEEP=1` to keep the temp directory for later inspection.
-- The demangled profile is a standard Firefox Profiler JSON. Function names live in `threads[i].stringArray`, indexed by `threads[i].funcTable.name`.

.claude/skills/zulip-extract/SKILL.md

@@ -1,17 +0,0 @@
----
-name: zulip-extract
-description: Extract Zulip thread HTML dumps into readable plain text. Use when the user provides a Zulip HTML file or asks to parse/read/convert/summarize a Zulip thread.
----
-
-# Zulip Thread Extractor
-
-Run the bundled script to convert a Zulip HTML page dump into plain text.
-
-## Usage
-```bash
-python3 .claude/skills/zulip-extract/zulip_thread_extract.py input.html output.txt
-```
-
-The script has zero dependencies beyond Python 3 stdlib.
-It extracts sender, timestamp, message content (with code blocks,
-links, quotes, mentions), and reactions.

.claude/skills/zulip-extract/zulip_thread_extract.py

@@ -1,313 +0,0 @@
-#!/usr/bin/env python3
-"""
-Convert a Zulip HTML page dump to plain text (the visible message thread).
-
-Zero external dependencies — uses only the Python standard library.
-
-Usage:
-    python3 zulip_thread_extract.py input.html [output.txt]
-"""
-
-import sys
-import re
-from html.parser import HTMLParser
-from html import unescape
-
-
-# ---------------------------------------------------------------------------
-# Minimal DOM built from stdlib HTMLParser
-# ---------------------------------------------------------------------------
-
-class Node:
-    """A lightweight DOM node."""
-    __slots__ = ('tag', 'attrs', 'children', 'parent', 'text')
-
-    def __init__(self, tag='', attrs=None):
-        self.tag = tag
-        self.attrs = dict(attrs) if attrs else {}
-        self.children = []
-        self.parent = None
-        self.text = ''  # for text nodes only (tag == '')
-
-    @property
-    def cls(self):
-        return self.attrs.get('class', '')
-
-    def has_class(self, c):
-        return c in self.cls.split()
-
-    def find_all(self, tag=None, class_=None):
-        """Depth-first search for matching descendants."""
-        for child in self.children:
-            if child.tag == '':
-                continue
-            match = True
-            if tag and child.tag != tag:
-                match = False
-            if class_ and not child.has_class(class_):
-                match = False
-            if match:
-                yield child
-            yield from child.find_all(tag, class_)
-
-    def find(self, tag=None, class_=None):
-        return next(self.find_all(tag, class_), None)
-
-    def get_text(self):
-        if self.tag == '':
-            return self.text
-        return ''.join(c.get_text() for c in self.children)
-
-
-class DOMBuilder(HTMLParser):
-    """Build a minimal DOM tree from HTML."""
-
-    VOID_ELEMENTS = frozenset([
-        'area', 'base', 'br', 'col', 'embed', 'hr', 'img', 'input',
-        'link', 'meta', 'param', 'source', 'track', 'wbr',
-    ])
-
-    def __init__(self):
-        super().__init__()
-        self.root = Node('root')
-        self._cur = self.root
-
-    def handle_starttag(self, tag, attrs):
-        node = Node(tag, attrs)
-        node.parent = self._cur
-        self._cur.children.append(node)
-        if tag not in self.VOID_ELEMENTS:
-            self._cur = node
-
-    def handle_endtag(self, tag):
-        # Walk up to find the matching open tag (tolerates misnesting)
-        n = self._cur
-        while n and n.tag != tag and n.parent:
-            n = n.parent
-        if n and n.parent:
-            self._cur = n.parent
-
-    def handle_data(self, data):
-        t = Node()
-        t.text = data
-        t.parent = self._cur
-        self._cur.children.append(t)
-
-    def handle_entityref(self, name):
-        self.handle_data(unescape(f'&{name};'))
-
-    def handle_charref(self, name):
-        self.handle_data(unescape(f'&#{name};'))
-
-
-def parse_html(path):
-    with open(path, 'r', encoding='utf-8') as f:
-        html = f.read()
-    builder = DOMBuilder()
-    builder.feed(html)
-    return builder.root
-
-
-# ---------------------------------------------------------------------------
-# Content extraction
-# ---------------------------------------------------------------------------
-
-SKIP_CLASSES = {
-    'message_controls', 'message_length_controller',
-    'code-buttons-container', 'copy_codeblock', 'code_external_link',
-    'message_edit_notice', 'edit-notifications',
-}
-
-def should_skip(node):
-    return bool(SKIP_CLASSES & set(node.cls.split()))
-
-
-def extract_content(node):
-    """Recursively convert a message_content node into readable text."""
-    parts = []
-    for child in node.children:
-        # Text node
-        if child.tag == '':
-            parts.append(child.text)
-            continue
-
-        if should_skip(child):
-            continue
-
-        cls_set = set(child.cls.split())
-
-        # Code block wrappers  (div.codehilite / div.zulip-code-block)
-        if child.tag == 'div' and ({'codehilite', 'zulip-code-block'} & cls_set):
-            code = child.find('code')
-            lang = child.attrs.get('data-code-language', '')
-            text = code.get_text() if code else child.get_text()
-            parts.append(f'\n```{lang}\n{text}```\n')
-            continue
-
-        # <pre> (bare code blocks without wrapper div)
-        if child.tag == 'pre':
-            code = child.find('code')
-            text = code.get_text() if code else child.get_text()
-            parts.append(f'\n```\n{text}```\n')
-            continue
-
-        # Inline <code>
-        if child.tag == 'code':
-            parts.append(f'`{child.get_text()}`')
-            continue
-
-        # Paragraph
-        if child.tag == 'p':
-            inner = extract_content(child)
-            parts.append(f'\n{inner}\n')
-            continue
-
-        # Line break
-        if child.tag == 'br':
-            parts.append('\n')
-            continue
-
-        # Links
-        if child.tag == 'a':
-            href = child.attrs.get('href', '')
-            text = child.get_text().strip()
-            if href and not href.startswith('#') and text:
-                parts.append(f'[{text}]({href})')
-            else:
-                parts.append(text)
-            continue
-
-        # Block quotes
-        if child.tag == 'blockquote':
-            bq = extract_content(child).strip()
-            parts.append('\n' + '\n'.join(f'> {l}' for l in bq.split('\n')) + '\n')
-            continue
-
-        # Lists
-        if child.tag in ('ul', 'ol'):
-            for i, li in enumerate(c for c in child.children if c.tag == 'li'):
-                pfx = f'{i+1}.' if child.tag == 'ol' else '-'
-                parts.append(f'\n{pfx} {extract_content(li).strip()}')
-            parts.append('\n')
-            continue
-
-        # User mentions
-        if 'user-mention' in cls_set:
-            parts.append(f'@{child.get_text().strip().lstrip("@")}')
-            continue
-
-        # Emoji
-        if 'emoji' in cls_set:
-            alt = child.attrs.get('alt', '') or child.attrs.get('title', '')
-            if alt:
-                parts.append(alt)
-            continue
-
-        # Recurse into everything else
-        parts.append(extract_content(child))
-
-    return ''.join(parts)
-
-
-# ---------------------------------------------------------------------------
-# Thread extraction
-# ---------------------------------------------------------------------------
-
-def extract_thread(html_path, output_path=None):
-    root = parse_html(html_path)
-
-    # Find the message list
-    msg_list = root.find('div', class_='message-list')
-    if not msg_list:
-        print("ERROR: Could not find message list.", file=sys.stderr)
-        sys.exit(1)
-
-    # Topic header
-    header = msg_list.find('div', class_='message_header')
-    stream_name = topic_name = date_str = ''
-    if header:
-        el = header.find('span', class_='message-header-stream-name')
-        if el: stream_name = el.get_text().strip()
-        el = header.find('span', class_='stream-topic-inner')
-        if el: topic_name = el.get_text().strip()
-        el = header.find('span', class_='recipient_row_date')
-        if el:
-            tr = el.find('span', class_='timerender-content')
-            if tr:
-                date_str = tr.attrs.get('data-tippy-content', '') or tr.get_text().strip()
-
-    # Messages
-    messages = []
-    for row in msg_list.find_all('div', class_='message_row'):
-        if not row.has_class('messagebox-includes-sender'):
-            continue
-
-        msg = {}
-
-        sn = row.find('span', class_='sender_name_text')
-        if sn:
-            un = sn.find('span', class_='user-name')
-            msg['sender'] = (un or sn).get_text().strip()
-
-        tm = row.find('a', class_='message-time')
-        if tm:
-            msg['time'] = tm.get_text().strip()
-
-        cd = row.find('div', class_='message_content')
-        if cd:
-            text = extract_content(cd)
-            text = re.sub(r'\n{3,}', '\n\n', text).strip()
-            msg['content'] = text
-
-        # Reactions
-        reactions = []
-        for rx in row.find_all('div', class_='message_reaction'):
-            em = rx.find('div', class_='emoji_alt_code')
-            if em:
-                reactions.append(em.get_text().strip())
-            else:
-                img = rx.find(tag='img')
-                if img:
-                    reactions.append(img.attrs.get('alt', ''))
-            cnt = rx.find('span', class_='message_reaction_count')
-            if cnt and reactions:
-                c = cnt.get_text().strip()
-                if c and c != '1':
-                    reactions[-1] += f' x{c}'
-        if reactions:
-            msg['reactions'] = reactions
-
-        if msg.get('content') or msg.get('sender'):
-            messages.append(msg)
-
-    # Format
-    lines = [
-        '=' * 70,
-        f'# {stream_name} > {topic_name}',
-    ]
-    if date_str:
-        lines.append(f'# Started: {date_str}')
-    lines += [f'# Messages: {len(messages)}', '=' * 70, '']
-
-    for msg in messages:
-        lines.append(f'--- {msg.get("sender","?")}  [{msg.get("time","")}] ---')
-        lines.append(msg.get('content', ''))
-        if msg.get('reactions'):
-            lines.append(f'  Reactions: {", ".join(msg["reactions"])}')
-        lines.append('')
-
-    result = '\n'.join(lines)
-    if output_path:
-        with open(output_path, 'w', encoding='utf-8') as f:
-            f.write(result)
-        print(f"Written {len(messages)} messages to {output_path}")
-    else:
-        print(result)
-
-
-if __name__ == '__main__':
-    if len(sys.argv) < 2:
-        print(f"Usage: {sys.argv[0]} input.html [output.txt]")
-        sys.exit(1)
-    extract_thread(sys.argv[1], sys.argv[2] if len(sys.argv) > 2 else None)
-

.gitattributes

@@ -4,4 +4,3 @@ RELEASES.md merge=union
 stage0/** binary linguist-generated
 # The following file is often manually edited, so do show it in diffs
 stage0/src/stdlib_flags.h -binary -linguist-generated
-doc/std/grove/GroveStdlib/Generated/** linguist-generated

.github/ISSUE_TEMPLATE/bug_report.md

@@ -9,7 +9,7 @@ assignees: ''
 
 ### Prerequisites
 
-<!-- Please put an X between the brackets as you perform the following steps: -->
+Please put an X between the brackets as you perform the following steps:
 
 * [ ] Check that your issue is not already filed:
       https://github.com/leanprover/lean4/issues

.github/actionlint.yaml

@@ -1,5 +0,0 @@
-self-hosted-runner:
-  labels:
-    - nscloud-ubuntu-22.04-amd64-4x16
-    - nscloud-ubuntu-22.04-amd64-8x16
-    - nscloud-macos-sonoma-arm64-6x14

.github/workflows/actionlint.yml

@@ -15,7 +15,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - name: Checkout
-      uses: actions/checkout@v6
+      uses: actions/checkout@v4
     - name: actionlint
       uses: raven-actions/actionlint@v2
       with:

.github/workflows/awaiting-manual.yml

@@ -1,41 +0,0 @@
-name: Check awaiting-manual label
-
-on:
-  merge_group:
-  pull_request_target:
-    types: [opened, synchronize, reopened, labeled, unlabeled]
-
-permissions:
-  pull-requests: read
-
-jobs:
-  check-awaiting-manual:
-    runs-on: ubuntu-latest
-    steps:
-      - name: Check awaiting-manual label
-        id: check-awaiting-manual-label
-        if: github.event_name == 'pull_request_target'
-        uses: actions/github-script@v8
-        with:
-          script: |
-            const { labels, number: prNumber } = context.payload.pull_request;
-            const hasAwaiting = labels.some(label => label.name == "awaiting-manual");
-            const hasBreaks = labels.some(label => label.name == "breaks-manual");
-            const hasBuilds = labels.some(label => label.name == "builds-manual");
-
-            if (hasAwaiting && hasBreaks) {
-              core.setFailed('PR has both "awaiting-manual" and "breaks-manual" labels.');
-            } else if (hasAwaiting && !hasBreaks && !hasBuilds) {
-              core.info('PR is marked "awaiting-manual" but neither "breaks-manual" nor "builds-manual" labels are present.');
-              core.setOutput('awaiting', 'true');
-            }
-      
-      - name: Wait for manual compatibility
-        if: github.event_name == 'pull_request_target' && steps.check-awaiting-manual-label.outputs.awaiting == 'true'
-        run: |
-          echo "::notice title=Awaiting manual::PR is marked 'awaiting-manual' but neither 'breaks-manual' nor 'builds-manual' labels are present."
-          echo "This check will remain in progress until the PR is updated with appropriate manual compatibility labels."
-          # Keep the job running indefinitely to show "in progress" status
-          while true; do
-            sleep 3600  # Sleep for 1 hour at a time
-          done

.github/workflows/awaiting-mathlib.yml

@@ -1,41 +0,0 @@
-name: Check awaiting-mathlib label
-
-on:
-  merge_group:
-  pull_request_target:
-    types: [opened, synchronize, reopened, labeled, unlabeled]
-
-permissions:
-  pull-requests: read
-
-jobs:
-  check-awaiting-mathlib:
-    runs-on: ubuntu-latest
-    steps:
-      - name: Check awaiting-mathlib label
-        id: check-awaiting-mathlib-label
-        if: github.event_name == 'pull_request_target'
-        uses: actions/github-script@v8
-        with:
-          script: |
-            const { labels, number: prNumber } = context.payload.pull_request;
-            const hasAwaiting = labels.some(label => label.name == "awaiting-mathlib");
-            const hasBreaks = labels.some(label => label.name == "breaks-mathlib");
-            const hasBuilds = labels.some(label => label.name == "builds-mathlib");
-
-            if (hasAwaiting && hasBreaks) {
-              core.setFailed('PR has both "awaiting-mathlib" and "breaks-mathlib" labels.');
-            } else if (hasAwaiting && !hasBreaks && !hasBuilds) {
-              core.info('PR is marked "awaiting-mathlib" but neither "breaks-mathlib" nor "builds-mathlib" labels are present.');
-              core.setOutput('awaiting', 'true');
-            }
-      
-      - name: Wait for mathlib compatibility
-        if: github.event_name == 'pull_request_target' && steps.check-awaiting-mathlib-label.outputs.awaiting == 'true'
-        run: |
-          echo "::notice title=Awaiting mathlib::PR is marked 'awaiting-mathlib' but neither 'breaks-mathlib' nor 'builds-mathlib' labels are present."
-          echo "This check will remain in progress until the PR is updated with appropriate mathlib compatibility labels."
-          # Keep the job running indefinitely to show "in progress" status
-          while true; do
-            sleep 3600  # Sleep for 1 hour at a time
-          done

.github/workflows/build-template.yml

@@ -1,266 +0,0 @@
-# instantiated by ci.yml
-name: build-template
-on:
-  workflow_call:
-    inputs:
-      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: ${{ endsWith(matrix.os, '-with-cache') && fromJSON(format('["{0}", "nscloud-git-mirror-1gb"]', matrix.os)) || 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: 11.0
-    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@v6
-        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-* tests/elab/importStructure.lean
-        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: Restore Cache
-        id: restore-cache
-        uses: actions/cache/restore@v5
-        with:
-          # NOTE: must be in sync with `save` below and with `restore-cache` in `update-stage0.yml`
-          path: |
-            .ccache
-            ${{ matrix.name == 'Linux Lake' && 'build/stage1/**/*.trace
-            build/stage1/**/*.olean*
-            build/stage1/**/*.ilean
-            build/stage1/**/*.ir
-            build/stage1/**/*.c
-            build/stage1/**/*.c.o*' || '' }}
-          key: ${{ matrix.name }}-build-v4-${{ github.sha }}
-          # fall back to (latest) previous cache
-          restore-keys: |
-            ${{ matrix.name }}-build-v4
-      # open nix-shell once for initial setup
-      - name: Setup
-        run: |
-          ccache --zero-stats
-        if: runner.os == 'Linux'
-      - name: Set up env
-        run: |
-          echo "NPROC=$(nproc 2>/dev/null || sysctl -n hw.logicalcpu 2>/dev/null || echo 4)" >> $GITHUB_ENV
-          if ! diff src/stdlib_flags.h stage0/src/stdlib_flags.h; then
-            echo "src/stdlib_flags.h and stage0/src/stdlib_flags.h differ, will test and pack stage 2"
-            echo "TARGET_STAGE=stage2" >> $GITHUB_ENV
-          else
-            echo "TARGET_STAGE=stage1" >> $GITHUB_ENV
-          fi
-      - name: Build
-        run: |
-          ulimit -c unlimited  # coredumps
-          [ -d build ] || mkdir build
-          cd build
-          # arguments passed to `cmake`
-          OPTIONS=(-DLEAN_EXTRA_MAKE_OPTS=-DwarningAsError=true)
-          if [[ -n '${{ matrix.release }}' ]]; then
-            # this also enables githash embedding into stage 1 library, which prohibits reusing
-            # `.olean`s across commits, so we don't do it in the fast non-release CI
-            OPTIONS+=(-DCHECK_OLEAN_VERSION=ON)
-          fi
-          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 ${{ matrix.llvm-url }}
-            PREPARE="$(${{ matrix.prepare-llvm }})"
-            if [ "$TARGET_STAGE" == "stage2" ]; then
-              cp -r stage1 stage2
-            fi
-            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 $TARGET_STAGE -j$NPROC
-      # Should be done as early as possible and in particular *before* "Check rebootstrap" which
-      # changes the state of stage1/
-      - name: Save Cache
-        # Caching on cancellation created some mysterious issues perhaps related to improper build
-        # shutdown
-        if: steps.restore-cache.outputs.cache-hit != 'true' && !cancelled()
-        uses: actions/cache/save@v5
-        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/**/*.ir
-            build/stage1/**/*.c
-            build/stage1/**/*.c.o*' || '' }}
-          key: ${{ steps.restore-cache.outputs.cache-primary-key }}
-      - name: Install
-        run: |
-          make -C build/$TARGET_STAGE 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@v5
-        if: matrix.release
-        with:
-          name: build-${{ matrix.name }}
-          path: pack/*
-      - name: Lean stats
-        run: |
-          build/$TARGET_STAGE/bin/lean --stats src/Lean.lean
-        if: ${{ !matrix.cross }}
-      - name: Test
-        id: test
-        run: |
-          ulimit -c unlimited  # coredumps
-          time ctest --preset ${{ matrix.CMAKE_PRESET || 'release' }} --test-dir build/$TARGET_STAGE -j$NPROC --output-junit test-results.xml ${{ matrix.CTEST_OPTIONS }}
-        if: matrix.test
-      - name: Test Summary
-        uses: test-summary/action@v2
-        with:
-          paths: build/${{ env.TARGET_STAGE }}/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: ${{ matrix.binary-check }} tests/compile/534.lean.out
-        if: (!matrix.cross) && steps.test.conclusion != 'skipped'
-      - name: Build Stage 2
-        run: |
-          make -C build -j$NPROC stage2
-        if: matrix.test-bench
-      - name: Check Stage 3
-        run: |
-          make -C build -j$NPROC check-stage3
-        if: matrix.check-stage3
-      - name: Test Benchmarks
-        run: |
-          cd tests
-          nix develop -c make -C ../build -j$NPROC bench
-        if: matrix.test-bench
-      - name: Check rebootstrap
-        run: |
-          set -e
-          # clean rebuild in case of Makefile changes/Lake does not detect uncommited stage 0
-          # changes yet
-          make -C build update-stage0
-          make -C build/stage1 clean-stdlib
-          time make -C build -j$NPROC
-          time ctest --preset ${{ matrix.CMAKE_PRESET || 'release' }} --test-dir build/stage1 -j$NPROC
-        if: matrix.check-rebootstrap
-      - 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

.github/workflows/check-prelude.yml

@@ -7,7 +7,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v6
+        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 }}

.github/workflows/check-stage0.yml

@@ -8,11 +8,11 @@ jobs:
   check-stage0-on-queue:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v6
+    - uses: actions/checkout@v4
       with:
         ref: ${{ github.event.pull_request.head.sha }}
+        filter: blob:none
         fetch-depth: 0
-        filter: tree:0
 
     - name: Find base commit
       if: github.event_name == 'pull_request'
@@ -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"
@@ -31,7 +33,7 @@ jobs:
 
     - if: github.event_name == 'pull_request'
       name: Set label
-      uses: actions/github-script@v8
+      uses: actions/github-script@v7
       with:
         script: |
           const { owner, repo, number: issue_number  } = context.issue;

.github/workflows/check-stdlib-flags.yml

@@ -1,60 +0,0 @@
-name: Check stdlib_flags.h modifications
-
-on:
-  pull_request_target:
-    types: [opened, synchronize, reopened, labeled, unlabeled]
-
-permissions:
-  pull-requests: read
-
-jobs:
-  check-stdlib-flags:
-    runs-on: ubuntu-latest
-    steps:
-      - name: Check if stdlib_flags.h was modified
-        uses: actions/github-script@v8
-        with:
-          script: |
-            // Get the list of files changed in this PR
-            const files = await github.paginate(
-              github.rest.pulls.listFiles,
-              {
-                owner: context.repo.owner,
-                repo: context.repo.repo,
-                pull_number: context.payload.pull_request.number,
-              }
-            );
-
-            // Check if stdlib_flags.h was modified
-            const stdlibFlagsModified = files.some(file =>
-              file.filename === 'src/stdlib_flags.h'
-            );
-
-            if (stdlibFlagsModified) {
-              console.log('src/stdlib_flags.h was modified in this PR');
-
-              // Check if the unlock label is present
-
-              const { data: pr } = await github.rest.pulls.get({
-                owner: context.repo.owner,
-                repo: context.repo.repo,
-                pull_number: context.issue.number,
-              });
-
-              const hasUnlockLabel = pr.labels.some(label =>
-                label.name === 'unlock-upstream-stdlib-flags'
-              );
-
-              if (!hasUnlockLabel) {
-                core.setFailed(
-                  'src/stdlib_flags.h was modified. This is likely a mistake. If you would like to change ' +
-                  'bootstrapping settings or request a stage0 update, you should modify stage0/src/stdlib_flags.h. ' +
-                  'If you really want to change src/stdlib_flags.h (which should be extremely rare), set the ' +
-                  'unlock-upstream-stdlib-flags label.'
-                );
-              } else {
-                console.log('Found unlock-upstream-stdlib-flags');
-              }
-            } else {
-              console.log('src/stdlib_flags.h was not modified');
-            }

.github/workflows/ci.yml

@@ -31,10 +31,12 @@ jobs:
   configure:
     runs-on: ubuntu-latest
     outputs:
+      # 0: PRs without special label
+      # 1: PRs with `merge-ci` label, merge queue checks, master commits
+      # 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?
@@ -50,9 +52,9 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v6
+        uses: actions/checkout@v4
         # don't schedule nightlies on forks
-        if: github.event_name == 'schedule' && github.repository == 'leanprover/lean4' || inputs.action == 'release nightly' || (startsWith(github.ref, 'refs/tags/') && github.repository == 'leanprover/lean4')
+        if: github.event_name == 'schedule' && github.repository == 'leanprover/lean4' || inputs.action == 'release nightly'
       - name: Set Nightly
         if: github.event_name == 'schedule' && github.repository == 'leanprover/lean4' || inputs.action == 'release nightly'
         id: set-nightly
@@ -60,23 +62,10 @@ jobs:
           if [[ -n '${{ secrets.PUSH_NIGHTLY_TOKEN }}' ]]; then
             git remote add nightly https://foo:'${{ secrets.PUSH_NIGHTLY_TOKEN }}'@github.com/${{ github.repository_owner }}/lean4-nightly.git
             git fetch nightly --tags
-            if [[ '${{ github.event_name }}' == 'workflow_dispatch' ]]; then
-              # Manual re-release: create a revision of the most recent nightly
-              BASE_NIGHTLY=$(git tag -l 'nightly-*' | sort -rV | head -1)
-              # Strip any existing -revK suffix to get the base date tag
-              BASE_NIGHTLY="${BASE_NIGHTLY%%-rev*}"
-              REV=1
-              while git rev-parse "refs/tags/${BASE_NIGHTLY}-rev${REV}" >/dev/null 2>&1; do
-                REV=$((REV + 1))
-              done
-              LEAN_VERSION_STRING="${BASE_NIGHTLY}-rev${REV}"
+            LEAN_VERSION_STRING="nightly-$(date -u +%F)"
+            # do nothing if commit already has a different tag
+            if [[ "$(git name-rev --name-only --tags --no-undefined HEAD 2> /dev/null || echo "$LEAN_VERSION_STRING")" == "$LEAN_VERSION_STRING" ]]; then
               echo "nightly=$LEAN_VERSION_STRING" >> "$GITHUB_OUTPUT"
-            else
-              # Scheduled: do nothing if commit already has a different tag
-              LEAN_VERSION_STRING="nightly-$(date -u +%F)"
-              if [[ "$(git name-rev --name-only --tags --no-undefined HEAD 2> /dev/null || echo "$LEAN_VERSION_STRING")" == "$LEAN_VERSION_STRING" ]]; then
-                echo "nightly=$LEAN_VERSION_STRING" >> "$GITHUB_OUTPUT"
-              fi
             fi
           fi
 
@@ -112,61 +101,6 @@ jobs:
             echo "Tag ${TAG_NAME} did not match SemVer regex."
           fi
 
-      - name: Check for custom releases (e.g., not in the main lean repository)
-        if: startsWith(github.ref, 'refs/tags/') && github.repository != 'leanprover/lean4'
-        id: set-release-custom
-        run: |
-          TAG_NAME="${GITHUB_REF##*/}"
-          echo "RELEASE_TAG=$TAG_NAME" >> "$GITHUB_OUTPUT"
-
-      - name: Validate CMakeLists.txt version matches tag
-        if: steps.set-release.outputs.RELEASE_TAG != ''
-        run: |
-          echo "Validating CMakeLists.txt version matches tag ${{ steps.set-release.outputs.RELEASE_TAG }}"
-
-          # Extract version values from CMakeLists.txt
-          CMAKE_MAJOR=$(grep -E "^set\(LEAN_VERSION_MAJOR " src/CMakeLists.txt | grep -oE '[0-9]+')
-          CMAKE_MINOR=$(grep -E "^set\(LEAN_VERSION_MINOR " src/CMakeLists.txt | grep -oE '[0-9]+')
-          CMAKE_PATCH=$(grep -E "^set\(LEAN_VERSION_PATCH " src/CMakeLists.txt | grep -oE '[0-9]+')
-          CMAKE_IS_RELEASE=$(grep -m 1 -E "^set\(LEAN_VERSION_IS_RELEASE " src/CMakeLists.txt | sed -nE 's/^set\(LEAN_VERSION_IS_RELEASE ([0-9]+)\).*/\1/p')
-
-          # Expected values from tag parsing
-          TAG_MAJOR="${{ steps.set-release.outputs.LEAN_VERSION_MAJOR }}"
-          TAG_MINOR="${{ steps.set-release.outputs.LEAN_VERSION_MINOR }}"
-          TAG_PATCH="${{ steps.set-release.outputs.LEAN_VERSION_PATCH }}"
-
-          ERRORS=""
-
-          if [[ "$CMAKE_MAJOR" != "$TAG_MAJOR" ]]; then
-            ERRORS+="LEAN_VERSION_MAJOR: expected $TAG_MAJOR, found $CMAKE_MAJOR\n"
-          fi
-          if [[ "$CMAKE_MINOR" != "$TAG_MINOR" ]]; then
-            ERRORS+="LEAN_VERSION_MINOR: expected $TAG_MINOR, found $CMAKE_MINOR\n"
-          fi
-          if [[ "$CMAKE_PATCH" != "$TAG_PATCH" ]]; then
-            ERRORS+="LEAN_VERSION_PATCH: expected $TAG_PATCH, found $CMAKE_PATCH\n"
-          fi
-          if [[ "$CMAKE_IS_RELEASE" != "1" ]]; then
-            ERRORS+="LEAN_VERSION_IS_RELEASE: expected 1, found $CMAKE_IS_RELEASE\n"
-          fi
-
-          if [[ -n "$ERRORS" ]]; then
-            echo "::error::Version mismatch between tag and src/CMakeLists.txt"
-            echo ""
-            echo "Tag ${{ steps.set-release.outputs.RELEASE_TAG }} expects version $TAG_MAJOR.$TAG_MINOR.$TAG_PATCH"
-            echo "But src/CMakeLists.txt has mismatched values:"
-            echo -e "$ERRORS"
-            echo ""
-            echo "Fix src/CMakeLists.txt, delete the tag, and re-tag."
-            exit 1
-          fi
-
-          echo "Version validation passed: $TAG_MAJOR.$TAG_MINOR.$TAG_PATCH"
-
-      # 0: PRs without special label
-      # 1: PRs with `merge-ci` label, merge queue checks, master commits
-      # 2: nightlies
-      # 3: PRs with `release-ci` or `lake-ci` label, full releases
       - name: Set check level
         id: set-level
         # We do not use github.event.pull_request.labels.*.name here because
@@ -174,257 +108,348 @@ jobs:
         # rerun the workflow run after setting the `release-ci`/`merge-ci` labels.
         run: |
           check_level=0
-          fast=false
-          lake_ci=false
 
-          if [[ -n "${{ steps.set-release.outputs.RELEASE_TAG }}" || -n "${{ steps.set-release-custom.outputs.RELEASE_TAG }}" ]]; then
-            check_level=3
-          elif [[ -n "${{ steps.set-nightly.outputs.nightly }}" ]]; then
+          if [[ -n "${{ steps.set-nightly.outputs.nightly }}" || -n "${{ steps.set-release.outputs.RELEASE_TAG }}" ]]; then
             check_level=2
           elif [[ "${{ github.event_name }}" != "pull_request" ]]; then
             check_level=1
           else
             labels="$(gh api repos/${{ github.repository_owner }}/${{ github.event.repository.name }}/pulls/${{ github.event.pull_request.number }} --jq '.labels')"
             if echo "$labels" | grep -q "release-ci"; then
-              check_level=3
+              check_level=2
             elif echo "$labels" | grep -q "merge-ci"; then
               check_level=1
             fi
-            if echo "$labels" | grep -q "lake-ci"; then
-              lake_ci=true
-            fi
-            if echo "$labels" | grep -q "fast-ci"; then
-              fast=true
-            fi
           fi
 
-          {
-            echo "check-level=$check_level"
-            echo "fast=$fast"
-            echo "lake-ci=$lake_ci"
-          } >> "$GITHUB_OUTPUT"
+          echo "check-level=$check_level" >> "$GITHUB_OUTPUT"
         env:
           GH_TOKEN: ${{ github.token }}
 
       - name: Configure build matrix
         id: set-matrix
-        uses: actions/github-script@v8
+        uses: actions/github-script@v7
         with:
           script: |
             const level = ${{ steps.set-level.outputs.check-level }};
-            const fast = ${{ steps.set-level.outputs.fast }};
-            const lakeCi = "${{ steps.set-level.outputs.lake-ci }}" == "true";
-            console.log(`level: ${level}, fast: ${fast}`);
+            console.log(`level: ${level}`);
             // use large runners where available (original repo)
             let large = ${{ github.repository == 'leanprover/lean4' }};
-            const isPr = "${{ github.event_name }}" == "pull_request";
-            const isPushToMaster = "${{ github.event_name }}" == "push" && "${{ github.ref_name }}" == "master";
             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,
-                "enabled": level >= 2,
-                "test": true,
+                "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",
-                // usually not a bottleneck so make exclusive to `fast-ci`
-                "os": large && fast ? "nscloud-ubuntu-22.04-amd64-8x16-with-cache" : "ubuntu-latest",
+                "os": large ? "nscloud-ubuntu-22.04-amd64-4x8" : "ubuntu-latest",
                 "release": true,
-                // Special handling for release jobs. We want:
-                // 1. To run it in PRs so developers get PR toolchains (so secondary without tests is sufficient)
-                // 2. To skip it in merge queues as it takes longer than the
-                //    Linux lake build and adds little value in the merge queue
-                // 3. To run it in release (obviously)
-                // 4. To run it for pushes to master so that pushes to master have a Linux toolchain
-                //    available as an artifact for Grove to use.
-                "enabled": isPr || level != 1 || isPushToMaster,
-                "test": level >= 1,
-                "secondary": level == 0,
+                "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'",
+                "CTEST_OPTIONS": "-E 'foreign'"
               },
               {
-                "name": "Linux Lake",
-                "os": large ? "nscloud-ubuntu-22.04-amd64-8x16-with-cache" : "ubuntu-latest",
-                "enabled": true,
-                "check-rebootstrap": level >= 1,
+                "name": "Linux",
+                "os": large ? "nscloud-ubuntu-22.04-amd64-4x8" : "ubuntu-latest",
                 "check-stage3": level >= 2,
-                "test": true,
-                // NOTE: `test-bench` currently seems to be broken on `ubuntu-latest`
-                "test-bench": large && level >= 2,
-                // We are not warning-free yet on all platforms, start here
-                "CMAKE_OPTIONS": "-DLEAN_EXTRA_CXX_FLAGS=-Werror",
+                "test-speedcenter": level >= 2,
+                "check-level": 1,
               },
               {
-                "name": "Linux Reldebug",
+                "name": "Linux Debug",
                 "os": "ubuntu-latest",
-                "enabled": level >= 2,
-                "test": true,
-                "CMAKE_PRESET": "reldebug",
-                // * `elab_bench/big_do` crashes with exit code 134
-                "CTEST_OPTIONS": "-E 'elab_bench/big_do'",
+                "check-level": 2,
+                "CMAKE_PRESET": "debug",
+                // exclude seriously slow tests
+                "CTEST_OPTIONS": "-E 'interactivetest|leanpkgtest|laketest|benchtest|bv_bitblast_stress'"
               },
-              {
+              // TODO: suddenly started failing in CI
+              /*{
                 "name": "Linux fsanitize",
-                // Always run on large if available, more reliable regarding timeouts
-                "os": large ? "nscloud-ubuntu-22.04-amd64-16x32-with-cache" : "ubuntu-latest",
-                "enabled": level >= 2,
-                // do not fail nightlies on this for now
-                "secondary": level <= 2,
-                "test": true,
+                "os": "ubuntu-latest",
+                "check-level": 2,
                 // turn off custom allocator & symbolic functions to make LSAN do its magic
                 "CMAKE_PRESET": "sanitize",
-                // * `StackOverflow*` correctly triggers ubsan.
-                // * `reverse-ffi` fails to link in sanitizers.
-                // * `interactive` and `async_select_channel` fail nondeterministically, would need
-                //   to be investigated..
-                // * 9366 is too close to timeout.
-                // * `bv_` sometimes times out calling into cadical even though we should be using
-                //   the standard compile flags for it.
-                // * `grind_guide` always times out.
-                // * `pkg/|lake/` tests sometimes time out (likely even hang), related to Lake CI
-                //   failures?
-                "CTEST_OPTIONS": "-E 'StackOverflow|reverse-ffi|interactive|async_select_channel|9366|run/bv_|grind_guide|grind_bitvec2|grind_constProp|grind_indexmap|grind_list|grind_lint|grind_array_attach|grind_ite_trace|pkg/|lake/'"
-              },
+                // exclude seriously slow/problematic tests (laketests crash)
+                "CTEST_OPTIONS": "-E 'interactivetest|leanpkgtest|laketest|benchtest'"
+              },*/
               {
                 "name": "macOS",
-                "os": "macos-15-intel",
+                "os": "macos-13",
                 "release": true,
-                "test": false,  // Tier 2 platform
-                "enabled": level >= 2,
+                "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
-                "CTEST_OPTIONS": "-E 'leanlaketest_hello'", // started failing from unpack
+                "tar": "gtar" // https://github.com/actions/runner-images/issues/2619
               },
               {
                 "name": "macOS aarch64",
-                // standard GH runner only comes with 7GB so use large runner if possible when running tests
-                "os": large && (fast || level >= 1) ? "nscloud-macos-sequoia-arm64-6x14" : "macos-15",
+                "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
-                // See "Linux release" for release job levels; Grove is not a concern here
-                "enabled": isPr || level != 1,
-                "test": level >= 1,
-                "secondary": level == 0,
+                "tar": "gtar" // https://github.com/actions/runner-images/issues/2619
               },
               {
                 "name": "Windows",
-                "os": large && (fast || level >= 2) ? "namespace-profile-windows-amd64-4x16" : "windows-2022",
+                "os": "windows-2022",
                 "release": true,
-                "enabled": level >= 2,
-                "test": true,
+                "check-level": 2,
                 "shell": "msys2 {0}",
                 "CMAKE_OPTIONS": "-G \"Unix Makefiles\"",
-                "llvm-url": "https://github.com/leanprover/lean-llvm/releases/download/19.1.2/lean-llvm-x86_64-w64-windows-gnu.tar.zst",
+                // for reasons unknown, interactivetests are flaky on Windows
+                "CTEST_OPTIONS": "--repeat until-pass:2",
+                "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",
+                "binary-check": "ldd"
               },
               {
                 "name": "Linux aarch64",
-                "os": "nscloud-ubuntu-22.04-arm64-4x16",
+                "os": "nscloud-ubuntu-22.04-arm64-4x8",
                 "CMAKE_OPTIONS": "-DLEAN_INSTALL_SUFFIX=-linux_aarch64",
                 "release": true,
-                "enabled": level >= 2,
-                "test": 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",
-                "prepare-llvm": "../script/prepare-llvm-linux.sh lean-llvm*",
+                "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,
-              //  "enabled": level >= 2,
-              //  "cross": true,
-              //  "shell": "bash -euxo pipefail {0}"
-              //}
-              // {
-              //   "name": "Web Assembly",
-              //   "os": "ubuntu-latest",
-              //   // Build a native 32bit binary in stage0 and use it to compile the oleans and the wasm build
-              //   "CMAKE_OPTIONS": "-DCMAKE_C_COMPILER_WORKS=1 -DSTAGE0_USE_GMP=OFF -DSTAGE0_LEAN_EXTRA_CXX_FLAGS='-m32' -DSTAGE0_LEANC_OPTS='-m32' -DSTAGE0_CMAKE_CXX_COMPILER=clang++ -DSTAGE0_CMAKE_C_COMPILER=clang -DSTAGE0_CMAKE_EXECUTABLE_SUFFIX=\"\" -DUSE_GMP=OFF -DMMAP=OFF -DSTAGE0_MMAP=OFF -DCMAKE_AR=../emsdk/emsdk-main/upstream/emscripten/emar -DCMAKE_TOOLCHAIN_FILE=../emsdk/emsdk-main/upstream/emscripten/cmake/Modules/Platform/Emscripten.cmake -DLEAN_INSTALL_SUFFIX=-linux_wasm32 -DSTAGE0_CMAKE_LIBRARY_PATH=/usr/lib/i386-linux-gnu/",
-              //   "wasm": true,
-              //   "cmultilib": true,
-              //   "release": true,
-              //   "enabled": level >= 2,
-              //   "cross": true,
-              //   "shell": "bash -euxo pipefail {0}",
-              //   // Just a few selected tests because wasm is slow
-              //   "CTEST_OPTIONS": "-R \"leantest_1007\\.lean|leantest_Format\\.lean|leanruntest\\_1037.lean|leanruntest_ac_rfl\\.lean|leanruntest_tempfile.lean\\.|leanruntest_libuv\\.lean\""
-              // }
+              {
+                "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/",
+                "cmultilib": true,
+                "release": true,
+                "check-level": 2,
+                "cross": true,
+                "shell": "bash -euxo pipefail {0}"
+              },
+              {
+                "name": "Web Assembly",
+                "os": "ubuntu-latest",
+                // Build a native 32bit binary in stage0 and use it to compile the oleans and the wasm build
+                "CMAKE_OPTIONS": "-DCMAKE_C_COMPILER_WORKS=1 -DSTAGE0_USE_GMP=OFF -DSTAGE0_LEAN_EXTRA_CXX_FLAGS='-m32' -DSTAGE0_LEANC_OPTS='-m32' -DSTAGE0_CMAKE_CXX_COMPILER=clang++ -DSTAGE0_CMAKE_C_COMPILER=clang -DSTAGE0_CMAKE_EXECUTABLE_SUFFIX=\"\" -DUSE_GMP=OFF -DMMAP=OFF -DSTAGE0_MMAP=OFF -DCMAKE_AR=../emsdk/emsdk-main/upstream/emscripten/emar -DCMAKE_TOOLCHAIN_FILE=../emsdk/emsdk-main/upstream/emscripten/cmake/Modules/Platform/Emscripten.cmake -DLEAN_INSTALL_SUFFIX=-linux_wasm32 -DSTAGE0_CMAKE_LIBRARY_PATH=/usr/lib/i386-linux-gnu/",
+                "wasm": true,
+                "cmultilib": true,
+                "release": true,
+                "check-level": 2,
+                "cross": true,
+                "shell": "bash -euxo pipefail {0}",
+                // Just a few selected tests because wasm is slow
+                "CTEST_OPTIONS": "-R \"leantest_1007\\.lean|leantest_Format\\.lean|leanruntest\\_1037.lean|leanruntest_ac_rfl\\.lean|leanruntest_tempfile.lean\\.|leanruntest_libuv\\.lean\""
+              }
             ];
-            for (const job of matrix) {
-              if (job["prepare-llvm"]) {
-                // `USE_LAKE` is not compatible with `prepare-llvm` currently
-                job["CMAKE_OPTIONS"] = (job["CMAKE_OPTIONS"] ? job["CMAKE_OPTIONS"] + " " : "") + "-DUSE_LAKE=OFF";
-              }
-            }
-            if (lakeCi) {
-              for (const job of matrix) {
-                job["CMAKE_OPTIONS"] = (job["CMAKE_OPTIONS"] ? job["CMAKE_OPTIONS"] + " " : "") + "-DLAKE_CI=ON";
-              }
-            }
-            console.log(`matrix:\n${JSON.stringify(matrix, null, 2)}`);
-            matrix = matrix.filter((job) => job["enabled"]);
-            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}}
-      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}}
-      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
+        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
@@ -448,7 +473,7 @@ jobs:
         content: |
           A build of `${{ github.ref_name }}`, triggered by event `${{ github.event_name }}`, [failed](https://github.com/${{ github.repository }}/actions/runs/${{ github.run_id }}).
     - if: contains(needs.*.result, 'failure')
-      uses: actions/github-script@v8
+      uses: actions/github-script@v7
       with:
         script: |
             core.setFailed('Some jobs failed')
@@ -456,16 +481,18 @@ 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
     needs: build
     steps:
-      - uses: actions/download-artifact@v7
+      - uses: actions/download-artifact@v4
         with:
           path: artifacts
       - name: Release
-        uses: softprops/action-gh-release@a06a81a03ee405af7f2048a818ed3f03bbf83c7b
+        uses: softprops/action-gh-release@v2
         with:
           files: artifacts/*/*
           fail_on_unmatched_files: true
@@ -486,14 +513,12 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v6
+        uses: actions/checkout@v4
         with:
           # needed for tagging
           fetch-depth: 0
-          # Doesn't seem to be working when additionally fetching from lean4-nightly
-          #filter: tree:0
           token: ${{ secrets.PUSH_NIGHTLY_TOKEN }}
-      - uses: actions/download-artifact@v7
+      - uses: actions/download-artifact@v4
         with:
           path: artifacts
       - name: Prepare Nightly Release
@@ -503,7 +528,7 @@ jobs:
           git tag "${{ needs.configure.outputs.nightly }}"
           git push nightly "${{ needs.configure.outputs.nightly }}"
           git push -f origin refs/tags/${{ needs.configure.outputs.nightly }}:refs/heads/nightly
-          last_tag="$(git log HEAD^ --simplify-by-decoration --pretty="format:%d" | grep -o "nightly-[^ ,)]*" | head -n 1)"
+          last_tag="$(git log HEAD^ --simplify-by-decoration --pretty="format:%d" | grep -o "nightly-[-0-9]*" | head -n 1)"
           echo -e "*Changes since ${last_tag}:*\n\n" > diff.md
           git show "$last_tag":RELEASES.md > old.md
           #./script/diff_changelogs.py old.md doc/changes.md >> diff.md
@@ -511,7 +536,7 @@ jobs:
           echo -e "\n*Full commit log*\n" >> diff.md
           git log --oneline "$last_tag"..HEAD | sed 's/^/* /' >> diff.md
       - name: Release Nightly
-        uses: softprops/action-gh-release@a06a81a03ee405af7f2048a818ed3f03bbf83c7b
+        uses: softprops/action-gh-release@v2
         with:
           body_path: diff.md
           prerelease: true
@@ -526,18 +551,8 @@ jobs:
           gh workflow -R leanprover/release-index run update-index.yml
         env:
           GITHUB_TOKEN: ${{ secrets.RELEASE_INDEX_TOKEN }}
-      - name: Generate mathlib nightly-testing app token
-        id: mathlib-app-token
-        uses: actions/create-github-app-token@29824e69f54612133e76f7eaac726eef6c875baf # v2.2.1
-        continue-on-error: true
-        with:
-          app-id: ${{ secrets.MATHLIB_NIGHTLY_TESTING_APP_ID }}
-          private-key: ${{ secrets.MATHLIB_NIGHTLY_TESTING_PRIVATE_KEY }}
-          owner: leanprover-community
-          repositories: mathlib4-nightly-testing
       - name: Update toolchain on mathlib4's nightly-testing branch
-        if: steps.mathlib-app-token.outcome == 'success'
         run: |
-          gh workflow -R leanprover-community/mathlib4-nightly-testing run nightly_bump_and_merge.yml
+          gh workflow -R leanprover-community/mathlib4 run nightly_bump_toolchain.yml
         env:
-          GITHUB_TOKEN: ${{ steps.mathlib-app-token.outputs.token }}
+          GITHUB_TOKEN: ${{ secrets.MATHLIB4_BOT }}

.github/workflows/copyright-header.yml

@@ -6,7 +6,7 @@ jobs:
   check-lean-files:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v6
+    - uses: actions/checkout@v4
 
     - name: Verify .lean files start with a copyright header.
       run: |

.github/workflows/grove.yml

@@ -1,162 +0,0 @@
-name: Grove
-
-on:
-  workflow_run: # https://docs.github.com/en/actions/using-workflows/events-that-trigger-workflows#workflow_run
-    workflows: [CI]
-    types: [completed]
-
-permissions:
-  pull-requests: write
-
-jobs:
-  grove-build:
-    runs-on: ubuntu-latest
-    if: github.event.workflow_run.conclusion == 'success' && github.repository == 'leanprover/lean4'
-
-    steps:
-      - name: Retrieve information about the original workflow
-        uses: potiuk/get-workflow-origin@v1_1 # https://github.com/marketplace/actions/get-workflow-origin
-        # This action is deprecated and archived, but it seems hard to find a
-        # better solution for getting the PR number
-        # see https://github.com/orgs/community/discussions/25220 for some discussion
-        id: workflow-info
-        with:
-          token: ${{ secrets.GITHUB_TOKEN }}
-          sourceRunId: ${{ github.event.workflow_run.id }}
-
-      - name: Check if should run
-        id: should-run
-        run: |
-          # Check if it's a push to master (no PR number and target branch is master)
-          if [ -z "${{ steps.workflow-info.outputs.pullRequestNumber }}" ]; then
-            if [ "${{ github.event.workflow_run.head_branch }}" = "master" ]; then
-              echo "Push to master detected. Running Grove."
-              echo "should-run=true" >> "$GITHUB_OUTPUT"
-            else
-              echo "Push to non-master branch, skipping"
-              echo "should-run=false" >> "$GITHUB_OUTPUT"
-            fi
-          else
-            # Check if it's a PR with grove label
-            PR_LABELS='${{ steps.workflow-info.outputs.pullRequestLabels }}'
-            if echo "$PR_LABELS" | grep -q '"grove"'; then
-              echo "PR with grove label detected. Running Grove."
-              echo "should-run=true" >> "$GITHUB_OUTPUT"
-            else
-              echo "PR without grove label, skipping"
-              echo "should-run=false" >> "$GITHUB_OUTPUT"
-            fi
-          fi
-
-      - name: Fetch upstream invalidated facts
-        if: ${{ steps.should-run.outputs.should-run == 'true' && steps.workflow-info.outputs.pullRequestNumber != '' }}
-        id: fetch-upstream
-        uses: TwoFx/grove-action/fetch-upstream@v0.5
-        with:
-          artifact-name: grove-invalidated-facts
-          base-ref: master
-
-      - name: Download toolchain for this commit
-        if: ${{ steps.should-run.outputs.should-run == 'true' }}
-        id: download-toolchain
-        uses: dawidd6/action-download-artifact@v11
-        with:
-          commit: ${{ steps.workflow-info.outputs.sourceHeadSha }}
-          workflow: ci.yml
-          path: artifacts
-          name: "build-Linux release"
-          allow_forks: true
-          name_is_regexp: true
-
-      - name: Unpack toolchain
-        if: ${{ steps.should-run.outputs.should-run == 'true' }}
-        id: unpack-toolchain
-        run: |
-          cd artifacts
-          # Find the tar.zst file
-          TAR_FILE=$(find . -name "lean-*.tar.zst" -type f | head -1)
-          if [ -z "$TAR_FILE" ]; then
-            echo "Error: No lean-*.tar.zst file found"
-            exit 1
-          fi
-          echo "Found archive: $TAR_FILE"
-
-          # Extract the archive
-          tar --zstd -xf "$TAR_FILE"
-
-          # Find the extracted directory name
-          LEAN_DIR=$(find . -maxdepth 1 -name "lean-*" -type d | head -1)
-          if [ -z "$LEAN_DIR" ]; then
-            echo "Error: No lean-* directory found after extraction"
-            exit 1
-          fi
-          echo "Extracted directory: $LEAN_DIR"
-          echo "lean-dir=$LEAN_DIR" >> "$GITHUB_OUTPUT"
-
-      - name: Build
-        if: ${{ steps.should-run.outputs.should-run == 'true' }}
-        id: build
-        uses: TwoFx/grove-action/build@v0.5
-        with:
-          project-path: doc/std/grove
-          script-name: grove-stdlib
-          invalidated-facts-artifact-name: grove-invalidated-facts
-          comment-artifact-name: grove-comment
-          toolchain-id: lean4
-          toolchain-path: artifacts/${{ steps.unpack-toolchain.outputs.lean-dir }}
-          project-ref: ${{ steps.workflow-info.outputs.sourceHeadSha }}
-
-      # deploy-alias computes a URL component for the PR preview. This
-      # is so we can have a stable name to use for feedback on draft
-      # material.
-      - id: deploy-alias
-        if: ${{ steps.should-run.outputs.should-run == 'true' }}
-        uses: actions/github-script@v8
-        name: Compute Alias
-        with:
-          result-encoding: string
-          script: |
-            if (process.env.PR) {
-                return `pr-${process.env.PR}`
-            } else {
-                return 'deploy-preview-main';
-            }
-        env:
-          PR: ${{ steps.workflow-info.outputs.pullRequestNumber }}
-
-      - name: Deploy to Netlify
-        if: ${{ steps.should-run.outputs.should-run == 'true' }}
-        id: deploy-draft
-        uses: nwtgck/actions-netlify@v3.0
-        with:
-          publish-dir: ${{ steps.build.outputs.out-path }}
-          production-deploy: false
-          github-token: ${{ secrets.GITHUB_TOKEN }}
-          alias: ${{ steps.deploy-alias.outputs.result }}
-          enable-commit-comment: false
-          enable-pull-request-comment: false
-          fails-without-credentials: true
-          enable-github-deployment: false
-          enable-commit-status: false
-        env:
-          NETLIFY_AUTH_TOKEN: ${{ secrets.NETLIFY_AUTH_TOKEN }}
-          NETLIFY_SITE_ID: "1cacfa39-a11c-467c-99e7-2e01d7b4089e"
-
-      # actions-netlify cannot add deploy links to a PR because it assumes a
-      # pull_request context, not a workflow_run context, see
-      # https://github.com/nwtgck/actions-netlify/issues/545
-      # We work around by using a comment to post the latest link
-      - name: "Comment on PR with preview links"
-        uses: marocchino/sticky-pull-request-comment@v2
-        if: ${{ steps.should-run.outputs.should-run == 'true' && steps.workflow-info.outputs.pullRequestNumber != '' }}
-        with:
-          number: ${{ env.PR_NUMBER }}
-          header: preview-comment
-          recreate: true
-          message: |
-            [Grove](${{ steps.deploy-draft.outputs.deploy-url }}) for revision ${{ steps.workflow-info.outputs.sourceHeadSha }}.
-
-            ${{ steps.build.outputs.comment-text }}
-        env:
-          PR_NUMBER: ${{ steps.workflow-info.outputs.pullRequestNumber }}
-          PR_HEADSHA: ${{ steps.workflow-info.outputs.sourceHeadSha }}

.github/workflows/labels-from-comments.yml

@@ -1,5 +1,5 @@
 # This workflow allows any user to add one of the `awaiting-review`, `awaiting-author`, `WIP`,
-# `release-ci`, `lake-ci`, or a `changelog-XXX` label by commenting on the PR or issue.
+# `release-ci`, or a `changelog-XXX` label by commenting on the PR or issue.
 # If any labels from the set {`awaiting-review`, `awaiting-author`, `WIP`} are added, other labels
 # from that set are removed automatically at the same time.
 # Similarly, if any `changelog-XXX` label is added, other `changelog-YYY` labels are removed.
@@ -12,12 +12,12 @@ on:
 
 jobs:
   update-label:
-    if: github.event.issue.pull_request != null && (contains(github.event.comment.body, 'awaiting-review') || contains(github.event.comment.body, 'awaiting-author') || contains(github.event.comment.body, 'WIP') || contains(github.event.comment.body, 'release-ci') || contains(github.event.comment.body, 'lake-ci') || contains(github.event.comment.body, 'changelog-'))
+    if: github.event.issue.pull_request != null && (contains(github.event.comment.body, 'awaiting-review') || contains(github.event.comment.body, 'awaiting-author') || contains(github.event.comment.body, 'WIP') || contains(github.event.comment.body, 'release-ci') || contains(github.event.comment.body, 'changelog-'))
     runs-on: ubuntu-latest
 
     steps:
     - name: Add label based on comment
-      uses: actions/github-script@v8
+      uses: actions/github-script@v7
       with:
         github-token: ${{ secrets.GITHUB_TOKEN }}
         script: |
@@ -28,7 +28,6 @@ jobs:
           const awaitingAuthor = commentLines.includes('awaiting-author');
           const wip = commentLines.includes('WIP');
           const releaseCI = commentLines.includes('release-ci');
-          const lakeCI = commentLines.includes('lake-ci');
           const changelogMatch = commentLines.find(line => line.startsWith('changelog-'));
 
           if (awaitingReview || awaitingAuthor || wip) {
@@ -50,9 +49,6 @@ jobs:
           if (releaseCI) {
             await github.rest.issues.addLabels({ owner, repo, issue_number, labels: ['release-ci'] });
           }
-          if (lakeCI) {
-            await github.rest.issues.addLabels({ owner, repo, issue_number, labels: ['lake-ci'] });
-          }
 
           if (changelogMatch) {
             const changelogLabel = changelogMatch.trim();

.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-body.yml

@@ -2,23 +2,17 @@ name: Check PR body for changelog convention
 
 on:
   merge_group:
-  pull_request_target:
+  pull_request:
     types: [opened, synchronize, reopened, edited, labeled, converted_to_draft, ready_for_review]
 
-permissions:
-  pull-requests: read
-
 jobs:
   check-pr-body:
     runs-on: ubuntu-latest
     steps:
       - name: Check PR body
-        if: github.event_name == 'pull_request_target'
-        uses: actions/github-script@v8
+        if: github.event_name == 'pull_request'
+        uses: actions/github-script@v7
         with:
-          # Safety note: this uses pull_request_target, so the workflow has elevated privileges.
-          # The PR title and body are only used in regex tests (read-only string matching),
-          # never interpolated into shell commands, eval'd, or written to GITHUB_ENV/GITHUB_OUTPUT.
           script: |
             const { title, body, labels, draft } = context.payload.pull_request;
             if (!draft && /^(feat|fix):/.test(title) && !labels.some(label => label.name == "changelog-no")) {

.github/workflows/pr-release.yml

@@ -20,9 +20,7 @@ on:
 jobs:
   on-success:
     runs-on: ubuntu-latest
-    # Run even if CI fails, as long as build artifacts are available
-    # The "Verify release artifacts exist" step will fail if necessary artifacts are missing
-    if: github.event.workflow_run.event == 'pull_request' && github.repository == 'leanprover/lean4'
+    if: github.event.workflow_run.conclusion == 'success' && github.event.workflow_run.event == 'pull_request' && github.repository == 'leanprover/lean4'
     steps:
       - name: Retrieve information about the original workflow
         uses: potiuk/get-workflow-origin@v1_1 # https://github.com/marketplace/actions/get-workflow-origin
@@ -36,26 +34,13 @@ jobs:
       - name: Download artifact from the previous workflow.
         if: ${{ steps.workflow-info.outputs.pullRequestNumber != '' }}
         id: download-artifact
-        uses: dawidd6/action-download-artifact@v11 # 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
           name: build-.*
           name_is_regexp: true
 
-      # Verify artifacts were downloaded before any side effects (tag creation, release deletion).
-      - name: Verify release artifacts exist
-        if: ${{ steps.workflow-info.outputs.pullRequestNumber != '' }}
-        run: |
-          shopt -s nullglob
-          files=(artifacts/*/*)
-          if [ ${#files[@]} -eq 0 ]; then
-            echo "::error::No artifacts found matching artifacts/*/*"
-            exit 1
-          fi
-          echo "Found ${#files[@]} artifacts to upload:"
-          printf '%s\n' "${files[@]}"
-
       - name: Push tag
         if: ${{ steps.workflow-info.outputs.pullRequestNumber != '' }}
         run: |
@@ -63,62 +48,34 @@ jobs:
           git -C lean4.git remote add origin https://github.com/${{ github.repository_owner }}/lean4.git
           git -C lean4.git fetch -n origin master
           git -C lean4.git fetch -n origin "${{ steps.workflow-info.outputs.sourceHeadSha }}"
-
-          # Create both the original tag and the SHA-suffixed tag
-          SHORT_SHA="${{ steps.workflow-info.outputs.sourceHeadSha }}"
-          SHORT_SHA="${SHORT_SHA:0:7}"
-
-          # Export the short SHA for use in subsequent steps
-          echo "SHORT_SHA=${SHORT_SHA}" >> "$GITHUB_ENV"
-
           git -C lean4.git tag -f pr-release-${{ steps.workflow-info.outputs.pullRequestNumber }} "${{ steps.workflow-info.outputs.sourceHeadSha }}"
-          git -C lean4.git tag -f pr-release-${{ steps.workflow-info.outputs.pullRequestNumber }}-"${SHORT_SHA}" "${{ steps.workflow-info.outputs.sourceHeadSha }}"
-
           git -C lean4.git remote add pr-releases https://foo:'${{ secrets.PR_RELEASES_TOKEN }}'@github.com/${{ github.repository_owner }}/lean4-pr-releases.git
           git -C lean4.git push -f pr-releases pr-release-${{ steps.workflow-info.outputs.pullRequestNumber }}
-          git -C lean4.git push -f pr-releases pr-release-${{ steps.workflow-info.outputs.pullRequestNumber }}-"${SHORT_SHA}"
-      - name: Delete existing releases if present
+      - name: Delete existing release if present
         if: ${{ steps.workflow-info.outputs.pullRequestNumber != '' }}
         run: |
-          # Delete any existing releases for this PR.
-          # The short format release is always recreated with the latest commit.
-          # The SHA-suffixed release should be unique per commit, but delete just in case.
+          # Try to delete any existing release for the current PR.
           gh release delete --repo ${{ github.repository_owner }}/lean4-pr-releases pr-release-${{ steps.workflow-info.outputs.pullRequestNumber }} -y || true
-          gh release delete --repo ${{ github.repository_owner }}/lean4-pr-releases pr-release-${{ steps.workflow-info.outputs.pullRequestNumber }}-${{ env.SHORT_SHA }} -y || true
         env:
           GH_TOKEN: ${{ secrets.PR_RELEASES_TOKEN }}
-      # We use `gh release create` instead of `softprops/action-gh-release` because
-      # the latter enumerates all releases to check for existing ones, which fails
-      # when the repository has more than 10000 releases (GitHub API pagination limit).
-      # Upstream fix: https://github.com/softprops/action-gh-release/pull/725
-      - name: Release (short format)
+      - name: Release
         if: ${{ steps.workflow-info.outputs.pullRequestNumber != '' }}
-        run: |
-          # There are coredump files in deeper subdirectories; artifacts/*/* gets the release archives.
-          gh release create \
-            --repo ${{ github.repository_owner }}/lean4-pr-releases \
-            --title "Release for PR ${{ steps.workflow-info.outputs.pullRequestNumber }}" \
-            --notes "" \
-            pr-release-${{ steps.workflow-info.outputs.pullRequestNumber }} \
-            artifacts/*/*
+        uses: softprops/action-gh-release@v2
+        with:
+          name: Release for PR ${{ steps.workflow-info.outputs.pullRequestNumber }}
+          # There are coredumps files here as well, but all in deeper subdirectories.
+          files: artifacts/*/*
+          fail_on_unmatched_files: true
+          draft: false
+          tag_name: pr-release-${{ steps.workflow-info.outputs.pullRequestNumber }}
+          repository: ${{ github.repository_owner }}/lean4-pr-releases
         env:
-          GH_TOKEN: ${{ secrets.PR_RELEASES_TOKEN }}
+          # The token used here must have `workflow` privileges.
+          GITHUB_TOKEN: ${{ secrets.PR_RELEASES_TOKEN }}
 
-      - name: Release (SHA-suffixed format)
+      - name: Report release status
         if: ${{ steps.workflow-info.outputs.pullRequestNumber != '' }}
-        run: |
-          gh release create \
-            --repo ${{ github.repository_owner }}/lean4-pr-releases \
-            --title "Release for PR ${{ steps.workflow-info.outputs.pullRequestNumber }} (${{ steps.workflow-info.outputs.sourceHeadSha }})" \
-            --notes "" \
-            pr-release-${{ steps.workflow-info.outputs.pullRequestNumber }}-${{ env.SHORT_SHA }} \
-            artifacts/*/*
-        env:
-          GH_TOKEN: ${{ secrets.PR_RELEASES_TOKEN }}
-
-      - name: Report release status (short format)
-        if: ${{ steps.workflow-info.outputs.pullRequestNumber != '' }}
-        uses: actions/github-script@v8
+        uses: actions/github-script@v7
         with:
           script: |
             await github.rest.repos.createCommitStatus({
@@ -130,23 +87,9 @@ jobs:
               description: "${{ github.repository_owner }}/lean4-pr-releases:pr-release-${{ steps.workflow-info.outputs.pullRequestNumber }}",
             });
 
-      - name: Report release status (SHA-suffixed format)
+      - name: Add label
         if: ${{ steps.workflow-info.outputs.pullRequestNumber != '' }}
-        uses: actions/github-script@v8
-        with:
-          script: |
-            await github.rest.repos.createCommitStatus({
-              owner: context.repo.owner,
-              repo: context.repo.repo,
-              sha: "${{ steps.workflow-info.outputs.sourceHeadSha }}",
-              state: "success",
-              context: "PR toolchain (SHA-suffixed)",
-              description: "${{ github.repository_owner }}/lean4-pr-releases:pr-release-${{ steps.workflow-info.outputs.pullRequestNumber }}-${{ env.SHORT_SHA }}",
-            });
-
-      - name: Add toolchain-available label
-        if: ${{ steps.workflow-info.outputs.pullRequestNumber != '' }}
-        uses: actions/github-script@v8
+        uses: actions/github-script@v7
         with:
           script: |
             await github.rest.issues.addLabels({
@@ -168,22 +111,10 @@ jobs:
 
       - name: 'Setup jq'
         if: ${{ steps.workflow-info.outputs.pullRequestNumber != '' }}
-        uses: dcarbone/install-jq-action@v3.2.0
-
-      # Generate a token for posting comments to Lean PRs about mathlib compatibility.
-      # This app is in the leanprover org and installed on leanprover/lean4.
-      - name: Generate GitHub App token for Lean PR comments
-        if: ${{ steps.workflow-info.outputs.pullRequestNumber != '' }}
-        id: mathlib-comment-token
-        uses: actions/create-github-app-token@3ff1caaa28b64c9cc276ce0a02e2ff584f3900c5 # v2.0.2
-        with:
-          app-id: ${{ secrets.MATHLIB_LEAN_PR_TESTING_APP_ID }}
-          private-key: ${{ secrets.MATHLIB_LEAN_PR_TESTING_PRIVATE_KEY }}
-          owner: leanprover
-          repositories: lean4
+        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 for Mathlib/Batteries
+      - name: Check merge-base and nightly-testing-YYYY-MM-DD
         if: ${{ steps.workflow-info.outputs.pullRequestNumber != '' }}
         id: ready
         run: |
@@ -195,15 +126,24 @@ jobs:
           if [ "$NIGHTLY_SHA" = "$MERGE_BASE_SHA" ]; then
             echo "The merge base of this PR coincides with the nightly release"
 
-            MATHLIB_REMOTE_TAGS="$(git ls-remote https://github.com/leanprover-community/mathlib4-nightly-testing.git nightly-testing-"$MOST_RECENT_NIGHTLY")"
+            BATTERIES_REMOTE_TAGS="$(git ls-remote https://github.com/leanprover-community/batteries.git nightly-testing-"$MOST_RECENT_NIGHTLY")"
+            MATHLIB_REMOTE_TAGS="$(git ls-remote https://github.com/leanprover-community/mathlib4.git nightly-testing-"$MOST_RECENT_NIGHTLY")"
 
-            if [[ -n "$MATHLIB_REMOTE_TAGS" ]]; then
-              echo "... and Mathlib has a 'nightly-testing-$MOST_RECENT_NIGHTLY' tag."
+            if [[ -n "$BATTERIES_REMOTE_TAGS" ]]; then
+              echo "... and Batteries has a 'nightly-testing-$MOST_RECENT_NIGHTLY' tag."
               MESSAGE=""
+
+              if [[ -n "$MATHLIB_REMOTE_TAGS" ]]; then
+                echo "... and Mathlib has a 'nightly-testing-$MOST_RECENT_NIGHTLY' tag."
+              else
+                echo "... but Mathlib does not yet have a 'nightly-testing-$MOST_RECENT_NIGHTLY' tag."
+                MESSAGE="- ❗ Mathlib CI can not be attempted yet, as the \`nightly-testing-$MOST_RECENT_NIGHTLY\` tag does not exist there yet. We will retry when you push more commits. If you rebase your branch onto \`nightly-with-mathlib\`, Mathlib CI should run now."
+              fi
             else
-              echo "... but Mathlib does not yet have a 'nightly-testing-$MOST_RECENT_NIGHTLY' tag."
-              MESSAGE="- ❗ Mathlib CI can not be attempted yet, as the \`nightly-testing-$MOST_RECENT_NIGHTLY\` tag does not exist there yet. We will retry when you push more commits. If you rebase your branch onto \`nightly-with-mathlib\`, Mathlib CI should run now."
+              echo "... but Batteries does not yet have a 'nightly-testing-$MOST_RECENT_NIGHTLY' tag."
+              MESSAGE="- ❗ Batteries CI can not be attempted yet, as the \`nightly-testing-$MOST_RECENT_NIGHTLY\` tag does not exist there yet. We will retry when you push more commits. If you rebase your branch onto \`nightly-with-mathlib\`, Batteries CI should run now."
             fi
+
           else
             echo "The most recently nightly tag on this branch has SHA: $NIGHTLY_SHA"
             echo "but 'git merge-base origin/master HEAD' reported: $MERGE_BASE_SHA"
@@ -215,21 +155,6 @@ jobs:
           fi
 
           if [[ -n "$MESSAGE" ]]; then
-            # Check if force-mathlib-ci label is present
-            # Use GITHUB_TOKEN for read-only label fetch (MATHLIB4_COMMENT_BOT is only for posting comments)
-            LABELS="$(curl --retry 3 --location --silent \
-                          -H "Authorization: token ${{ secrets.GITHUB_TOKEN }}" \
-                          -H "Accept: application/vnd.github.v3+json" \
-                          "https://api.github.com/repos/leanprover/lean4/issues/${{ 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"
 
@@ -239,10 +164,10 @@ jobs:
 
             # Use GitHub API to check if a comment already exists
             existing_comment="$(curl --retry 3 --location --silent \
-                                    -H "Authorization: token ${{ steps.mathlib-comment-token.outputs.token }}" \
+                                    -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 }}/comments" \
-                                    | jq 'first(.[] | select(.body | test("^- . Mathlib") or startswith("Mathlib CI status")) | select(.user.login == "mathlib-lean-pr-testing[bot]"))')"
+                                    | jq 'first(.[] | select(.body | test("^- . Mathlib") or startswith("Mathlib CI status")) | select(.user.login == "leanprover-community-bot"))')"
             existing_comment_id="$(echo "$existing_comment" | jq -r .id)"
             existing_comment_body="$(echo "$existing_comment" | jq -r .body)"
 
@@ -252,14 +177,14 @@ jobs:
               echo "Posting message to the comments: $MESSAGE"
 
               # Append new result to the existing comment or post a new comment
-              # Use the mathlib-lean-pr-testing app token so Mathlib CI can subsequently edit the comment.
+              # It's essential we use the MATHLIB4_COMMENT_BOT token here, so that Mathlib CI can subsequently edit the comment.
               if [ -z "$existing_comment_id" ]; then
                 INTRO="Mathlib CI status ([docs](https://leanprover-community.github.io/contribute/tags_and_branches.html)):"
                 # Post new comment with a bullet point
                 echo "Posting as new comment at leanprover/lean4/issues/${{ steps.workflow-info.outputs.pullRequestNumber }}/comments"
                 curl -L -s \
                   -X POST \
-                  -H "Authorization: token ${{ steps.mathlib-comment-token.outputs.token }}" \
+                  -H "Authorization: token ${{ secrets.MATHLIB4_COMMENT_BOT }}" \
                   -H "Accept: application/vnd.github.v3+json" \
                   -d "$(jq --null-input --arg intro "$INTRO" --arg val "$MESSAGE" '{"body":($intro + "\n" + $val)}')" \
                   "https://api.github.com/repos/leanprover/lean4/issues/${{ steps.workflow-info.outputs.pullRequestNumber }}/comments"
@@ -268,7 +193,7 @@ jobs:
                 echo "Appending to existing comment at leanprover/lean4/issues/${{ steps.workflow-info.outputs.pullRequestNumber }}/comments"
                 curl -L -s \
                   -X PATCH \
-                  -H "Authorization: token ${{ steps.mathlib-comment-token.outputs.token }}" \
+                  -H "Authorization: token ${{ secrets.MATHLIB4_COMMENT_BOT }}" \
                   -H "Accept: application/vnd.github.v3+json" \
                   -d "$(jq --null-input --arg existing "$existing_comment_body" --arg message "$MESSAGE" '{"body":($existing + "\n" + $message)}')" \
                   "https://api.github.com/repos/leanprover/lean4/issues/comments/$existing_comment_id"
@@ -276,121 +201,14 @@ 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
 
-      - name: Check merge-base and nightly-testing-YYYY-MM-DD for reference manual
-        if: ${{ steps.workflow-info.outputs.pullRequestNumber != '' }}
-        id: reference-manual-ready
-        run: |
-          echo "Most recent nightly release in your branch: $MOST_RECENT_NIGHTLY"
-          NIGHTLY_SHA=$(git -C lean4.git rev-parse "nightly-$MOST_RECENT_NIGHTLY^{commit}")
-          echo "SHA of most recent nightly release: $NIGHTLY_SHA"
-          MERGE_BASE_SHA=$(git -C lean4.git merge-base origin/master "${{ steps.workflow-info.outputs.sourceHeadSha }}")
-          echo "SHA of merge-base: $MERGE_BASE_SHA"
-          if [ "$NIGHTLY_SHA" = "$MERGE_BASE_SHA" ]; then
-            echo "The merge base of this PR coincides with the nightly release"
-
-            MANUAL_REMOTE_TAGS="$(git ls-remote https://github.com/leanprover/reference-manual.git nightly-testing-"$MOST_RECENT_NIGHTLY")"
-            if [[ -n "$MANUAL_REMOTE_TAGS" ]]; then
-              echo "... and the reference manual has a 'nightly-testing-$MOST_RECENT_NIGHTLY' tag."
-              MESSAGE=""
-            else
-              echo "... but the reference manual does not yet have a 'nightly-testing-$MOST_RECENT_NIGHTLY' tag."
-              MESSAGE="- ❗ Reference manual CI can not be attempted yet, as the \`nightly-testing-$MOST_RECENT_NIGHTLY\` tag does not exist there yet. We will retry when you push more commits. If you rebase your branch onto \`nightly-with-manual\`, reference manual CI should run now."
-            fi
-          else
-            echo "The most recently nightly tag on this branch has SHA: $NIGHTLY_SHA"
-            echo "but 'git merge-base origin/master HEAD' reported: $MERGE_BASE_SHA"
-            git -C lean4.git log -10 origin/master
-
-            git -C lean4.git fetch origin nightly-with-manual
-            NIGHTLY_WITH_MANUAL_SHA="$(git -C lean4.git rev-parse "origin/nightly-with-manual")"
-            MESSAGE="- ❗ Reference manual CI will not be attempted unless your PR branches off the \`nightly-with-manual\` branch. Try \`git rebase $MERGE_BASE_SHA --onto $NIGHTLY_WITH_MANUAL_SHA\`."
-          fi
-
-          if [[ -n "$MESSAGE" ]]; then
-            # Check if force-manual-ci label is present
-            LABELS="$(curl --retry 3 --location --silent \
-                          -H "Authorization: token ${{ secrets.MANUAL_COMMENT_BOT }}" \
-                          -H "Accept: application/vnd.github.v3+json" \
-                          "https://api.github.com/repos/leanprover/lean4/issues/${{ steps.workflow-info.outputs.pullRequestNumber }}/labels" \
-                          | jq -r '.[].name')"
-
-            if echo "$LABELS" | grep -q "^force-manual-ci$"; then
-              echo "force-manual-ci label detected, forcing CI despite issues"
-              MESSAGE="Forcing reference manual CI because the \`force-manual-ci\` label is present, despite problem: $MESSAGE"
-              FORCE_CI=true
-            else
-              MESSAGE="$MESSAGE You can force reference manual CI using the \`force-manual-ci\` label."
-            fi
-
-            echo "Checking existing messages"
-
-            # The code for updating comments is duplicated in the reference manual's
-            # scripts/lean-pr-testing-comments.sh
-            # so keep in sync
-
-            # Use GitHub API to check if a comment already exists
-            existing_comment="$(curl --retry 3 --location --silent \
-                                    -H "Authorization: token ${{ secrets.MANUAL_COMMENT_BOT }}" \
-                                    -H "Accept: application/vnd.github.v3+json" \
-                                    "https://api.github.com/repos/leanprover/lean4/issues/${{ steps.workflow-info.outputs.pullRequestNumber }}/comments" \
-                                    | jq 'first(.[] | select(.body | test("^- . Manual") or startswith("Reference manual CI status")) | select(.user.login == "leanprover-bot"))')"
-            existing_comment_id="$(echo "$existing_comment" | jq -r .id)"
-            existing_comment_body="$(echo "$existing_comment" | jq -r .body)"
-
-            if [[ "$existing_comment_body" != *"$MESSAGE"* ]]; then
-              MESSAGE="$MESSAGE ($(date "+%Y-%m-%d %H:%M:%S"))"
-
-              echo "Posting message to the comments: $MESSAGE"
-
-              # Append new result to the existing comment or post a new comment
-              # It's essential we use the MANUAL_COMMENT_BOT token here, so that reference manual CI can subsequently edit the comment.
-              if [ -z "$existing_comment_id" ]; then
-                INTRO="Reference manual CI status:"
-                # Post new comment with a bullet point
-                echo "Posting as new comment at leanprover/lean4/issues/${{ steps.workflow-info.outputs.pullRequestNumber }}/comments"
-                curl -L -s \
-                  -X POST \
-                  -H "Authorization: token ${{ secrets.MANUAL_COMMENT_BOT }}" \
-                  -H "Accept: application/vnd.github.v3+json" \
-                  -d "$(jq --null-input --arg intro "$INTRO" --arg val "$MESSAGE" '{"body":($intro + "\n" + $val)}')" \
-                  "https://api.github.com/repos/leanprover/lean4/issues/${{ steps.workflow-info.outputs.pullRequestNumber }}/comments"
-              else
-                # Append new result to the existing comment
-                echo "Appending to existing comment at leanprover/lean4/issues/${{ steps.workflow-info.outputs.pullRequestNumber }}/comments"
-                curl -L -s \
-                  -X PATCH \
-                  -H "Authorization: token ${{ secrets.MANUAL_COMMENT_BOT }}" \
-                  -H "Accept: application/vnd.github.v3+json" \
-                  -d "$(jq --null-input --arg existing "$existing_comment_body" --arg message "$MESSAGE" '{"body":($existing + "\n" + $message)}')" \
-                  "https://api.github.com/repos/leanprover/lean4/issues/comments/$existing_comment_id"
-              fi
-            else
-              echo "The message already exists in the comment body."
-            fi
-
-            if [[ "$FORCE_CI" == "true" ]]; then
-              echo "manual_ready=true" >> "$GITHUB_OUTPUT"
-            else
-              echo "manual_ready=false" >> "$GITHUB_OUTPUT"
-            fi
-          else
-            echo "manual_ready=true" >> "$GITHUB_OUTPUT"
-          fi
-
-
       - name: Report mathlib base
         if: ${{ steps.workflow-info.outputs.pullRequestNumber != '' && steps.ready.outputs.mathlib_ready == 'true' }}
-        uses: actions/github-script@v8
+        uses: actions/github-script@v7
         with:
           script: |
             const description =
@@ -409,18 +227,6 @@ jobs:
       # We next automatically create a Batteries branch using this toolchain.
       # Batteries doesn't itself have a mechanism to report results of CI from this branch back to Lean
       # Instead this is taken care of by Mathlib CI, which will fail if Batteries fails.
-
-      # Generate a token from the mathlib-nightly-testing GitHub App for cross-org access
-      - name: Generate GitHub App token for leanprover-community repos
-        if: steps.workflow-info.outputs.pullRequestNumber != '' && steps.ready.outputs.mathlib_ready == 'true'
-        id: mathlib-app-token
-        uses: actions/create-github-app-token@3ff1caaa28b64c9cc276ce0a02e2ff584f3900c5 # v2.0.2
-        with:
-          app-id: ${{ secrets.MATHLIB_NIGHTLY_TESTING_APP_ID }}
-          private-key: ${{ secrets.MATHLIB_NIGHTLY_TESTING_PRIVATE_KEY }}
-          owner: leanprover-community
-          repositories: batteries,mathlib4-nightly-testing
-
       - name: Cleanup workspace
         if: steps.workflow-info.outputs.pullRequestNumber != '' && steps.ready.outputs.mathlib_ready == 'true'
         run: |
@@ -429,13 +235,12 @@ jobs:
       # Checkout the Batteries repository with all branches
       - name: Checkout Batteries repository
         if: steps.workflow-info.outputs.pullRequestNumber != '' && steps.ready.outputs.mathlib_ready == 'true'
-        uses: actions/checkout@v6
+        uses: actions/checkout@v4
         with:
           repository: leanprover-community/batteries
-          token: ${{ steps.mathlib-app-token.outputs.token }}
+          token: ${{ secrets.MATHLIB4_BOT }}
           ref: nightly-testing
           fetch-depth: 0 # This ensures we check out all tags and branches.
-          filter: tree:0
 
       - name: Check if tag exists
         if: steps.workflow-info.outputs.pullRequestNumber != '' && steps.ready.outputs.mathlib_ready == 'true'
@@ -447,7 +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
 
@@ -458,18 +263,16 @@ jobs:
           if [ "$EXISTS" = "0" ]; then
             echo "Branch does not exist, creating it."
             git switch -c lean-pr-testing-${{ steps.workflow-info.outputs.pullRequestNumber }} "$BASE"
-            echo "leanprover/lean4-pr-releases:pr-release-${{ steps.workflow-info.outputs.pullRequestNumber }}-${{ env.SHORT_SHA }}" > lean-toolchain
+            echo "leanprover/lean4-pr-releases:pr-release-${{ steps.workflow-info.outputs.pullRequestNumber }}" > lean-toolchain
             git add lean-toolchain
-            git commit --allow-empty -m "Update lean-toolchain for testing https://github.com/leanprover/lean4/pull/${{ steps.workflow-info.outputs.pullRequestNumber }}"
+            git commit -m "Update lean-toolchain for testing https://github.com/leanprover/lean4/pull/${{ steps.workflow-info.outputs.pullRequestNumber }}"
           else
-            echo "Branch already exists, updating lean-toolchain."
+            echo "Branch already exists, pushing an empty commit."
             git switch lean-pr-testing-${{ steps.workflow-info.outputs.pullRequestNumber }}
             # The Batteries `nightly-testing` or `nightly-testing-YYYY-MM-DD` branch may have moved since this branch was created, so merge their changes.
             # (This should no longer be possible once `nightly-testing-YYYY-MM-DD` is a tag, but it is still safe to merge.)
             git merge "$BASE" --strategy-option ours --no-commit --allow-unrelated-histories
-            echo "leanprover/lean4-pr-releases:pr-release-${{ steps.workflow-info.outputs.pullRequestNumber }}-${{ env.SHORT_SHA }}" > lean-toolchain
-            git add lean-toolchain
-            git commit --allow-empty -m "Update lean-toolchain for https://github.com/leanprover/lean4/pull/${{ steps.workflow-info.outputs.pullRequestNumber }}"
+            git commit --allow-empty -m "Trigger CI for https://github.com/leanprover/lean4/pull/${{ steps.workflow-info.outputs.pullRequestNumber }}"
           fi
 
       - name: Push changes
@@ -489,13 +292,12 @@ jobs:
       # Checkout the mathlib4 repository with all branches
       - name: Checkout mathlib4 repository
         if: steps.workflow-info.outputs.pullRequestNumber != '' && steps.ready.outputs.mathlib_ready == 'true'
-        uses: actions/checkout@v6
+        uses: actions/checkout@v4
         with:
-          repository: leanprover-community/mathlib4-nightly-testing
-          token: ${{ steps.mathlib-app-token.outputs.token }}
+          repository: leanprover-community/mathlib4
+          token: ${{ secrets.MATHLIB4_BOT }}
           ref: nightly-testing
           fetch-depth: 0 # This ensures we check out all tags and branches.
-          filter: tree:0
 
       - name: install elan
         run: |
@@ -514,7 +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
 
@@ -525,99 +327,24 @@ jobs:
           if [ "$EXISTS" = "0" ]; then
             echo "Branch does not exist, creating it."
             git switch -c lean-pr-testing-${{ steps.workflow-info.outputs.pullRequestNumber }} "$BASE"
-            echo "leanprover/lean4-pr-releases:pr-release-${{ steps.workflow-info.outputs.pullRequestNumber }}-${{ env.SHORT_SHA }}" > lean-toolchain
+            echo "leanprover/lean4-pr-releases:pr-release-${{ steps.workflow-info.outputs.pullRequestNumber }}" > lean-toolchain
             git add lean-toolchain
             sed -i 's,require "leanprover-community" / "batteries" @ git ".\+",require "leanprover-community" / "batteries" @ git "lean-pr-testing-${{ steps.workflow-info.outputs.pullRequestNumber }}",' lakefile.lean
             lake update batteries
             git add lakefile.lean lake-manifest.json
-            git commit --allow-empty -m "Update lean-toolchain for testing https://github.com/leanprover/lean4/pull/${{ steps.workflow-info.outputs.pullRequestNumber }}"
+            git commit -m "Update lean-toolchain for testing https://github.com/leanprover/lean4/pull/${{ steps.workflow-info.outputs.pullRequestNumber }}"
           else
-            echo "Branch already exists, updating lean-toolchain and bumping Batteries."
+            echo "Branch already exists, merging $BASE and bumping Batteries."
             git switch lean-pr-testing-${{ steps.workflow-info.outputs.pullRequestNumber }}
             # The Mathlib `nightly-testing` branch or `nightly-testing-YYYY-MM-DD` tag may have moved since this branch was created, so merge their changes.
             # (This should no longer be possible once `nightly-testing-YYYY-MM-DD` is a tag, but it is still safe to merge.)
             git merge "$BASE" --strategy-option ours --no-commit --allow-unrelated-histories
-            echo "leanprover/lean4-pr-releases:pr-release-${{ steps.workflow-info.outputs.pullRequestNumber }}-${{ env.SHORT_SHA }}" > lean-toolchain
-            git add lean-toolchain
             lake update batteries
             git add lake-manifest.json
-            git commit --allow-empty -m "Update lean-toolchain for https://github.com/leanprover/lean4/pull/${{ steps.workflow-info.outputs.pullRequestNumber }}"
+            git commit --allow-empty -m "Trigger CI for https://github.com/leanprover/lean4/pull/${{ steps.workflow-info.outputs.pullRequestNumber }}"
           fi
 
       - name: Push changes
         if: steps.workflow-info.outputs.pullRequestNumber != '' && steps.ready.outputs.mathlib_ready == 'true'
         run: |
           git push origin lean-pr-testing-${{ steps.workflow-info.outputs.pullRequestNumber }}
-
-      - name: Add mathlib4-nightly-available label
-        if: steps.workflow-info.outputs.pullRequestNumber != '' && steps.ready.outputs.mathlib_ready == 'true'
-        uses: actions/github-script@v8
-        with:
-          script: |
-            await github.rest.issues.addLabels({
-              issue_number: ${{ steps.workflow-info.outputs.pullRequestNumber }},
-              owner: context.repo.owner,
-              repo: context.repo.repo,
-              labels: ['mathlib4-nightly-available']
-            })
-
-      # We next automatically create a reference manual branch using this toolchain.
-      # Reference manual CI will be responsible for reporting back success or failure
-      # to the PR comments asynchronously (and thus transitively SubVerso/Verso).
-      - name: Cleanup workspace
-        if: steps.workflow-info.outputs.pullRequestNumber != '' && steps.reference-manual-ready.outputs.manual_ready == 'true'
-        run: |
-          sudo rm -rf ./*
-
-      # Checkout the reference manual repository with all branches
-      - name: Checkout mathlib4 repository
-        if: steps.workflow-info.outputs.pullRequestNumber != '' && steps.reference-manual-ready.outputs.manual_ready == 'true'
-        uses: actions/checkout@v6
-        with:
-          repository: leanprover/reference-manual
-          token: ${{ secrets.MANUAL_PR_BOT }}
-          ref: nightly-testing
-          fetch-depth: 0 # This ensures we check out all tags and branches.
-          filter: tree:0
-
-      - name: Check if tag in reference manual exists
-        if: steps.workflow-info.outputs.pullRequestNumber != '' && steps.reference-manual-ready.outputs.manual_ready == 'true'
-        id: check_manual_tag
-        run: |
-          git config user.name "leanprover-bot"
-          git config user.email "leanprover-bot@lean-fro.org"
-
-          if git ls-remote --heads --tags --exit-code origin "nightly-testing-${MOST_RECENT_NIGHTLY}" >/dev/null; then
-            BASE="nightly-testing-${MOST_RECENT_NIGHTLY}"
-          else
-            echo "Couldn't find a 'nightly-testing-${MOST_RECENT_NIGHTLY}' branch in the reference manual. Falling back to 'nightly-testing'."
-            BASE=nightly-testing
-          fi
-
-          echo "Using base tag: $BASE"
-
-          EXISTS="$(git ls-remote --heads origin lean-pr-testing-${{ steps.workflow-info.outputs.pullRequestNumber }} | wc -l)"
-          echo "Branch exists: $EXISTS"
-          if [ "$EXISTS" = "0" ]; then
-            echo "Branch does not exist, creating it."
-            git switch -c lean-pr-testing-${{ steps.workflow-info.outputs.pullRequestNumber }} "$BASE"
-            echo "leanprover/lean4-pr-releases:pr-release-${{ steps.workflow-info.outputs.pullRequestNumber }}-${{ env.SHORT_SHA }}" > lean-toolchain
-            git add lean-toolchain
-            git add lakefile.lean lake-manifest.json
-            git commit --allow-empty -m "Update lean-toolchain for testing https://github.com/leanprover/lean4/pull/${{ steps.workflow-info.outputs.pullRequestNumber }}"
-          else
-            echo "Branch already exists, updating lean-toolchain."
-            git switch lean-pr-testing-${{ steps.workflow-info.outputs.pullRequestNumber }}
-            # The reference manual's `nightly-testing` branch or `nightly-testing-YYYY-MM-DD` tag may have moved since this branch was created, so merge their changes.
-            # (This should no longer be possible once `nightly-testing-YYYY-MM-DD` is a tag, but it is still safe to merge.)
-            git merge "$BASE" --strategy-option ours --no-commit --allow-unrelated-histories
-            echo "leanprover/lean4-pr-releases:pr-release-${{ steps.workflow-info.outputs.pullRequestNumber }}-${{ env.SHORT_SHA }}" > lean-toolchain
-            git add lean-toolchain
-            git add lake-manifest.json
-            git commit --allow-empty -m "Update lean-toolchain for https://github.com/leanprover/lean4/pull/${{ steps.workflow-info.outputs.pullRequestNumber }}"
-          fi
-
-      - name: Push changes
-        if: steps.workflow-info.outputs.pullRequestNumber != '' && steps.reference-manual-ready.outputs.manual_ready == 'true'
-        run: |
-          git push origin lean-pr-testing-${{ steps.workflow-info.outputs.pullRequestNumber }}

.github/workflows/pr-title.yml

@@ -10,11 +10,11 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Check PR title
-        uses: actions/github-script@v8
+        uses: actions/github-script@v7
         with:
           script: |
             const msg = context.payload.pull_request? context.payload.pull_request.title : context.payload.merge_group.head_commit.message;
             console.log(`Message: ${msg}`)
-            if (!/^(feat|fix|doc|style|refactor|test|chore|perf): (?![A-Z][a-z]).*[^.]($|\n\n)/.test(msg)) {
+            if (!/^(feat|fix|doc|style|refactor|test|chore|perf): .*[^.]($|\n\n)/.test(msg)) {
               core.setFailed('PR title does not follow the Commit Convention (https://leanprover.github.io/lean4/doc/dev/commit_convention.html).');
             }

.github/workflows/restart-on-label.yml

@@ -7,7 +7,7 @@ on:
 jobs:
   restart-on-label:
     runs-on: ubuntu-latest
-    if: contains(github.event.label.name, 'merge-ci') || contains(github.event.label.name, 'release-ci') || contains(github.event.label.name, 'lake-ci')
+    if: contains(github.event.label.name, 'merge-ci') || contains(github.event.label.name, 'release-ci')
     steps:
     - run: |
         # Finding latest CI workflow run on current pull request

.github/workflows/stale.yml

@@ -11,7 +11,7 @@ jobs:
   stale:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/stale@v10
+      - uses: actions/stale@v9
         with:
           days-before-stale: -1
           days-before-pr-stale: 30

.github/workflows/update-stage0.yml

@@ -18,16 +18,12 @@ concurrency:
 
 jobs:
   update-stage0:
-    runs-on: nscloud-ubuntu-22.04-amd64-8x16
-    env:
-      CCACHE_DIR: ${{ github.workspace }}/.ccache
-      CCACHE_COMPRESS: true
-      CCACHE_MAXSIZE: 400M
+    runs-on: ubuntu-latest
     steps:
     # This action should push to an otherwise protected branch, so it
     # uses a deploy key with write permissions, as suggested at
     # https://stackoverflow.com/a/76135647/946226
-    - uses: actions/checkout@v6
+    - uses: actions/checkout@v4
       with:
         ssh-key: ${{secrets.STAGE0_SSH_KEY}}
     - run: echo "should_update_stage0=yes" >> "$GITHUB_ENV"
@@ -44,45 +40,34 @@ jobs:
       run: |
           git config --global user.name "Lean stage0 autoupdater"
           git config --global user.email "<>"
+    # Would be nice, but does not work yet:
+    # https://github.com/DeterminateSystems/magic-nix-cache/issues/39
+    # This action does not run that often and building runs in a few minutes, so ok for now
+    #- if: env.should_update_stage0 == 'yes'
+    #  uses: DeterminateSystems/magic-nix-cache-action@v2
+    - if: env.should_update_stage0 == 'yes'
+      name: Restore Build Cache
+      uses: actions/cache/restore@v4
+      with:
+        path: nix-store-cache
+        key: Nix Linux-nix-store-cache-${{ github.sha }}
+        # fall back to (latest) previous cache
+        restore-keys: |
+          Nix Linux-nix-store-cache
+    - if: env.should_update_stage0 == 'yes'
+      name: Further Set Up Nix Cache
+      shell: bash -euxo pipefail {0}
+      run: |
+        # Nix seems to mutate the cache, so make a copy
+        cp -r nix-store-cache nix-store-cache-copy || true
     - if: env.should_update_stage0 == 'yes'
       name: Install Nix
       uses: DeterminateSystems/nix-installer-action@main
-    - name: Open Nix shell once
-      if: env.should_update_stage0 == 'yes'
-      run: true
-      shell: 'nix develop -c bash -euxo pipefail {0}'
-    - name: Set up NPROC
-      if: env.should_update_stage0 == 'yes'
-      run: |
-        echo "NPROC=$(nproc 2>/dev/null || sysctl -n hw.logicalcpu 2>/dev/null || echo 4)" >> $GITHUB_ENV
-      shell: 'nix develop -c bash -euxo pipefail {0}'
-    - name: Restore Cache
-      if: env.should_update_stage0 == 'yes'
-      uses: actions/cache/restore@v5
       with:
-        # NOTE: must be in sync with `restore-cache` in `build-template.yml`
-        path: |
-          .ccache
-          build/stage1/**/*.trace
-          build/stage1/**/*.olean*
-          build/stage1/**/*.ilean
-          build/stage1/**/*.ir
-          build/stage1/**/*.c
-          build/stage1/**/*.c.o*
-        key: Linux Lake-build-v4-${{ github.sha }}
-        # fall back to (latest) previous cache
-        restore-keys: |
-          Linux Lake-build-v4
+        extra-conf: |
+          substituters = file://${{ github.workspace }}/nix-store-cache-copy?priority=10&trusted=true https://cache.nixos.org  
     - if: env.should_update_stage0 == 'yes'
-      # sync options with `Linux Lake` to ensure cache reuse
-      run: |
-        mkdir -p build
-        cmake --preset release -B build -DLEAN_EXTRA_MAKE_OPTS=-DwarningAsError=true
-      shell: 'nix develop -c bash -euxo pipefail {0}'
-    - if: env.should_update_stage0 == 'yes'
-      run: |
-        make -j$NPROC -C build update-stage0-commit
-      shell: 'nix develop -c bash -euxo pipefail {0}'
+      run: nix run .#update-stage0-commit
     - if: env.should_update_stage0 == 'yes'
       run: git show --stat
     - if: env.should_update_stage0 == 'yes' && github.event_name == 'push'

.gitignore

@@ -1,10 +1,12 @@
 *~
 \#*
 .#*
+*.lock
 .lake
 lake-manifest.json
 /build
 /src/lakefile.toml
+/tests/lakefile.toml
 /lakefile.toml
 GPATH
 GRTAGS
@@ -17,13 +19,9 @@ compile_commands.json
 *.idea
 tasks.json
 settings.json
-!.claude/settings.json
 .gdb_history
 .vscode/*
 !.vscode/settings.json
-!.vscode/tasks.json
-!.vscode/extensions.json
-script/__pycache__
 *.produced.out
 CMakeSettings.json
 CppProperties.json
@@ -33,4 +31,3 @@ fwOut.txt
 wdErr.txt
 wdIn.txt
 wdOut.txt
-downstream_releases/

.gitpod.Dockerfile

@@ -1,14 +0,0 @@
-# You can find the new timestamped tags here: https://hub.docker.com/r/gitpod/workspace-full/tags
-FROM gitpod/workspace-full
-
-USER root
-RUN apt-get update && apt-get install git libgmp-dev libuv1-dev cmake ccache clang -y && apt-get clean
-
-USER gitpod
-
-# Install and configure elan
-RUN curl https://raw.githubusercontent.com/leanprover/elan/master/elan-init.sh -sSf | sh -s -- -y --default-toolchain none
-ENV PATH="/home/gitpod/.elan/bin:${PATH}"
-# Create a dummy toolchain so that we can pre-register it with elan
-RUN mkdir -p /workspace/lean4/build/release/stage1/bin && touch /workspace/lean4/build/release/stage1/bin/lean && elan toolchain link lean4 /workspace/lean4/build/release/stage1
-RUN mkdir -p /workspace/lean4/build/release/stage0/bin && touch /workspace/lean4/build/release/stage0/bin/lean && elan toolchain link lean4-stage0 /workspace/lean4/build/release/stage0

.gitpod.yml

@@ -1,11 +0,0 @@
-image:
-    file: .gitpod.Dockerfile
-
-vscode:
-  extensions:
-    - leanprover.lean4
-
-tasks:
-  - name: Release build
-    init: cmake --preset release
-    command: make -C build/release -j$(nproc || sysctl -n hw.logicalcpu)

.vscode/extensions.json

@@ -1,5 +0,0 @@
-{
-	"recommendations": [
-		"leanprover.lean4"
-	]
-}

.vscode/settings.json

@@ -1,12 +0,0 @@
-{
-	"files.insertFinalNewline": true,
-	"files.trimTrailingWhitespace": true,
-	// These require the CMake Tools extension (ms-vscode.cmake-tools).
-	"cmake.buildDirectory": "${workspaceFolder}/build/release",
-	"cmake.generator": "Unix Makefiles",
-	"[lean4]": {
-		"editor.rulers": [
-			100
-		]
-	}
-}

.vscode/tasks.json

@@ -1,34 +0,0 @@
-{
-	"version": "2.0.0",
-	"tasks": [
-		{
-			"label": "build",
-			"type": "shell",
-			"command": "make -C build/release -j$(nproc 2>/dev/null || sysctl -n hw.logicalcpu 2>/dev/null || echo 4)",
-			"problemMatcher": [],
-			"group": {
-				"kind": "build",
-				"isDefault": true
-			}
-		},
-		{
-			"label": "build-old",
-			"type": "shell",
-			"command": "make -C build/release -j$(nproc 2>/dev/null || sysctl -n hw.logicalcpu 2>/dev/null || echo 4) LAKE_EXTRA_ARGS=--old",
-			"problemMatcher": [],
-			"group": {
-				"kind": "build"
-			}
-		},
-		{
-			"label": "test",
-			"type": "shell",
-			"command": "NPROC=$(nproc 2>/dev/null || sysctl -n hw.logicalcpu 2>/dev/null || echo 4); CTEST_OUTPUT_ON_FAILURE=1 make -C build/release test -j$NPROC ARGS=\"-j$NPROC\"",
-			"problemMatcher": [],
-			"group": {
-				"kind": "test",
-				"isDefault": true
-			}
-		}
-	]
-}

CMakeLists.txt

@@ -1,35 +1,24 @@
-cmake_minimum_required(VERSION 3.21)
-
-if(NOT CMAKE_GENERATOR MATCHES "Makefiles")
-  message(FATAL_ERROR "Only makefile generators are supported")
-endif()
-
-option(USE_MIMALLOC "use mimalloc" ON)
-
+cmake_minimum_required(VERSION 3.11)
 # 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_(.*)")
+  if("${var}" MATCHES "STAGE0_(.*)")
     list(APPEND STAGE0_ARGS "-D${CMAKE_MATCH_1}=${${var}}")
-  elseif(var MATCHES "STAGE1_(.*)")
-    list(APPEND STAGE1_ARGS "-D${CMAKE_MATCH_1}=${${var}}")
-  elseif(currentHelpString MATCHES "No help, variable specified on the command line." OR currentHelpString STREQUAL "")
+  elseif("${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|LEAN_VERSION_.*|LEAN_SPECIAL_VERSION_DESC")
+    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()
-  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"))
+  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()
 endforeach()
@@ -38,188 +27,96 @@ include(ExternalProject)
 project(LEAN CXX C)
 
 if(NOT (DEFINED STAGE0_CMAKE_EXECUTABLE_SUFFIX))
-  set(STAGE0_CMAKE_EXECUTABLE_SUFFIX "${CMAKE_EXECUTABLE_SUFFIX}")
+    set(STAGE0_CMAKE_EXECUTABLE_SUFFIX "${CMAKE_EXECUTABLE_SUFFIX}")
 endif()
 
-# Don't do anything with cadical/leantar on wasm
-if(NOT CMAKE_SYSTEM_NAME MATCHES "Emscripten")
+# 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 ${CMAKE_CXX_COMPILER})
-      # Use same platform flags as for Lean executables, in particular from `prepare-llvm-linux.sh`,
-      # but not Lean-specific `LEAN_EXTRA_CXX_FLAGS` such as fsanitize.
-      set(CADICAL_CXXFLAGS "${CMAKE_CXX_FLAGS}")
-      set(CADICAL_LDFLAGS "-Wl,-rpath=\\$$ORIGIN/../lib")
-    endif()
     find_program(CCACHE ccache)
     if(CCACHE)
       set(CADICAL_CXX "${CCACHE} ${CADICAL_CXX}")
     endif()
     # missing stdio locking API on Windows
-    if(CMAKE_SYSTEM_NAME MATCHES "Windows")
+    if(${CMAKE_SYSTEM_NAME} MATCHES "Windows")
       string(APPEND CADICAL_CXXFLAGS " -DNUNLOCKED")
     endif()
-    string(APPEND CADICAL_CXXFLAGS " -DNCLOSEFROM")
-    ExternalProject_Add(
-      cadical
+    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})
-    list(APPEND EXTRA_DEPENDS cadical)
+      INSTALL_COMMAND "")
+    set(CADICAL ${CMAKE_BINARY_DIR}/cadical/cadical${CMAKE_EXECUTABLE_SUFFIX} CACHE FILEPATH "path to cadical binary" FORCE)
+    set(EXTRA_DEPENDS "cadical")
   endif()
-  find_program(LEANTAR leantar)
-  if(NOT LEANTAR)
-    set(LEANTAR_VERSION v0.1.19)
-    if(CMAKE_SYSTEM_NAME MATCHES "Windows")
-      set(LEANTAR_ARCHIVE_SUFFIX .zip)
-      set(LEANTAR_TARGET x86_64-pc-windows-msvc)
-    else()
-      set(LEANTAR_ARCHIVE_SUFFIX .tar.gz)
-      if(CMAKE_SYSTEM_PROCESSOR MATCHES "arm64")
-        set(LEANTAR_TARGET_ARCH aarch64)
-      else()
-        set(LEANTAR_TARGET_ARCH x86_64)
-      endif()
-      if(CMAKE_SYSTEM_NAME MATCHES "Darwin")
-        set(LEANTAR_TARGET_OS apple-darwin)
-      else()
-        set(LEANTAR_TARGET_OS unknown-linux-musl)
-      endif()
-      set(LEANTAR_TARGET ${LEANTAR_TARGET_ARCH}-${LEANTAR_TARGET_OS})
-    endif()
-    set(
-      LEANTAR
-      ${CMAKE_BINARY_DIR}/leantar/leantar-${LEANTAR_VERSION}-${LEANTAR_TARGET}/leantar${CMAKE_EXECUTABLE_SUFFIX}
-    )
-    if(NOT EXISTS "${LEANTAR}")
-      file(
-        DOWNLOAD
-          https://github.com/digama0/leangz/releases/download/${LEANTAR_VERSION}/leantar-${LEANTAR_VERSION}-${LEANTAR_TARGET}${LEANTAR_ARCHIVE_SUFFIX}
-        ${CMAKE_BINARY_DIR}/leantar${LEANTAR_ARCHIVE_SUFFIX}
-      )
-      file(
-        ARCHIVE_EXTRACT
-        INPUT ${CMAKE_BINARY_DIR}/leantar${LEANTAR_ARCHIVE_SUFFIX}
-        DESTINATION ${CMAKE_BINARY_DIR}/leantar
-      )
-    endif()
-  endif()
-  list(APPEND CL_ARGS -DCADICAL=${CADICAL} -DLEANTAR=${LEANTAR})
+  list(APPEND CL_ARGS -DCADICAL=${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 ${EXTRA_DEPENDS}
-  )
-  list(APPEND EXTRA_DEPENDS stage0)
-endif()
-ExternalProject_Add(
-  stage1
+ExternalProject_add(stage0
+  SOURCE_DIR "${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 ${EXTRA_DEPENDS}
-  STEP_TARGETS configure
+  DEPENDS stage0
 )
-ExternalProject_Add(
-  stage2
+ExternalProject_add(stage2
   SOURCE_DIR "${LEAN_SOURCE_DIR}"
   SOURCE_SUBDIR src
   BINARY_DIR stage2
-  CMAKE_ARGS
-    -DSTAGE=2 -DPREV_STAGE=${CMAKE_BINARY_DIR}/stage1 -DPREV_STAGE_CMAKE_EXECUTABLE_SUFFIX=${CMAKE_EXECUTABLE_SUFFIX}
-    ${CL_ARGS}
+  CMAKE_ARGS -DSTAGE=2 -DPREV_STAGE=${CMAKE_BINARY_DIR}/stage1 -DPREV_STAGE_CMAKE_EXECUTABLE_SUFFIX=${CMAKE_EXECUTABLE_SUFFIX} ${CL_ARGS}
   BUILD_ALWAYS ON
   INSTALL_COMMAND ""
   DEPENDS stage1
   EXCLUDE_FROM_ALL ON
-  STEP_TARGETS configure
 )
-ExternalProject_Add(
-  stage3
+ExternalProject_add(stage3
   SOURCE_DIR "${LEAN_SOURCE_DIR}"
   SOURCE_SUBDIR src
   BINARY_DIR stage3
-  CMAKE_ARGS
-    -DSTAGE=3 -DPREV_STAGE=${CMAKE_BINARY_DIR}/stage2 -DPREV_STAGE_CMAKE_EXECUTABLE_SUFFIX=${CMAKE_EXECUTABLE_SUFFIX}
-    ${CL_ARGS}
+  CMAKE_ARGS -DSTAGE=3 -DPREV_STAGE=${CMAKE_BINARY_DIR}/stage2 -DPREV_STAGE_CMAKE_EXECUTABLE_SUFFIX=${CMAKE_EXECUTABLE_SUFFIX} ${CL_ARGS}
   BUILD_ALWAYS ON
   INSTALL_COMMAND ""
   DEPENDS stage2
   EXCLUDE_FROM_ALL ON
-  STEP_TARGETS configure
 )
 
 # targets forwarded to appropriate stages
 
-add_custom_target(update-stage0 COMMAND $(MAKE) -C stage1 update-stage0 DEPENDS stage1)
+add_custom_target(update-stage0
+  COMMAND $(MAKE) -C stage1 update-stage0
+  DEPENDS stage1)
 
-add_custom_target(update-stage0-commit COMMAND $(MAKE) -C stage1 update-stage0-commit DEPENDS stage1)
+add_custom_target(update-stage0-commit
+  COMMAND $(MAKE) -C stage1 update-stage0-commit
+  DEPENDS stage1)
 
-add_custom_target(test COMMAND $(MAKE) -C stage1 test DEPENDS stage1)
-
-add_custom_target(
-  bench
-  COMMAND $(MAKE) -C stage2
-  COMMAND $(MAKE) -C stage2 -j1 bench
-  DEPENDS stage2
-)
-add_custom_target(
-  bench-part1
-  COMMAND $(MAKE) -C stage2
-  COMMAND $(MAKE) -C stage2 -j1 bench-part1
-  DEPENDS stage2
-)
-add_custom_target(
-  bench-part2
-  COMMAND $(MAKE) -C stage2
-  COMMAND $(MAKE) -C stage2 -j1 bench-part2
-  DEPENDS stage2
-)
-
-add_custom_target(clean-stdlib COMMAND $(MAKE) -C stage1 clean-stdlib DEPENDS stage1)
+add_custom_target(test
+  COMMAND $(MAKE) -C stage1 test
+  DEPENDS stage1)
 
 install(CODE "execute_process(COMMAND make -C stage1 install)")
 
-add_custom_target(check-stage3 COMMAND diff "stage2/bin/lean" "stage3/bin/lean" DEPENDS stage3)
+add_custom_target(check-stage3
+  COMMAND diff "stage2/bin/lean" "stage3/bin/lean"
+  DEPENDS stage3)

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 TEST_STACK_SIZE=16000 LSAN_OPTIONS=max_leaks=10"
+        "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/ @hargoniX
 /src/lake/ @tydeu
-/src/Lean/Compiler/ @leodemoura @hargoniX
+/src/Lean/Compiler/ @leodemoura
 /src/Lean/Data/Lsp/ @mhuisi
 /src/Lean/Elab/Deriving/ @kim-em
 /src/Lean/Elab/Tactic/ @kim-em
@@ -45,10 +44,3 @@
 /src/Std/Tactic/BVDecide/ @hargoniX
 /src/Lean/Elab/Tactic/BVDecide/ @hargoniX
 /src/Std/Sat/ @hargoniX
-/src/Std/Do @sgraf812
-/src/Std/Tactic/Do @sgraf812
-/src/Lean/Elab/Tactic/Do @sgraf812
-/src/Init/Data/Range/Polymorphic @datokrat
-/src/Init/Data/Slice @datokrat
-/src/Init/Data/Iterators @datokrat
-/src/Std/Data/Iterators @datokrat

CONTRIBUTING.md

@@ -7,7 +7,7 @@ Helpful links
 -------
 
 * [Development Setup](./doc/dev/index.md)
-* [Testing](./tests/README.md)
+* [Testing](./doc/dev/testing.md)
 * [Commit convention](./doc/dev/commit_convention.md)
 
 Before You Submit a Pull Request (PR):

LICENSES

@@ -1370,208 +1370,4 @@ 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.
-==============================================================================
-leantar is by Mario Carneiro and distributed under the Apache 2.0 License:
-==============================================================================
-                                 Apache License
-                           Version 2.0, January 2004
-                        http://www.apache.org/licenses/
-
-   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
-
-   1. Definitions.
-
-      "License" shall mean the terms and conditions for use, reproduction,
-      and distribution as defined by Sections 1 through 9 of this document.
-
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-
-      "Legal Entity" shall mean the union of the acting entity and all
-      other entities that control, are controlled by, or are under common
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-      direction or management of such entity, whether by contract or
-      otherwise, or (ii) ownership of fifty percent (50%) or more of the
-      outstanding shares, or (iii) beneficial ownership of such entity.
-
-      "You" (or "Your") shall mean an individual or Legal Entity
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-
-      "Source" form shall mean the preferred form for making modifications,
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-      "Work" shall mean the work of authorship, whether in Source or
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-   Licensed under the Apache License, Version 2.0 (the "License");
-   you may not use this file except in compliance with the License.
-   You may obtain a copy of the License at
-
-       http://www.apache.org/licenses/LICENSE-2.0
-
-   Unless required by applicable law or agreed to in writing, software
-   distributed under the License is distributed on an "AS IS" BASIS,
-   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-   See the License for the specific language governing permissions and
-   limitations under the License.
+SOFTWARE.

README.md

@@ -2,19 +2,19 @@ This is the repository for **Lean 4**.
 
 # About
 
-- [Quickstart](https://lean-lang.org/install/)
+- [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/learn/)
-- [Language Reference](https://lean-lang.org/doc/reference/latest/)
+- [Manual](https://lean-lang.org/lean4/doc/)
 - [Release notes](RELEASES.md) starting at v4.0.0-m3
-- [Examples](https://lean-lang.org/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 [Install Lean](https://lean-lang.org/install/).
+See [Setting Up Lean](https://lean-lang.org/lean4/doc/setup.html).
 
 # Contributing
 
@@ -22,4 +22,4 @@ 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/.gitignore

@@ -0,0 +1 @@
+out

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 +1,94 @@
+# 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)
+
+# Language Manual
+<!-- - [Using Lean](./using_lean.md) -->
+<!-- - [Lexical Structure](./lexical_structure.md) -->
+<!-- - [Expressions](./expressions.md) -->
+<!-- - [Declarations](./declarations.md) -->
+- [Organizational features](./organization.md)
+  - [Sections](./sections.md)
+  - [Namespaces](./namespaces.md)
+  - [Implicit Arguments](./implicit.md)
+  - [Auto Bound Implicit Arguments](./autobound.md)
+<!-- - [Dependent Types](./deptypes.md) -->
+<!--   - [Simple Type Theory](./simptypes.md) -->
+<!--   - [Types as objects](./typeobjs.md) -->
+<!--   - [Function Abstraction and Evaluation](./funabst.md) -->
+<!--   - [Introducing Definitions](./introdef.md) -->
+<!--   - [What makes dependent type theory dependent?](./dep.md) -->
+<!-- - [Tactics](./tactics.md) -->
+- [Syntax Extensions](./syntax.md)
+  - [The `do` Notation](./do.md)
+  - [String Interpolation](./stringinterp.md)
+  - [User-Defined Notation](./notation.md)
+  - [Macro Overview](./macro_overview.md)
+  - [Elaborators](./elaborators.md)
+  - [Examples](./syntax_examples.md)
+    - [Balanced Parentheses](./syntax_example.md)
+    - [Arithmetic DSL](./metaprogramming-arith.md)
+- [Declaring New Types](./decltypes.md)
+  - [Enumerated Types](./enum.md)
+  - [Inductive Types](./inductive.md)
+  - [Structures](./struct.md)
+  - [Type classes](./typeclass.md)
+  - [Unification Hints](./unifhint.md)
+- [Builtin Types](./builtintypes.md)
+  - [Natural number](./nat.md)
+  - [Integer](./int.md)
+  - [Fixed precision unsigned integer](./uint.md)
+  - [Float](./float.md)
+  - [Array](./array.md)
+  - [List](./list.md)
+  - [Character](./char.md)
+  - [String](./string.md)
+  - [Option](./option.md)
+  - [Thunk](./thunk.md)
+  - [Task and Thread](./task.md)
+- [Functions](./functions.md)
+- [Monads](./monads/intro.md)
+  - [Functor](./monads/functors.lean.md)
+  - [Applicative](./monads/applicatives.lean.md)
+  - [Monad](./monads/monads.lean.md)
+  - [Reader](./monads/readers.lean.md)
+  - [State](./monads/states.lean.md)
+  - [Except](./monads/except.lean.md)
+  - [Transformers](./monads/transformers.lean.md)
+  - [Laws](./monads/laws.lean.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 {
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+}
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+    font-size: inherit;
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+
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+
+/* Undo <small> and <blockquote>, added to improve RSS rendering. */
+
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+}
+
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+    font-weight: normal;
+    font-size: inherit;
+}
+
+/***************/
+/* Main styles */
+/***************/
+
+.alectryon-coqdoc .doc .code,
+.alectryon-coqdoc .doc .comment,
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+    font-feature-settings: "COQX" 1 /* Coq ligatures */, "XV00" 1 /* Legacy */, "calt" 1 /* Fallback */;
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+}
+
+.alectryon-io, .alectryon-block, .alectryon-toggle-label, .alectryon-banner {
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+    overflow-wrap: break-word;
+    position: relative;
+    white-space: pre-wrap;
+}
+
+/*
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+
+.alectryon-io span {
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+In any case, make an exception for comments:
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+.highlight .c {
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+    unicode-bidi: initial;
+}
+*/
+
+.alectryon-mref,
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+    font-size: 80%;
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+    margin: -0.25em 0.15em -0.25em 0.625em; /* 625 = 0.5em / 80% */
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+
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+    margin: -0.5em 0.25em;
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+:target > .alectryon-mref-marker {
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+@keyframes blink {
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+}
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+}
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+    margin-right: -1em; /* Compensate for the anti-wrapping space */
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+}
+
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+   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 */
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+
+    .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 {
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+}
+
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+    border-color: #babdb6;
+}
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+}
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+}
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+}
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+}
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+}
+
+
+/* Show just a small preview of the other goals; this is undone by the
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+}
+
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+.alectryon-io .alectryon-messages {
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+	/*border: thin solid #d3d7cf; /* Convenient when pre's background is already #EEE */
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+    padding: 0.25em;
+}
+
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+}
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+}
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+}
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+}
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+    overflow-y: unset;
+}
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+}
+
+.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/array.md

@@ -0,0 +1,77 @@
+# Arrays
+
+The `Array` type implements a *dynamic* (aka growable) array.
+It is defined as
+```lean
+# namespace hidden
+structure Array (α : Type u) where
+  data : List α
+# end hidden
+```
+but its execution time representation is optimized, and it is similar to C++ `std::vector<T>` and Rust `Vec<T>`.
+The Lean type checker has no special support for reducing `Array`s.
+
+You can create arrays in several ways. You can create a small array by listing consecutive values between
+`#[` and `]` and separated by commas, as shown in the following examples.
+
+```lean
+#check #[1, 2, 3] -- Array Nat
+
+#check #[] -- Array ?m
+```
+
+The type of the array elements is inferred from the literals used and must be consistent.
+```lean
+#check #["hello", "world"] -- Array String
+
+-- The following is not valid
+#check_failure #[10, "hello"]
+```
+Recall that the command `#check_failure <term>` only succeeds when the given term is not type correct.
+
+To create an array of size `n` in which all the elements are initialized to some value `a`, use `mkArray`.
+```lean
+#eval mkArray 5 'a'
+-- #['a', 'a', 'a', 'a', 'a']
+```
+
+## Accessing elements
+
+You can access array elements by using brackets (`[` and `]`).
+```lean
+def f (a : Array Nat) (i : Fin a.size) :=
+  a[i] + a[i]
+```
+Note that the index `i` has type `Fin a.size`, i.e., it is natural number less than `a.size`.
+You can also write
+```lean
+def f (a : Array Nat) (i : Nat) (h  : i < a.size) :=
+  a[i] + a[i]
+```
+The bracket operator is whitespace sensitive.
+
+```lean
+def f (xs : List Nat) : List Nat :=
+  xs ++ xs
+
+def as : Array Nat :=
+  #[1, 2, 3, 4]
+
+def idx : Fin 4 :=
+  2
+
+#eval f [1, 2, 3] -- This is a function application
+
+#eval as[idx] -- This is an array access
+```
+The notation `a[i]` has two variants: `a[i]!` and `a[i]?`. In both cases, `i` has type `Nat`. The first one
+produces a panic error message if the index `i` is out of bounds. The latter returns an `Option` type.
+
+```lean
+#eval #['a', 'b', 'c'][1]?
+-- some 'b'
+#eval #['a', 'b', 'c'][5]?
+-- none
+#eval #['a', 'b', 'c'][1]!
+-- 'b!
+```

doc/autobound.md

@@ -0,0 +1,47 @@
+## Auto Bound Implicit Arguments
+
+In the previous section, we have shown how implicit arguments make functions more convenient to use.
+However, functions such as `compose` are still quite verbose to define. Note that the universe
+polymorphic `compose` is even more verbose than the one previously defined.
+
+```lean
+universe u v w
+def compose {α : Type u} {β : Type v} {γ : Type w}
+            (g : β → γ) (f : α → β) (x : α) : γ :=
+  g (f x)
+```
+
+You can avoid the `universe` command by providing the universe parameters when defining `compose`.
+
+```lean
+def compose.{u, v, w}
+            {α : Type u} {β : Type v} {γ : Type w}
+            (g : β → γ) (f : α → β) (x : α) : γ :=
+  g (f x)
+```
+
+Lean 4 supports a new feature called *auto bound implicit arguments*. It makes functions such as
+`compose` much more convenient to write. When Lean processes the header of a declaration,
+any unbound identifier is automatically added as an implicit argument *if* it is a single lower case or
+greek letter. With this feature, we can write `compose` as
+
+```lean
+def compose (g : β → γ) (f : α → β) (x : α) : γ :=
+  g (f x)
+
+#check @compose
+-- {β : Sort u_1} → {γ : Sort u_2} → {α : Sort u_3} → (β → γ) → (α → β) → α → γ
+```
+Note that, Lean inferred a more general type using `Sort` instead of `Type`.
+
+Although we love this feature and use it extensively when implementing Lean,
+we realize some users may feel uncomfortable with it. Thus, you can disable it using
+the command `set_option autoImplicit false`.
+```lean
+set_option autoImplicit false
+/- The following definition produces `unknown identifier` errors -/
+-- def compose (g : β → γ) (f : α → β) (x : α) : γ :=
+--   g (f x)
+```
+The Lean language server provides [semantic highlighting](./semantic_highlighting.md) information to editors, and it provides
+visual feedback whether an identifier has been interpreted as an auto bound implicit argument.

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 Manual"
+
+[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/builtintypes.md

@@ -0,0 +1,25 @@
+# Builtin Types
+
+## Numeric Operations
+
+Lean supports the basic mathematical operations you’d expect for all of the number types: addition, subtraction, multiplication, division, and remainder.
+The following code shows how you’d use each one in a `def` commands:
+
+```lean
+-- addition
+def sum := 5 + 10
+
+-- subtraction
+def difference := 95.5 - 4.3
+
+-- multiplication
+def product := 4 * 30
+
+-- division
+def quotient := 53.7 / 32.2
+
+-- remainder/modulo
+def modulo := 43 % 5
+```
+
+Each expression in these statements uses a mathematical operator and evaluates to a single value.

doc/char.md

@@ -0,0 +1,11 @@
+# Characters
+
+A value of type `Char`, also known as a character, is a [Unicode scalar value](https://www.unicode.org/glossary/#unicode_scalar_value). It is represented using an unsigned 32-bit integer and is statically guaranteed to be a valid Unicode scalar value.
+
+Syntactically, character literals are enclosed in single quotes.
+```lean
+#eval 'a' -- 'a'
+#eval '∀' -- '∀'
+```
+
+Characters are ordered and can be decidably compared using the relational operators `=`, `<`, `≤`, `>`, `≥`.

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/decltypes.md

@@ -0,0 +1,29 @@
+# Declaring New Types
+
+In Lean's library, every concrete type other than the universes and every type constructor other than the dependent function type is
+an instance of a general family of type constructions known as *inductive types*. It is remarkable that it is possible to develop
+complex programs and formalize mathematics based on nothing more than the type universes, dependent function types,
+and inductive types; everything else follows from those.
+
+Intuitively, an inductive type is built up from a specified list of constructors. In Lean, the basic syntax for specifying such a type is as follows:
+```
+inductive NewType where
+  | constructor_1 : ... → NewType
+  | constructor_2 : ... → NewType
+  ...
+  | constructor_n : ... → NewType
+```
+
+The intuition is that each constructor specifies a way of building new objects of ``NewType``, possibly from previously constructed values.
+The type ``NewType`` consists of nothing more than the objects that are constructed in this way.
+
+We will see below that the arguments to the constructors can include objects of type ``NewType``,
+subject to a certain "positivity" constraint, which guarantees that elements of ``NewType`` are built
+from the bottom up. Roughly speaking, each ``...`` can be any function type constructed from ``NewType``
+and previously defined types, in which ``NewType`` appears, if at all, only as the "target" of the function type.
+
+We will provide a number of examples of inductive types. We will also consider slight generalizations of the scheme above,
+to mutually defined inductive types, and so-called *inductive families*.
+
+Every inductive type comes with constructors, which show how to construct an element of the type, and elimination rules,
+which show how to "use" an element of the type in another construction.

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/bootstrap.md

@@ -1,12 +1,12 @@
 # Lean Build Bootstrapping
 
-Lean is a bootstrapped program: the
+Since version 4, Lean is a partially bootstrapped program: most parts of the
 frontend and compiler are written in Lean itself and thus need to be built before
 building Lean itself - which is needed to again build those parts. This cycle is
 broken by using pre-built C files checked into the repository (which ultimately
 go back to a point where the Lean compiler was not written in Lean) in place of
 these Lean inputs and then compiling everything in multiple stages up to a fixed
-point. The build directory is organized into these stages:
+point. The build directory is organized in these stages:
 
 ```bash
 stage0/
@@ -72,14 +72,6 @@ update the archived C source code of the stage 0 compiler in `stage0/src`.
 
 The github repository will automatically update stage0 on `master` once
 `src/stdlib_flags.h` and `stage0/src/stdlib_flags.h` are out of sync.
-To trigger this, modify `stage0/src/stdlib_flags.h` (e.g., by adding or changing
-a comment). When `update-stage0` runs, it will overwrite `stage0/src/stdlib_flags.h`
-with the contents of `src/stdlib_flags.h`, bringing them back in sync.
-
-NOTE: A full rebuild of stage 1 will only be triggered when the *committed* contents of `stage0/` are changed.
-Thus if you change files in it manually instead of through `update-stage0-commit` (see below) or fetching updates from git, you either need to commit those changes first or run `make -C build/release clean-stdlib`.
-The same is true for further stages except that a rebuild of them is retriggered on any committed change, not just to a specific directory.
-Thus when debugging e.g. stage 2 failures, you can resume the build from these failures on but you may want to explicitly call `clean-stdlib` to either observe changes from `.olean` files of modules that built successfully or to check that you did not break modules that built successfully at some prior point.
 
 If you have write access to the lean4 repository, you can also manually
 trigger that process, for example to be able to use new features in the compiler itself.
@@ -90,18 +82,18 @@ gh workflow run update-stage0.yml
 ```
 
 Leaving stage0 updates to the CI automation is preferable, but should you need
-to do it locally, you can use `make -C build/release update-stage0-commit` to
-update `stage0` from `stage1` or `make -C build/release/stageN update-stage0-commit` to
+to do it locally, you can use `make update-stage0-commit` in `build/release` to
+update `stage0` from `stage1` or `make -C stageN update-stage0-commit` to
 update from another stage. This command will automatically stage the updated files
-and introduce a commit, so make sure to commit your work before that.
+and introduce a commit,so make sure to commit your work before that.
 
 If you rebased the branch (either onto a newer version of `master`, or fixing
-up some commits prior to the stage0 update), recreate the stage0 update commits.
+up some commits prior to the stage0 update, recreate the stage0 update commits.
 The script `script/rebase-stage0.sh` can be used for that.
 
 The CI should prevent PRs with changes to stage0 (besides `stdlib_flags.h`)
 from entering `master` through the (squashing!) merge queue, and label such PRs
-with the `changes-stage0` label. Such PRs should have a cleaned-up history,
+with the `changes-stage0` label. Such PRs should have a cleaned up history,
 with separate stage0 update commits; then coordinate with the admins to merge
 your PR using rebase merge, bypassing the merge queue.
 

doc/dev/commit_convention.md

@@ -33,9 +33,6 @@ Format of the commit message
  - chore (maintain, ex: travis-ci)
  - perf (performance improvement, optimization, ...)
 
-Every `feat` or `fix` commit must have a `changelog-*` label, and a commit message
-beginning with "This PR " that will be included in the changelog.
-
 ``<subject>`` has the following constraints:
 
  - use imperative, present tense: "change" not "changed" nor "changes"
@@ -47,7 +44,6 @@ beginning with "This PR " that will be included in the changelog.
  - just as in ``<subject>``, use imperative, present tense
  - includes motivation for the change and contrasts with previous
    behavior
- - If a `changelog-*` label is present, the body must begin with "This PR ".
 
 ``<footer>`` is optional and may contain two items:
 
@@ -64,21 +60,17 @@ Examples
 
 fix: add declarations for operator<<(std::ostream&, expr const&) and operator<<(std::ostream&, context const&) in the kernel
 
-This PR adds declarations `operator<<` for raw printing.
 The actual implementation of these two operators is outside of the
-kernel. They are implemented in the file 'library/printer.cpp'.
-
-We declare them in the kernel to prevent the following problem.
-Suppose there is a file 'foo.cpp' that does not include 'library/printer.h',
+kernel. They are implemented in the file 'library/printer.cpp'. We
+declare them in the kernel to prevent the following problem. Suppose
+there is a file 'foo.cpp' that does not include 'library/printer.h',
 but contains
-```cpp
-expr a;
-...
-std::cout << a << "\n";
-...
-```
+
+    expr a;
+    ...
+    std::cout << a << "\n";
+    ...
 
 The compiler does not generate an error message. It silently uses the
 operator bool() to coerce the expression into a Boolean. This produces
 counter-intuitive behavior, and may confuse developers.
-

doc/dev/ffi.md

@@ -1,9 +1,182 @@
 # Foreign Function Interface
 
-The Lean FFI documentation is now part of the [Lean language reference](https://lean-lang.org/doc/reference/latest/).
+NOTE: The current interface was designed for internal use in Lean and should be considered **unstable**.
+It will be refined and extended in the future.
 
- * [General FFI](https://lean-lang.org/doc/reference/latest/find/?domain=Verso.Genre.Manual.section&name=ffi)
- * [Representation of inductive types](https://lean-lang.org/doc/reference/latest/find/?domain=Verso.Genre.Manual.section&name=inductive-types-ffi)
- * [String](https://lean-lang.org/doc/reference/latest/find/?domain=Verso.Genre.Manual.section&name=string-ffi)
- * [Array](https://lean-lang.org/doc/reference/latest/find/?domain=Verso.Genre.Manual.section&name=array-ffi)
+As Lean is written partially in Lean itself and partially in C++, it offers efficient interoperability between the two languages (or rather, between Lean and any language supporting C interfaces).
+This support is however currently limited to transferring Lean data types; in particular, it is not possible yet to pass or return compound data structures such as C `struct`s by value from or to Lean.
 
+There are two primary attributes for interoperating with other languages:
+* `@[extern "sym"] constant leanSym : ...` binds a Lean declaration to the external symbol `sym`.
+  It can also be used with `def` to provide an internal definition, but ensuring consistency of both definitions is up to the user.
+* `@[export sym] def leanSym : ...` exports `leanSym` under the unmangled symbol name `sym`.
+
+For simple examples of how to call foreign code from Lean and vice versa, see <https://github.com/leanprover/lean4/blob/master/src/lake/examples/ffi> and <https://github.com/leanprover/lean4/blob/master/src/lake/examples/reverse-ffi>, respectively.
+
+## The Lean ABI
+
+The Lean Application Binary Interface (ABI) describes how the signature of a Lean declaration is encoded as a native calling convention.
+It is based on the standard C ABI and calling convention of the target platform.
+For a Lean declaration marked with either `@[extern "sym"]` or `@[export sym]` for some symbol name `sym`, let `α₁ → ... → αₙ → β` be the normalized declaration's type.
+If `n` is 0, the corresponding C declaration is
+```c
+extern s sym;
+```
+where `s` is the C translation of `β` as specified in the next section.
+In the case of an `@[extern]` definition, the symbol's value is guaranteed to be initialized only after calling the Lean module's initializer or that of an importing module; see [Initialization](#initialization).
+
+If `n` is greater than 0, the corresponding C declaration is
+```c
+s sym(t₁, ..., tₘ);
+```
+where the parameter types `tᵢ` are the C translation of the `αᵢ` as in the next section.
+In the case of `@[extern]` all *irrelevant* types are removed first; see next section.
+
+### Translating Types from Lean to C
+
+* The integer types `UInt8`, ..., `UInt64`, `USize` are represented by the C types `uint8_t`, ..., `uint64_t`, `size_t`, respectively
+* `Char` is represented by `uint32_t`
+* `Float` is represented by `double`
+* An *enum* inductive type of at least 2 and at most 2^32 constructors, each of which with no parameters, is represented by the first type of `uint8_t`, `uint16_t`, `uint32_t` that is sufficient to represent all constructor indices.
+
+  For example, the type `Bool` is represented as `uint8_t` with values `0` for `false` and `1` for `true`.
+* `Decidable α` is represented the same way as `Bool`
+* An inductive type with a *trivial structure*, that is,
+  * it is none of the types described above
+  * it is not marked `unsafe`
+  * it has a single constructor with a single parameter of *relevant* type
+
+  is represented by the representation of that parameter's type.
+
+  For example, `{ x : α // p }`, the `Subtype` structure of a value of type `α` and an irrelevant proof, is represented by the representation of `α`.
+* `Nat` is represented by `lean_object *`.
+  Its runtime value is either a pointer to an opaque bignum object or, if the lowest bit of the "pointer" is 1 (`lean_is_scalar`), an encoded unboxed natural number (`lean_box`/`lean_unbox`).
+* A universe `Sort u`, type constructor `... → Sort u`, or proposition `p : Prop` is *irrelevant* and is either statically erased (see above) or represented as a `lean_object *` with the runtime value `lean_box(0)`
+* Any other type is represented by `lean_object *`.
+  Its runtime value is a pointer to an object of a subtype of `lean_object` (see the "Inductive types" section below) or the unboxed value `lean_box(cidx)` for the `cidx`th constructor of an inductive type if this constructor does not have any relevant parameters.
+
+  Example: the runtime value of `u : Unit` is always `lean_box(0)`.
+
+#### Inductive types
+
+For inductive types which are in the fallback `lean_object *` case above and not trivial constructors, the type is stored as a `lean_ctor_object`, and `lean_is_ctor` will return true. A `lean_ctor_object` stores the constructor index in the header, and the fields are stored in the `m_objs` portion of the object.
+
+The memory order of the fields is derived from the types and order of the fields in the declaration. They are ordered as follows:
+
+* Non-scalar fields stored as `lean_object *`
+* Fields of type `USize`
+* Other scalar fields, in decreasing order by size
+
+Within each group the fields are ordered in declaration order. **Warning**: Trivial wrapper types still count toward a field being treated as non-scalar for this purpose.
+
+* To access fields of the first kind, use `lean_ctor_get(val, i)` to get the `i`th non-scalar field.
+* To access `USize` fields, use `lean_ctor_get_usize(val, n+i)` to get the `i`th usize field and `n` is the total number of fields of the first kind.
+* To access other scalar fields, use `lean_ctor_get_uintN(val, off)` or `lean_ctor_get_usize(val, off)` as appropriate. Here `off` is the byte offset of the field in the structure, starting at `n*sizeof(void*)` where `n` is the number of fields of the first two kinds.
+
+For example, a structure such as
+```lean
+structure S where
+  ptr_1 : Array Nat
+  usize_1 : USize
+  sc64_1 : UInt64
+  ptr_2 : { x : UInt64 // x > 0 } -- wrappers don't count as scalars
+  sc64_2 : Float -- `Float` is 64 bit
+  sc8_1 : Bool
+  sc16_1 : UInt16
+  sc8_2 : UInt8
+  sc64_3 : UInt64
+  usize_2 : USize
+  ptr_3 : Char -- trivial wrapper around `UInt32`
+  sc32_1 : UInt32
+  sc16_2 : UInt16
+```
+would get re-sorted into the following memory order:
+
+* `S.ptr_1` - `lean_ctor_get(val, 0)`
+* `S.ptr_2` - `lean_ctor_get(val, 1)`
+* `S.ptr_3` - `lean_ctor_get(val, 2)`
+* `S.usize_1` - `lean_ctor_get_usize(val, 3)`
+* `S.usize_2` - `lean_ctor_get_usize(val, 4)`
+* `S.sc64_1` - `lean_ctor_get_uint64(val, sizeof(void*)*5)`
+* `S.sc64_2` - `lean_ctor_get_float(val, sizeof(void*)*5 + 8)`
+* `S.sc64_3` - `lean_ctor_get_uint64(val, sizeof(void*)*5 + 16)`
+* `S.sc32_1` - `lean_ctor_get_uint32(val, sizeof(void*)*5 + 24)`
+* `S.sc16_1` - `lean_ctor_get_uint16(val, sizeof(void*)*5 + 28)`
+* `S.sc16_2` - `lean_ctor_get_uint16(val, sizeof(void*)*5 + 30)`
+* `S.sc8_1` - `lean_ctor_get_uint8(val, sizeof(void*)*5 + 32)`
+* `S.sc8_2` - `lean_ctor_get_uint8(val, sizeof(void*)*5 + 33)`
+
+### Borrowing
+
+By default, all `lean_object *` parameters of an `@[extern]` function are considered *owned*, i.e. the external code is passed a "virtual RC token" and is responsible for passing this token along to another consuming function (exactly once) or freeing it via `lean_dec`.
+To reduce reference counting overhead, parameters can be marked as *borrowed* by prefixing their type with `@&`.
+Borrowed objects must only be passed to other non-consuming functions (arbitrarily often) or converted to owned values using `lean_inc`.
+In `lean.h`, the `lean_object *` aliases `lean_obj_arg` and `b_lean_obj_arg` are used to mark this difference on the C side.
+
+Return values and `@[export]` parameters are always owned at the moment.
+
+## Initialization
+
+When including Lean code as part of a larger program, modules must be *initialized* before accessing any of their declarations.
+Module initialization entails
+* initialization of all "constants" (nullary functions), including closed terms lifted out of other functions
+* execution of all `[init]` functions
+* execution of all `[builtin_init]` functions, if the `builtin` parameter of the module initializer has been set
+
+The module initializer is automatically run with the `builtin` flag for executables compiled from Lean code and for "plugins" loaded with `lean --plugin`.
+For all other modules imported by `lean`, the initializer is run without `builtin`.
+Thus `[init]` functions are run iff their module is imported, regardless of whether they have native code available or not, while `[builtin_init]` functions are only run for native executable or plugins, regardless of whether their module is imported or not.
+`lean` uses built-in initializers for e.g. registering basic parsers that should be available even without importing their module (which is necessary for bootstrapping).
+
+The initializer for module `A.B` is called `initialize_A_B` and will automatically initialize any imported modules.
+Module initializers are idempotent (when run with the same `builtin` flag), but not thread-safe.
+Together with initialization of the Lean runtime, you should execute code like the following exactly once before accessing any Lean declarations:
+```c
+void lean_initialize_runtime_module();
+void lean_initialize();
+lean_object * initialize_A_B(uint8_t builtin, lean_object *);
+lean_object * initialize_C(uint8_t builtin, lean_object *);
+...
+
+lean_initialize_runtime_module();
+//lean_initialize();  // necessary if you (indirectly) access the `Lean` package
+
+lean_object * res;
+// use same default as for Lean executables
+uint8_t builtin = 1;
+res = initialize_A_B(builtin, lean_io_mk_world());
+if (lean_io_result_is_ok(res)) {
+    lean_dec_ref(res);
+} else {
+    lean_io_result_show_error(res);
+    lean_dec(res);
+    return ...;  // do not access Lean declarations if initialization failed
+}
+res = initialize_C(builtin, lean_io_mk_world());
+if (lean_io_result_is_ok(res)) {
+...
+
+//lean_init_task_manager();  // necessary if you (indirectly) use `Task`
+lean_io_mark_end_initialization();
+```
+
+In addition, any other thread not spawned by the Lean runtime itself must be initialized for Lean use by calling
+```c
+void lean_initialize_thread();
+```
+and should be finalized in order to free all thread-local resources by calling
+```c
+void lean_finalize_thread();
+```
+
+## `@[extern]` in the Interpreter
+
+The interpreter can run Lean declarations for which symbols are available in loaded shared libraries, which includes `@[extern]` declarations.
+Thus to e.g. run `#eval` on such a declaration, you need to
+1. compile (at least) the module containing the declaration and its dependencies into a shared library, and then
+1. pass this library to `lean --load-dynlib=` to run code `import`ing this module.
+
+Note that it is not sufficient to load the foreign library containing the external symbol because the interpreter depends on code that is emitted for each `@[extern]` declaration.
+Thus it is not possible to interpret an `@[extern]` declaration in the same file.
+
+See [`tests/compiler/foreign`](https://github.com/leanprover/lean4/tree/master/tests/compiler/foreign/) for an example.

doc/dev/index.md

@@ -1,17 +1,15 @@
 # Development Workflow
 
 If you want to make changes to Lean itself, start by [building Lean](../make/index.md) from a clean checkout to make sure that everything is set up correctly.
-After that, read on below to find out how to set up your editor for changing the Lean source code,
-followed by further sections of the development manual where applicable
-such as on the [test suite](../../tests/README.md) and [commit convention](commit_convention.md).
+After that, read on below to find out how to set up your editor for changing the Lean source code, followed by further sections of the development manual where applicable such as on the [test suite](testing.md) and [commit convention](commit_convention.md).
 
 If you are planning to make any changes that may affect the compilation of Lean itself, e.g. changes to the parser, elaborator, or compiler, you should first read about the [bootstrapping pipeline](bootstrap.md).
 You should not edit the `stage0` directory except using the commands described in that section when necessary.
 
 ## Development Setup
 
-You can use any of the [supported editors](https://lean-lang.org/install/manual/) for editing the Lean source code.
-Please see below for specific instructions for VS Code.
+You can use any of the [supported editors](../setup.md) for editing the Lean source code.
+If you set up `elan` as below, opening `src/` as a *workspace folder* should ensure that stage 0 (i.e. the stage that first compiles `src/`) will be used for files in that directory.
 
 ### Dev setup using elan
 
@@ -63,17 +61,13 @@ you can then put `my_name/lean4:my-tag` in your `lean-toolchain` file in a proje
 
 ### VS Code
 
-There is a `.vscode/` directory that correctly sets up VS Code with settings, tasks, and recommended extensions.
-Simply open the repository folder in VS Code, such as by invoking
+There is a `lean.code-workspace` file that correctly sets up VS Code with workspace roots for the stage0/stage1 setup described above as well as with other settings.
+You should always load it when working on Lean, such as by invoking
 ```
-code .
+code lean.code-workspace
 ```
 on the command line.
 
-You can use the `Refresh File Dependencies` command as in other projects to rebuild modules from inside VS Code but be aware that this does not trigger any non-Lake build targets.
-In particular, after updating `stage0/` (or fetching an update to it), you will want to invoke `make` directly to rebuild `stage0/bin/lean` as described in [building Lean](../make/index.md).
-You should then run the `Restart Server` command to update all open files and the server watchdog process as well.
-
 ### `ccache`
 
 Lean's build process uses [`ccache`](https://ccache.dev/) if it is
@@ -86,34 +80,3 @@ Unlike most Lean projects, all submodules of the `Lean` module begin with the
 `prelude` keyword. This disables the automated import of `Init`, meaning that
 developers need to figure out their own subset of `Init` to import. This is done
 such that changing files in `Init` doesn't force a full rebuild of `Lean`.
-
-### Testing against Mathlib/Batteries
-You can test a Lean PR against Mathlib and Batteries by rebasing your PR
-on to `nightly-with-mathlib` branch. (It is fine to force push after rebasing.)
-CI will generate a branch of Mathlib and Batteries called `lean-pr-testing-NNNN`
-on the `leanprover-community/mathlib4-nightly-testing` fork of Mathlib.
-This branch uses the toolchain for your PR, and will report back to the Lean PR with results from Mathlib CI.
-See https://leanprover-community.github.io/contribute/tags_and_branches.html for more details.
-
-### Testing against the Lean Language Reference
-You can test a Lean PR against the reference manual by rebasing your PR
-on to `nightly-with-manual` branch. (It is fine to force push after rebasing.)
-CI will generate a branch of the reference manual called `lean-pr-testing-NNNN`
-in `leanprover/reference-manual`. This branch uses the toolchain for your PR,
-and will report back to the Lean PR with results from Mathlib CI.
-
-### Avoiding rebuilds for downstream projects
-
-If you want to test changes to Lean on downstream projects and would like to avoid rebuilding modules you have already built/fetched using the project's configured Lean toolchain, you can often do so as long as your build of Lean is close enough to that Lean toolchain (compatible .olean format including structure of all relevant environment extensions).
-
-To override the toolchain without rebuilding for a single command, for example `lake build` or `lake lean`, you can use the prefix
-```
-LEAN_GITHASH=$(lean --githash) lake +lean4 ...
-```
-Alternatively, use
-```
-export LEAN_GITHASH=$(lean --githash)
-export ELAN_TOOLCHAIN=lean4
-```
-to persist these changes for the lifetime of the current shell, which will affect any processes spawned from it such as VS Code started via `code .`.
-If you use a setup where you cannot directly start your editor from the command line, such as VS Code Remote, you might want to consider using [direnv](https://direnv.net/) together with an editor extension for it instead so that you can put the lines above into `.envrc`.

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

@@ -5,116 +5,128 @@ 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`.
+- One week before the planned release, ensure that
+  (1) someone has written the release notes and
+  (2) someone has written the first draft of the release blog post.
+  If there is any material in `./releases_drafts/` on the `releases/v4.6.0` branch, then the release notes are not done.
+  (See the section "Writing the release notes".)
 - `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 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 additional 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).
-      - **Important:** After creating and pushing the ProofWidgets4 tag (see above),
-        the mathlib4 lakefile must be updated to reference the new tag (e.g. `v0.0.87`).
-        The `release_steps.py` script handles this automatically by looking up the latest
-        ProofWidgets4 tag compatible with the target toolchain.
-      - Push the PR branch to the main Mathlib repository rather than a fork, or CI may not work reliably
-      - The "Verify Transient and Automated Commits" CI check on toolchain bump PRs can be ignored —
-        it often fails on automated commits (`x:` prefixed) from the nightly-testing history that can't be
-        reproduced in CI. This does not block merging.
-    - `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.
-    - `lean-fro.org`:
-      After updating the toolchains and running `lake update`, you must run `scripts/update.sh` to regenerate
-      the site content. This script updates generated files that depend on the Lean version.
-      The `release_steps.py` script handles this automatically.
-- 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:
+    - [lean4checker](https://github.com/leanprover/lean4checker)
+      - No dependencies
+      - Toolchain bump PR
+      - Create and push the tag
+      - Merge the tag into `stable`
+    - [Batteries](https://github.com/leanprover-community/batteries)
+      - No dependencies
+      - Toolchain bump PR
+      - Create and push the tag
+      - Merge the tag into `stable`
+    - [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`
+    - [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
+    - [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
+    - [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`
+- 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.
 
 This checklist walks you through creating the first release candidate for a version of Lean.
 
-For subsequent release candidates, the process is essentially the same, but we start out with the `releases/v4.7.0` branch already created.
-
 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`.
@@ -125,71 +137,79 @@ 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/v4.7.0
     ```
+- In `RELEASES.md` replace `Development in progress` in the `v4.7.0` section with `Release notes to be written.`
+- We will rely on automatically generated release notes for release candidates,
+  and the written release notes will be used for stable versions only.
+  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`
+- Ping the FRO Zulip that release notes need to be written. The release notes do not block completing the rest of this checklist.
 - 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.
-    * The `nightly-testing` branch may also contain temporary fix scripts (e.g. `fix_backward_defeq.py`,
-      `fix_deprecations.py`) that were used to adapt to breaking changes during the nightly cycle.
-      These should be reviewed and removed if no longer needed, as they can interfere with CI checks.
-  - 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.
@@ -228,142 +248,15 @@ Please read https://leanprover-community.github.io/contribute/tags_and_branches.
 
 # Writing the release notes
 
-Release notes content is only written for the first release candidate (`-rc1`). For subsequent RCs and stable releases,
-just update the title in the existing release notes file (see "Release notes title format" below).
+We are currently trying a system where release notes are compiled all at once from someone looking through the commit history.
+The exact steps are a work in progress.
+Here is the general idea:
 
-## Release notes title format
+* The work is done right on the `releases/v4.6.0` branch sometime after it is created but before the stable release is made.
+  The release notes for `v4.6.0` will later be copied to `master` when we begin a new development cycle.
+* There can be material for release notes entries in commit messages.
+* 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.
+* The release notes should be written from a downstream expert user's point of view.
 
-The title in the `#doc (Manual)` line must follow these formats:
-
-- **For -rc1**: `"Lean 4.7.0-rc1 (2024-03-15)"` — Include the RC suffix and the release date
-- **For -rc2, -rc3, etc.**: `"Lean 4.7.0-rc2 (2024-03-20)"` — Update the RC number and date
-- **For stable release**: `"Lean 4.7.0 (2024-04-01)"` — Remove the RC suffix but keep the date
-
-The date should be the actual date when the tag was pushed (or when CI completed and created the release page).
-
-## Generating the release notes
-
-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.
-
-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.
-
-## Reviewing and fixing the generated markdown
-
-Before adding the release notes to the reference manual, carefully review the generated markdown for these common issues:
-
-1. **Unterminated code blocks**: PR descriptions sometimes have unclosed code fences. Look for code blocks
-   that don't have a closing ` ``` `. If found, fetch the original PR description with `gh pr view <number>`
-   and repair the code block with the complete content.
-
-2. **Truncated descriptions**: Some PR descriptions may end abruptly mid-sentence. Review these and complete
-   the descriptions based on the original PR.
-
-3. **Markdown syntax issues**: Check for other markdown problems that could cause parsing errors.
-
-## Creating the release notes file
-
-The release notes go in `Manual/Releases/v4_7_0.lean` in the reference-manual repository.
-
-The file structure must follow the Verso format:
-
-```lean
-/-
-Copyright (c) 2025 Lean FRO LLC. All rights reserved.
-Released under Apache 2.0 license as described in the file LICENSE.
-Author: <Your Name>
--/
-
-import VersoManual
-import Manual.Meta
-import Manual.Meta.Markdown
-
-open Manual
-open Verso.Genre
-open Verso.Genre.Manual
-open Verso.Genre.Manual.InlineLean
-
-#doc (Manual) "Lean 4.7.0-rc1 (2024-03-15)" =>
-%%%
-tag := "release-v4.7.0"
-file := "v4.7.0"
-%%%
-
-<release notes content here>
-```
-
-**Important formatting rules for Verso:**
-- Use `#` for section headers inside the document, not `##` (Verso uses header level 1 for subsections)
-- Use plain ` ``` ` for code blocks, not ` ```lean ` (the latter will cause Lean to execute the code)
-- Identifiers with underscores like `bv_decide` should be wrapped in backticks: `` `bv_decide` ``
-  (otherwise the underscore may be interpreted as markdown emphasis)
-
-## Updating Manual/Releases.lean
-
-After creating the release notes file, update `Manual/Releases.lean` to include it:
-
-1. Add the import near the top with other version imports:
-   ```lean
-   import Manual.Releases.«v4_7_0»
-   ```
-
-2. Add the include statement after the other includes:
-   ```lean
-   {include 0 Manual.Releases.«v4_7_0»}
-   ```
-
-## Building and verifying
-
-Build the release notes to check for errors:
-```bash
-lake build Manual.Releases.v4_7_0
-```
-
-Common errors and fixes:
-- "Wrong header nesting - got ## but expected at most #": Change `##` to `#`
-- "Tactic 'X' failed" or similar: Code is being executed; change ` ```lean ` to ` ``` `
-- "'_'" errors: Underscore in identifier being parsed as emphasis; wrap in backticks
-
-## Creating the PR
-
-**Important: Timing with the reference-manual tag**
-
-The reference-manual repository deploys documentation when a version tag is pushed. If you merge
-release notes AFTER the tag is created, the deployed documentation won't include them.
-
-You have two options:
-
-1. **Preferred**: Include the release notes in the same PR as the toolchain bump (or merge the
-   release notes PR before creating the tag). This ensures the tag includes the release notes.
-
-2. **If release notes are merged after the tag**: You must regenerate the tag to trigger a new deployment:
-   ```bash
-   cd /path/to/reference-manual
-   git fetch origin
-   git tag -d v4.7.0-rc1  # Delete local tag
-   git tag v4.7.0-rc1 origin/main  # Create tag at current main (which has release notes)
-   git push origin :refs/tags/v4.7.0-rc1  # Delete remote tag
-   git push origin v4.7.0-rc1  # Push new tag (triggers Deploy workflow)
-   ```
-
-If creating a separate PR for release notes:
-```bash
-git checkout -b v4.7.0-release-notes
-git add Manual/Releases/v4_7_0.lean Manual/Releases.lean
-git commit -m "doc: add v4.7.0 release notes"
-git push -u origin v4.7.0-release-notes
-gh pr create --title "doc: add v4.7.0 release notes" --body "This PR adds the release notes for Lean v4.7.0."
-```
-
-See `./releases_drafts/README.md` for more information about pre-written release note entries.
-See `./releases_drafts/README.md` for more information.
+This section will be updated when the next release notes are written (for `v4.10.0`).

doc/dev/testing.md

@@ -0,0 +1,134 @@
+# Test Suite
+
+After [building Lean](../make/index.md) you can run all the tests using
+```
+cd build/release
+make test ARGS=-j4
+```
+Change the 4 to the maximum number of parallel tests you want to
+allow. The best choice is the number of CPU cores on your machine as
+the tests are mostly CPU bound.  You can find the number of processors
+on linux using `nproc` and on Windows it is the `NUMBER_OF_PROCESSORS`
+environment variable.
+
+You can run tests after [building a specific stage](bootstrap.md) by
+adding the `-C stageN` argument. The default when run as above is stage 1.  The
+Lean tests will automatically use that stage's corresponding Lean
+executables
+
+Running `make test` will not pick up new test files; run
+```bash
+cmake build/release/stage1
+```
+to update the list of tests.
+
+You can also use `ctest` directly if you are in the right folder.  So
+to run stage1 tests with a 300 second timeout run this:
+
+```bash
+cd build/release/stage1
+ctest -j 4 --output-on-failure --timeout 300
+```
+Useful `ctest` flags are `-R <name of test>` to run a single test, and
+`--rerun-failed` to run all tests that failed during the last run.
+You can also pass `ctest` flags via `make test ARGS="--rerun-failed"`.
+
+To get verbose output from ctest pass the `--verbose` command line
+option. Test output is normally suppressed and only summary
+information is displayed. This option will show all test output.
+
+## Test Suite Organization
+
+All these tests are included by [src/shell/CMakeLists.txt](https://github.com/leanprover/lean4/blob/master/src/shell/CMakeLists.txt):
+
+- [`tests/lean`](https://github.com/leanprover/lean4/tree/master/tests/lean/): contains tests that come equipped with a
+  .lean.expected.out file. The driver script [`test_single.sh`](https://github.com/leanprover/lean4/tree/master/tests/lean/test_single.sh) runs
+  each test and checks the actual output (*.produced.out) with the
+  checked in expected output.
+
+- [`tests/lean/run`](https://github.com/leanprover/lean4/tree/master/tests/lean/run/): contains tests that are run through the lean
+  command line one file at a time. These tests only look for error
+  codes and do not check the expected output even though output is
+  produced, it is ignored.
+
+- [`tests/lean/interactive`](https://github.com/leanprover/lean4/tree/master/tests/lean/interactive/): are designed to test server requests at a
+  given position in the input file. Each .lean file contains comments
+  that indicate how to simulate a client request at that position.
+  using a `--^` point to the line position. Example:
+    ```lean,ignore
+    open Foo in
+    theorem tst2 (h : a ≤ b) : a + 2 ≤ b + 2 :=
+    Bla.
+      --^ textDocument/completion
+    ```
+    In this example, the test driver [`test_single.sh`](https://github.com/leanprover/lean4/tree/master/tests/lean/interactive/test_single.sh) will simulate an
+    auto-completion request at `Bla.`. The expected output is stored in
+    a .lean.expected.out in the json format that is part of the
+    [Language Server
+    Protocol](https://microsoft.github.io/language-server-protocol/).
+
+    This can also be used to test the following additional requests:
+    ```
+    --^ textDocument/hover
+    --^ textDocument/typeDefinition
+    --^ textDocument/definition
+    --^ $/lean/plainGoal
+    --^ $/lean/plainTermGoal
+    --^ insert: ...
+    --^ collectDiagnostics
+    ```
+
+- [`tests/lean/server`](https://github.com/leanprover/lean4/tree/master/tests/lean/server/): Tests more of the Lean `--server` protocol.
+  There are just a few of them, and it uses .log files containing
+  JSON.
+
+- [`tests/compiler`](https://github.com/leanprover/lean4/tree/master/tests/compiler/): contains tests that will run the Lean compiler and
+  build an executable that is executed and the output is compared to
+  the .lean.expected.out file. This test also contains a subfolder
+  [`foreign`](https://github.com/leanprover/lean4/tree/master/tests/compiler/foreign/) which shows how to extend Lean using C++.
+
+- [`tests/lean/trust0`](https://github.com/leanprover/lean4/tree/master/tests/lean/trust0): tests that run Lean in a mode that Lean doesn't
+  even trust the .olean files (i.e., trust 0).
+
+- [`tests/bench`](https://github.com/leanprover/lean4/tree/master/tests/bench/): contains performance tests.
+
+- [`tests/plugin`](https://github.com/leanprover/lean4/tree/master/tests/plugin/): tests that compiled Lean code can be loaded into
+  `lean` via the `--plugin` command line option.
+
+## Writing Good Tests
+
+Every test file should contain:
+* an initial `/-! -/` module docstring summarizing the test's purpose
+* a module docstring for each test section that describes what is tested
+  and, if not 100% clear, why that is the desirable behavior
+
+At the time of writing, most tests do not follow these new guidelines yet.
+For an example of a conforming test, see [`tests/lean/1971.lean`](https://github.com/leanprover/lean4/tree/master/tests/lean/1971.lean).
+
+## Fixing Tests
+
+When the Lean source code or the standard library are modified, some of the
+tests break because the produced output is slightly different, and we have
+to reflect the changes in the `.lean.expected.out` files.
+We should not blindly copy the new produced output since we may accidentally
+miss a bug introduced by recent changes.
+The test suite contains commands that allow us to see what changed in a convenient way.
+First, we must install [meld](http://meldmerge.org/). On Ubuntu, we can do it by simply executing
+
+```
+sudo apt-get install meld
+```
+
+Now, suppose `bad_class.lean` test is broken. We can see the problem by going to [`tests/lean`](https://github.com/leanprover/lean4/tree/master/tests/lean) directory and
+executing
+
+```
+./test_single.sh -i bad_class.lean
+```
+
+When the `-i` option is provided, `meld` is automatically invoked
+whenever there is discrepancy between the produced and expected
+outputs. `meld` can also be used to repair the problems.
+
+In Emacs, we can also execute `M-x lean4-diff-test-file` to check/diff the file of the current buffer.
+To mass-copy all `.produced.out` files to the respective `.expected.out` file, use `tests/lean/copy-produced`.

doc/do.md

@@ -0,0 +1,417 @@
+# The `do` notation
+
+Lean is a pure functional programming language, but you can write effectful code using the `do` embedded domain specific language (DSL). The following simple program prints two strings "hello" and "world" in the standard output and terminates with exit code 0. Note that the type of the program is `IO UInt32`. You can read this type as the type of values that perform input-output effects and produce a value of type `UInt32`.
+
+```lean
+def main : IO UInt32 := do
+  IO.println "hello"
+  IO.println "world"
+  return 0
+```
+The type of `IO.println` is `String → IO Unit`. That is, it is a function from `String` to `IO Unit` which indicates it may perform input-output effects and produce a value of type `Unit`. We often say that functions that may perform effects are *methods*.
+We also say a method application, such as `IO.println "hello"` is an *action*.
+Note that the examples above also demonstrates that braceless `do` blocks are whitespace sensitive.
+If you like `;`s and curly braces, you can write the example above as
+```lean
+def main : IO UInt32 := do {
+  IO.println "hello";
+  IO.println "world";
+  return 0;
+}
+```
+Semicolons can be used even when curly braces are not used. They are particularly useful when you want to "pack" more than one action in a single line.
+```lean
+def main : IO UInt32 := do
+  IO.println "hello"; IO.println "world"
+  return 0
+```
+Whitespace sensitivity in programming languages is a controversial topic
+among programmers. You should use your own style. We, the Lean developers, **love** the
+braceless and semicolon-free style.
+We believe it is clean and beautiful.
+
+The `do` DSL expands into the core Lean language. Let's inspect the different components using the commands `#print` and `#check`.
+
+```lean
+# def main : IO UInt32 := do
+#  IO.println "hello"
+#  IO.println "world"
+#  return 0
+
+#check IO.println "hello"
+-- IO Unit
+#print main
+-- Output contains the infix operator `>>=` and `pure`
+-- The following `set_option` disables notation such as `>>=` in the output
+set_option pp.notation false in
+#print main
+-- Output contains `bind` and `pure`
+#print bind
+-- bind : {m : Type u → Type v} → [self : Bind m] → {α β : Type u} →
+--        m α → (α → m β) → m β
+#print pure
+-- pure : {m : Type u → Type v} → [self : Pure m] → {α : Type u} →
+--        α → m α
+
+-- IO implements the type classes `Bind` and `Pure`.
+#check (inferInstance : Bind IO)
+#check (inferInstance : Pure IO)
+```
+The types of `bind` and `pure` may look daunting at first sight.
+They both have many implicit arguments. Let's focus first on the explicit arguments.
+`bind` has two explicit arguments `m α` and `α → m β`. The first one should
+be viewed as an action with effects `m` and producing a value of type `α`.
+The second is a function that takes a value of type `α` and produces an action
+with effects `m` and a value of type `β`. The result is `m β`. The method `bind` is composing
+these two actions. We often say `bind` is an abstract semicolon. The method `pure` converts
+a value `α` into an action that produces an action `m α`.
+
+Here is the same function being defined using `bind` and `pure` without the `do` DSL.
+```lean
+def main : IO UInt32 :=
+  bind (IO.println "hello") fun _ =>
+  bind (IO.println "world") fun _ =>
+  pure 0
+```
+
+The notations `let x <- action1; action2` and `let x ← action1; action2` are just syntax sugar for `bind action1 fun x => action2`.
+Here is a small example using it.
+```lean
+def isGreaterThan0 (x : Nat) : IO Bool := do
+  IO.println s!"value: {x}"
+  return x > 0
+
+def f (x : Nat) : IO Unit := do
+  let c <- isGreaterThan0 x
+  if c then
+    IO.println s!"{x} is greater than 0"
+  else
+    pure ()
+
+#eval f 10
+-- value: 10
+-- 10 is greater than 0
+```
+
+
+## Nested actions
+
+Note that we cannot write `if isGreaterThan0 x then ... else ...` because the condition in a `if-then-else` is a **pure** value without effects, but `isGreaterThan0 x` has type `IO Bool`. You can use the nested action notation to avoid this annoyance. Here is an equivalent definition for `f` using a nested action.
+```lean
+# def isGreaterThan0 (x : Nat) : IO Bool := do
+#  IO.println s!"x: {x}"
+#  return x > 0
+
+def f (x : Nat) : IO Unit := do
+  if (<- isGreaterThan0 x) then
+    IO.println s!"{x} is greater than 0"
+  else
+    pure ()
+
+#print f
+```
+Lean "lifts" the nested actions and introduces the `bind` for us.
+Here is an example with two nested actions. Note that both actions are executed
+even if `x = 0`.
+```lean
+# def isGreaterThan0 (x : Nat) : IO Bool := do
+#  IO.println s!"x: {x}"
+#  return x > 0
+
+def f (x y : Nat) : IO Unit := do
+  if (<- isGreaterThan0 x) && (<- isGreaterThan0 y) then
+    IO.println s!"{x} and {y} are greater than 0"
+  else
+    pure ()
+
+#eval f 0 10
+-- value: 0
+-- value: 10
+
+-- The function `f` above is equivalent to
+def g (x y : Nat) : IO Unit := do
+  let c1 <- isGreaterThan0 x
+  let c2 <- isGreaterThan0 y
+  if c1 && c2 then
+    IO.println s!"{x} and {y} are greater than 0"
+  else
+    pure ()
+
+theorem fgEqual : f = g :=
+  rfl -- proof by reflexivity
+```
+Here are two ways to achieve the short-circuit semantics in the example above
+```lean
+# def isGreaterThan0 (x : Nat) : IO Bool := do
+#  IO.println s!"x: {x}"
+#  return x > 0
+
+def f1 (x y : Nat) : IO Unit := do
+  if (<- isGreaterThan0 x <&&> isGreaterThan0 y) then
+    IO.println s!"{x} and {y} are greater than 0"
+  else
+    pure ()
+
+-- `<&&>` is the effectful version of `&&`
+-- Given `x y : IO Bool`, `x <&&> y` : m Bool`
+-- It only executes `y` if `x` returns `true`.
+
+#eval f1 0 10
+-- value: 0
+#eval f1 1 10
+-- value: 1
+-- value: 10
+-- 1 and 10 are greater than 0
+
+def f2 (x y : Nat) : IO Unit := do
+  if (<- isGreaterThan0 x) then
+    if (<- isGreaterThan0 y) then
+      IO.println s!"{x} and {y} are greater than 0"
+    else
+      pure ()
+  else
+    pure ()
+```
+
+## `if-then` notation
+
+In the `do` DSL, we can write `if c then action` as a shorthand for `if c then action else pure ()`. Here is the method `f2` using this shorthand.
+```lean
+# def isGreaterThan0 (x : Nat) : IO Bool := do
+#  IO.println s!"x: {x}"
+#  return x > 0
+
+def f2 (x y : Nat) : IO Unit := do
+  if (<- isGreaterThan0 x) then
+    if (<- isGreaterThan0 y) then
+      IO.println s!"{x} and {y} are greater than 0"
+```
+
+## Reassignments
+
+When writing effectful code, it is natural to think imperatively.
+For example, suppose we want to create an empty array `xs`,
+add `0` if some condition holds, add `1` if another condition holds,
+and then print it. In the following example, we use variable
+"shadowing" to simulate this kind of "update".
+
+```lean
+def f (b1 b2 : Bool) : IO Unit := do
+  let xs := #[]
+  let xs := if b1 then xs.push 0 else xs
+  let xs := if b2 then xs.push 1 else xs
+  IO.println xs
+
+#eval f true true
+-- #[0, 1]
+#eval f false true
+-- #[1]
+#eval f true false
+-- #[0]
+#eval f false false
+-- #[]
+```
+
+We can use tuples to simulate updates on multiple variables.
+
+```lean
+def f (b1 b2 : Bool) : IO Unit := do
+  let xs := #[]
+  let ys := #[]
+  let (xs, ys) := if b1 then (xs.push 0, ys) else (xs, ys.push 0)
+  let (xs, ys) := if b2 then (xs.push 1, ys) else (xs, ys.push 1)
+  IO.println s!"xs: {xs}, ys: {ys}"
+
+#eval f true false
+-- xs: #[0], ys: #[1]
+```
+
+We can also simulate the control-flow above using *join-points*.
+A join-point is a `let` that is always tail called and fully applied.
+The Lean compiler implements them using `goto`s.
+Here is the same example using join-points.
+
+```lean
+def f (b1 b2 : Bool) : IO Unit := do
+  let jp1 xs ys := IO.println s!"xs: {xs}, ys: {ys}"
+  let jp2 xs ys := if b2 then jp1 (xs.push 1) ys else jp1 xs (ys.push 1)
+  let xs := #[]
+  let ys := #[]
+  if b1 then jp2 (xs.push 0) ys else jp2 xs (ys.push 0)
+
+#eval f true false
+-- xs: #[0], ys: #[1]
+```
+
+You can capture complex control-flow using join-points.
+The `do` DSL offers the variable reassignment feature to make this kind of code more comfortable to write. In the following example, the `mut` modifier at `let mut xs := #[]` indicates that variable `xs` can be reassigned. The example contains two reassignments `xs := xs.push 0` and `xs := xs.push 1`. The reassignments are compiled using join-points. There is no hidden state being updated.
+
+```lean
+def f (b1 b2 : Bool) : IO Unit := do
+  let mut xs := #[]
+  if b1 then xs := xs.push 0
+  if b2 then xs := xs.push 1
+  IO.println xs
+
+#eval f true true
+-- #[0, 1]
+```
+The notation `x <- action` reassigns `x` with the value produced by the action. It is equivalent to `x := (<- action)`
+
+## Iteration
+
+The `do` DSL provides a unified notation for iterating over datastructures. Here are a few examples.
+
+```lean
+def sum (xs : Array Nat) : IO Nat := do
+  let mut s := 0
+  for x in xs do
+    IO.println s!"x: {x}"
+    s := s + x
+  return s
+
+#eval sum #[1, 2, 3]
+-- x: 1
+-- x: 2
+-- x: 3
+-- 6
+
+-- We can write pure code using the `Id.run <| do` DSL too.
+def sum' (xs : Array Nat) : Nat := Id.run <| do
+  let mut s := 0
+  for x in xs do
+    s := s + x
+  return s
+
+#eval sum' #[1, 2, 3]
+-- 6
+
+def sumEven (xs : Array Nat) : IO Nat := do
+  let mut s := 0
+  for x in xs do
+    if x % 2 == 0 then
+      IO.println s!"x: {x}"
+      s := s + x
+  return s
+
+#eval sumEven #[1, 2, 3, 6]
+-- x: 2
+-- x: 6
+-- 8
+
+def splitEvenOdd (xs : List Nat) : IO Unit := do
+  let mut evens := #[]
+  let mut odds  := #[]
+  for x in xs do
+    if x % 2 == 0 then
+      evens := evens.push x
+    else
+      odds := odds.push x
+  IO.println s!"evens: {evens}, odds: {odds}"
+
+#eval splitEvenOdd [1, 2, 3, 4]
+-- evens: #[2, 4], odds: #[1, 3]
+
+def findNatLessThan (x : Nat) (p : Nat → Bool) : IO Nat := do
+  -- [:x] is notation for the range [0, x)
+  for i in [:x] do
+    if p i then
+      return i -- `return` from the `do` block
+  throw (IO.userError "value not found")
+
+#eval findNatLessThan 10 (fun x => x > 5 && x % 4 == 0)
+-- 8
+
+def sumOddUpTo (xs : List Nat) (threshold : Nat) : IO Nat := do
+  let mut s := 0
+  for x in xs do
+    if x % 2 == 0 then
+      continue -- it behaves like the `continue` statement in imperative languages
+    IO.println s!"x: {x}"
+    s := s + x
+    if s > threshold then
+      break -- it behaves like the `break` statement in imperative languages
+  IO.println s!"result: {s}"
+  return s
+
+#eval sumOddUpTo [2, 3, 4, 11, 20, 31, 41, 51, 107] 40
+-- x: 3
+-- x: 11
+-- x: 31
+-- result: 45
+-- 45
+```
+
+TODO: describe `forIn`
+
+## Try-catch
+
+TODO
+
+## Returning early from a failed match
+
+Inside a `do` block, the pattern `let _ ← <success> | <fail>` will continue with the rest of the block if the match on the left hand side succeeds, but will execute the right hand side and exit the block on failure:
+
+```lean
+def showUserInfo (getUsername getFavoriteColor : IO (Option String)) : IO Unit := do
+  let some n ← getUsername | IO.println "no username!"
+  IO.println s!"username: {n}"
+  let some c ← getFavoriteColor | IO.println "user didn't provide a favorite color!"
+  IO.println s!"favorite color: {c}"
+
+-- username: JohnDoe
+-- favorite color: red
+#eval showUserInfo (pure <| some "JohnDoe") (pure <| some "red")
+
+-- no username
+#eval showUserInfo (pure none) (pure <| some "purple")
+
+-- username: JaneDoe
+-- user didn't provide a favorite color
+#eval showUserInfo (pure <| some "JaneDoe") (pure none)
+```
+
+## If-let
+
+Inside a `do` block, users can employ the `if let` pattern to destructure actions:
+
+```lean
+def tryIncrement (getInput : IO (Option Nat)) : IO (Except String Nat) := do
+  if let some n ← getInput
+  then return Except.ok n.succ
+  else return Except.error "argument was `none`"
+
+-- Except.ok 2
+#eval tryIncrement (pure <| some 1)
+
+-- Except.error "argument was `none`"
+#eval tryIncrement (pure <| none)
+```
+
+## Pattern matching
+
+TODO
+
+## Monads
+
+TODO
+
+## ReaderT
+
+TODO
+
+## StateT
+
+TODO
+
+## StateRefT
+
+TODO
+
+## ExceptT
+
+TODO
+
+## MonadLift and automatic lifting
+
+TODO

doc/elaborators.md

@@ -0,0 +1,8 @@
+## Elaborators
+
+TODO. See [Lean Together 2021: Metaprogramming in Lean
+4](https://youtu.be/hxQ1vvhYN_U) for an overview as well [the
+continuation](https://youtu.be/vy4JWIiiXSY) about tactic programming.
+For more information on antiquotations, see also §4.1 of [Beyond
+Notations: Hygienic Macro Expansion for Theorem Proving
+Languages](https://arxiv.org/pdf/2001.10490.pdf#page=11).

doc/enum.md

@@ -0,0 +1,190 @@
+# Enumerated Types
+
+The simplest kind of inductive type is simply a type with a finite, enumerated list of elements.
+The following command declares the enumerated type `Weekday`.
+```lean
+inductive Weekday where
+  | sunday    : Weekday
+  | monday    : Weekday
+  | tuesday   : Weekday
+  | wednesday : Weekday
+  | thursday  : Weekday
+  | friday    : Weekday
+  | saturday  : Weekday
+```
+
+The `Weekday` type 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.
+```lean
+# inductive Weekday where
+#  | sunday    : Weekday
+#  | monday    : Weekday
+#  | tuesday   : Weekday
+#  | wednesday : Weekday
+#  | thursday  : Weekday
+#  | friday    : Weekday
+#  | saturday  : Weekday
+#check Weekday.sunday   -- Weekday
+#check Weekday.monday   -- Weekday
+```
+
+You can define functions by pattern matching.
+The following function converts a `Weekday` into a natural number.
+```lean
+# inductive Weekday where
+#  | sunday    : Weekday
+#  | monday    : Weekday
+#  | tuesday   : Weekday
+#  | wednesday : Weekday
+#  | thursday  : Weekday
+#  | friday    : Weekday
+#  | saturday  : Weekday
+def natOfWeekday (d : Weekday) : Nat :=
+  match d with
+  | Weekday.sunday    => 1
+  | Weekday.monday    => 2
+  | Weekday.tuesday   => 3
+  | Weekday.wednesday => 4
+  | Weekday.thursday  => 5
+  | Weekday.friday    => 6
+  | Weekday.saturday  => 7
+
+#eval natOfWeekday Weekday.tuesday -- 3
+```
+
+It is often useful to group definitions related to a type in a namespace with the same name.
+For example, we can put the function above into the ``Weekday`` namespace.
+We are then allowed to use the shorter name when we open the namespace.
+
+In the following example, we define functions from ``Weekday`` to ``Weekday`` in the namespace `Weekday`.
+```lean
+# inductive Weekday where
+#  | sunday    : Weekday
+#  | monday    : Weekday
+#  | tuesday   : Weekday
+#  | wednesday : Weekday
+#  | thursday  : Weekday
+#  | friday    : Weekday
+#  | saturday  : Weekday
+namespace Weekday
+
+def next (d : Weekday) : Weekday :=
+  match d with
+  | sunday    => monday
+  | monday    => tuesday
+  | tuesday   => wednesday
+  | wednesday => thursday
+  | thursday  => friday
+  | friday    => saturday
+  | saturday  => sunday
+
+end Weekday
+```
+It is so common to start a definition with a `match` in Lean, that Lean provides a syntax sugar for it.
+```lean
+# inductive Weekday where
+#  | sunday    : Weekday
+#  | monday    : Weekday
+#  | tuesday   : Weekday
+#  | wednesday : Weekday
+#  | thursday  : Weekday
+#  | friday    : Weekday
+#  | saturday  : Weekday
+# namespace Weekday
+def previous : Weekday -> Weekday
+  | sunday    => saturday
+  | monday    => sunday
+  | tuesday   => monday
+  | wednesday => tuesday
+  | thursday  => wednesday
+  | friday    => thursday
+  | saturday  => friday
+# end Weekday
+```
+We can use the command `#eval` to test our definitions.
+```lean
+# inductive Weekday where
+#  | sunday    : Weekday
+#  | monday    : Weekday
+#  | tuesday   : Weekday
+#  | wednesday : Weekday
+#  | thursday  : Weekday
+#  | friday    : Weekday
+#  | saturday  : Weekday
+# namespace Weekday
+# def next (d : Weekday) : Weekday :=
+#  match d with
+#  | sunday    => monday
+#  | monday    => tuesday
+#  | tuesday   => wednesday
+#  | wednesday => thursday
+#  | thursday  => friday
+#  | friday    => saturday
+#  | saturday  => sunday
+# def previous : Weekday -> Weekday
+#  | sunday    => saturday
+#  | monday    => sunday
+#  | tuesday   => monday
+#  | wednesday => tuesday
+#  | thursday  => wednesday
+#  | friday    => thursday
+#  | saturday  => friday
+def toString : Weekday -> String
+  | sunday    => "Sunday"
+  | monday    => "Monday"
+  | tuesday   => "Tuesday"
+  | wednesday => "Wednesday"
+  | thursday  => "Thursday"
+  | friday    => "Friday"
+  | saturday  => "Saturday"
+
+#eval toString (next sunday)             -- "Monday"
+#eval toString (next tuesday)            -- "Wednesday"
+#eval toString (previous wednesday)      -- "Tuesday"
+#eval toString (next (previous sunday))  -- "Sunday"
+#eval toString (next (previous monday))  -- "Monday"
+-- ..
+# end Weekday
+```
+We can now prove the general theorem that ``next (previous d) = d`` for any weekday ``d``.
+The idea is to perform a proof by cases using `match`, and rely on the fact for each constructor both
+sides of the equality reduce to the same term.
+```lean
+# inductive Weekday where
+#  | sunday    : Weekday
+#  | monday    : Weekday
+#  | tuesday   : Weekday
+#  | wednesday : Weekday
+#  | thursday  : Weekday
+#  | friday    : Weekday
+#  | saturday  : Weekday
+# namespace Weekday
+# def next (d : Weekday) : Weekday :=
+#  match d with
+#  | sunday    => monday
+#  | monday    => tuesday
+#  | tuesday   => wednesday
+#  | wednesday => thursday
+#  | thursday  => friday
+#  | friday    => saturday
+#  | saturday  => sunday
+# def previous : Weekday -> Weekday
+#  | sunday    => saturday
+#  | monday    => sunday
+#  | tuesday   => monday
+#  | wednesday => tuesday
+#  | thursday  => wednesday
+#  | friday    => thursday
+#  | saturday  => friday
+theorem nextOfPrevious (d : Weekday) : next (previous d) = d :=
+  match d with
+  | sunday    => rfl
+  | monday    => rfl
+  | tuesday   => rfl
+  | wednesday => rfl
+  | thursday  => rfl
+  | friday    => rfl
+  | saturday  => rfl
+# end Weekday
+```

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/.gitignore

@@ -1,2 +0,0 @@
-*.out.produced
-*.exit.produced

doc/examples/ICERM2022/meta.lean

@@ -29,7 +29,7 @@ def ex3 (declName : Name) : MetaM Unit := do
     for x in xs do
       trace[Meta.debug] "{x} : {← inferType x}"
 
-def myMin [LT α] [DecidableLT α] (a b : α) : α :=
+def myMin [LT α] [DecidableRel (α := α) (·<·)] (a b : α) : α :=
   if a < b then
     a
   else

doc/examples/IJCAR2026/README.md

@@ -1,6 +0,0 @@
-# IJCAR 2026: `grind`, An SMT-Inspired Tactic for Lean 4
-
-Ancillary materials for the paper.
-
-- `examples.lean`: interactive examples from the paper
-- `analyze_grind_loc.py`: script used for the evaluation section, analyzing `grind` adoption and lines-of-code changes in Mathlib

doc/examples/IJCAR2026/analyze_grind_loc.py

@@ -1,401 +0,0 @@
-#!/usr/bin/env python3
-"""
-Analyze grind adoption LoC changes in mathlib.
-
-For each theorem/lemma in master that uses grind, find the most recent
-commit where it didn't use grind, and measure the LoC change.
-
-This script was used in preparing the "Evaluation" section of the grind paper.
-"""
-
-import subprocess
-import re
-import csv
-import sys
-from pathlib import Path
-from dataclasses import dataclass
-from concurrent.futures import ThreadPoolExecutor, as_completed
-from typing import Iterator
-from functools import lru_cache
-
-
-@dataclass
-class GrindUsage:
-    file: str
-    line_no: int
-    decl_name: str
-    decl_type: str  # theorem, lemma, def, example, etc.
-
-
-@dataclass
-class LocChange:
-    file: str
-    decl_name: str
-    decl_type: str
-    old_loc: int
-    new_loc: int
-    loc_saved: int
-    commit_sha: str
-    commit_date: str
-
-
-def run_git(args: list[str], repo: str = ".") -> str:
-    """Run a git command and return stdout."""
-    result = subprocess.run(
-        ["git", "-C", repo] + args,
-        capture_output=True, text=True, check=True
-    )
-    return result.stdout
-
-
-def run_git_safe(args: list[str], repo: str = ".") -> str | None:
-    """Run a git command, return None on failure."""
-    result = subprocess.run(
-        ["git", "-C", repo] + args,
-        capture_output=True, text=True
-    )
-    if result.returncode != 0:
-        return None
-    return result.stdout
-
-
-@lru_cache(maxsize=4096)
-def get_file_at_commit(repo: str, commit: str, file_path: str) -> str | None:
-    """Get file contents at a specific commit (cached)."""
-    return run_git_safe(["show", f"{commit}:{file_path}"], repo)
-
-
-def find_grind_usages(repo: str = ".") -> tuple[list[GrindUsage], int, int]:
-    """Find all declarations using grind in current master.
-    Returns (usages, total_grind_calls, grind_in_decls) where:
-    - total_grind_calls is the count of grind tactic calls (after filtering comments/attrs)
-    - grind_in_decls is the count of those that are inside named declarations
-    """
-    # Use git grep to find lines containing 'grind' (excludes lake packages)
-    result = run_git(["grep", "-n", "grind", "master", "--", "Mathlib/"], repo)
-
-    usages = []
-    seen = set()  # (file, decl_name) to dedupe
-    total_grind_calls = 0
-    grind_in_decls = 0
-
-    for line in result.strip().split('\n'):
-        if not line:
-            continue
-        # Format: master:path/to/file.lean:123:line content
-        match = re.match(r'^master:(.+\.lean):(\d+):(.*)$', line)
-        if not match:
-            continue
-
-        file_path, line_no_str, content = match.groups()
-        line_no = int(line_no_str)
-
-        # Skip comments and attributes (not tactic calls)
-        content_stripped = content.strip()
-        if content_stripped.startswith('--') or content_stripped.startswith('/-'):
-            continue
-        if content_stripped.startswith('attribute'):
-            continue
-        if '@[' in content and 'grind' in content:
-            # Could be an attribute like @[grind =], skip
-            if 'by' not in content and ':=' not in content:
-                continue
-
-        total_grind_calls += 1
-
-        # Find the declaration this grind belongs to
-        decl_name, decl_type = find_decl_at_line(repo, file_path, line_no)
-        if decl_name is None:
-            continue
-
-        grind_in_decls += 1
-
-        key = (file_path, decl_name)
-        if key in seen:
-            continue
-        seen.add(key)
-
-        usages.append(GrindUsage(
-            file=file_path,
-            line_no=line_no,
-            decl_name=decl_name,
-            decl_type=decl_type
-        ))
-
-    return usages, total_grind_calls, grind_in_decls
-
-
-def find_decl_at_line(repo: str, file_path: str, grind_line: int) -> tuple[str | None, str | None]:
-    """
-    Find the declaration name and type that contains the grind at the given line.
-    Search backwards from grind_line to find the most recent declaration.
-    """
-    # Get file content at master
-    content = get_file_at_commit(repo, "master", file_path)
-    if content is None:
-        return None, None
-
-    lines = content.split('\n')
-
-    # Search backwards from grind_line for a declaration
-    # Match declarations with optional leading modifiers and attributes
-    decl_pattern = re.compile(r'^(?:@\[.*?\]\s*)*(?:private\s+|protected\s+|noncomputable\s+|scoped\s+)*(theorem|lemma|def|example|instance|abbrev|structure|class)\s+(\w+)')
-
-    for i in range(grind_line - 1, -1, -1):
-        if i >= len(lines):
-            continue
-        line = lines[i]
-        match = decl_pattern.match(line)
-        if match:
-            return match.group(2), match.group(1)
-
-    return None, None
-
-
-def find_grind_introduction_commit(repo: str, file_path: str, decl_name: str) -> str | None:
-    """
-    Find the commit that introduced grind to this declaration.
-    Returns None if the declaration was born with grind.
-    """
-    # First, find the line range of the declaration in master
-    content = get_file_at_commit(repo, "master", file_path)
-    if content is None:
-        return None
-
-    lines = content.split('\n')
-    decl_start = None
-    decl_end = None
-
-    # Find declaration start
-    decl_pattern = re.compile(rf'^(?:@\[.*?\]\s*)*(?:private\s+|protected\s+|noncomputable\s+|scoped\s+)*(theorem|lemma|def|example|instance|abbrev|structure|class)\s+{re.escape(decl_name)}\b')
-    for i, line in enumerate(lines):
-        if decl_pattern.match(line):
-            decl_start = i
-            break
-
-    if decl_start is None:
-        return None
-
-    # Find declaration end (next top-level declaration or EOF)
-    end_patterns = re.compile(r'^(?:private\s+|protected\s+|noncomputable\s+|scoped\s+)*(theorem|lemma|def|example|instance|abbrev|structure|class|namespace|section|end\s|@\[|#|/-)')
-    for i in range(decl_start + 1, len(lines)):
-        line = lines[i]
-        if line and not line[0].isspace() and end_patterns.match(line):
-            decl_end = i
-            break
-    if decl_end is None:
-        decl_end = len(lines)
-
-    # Find grind line within declaration
-    grind_line = None
-    for i in range(decl_start, decl_end):
-        if 'grind' in lines[i]:
-            grind_line = i + 1  # 1-indexed
-            break
-
-    if grind_line is None:
-        return None
-
-    # Use git blame to find when that grind line was added
-    blame_result = run_git_safe(["blame", "-L", f"{grind_line},{grind_line}", "--porcelain", "master", "--", file_path], repo)
-    if blame_result is None:
-        return None
-
-    # First line of porcelain output is the commit SHA
-    first_line = blame_result.split('\n')[0]
-    commit_sha = first_line.split()[0]
-
-    # Check if this declaration existed before this commit (without grind)
-    parent_sha = run_git_safe(["rev-parse", f"{commit_sha}^"], repo)
-    if parent_sha is None:
-        return None  # Initial commit, born with grind
-    parent_sha = parent_sha.strip()
-
-    # Check if declaration existed in parent
-    parent_content = get_file_at_commit(repo, parent_sha, file_path)
-    if parent_content is None:
-        # File didn't exist in parent - might be new file or renamed
-        return None
-
-    # Check if declaration existed and didn't have grind
-    if decl_name not in parent_content:
-        return None  # Declaration didn't exist - born with grind
-
-    # Check if it already had grind in parent
-    parent_lines = parent_content.split('\n')
-    in_decl = False
-    for line in parent_lines:
-        if decl_pattern.match(line):
-            in_decl = True
-        elif in_decl:
-            if line and not line[0].isspace() and end_patterns.match(line):
-                break
-            if 'grind' in line:
-                # Already had grind in parent — not the introduction commit
-                return None
-
-    return commit_sha
-
-
-def extract_proof_loc(repo: str, file_path: str, decl_name: str, commit: str) -> int | None:
-    """
-    Extract the number of lines in a declaration's proof at a given commit.
-    Returns None if the declaration doesn't exist at that commit.
-    """
-    content = get_file_at_commit(repo, commit, file_path)
-    if content is None:
-        return None
-
-    lines = content.split('\n')
-
-    # Find declaration start
-    decl_pattern = re.compile(rf'^(?:@\[.*?\]\s*)*(?:private\s+|protected\s+|noncomputable\s+|scoped\s+)*(theorem|lemma|def|example|instance|abbrev|structure|class)\s+{re.escape(decl_name)}\b')
-    decl_start = None
-    for i, line in enumerate(lines):
-        if decl_pattern.match(line):
-            decl_start = i
-            break
-
-    if decl_start is None:
-        return None
-
-    # Find declaration end
-    end_patterns = re.compile(r'^(?:private\s+|protected\s+|noncomputable\s+|scoped\s+)*(theorem|lemma|def|example|instance|abbrev|structure|class|namespace|section|end\s|@\[|#|/-)')
-    decl_end = None
-    for i in range(decl_start + 1, len(lines)):
-        line = lines[i]
-        if line and not line[0].isspace() and end_patterns.match(line):
-            decl_end = i
-            break
-    if decl_end is None:
-        decl_end = len(lines)
-
-    # Count non-empty lines in declaration
-    loc = sum(1 for i in range(decl_start, decl_end) if lines[i].strip())
-    return loc
-
-
-def get_commit_date(repo: str, sha: str) -> str:
-    """Get the date of a commit."""
-    result = run_git(["log", "-1", "--format=%ci", sha], repo)
-    return result.strip().split()[0]  # Just the date part
-
-
-def analyze_usage_detailed(repo: str, usage: GrindUsage) -> tuple[LocChange | None, str]:
-    """Analyze a single grind usage, returning (result, skip_reason)."""
-    commit = find_grind_introduction_commit(repo, usage.file, usage.decl_name)
-    if commit is None:
-        return None, "born_with_grind"
-
-    parent = run_git_safe(["rev-parse", f"{commit}^"], repo)
-    if parent is None:
-        return None, "no_parent"
-    parent = parent.strip()
-
-    old_loc = extract_proof_loc(repo, usage.file, usage.decl_name, parent)
-    new_loc = extract_proof_loc(repo, usage.file, usage.decl_name, "master")
-
-    if old_loc is None:
-        return None, "old_loc_failed"
-    if new_loc is None:
-        return None, "new_loc_failed"
-
-    commit_date = get_commit_date(repo, commit)
-
-    return LocChange(
-        file=usage.file,
-        decl_name=usage.decl_name,
-        decl_type=usage.decl_type,
-        old_loc=old_loc,
-        new_loc=new_loc,
-        loc_saved=old_loc - new_loc,
-        commit_sha=commit[:12],
-        commit_date=commit_date
-    ), "success"
-
-
-def main(repo: str = "."):
-    print("Finding grind usages in master...", file=sys.stderr)
-    usages, total_grind_calls, grind_in_decls = find_grind_usages(repo)
-    print(f"Found {len(usages)} declarations using grind ({grind_in_decls}/{total_grind_calls} grind calls)", file=sys.stderr)
-
-    print("Analyzing git history (this may take a while)...", file=sys.stderr)
-    results: list[LocChange] = []
-    skip_reasons: dict[str, int] = {}
-
-    with ThreadPoolExecutor(max_workers=64) as executor:
-        futures = {executor.submit(analyze_usage_detailed, repo, usage): usage for usage in usages}
-
-        for i, future in enumerate(as_completed(futures)):
-            if (i + 1) % 50 == 0:
-                print(f"  Progress: {i + 1}/{len(usages)}", file=sys.stderr, flush=True)
-
-            result, reason = future.result()
-            if result:
-                results.append(result)
-            else:
-                skip_reasons[reason] = skip_reasons.get(reason, 0) + 1
-
-    total_skipped = sum(skip_reasons.values())
-    print(f"\nAnalyzed {len(results)} declarations, skipped {total_skipped}:", file=sys.stderr)
-    for reason, count in sorted(skip_reasons.items(), key=lambda x: -x[1]):
-        print(f"  - {reason}: {count}", file=sys.stderr)
-
-    # Sort by LoC saved (descending)
-    results.sort(key=lambda r: r.loc_saved, reverse=True)
-
-    # Output CSV
-    writer = csv.writer(sys.stdout)
-    writer.writerow(["file", "declaration", "type", "old_loc", "new_loc", "loc_saved", "commit", "date"])
-    for r in results:
-        writer.writerow([r.file, r.decl_name, r.decl_type, r.old_loc, r.new_loc, r.loc_saved, r.commit_sha, r.commit_date])
-
-    # Summary stats to stderr
-    total_old = sum(r.old_loc for r in results) if results else 0
-    total_new = sum(r.new_loc for r in results) if results else 0
-    total_saved = sum(r.loc_saved for r in results) if results else 0
-    avg_saved = total_saved / len(results) if results else 0
-
-    print("\n" + "=" * 60, file=sys.stderr)
-    print("GRIND ADOPTION LOC ANALYSIS", file=sys.stderr)
-    print("=" * 60, file=sys.stderr)
-
-    print("\n## Declaration Counts\n", file=sys.stderr)
-    print(f"  Total grind tactic calls:         {total_grind_calls}", file=sys.stderr)
-    print(f"  In named declarations:            {grind_in_decls} ({total_grind_calls - grind_in_decls} in anonymous/other)", file=sys.stderr)
-    print(f"  Unique declarations:              {len(usages)}", file=sys.stderr)
-    print(f"  Converted to grind:               {len(results)}", file=sys.stderr)
-    print(f"  Born with grind:                  {skip_reasons.get('born_with_grind', 0)}", file=sys.stderr)
-    if skip_reasons.get('old_loc_failed', 0) > 0:
-        print(f"  Could not trace history:          {skip_reasons.get('old_loc_failed', 0)}", file=sys.stderr)
-
-    print("\n## Lines of Code Impact\n", file=sys.stderr)
-    print(f"  Total LoC before grind:           {total_old}", file=sys.stderr)
-    print(f"  Total LoC after grind:            {total_new}", file=sys.stderr)
-    print(f"  Total LoC saved:                  {total_saved}", file=sys.stderr)
-    print(f"  Average LoC saved per theorem:    {avg_saved:.1f}", file=sys.stderr)
-    big_savings = sum(1 for r in results if r.loc_saved >= 10)
-    print(f"  Declarations shrunk by 10+ lines: {big_savings}", file=sys.stderr)
-
-    if results:
-        print("\n## Top 10 Biggest LoC Savings\n", file=sys.stderr)
-        for r in results[:10]:
-            print(f"  {r.loc_saved:+4d} lines: {r.decl_name} ({r.file})", file=sys.stderr)
-
-        # Show any that got bigger (negative savings)
-        got_bigger = [r for r in results if r.loc_saved < 0]
-        if got_bigger:
-            print(f"\n## Declarations That Got Bigger ({len(got_bigger)} total)\n", file=sys.stderr)
-            print("  (showing 5 worst):", file=sys.stderr)
-            for r in got_bigger[-5:]:  # Show worst 5
-                print(f"  {r.loc_saved:+4d} lines: {r.decl_name} ({r.file})", file=sys.stderr)
-
-    print("\n" + "=" * 60, file=sys.stderr)
-
-
-if __name__ == "__main__":
-    import argparse
-    parser = argparse.ArgumentParser(description="Analyze grind LoC savings")
-    parser.add_argument("--repo", "-r", default=".", help="Repository path")
-    args = parser.parse_args()
-    main(args.repo)

doc/examples/IJCAR2026/examples.lean

@@ -1,127 +0,0 @@
-/- Examples from the paper "grind: An SMT-Inspired Tactic for Lean 4" -/
-open Lean Grind
-
-/- Congruence closure. -/
-
-example (f : Nat → Nat) (h : a = b) : f (f b) = f (f a) := by grind
-
-/-
-E-matching.
-
-Any `f` that is the left inverse of `g` would work on this example.
--/
-def f (x : Nat) := x - 1
-def g (x : Nat) := x + 1
-
-@[grind =] theorem fg : f (g x) = x := by simp [f, g]
-example : f a = b → a = g c → b = c := by grind
-
-/-
-Any `R` that is transitive and symmetric would work on this example.
--/
-def R : Nat → Nat → Prop := (· % 7 = · % 7)
-@[grind →] theorem Rtrans : R x y → R y z → R x z := by grind [R]
-@[grind →] theorem Rsymm  : R x y → R y x := by grind [R]
-example : R a b → R c b → R d c → R a d := by grind
-
-/- Big step operational semantics example. -/
-
-abbrev Variable := String
-def State := Variable → Nat
-inductive Stmt : Type where
-  | skip : Stmt
-  | assign : Variable → (State → Nat) → Stmt
-  | seq : Stmt → Stmt → Stmt
-  | ifThenElse : (State → Prop) → Stmt → Stmt → Stmt
-  | whileDo : (State → Prop) → Stmt → Stmt
-infix:60 ";; " => Stmt.seq
-export Stmt (skip assign seq ifThenElse whileDo)
-set_option quotPrecheck false in
-notation s:70 "[" x:70 "↦" n:70 "]" => (fun v ↦ if v = x then n else s v)
-inductive BigStep : Stmt → State → State → Prop where
-  | skip (s : State) : BigStep skip s s
-  | assign (x : Variable) (a : State → Nat) (s : State) : BigStep (assign x a) s (s[x ↦ a s])
-  | seq {S T : Stmt} {s t u : State} (hS : BigStep S s t) (hT : BigStep T t u) :
-    BigStep (S;; T) s u
-  | if_true {B : State → Prop} {s t : State} (hcond : B s) (S T : Stmt) (hbody : BigStep S s t) :
-    BigStep (ifThenElse B S T) s t
-  | if_false {B : State → Prop} {s t : State} (hcond : ¬ B s) (S T : Stmt) (hbody : BigStep T s t) :
-    BigStep (ifThenElse B S T) s t
-  | while_true {B S s t u} (hcond : B s) (hbody : BigStep S s t) (hrest : BigStep (whileDo B S) t u) :
-    BigStep (whileDo B S) s u
-  | while_false {B S s} (hcond : ¬ B s) : BigStep (whileDo B S) s s
-notation:55 "(" S:55 "," s:55 ")" " ==> " t:55 => BigStep S s t
-
-example {B S T s t} (hcond : B s) : (ifThenElse B S T, s) ==> t → (S, s) ==> t := by
-  grind [cases BigStep]
-
-theorem cases_if_of_true {B S T s t} (hcond : B s) : (ifThenElse B S T, s) ==> t → (S, s) ==> t := by
-  grind [cases BigStep]
-
-theorem cases_if_of_false {B S T s t} (hcond : ¬ B s) : (ifThenElse B S T, s) ==> t → (T, s) ==> t := by
-  grind [cases BigStep]
-
-example {B S T s t} : (ifThenElse B S T, s) ==> t ↔ (B s ∧ (S, s) ==> t) ∨ (¬ B s ∧ (T, s) ==> t) := by
-  grind [BigStep] -- shortcut for `cases BigStep` and `intro BigStep`
-
-attribute [grind] BigStep
-theorem if_iff {B S T s t} : (ifThenElse B S T, s) ==>
-    t ↔ (B s ∧ (S, s) ==> t) ∨ (¬ B s ∧ (T, s) ==> t) := by grind
-
-/- Dependent pattern matching. -/
-
-inductive Vec (α : Type u) : Nat → Type u
-  | nil : Vec α 0
-  | cons : α → Vec α n → Vec α (n+1)
-@[grind =] def Vec.head : Vec α (n+1) → α
-  | .cons a _ => a
-example (as bs : Vec Int (n+1)) : as.head = bs.head
-    → (match as, bs with
-       | .cons a _, .cons b _ => a + b) = 2 * as.head := by grind
-
-/- Theory solvers. -/
-
-example [CommRing α] (a b c : α) :
-    a + b + c = 3 →
-    a^2 + b^2 + c^2 = 5 →
-    a^3 + b^3 + c^3 = 7 →
-    a^4 + b^4 + c^4 = 9 := by grind
-
-example (x : BitVec 8) : (x - 16) * (x + 16) = x^2 := by grind
-
-example [CommSemiring α] [AddRightCancel α] (x y : α) :
-    x^2*y = 1 → x*y^2 = y → y*x = 1 := by grind
-
-example (a b : UInt32) : a ≤ 2 → b ≤ 3 → a + b ≤ 5 := by grind
-
-example [LE α] [Std.IsLinearPreorder α] (a b c d : α) :
-    a ≤ b → ¬ (c ≤ b) → ¬ (d ≤ c) → a ≤ d := by grind
-
-/- Theory combination. -/
-
-example [CommRing α] [NoNatZeroDivisors α]
-    (a b c : α) (f : α → Nat) :
-    a + b + c = 3 → a^2 + b^2 + c^2 = 5 → a^3 + b^3 + c^3 = 7 →
-    f (a^4 + b^4) + f (9 - c^4) ≠ 1 := by grind
-
-/- Interactive mode. -/
-
--- Remark: Mathlib contains the definition of `Real`, `sin`, and `cos`.
-axiom Real : Type
-instance : Lean.Grind.CommRing Real := sorry
-
-axiom cos : Real → Real
-axiom sin : Real → Real
-axiom trig_identity : ∀ x, (cos x)^2 + (sin x)^2 = 1
-
--- Manually specify the patterns for `trig_identity`
-grind_pattern trig_identity => cos x
-grind_pattern trig_identity => sin x
-
-example : (cos x + sin x)^2 = 2 * cos x * sin x + 1 := by
-  grind? -- Provides code action
-
-example : (cos x + sin x)^2 = 2 * cos x * sin x + 1 := by
-  grind =>
-    instantiate only [trig_identity]
-    ring

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))
 
 /-!
@@ -282,7 +282,7 @@ theorem BinTree.find_insert_of_ne (b : BinTree β) (ne : k ≠ k') (v : β)
   let ⟨t, h⟩ := b; simp
   induction t with simp
   | leaf =>
-    intro le
+    intros le
     exact Nat.lt_of_le_of_ne le ne
   | node left key value right ihl ihr =>
     let .node hl hr bl br := h

doc/examples/bintree.lean.md

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

doc/examples/bintree.lean.out.expected

@@ -1,2 +0,0 @@
-Tree.node (Tree.node (Tree.leaf) 1 "one" (Tree.leaf)) 2 "two" (Tree.node (Tree.leaf) 3 "three" (Tree.leaf))
-[(1, "one"), (2, "two"), (3, "three")]

doc/examples/compiler/run_test.sh

@@ -1,4 +0,0 @@
-leanmake --always-make bin
-
-capture ./build/bin/test hello world
-check_out_contains "[hello, world]"

doc/examples/compiler/test.lean.out.expected

@@ -1 +0,0 @@
-[hello, world]

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/interp.lean.out.expected

@@ -1,3 +0,0 @@
-30
-interp.lean:146:4: warning: declaration uses `sorry`
-3628800

doc/examples/palindromes.lean

@@ -94,8 +94,10 @@ theorem List.palindrome_of_eq_reverse (h : as.reverse = as) : Palindrome as := b
   next   => exact Palindrome.nil
   next a => exact Palindrome.single a
   next a b as ih =>
-    obtain ⟨rfl, h, -⟩ := by simpa using h
-    exact Palindrome.sandwich b (ih h)
+    have : a = b := by simp_all
+    subst this
+    have : as.reverse = as := by simp_all
+    exact Palindrome.sandwich a (ih this)
 
 /-!
 We now define a function that returns `true` iff `as` is a palindrome.

doc/examples/palindromes.lean.md

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

doc/examples/palindromes.lean.out.expected

@@ -1,2 +0,0 @@
-true
-false

doc/examples/phoas.lean.md

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

doc/examples/phoas.lean.out.expected

@@ -1,2 +0,0 @@
-"(((fun x_1 => (fun x_2 => (x_1 + x_2))) 1) 2)"
-"((((fun x_1 => (fun x_2 => (x_1 + x_2))) 1) 2) + 5)"

doc/examples/run_test.sh

@@ -1,4 +0,0 @@
-capture_only "$1" \
-  lean -Dlinter.all=false "$1"
-check_out_file
-check_exit_is_success

doc/examples/tc.lean.md

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

doc/examples/test_single.sh

@@ -0,0 +1,4 @@
+#!/usr/bin/env bash
+source ../../tests/common.sh
+
+exec_check_raw lean -Dlinter.all=false "$f"

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 +1,94 @@
+{
+  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 = "${pkg.name}-mds";
+        paths = map renderLeanMod (lib.attrValues pkg.mods);
+      };
+      literate = buildLeanPackage {
+        name = "literate";
+        src = ./.;
+        roots = [
+          { mod = "examples"; glob = "submodules"; }
+          { mod = "monads"; glob = "submodules"; }
+        ];
+      };
+      inked = renderPackage literate;
+      doc = book;
+    };
+    defaultPackage = self.packages.${system}.doc;
+  });
+}

doc/float.md

@@ -0,0 +1 @@
+# Float

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

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+## 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/functions.md

@@ -0,0 +1,153 @@
+# Functions
+
+Functions are the fundamental unit of program execution in any programming language.
+As in other languages, a Lean function has a name, can have parameters and take arguments, and has a body.
+Lean also supports functional programming constructs such as treating functions as values,
+using unnamed functions in expressions, composition of functions to form new functions,
+curried functions, and the implicit definition of functions by way of
+the partial application of function arguments.
+
+You define functions by using the `def` keyword followed by its name, a parameter list, return type and its body.
+The parameter list consists of successive parameters that are separated by spaces.
+You can specify an explicit type for each parameter.
+If you do not specify a specific argument type, the compiler tries to infer the type from the function body.
+An error is returned when it cannot be inferred.
+The expression that makes up the function body is typically a compound expression consisting of a number of expressions
+that culminate in a final expression that is the return value.
+The return type is a colon followed by a type and is optional.
+If you do not specify the type of the return value explicitly,
+the compiler tries to determine the return type from the final expression.
+
+```lean
+def f x := x + 1
+```
+In the previous example, the function name is `f`, the argument is `x`, which has type `Nat`,
+the function body is `x + 1`, and the return value is of type `Nat`.
+The following example defines the factorial recursive function using pattern matching.
+```lean
+def fact x :=
+  match x with
+  | 0   => 1
+  | n+1 => (n+1) * fact n
+
+#eval fact 100
+```
+By default, Lean only accepts total functions.
+The `partial` keyword may be used to define a recursive function without a termination proof; `partial` functions compute in compiled programs, but are opaque in proofs and during type checking.
+```lean
+partial def g (x : Nat) (p : Nat -> Bool) : Nat :=
+  if p x then
+    x
+  else
+    g (x+1) p
+
+#eval g 0 (fun x => x > 10)
+```
+In the previous example, `g x p` only terminates if there is a `y >= x` such that `p y` returns `true`.
+Of course, `g 0 (fun x => false)` never terminates.
+
+However, the use of `partial` is restricted to functions whose return type is not empty so the soundness
+of the system is not compromised.
+
+```lean,ignore
+partial def loop? : α := -- failed to compile partial definition 'loop?', failed to
+  loop?                  -- show that type is inhabited and non empty
+
+partial def loop [Inhabited α] : α := -- compiles
+  loop
+
+example : True := -- accepted
+  loop
+
+example : False :=
+  loop -- failed to synthesize instance Inhabited False
+```
+
+If we were able to partially define `loop?`, we could prove `False` with it.
+
+# Lambda expressions
+
+A lambda expression is an unnamed function.
+You define lambda expressions by using the `fun` keyword. A lambda expression resembles a function definition, except that instead of the `:=` token,
+the `=>` token is used to separate the argument list from the function body. As in a regular function definition,
+the argument types can be inferred or specified explicitly, and the return type of the lambda expression is inferred from the type of the
+last expression in the body.
+
+```lean
+def twice (f : Nat -> Nat) (x : Nat) : Nat :=
+  f (f x)
+
+#eval twice (fun x => x + 1) 3
+#eval twice (fun (x : Nat) => x * 2) 3
+
+#eval List.map (fun x => x + 1) [1, 2, 3]
+-- [2, 3, 4]
+
+#eval List.map (fun (x, y) => x + y) [(1, 2), (3, 4)]
+-- [3, 7]
+```
+
+# Syntax sugar for simple lambda expressions
+
+Simple functions can be defined using parentheses and `·` as a placeholder.
+```lean
+#check (· + 1)
+-- fun a => a + 1
+#check (2 - ·)
+-- fun a => 2 - a
+#eval [1, 2, 3, 4, 5].foldl (· * ·) 1
+-- 120
+
+def h (x y z : Nat) :=
+  x + y + z
+
+#check (h · 1 ·)
+-- fun a b => h a 1 b
+
+#eval [(1, 2), (3, 4), (5, 6)].map (·.1)
+-- [1, 3, 5]
+```
+In the previous example, the term `(·.1)` is syntax sugar for `fun x => x.1`.
+
+# Pipelining
+
+Pipelining enables function calls to be chained together as successive operations. Pipelining works as follows:
+
+```lean
+def add1 x := x + 1
+def times2 x := x * 2
+
+#eval times2 (add1 100)
+#eval 100 |> add1 |> times2
+#eval times2 <| add1 <| 100
+```
+The result of the previous `#eval` commands is 202.
+The forward pipeline `|>` operator takes a function and an argument and return a value.
+In contrast, the backward pipeline `<|` operator takes an argument and a function and returns a value.
+These operators are useful for minimizing the number of parentheses.
+```lean
+def add1Times3FilterEven (xs : List Nat) :=
+  List.filter (· % 2 == 0) (List.map (· * 3) (List.map (· + 1) xs))
+
+#eval add1Times3FilterEven [1, 2, 3, 4]
+-- [6, 12]
+
+-- Define the same function using pipes
+def add1Times3FilterEven' (xs : List Nat) :=
+  xs |> List.map (· + 1) |> List.map (· * 3) |> List.filter (· % 2 == 0)
+
+#eval add1Times3FilterEven' [1, 2, 3, 4]
+-- [6, 12]
+```
+Lean also supports the operator `|>.` which combines forward pipeline `|>` operator with the `.` field notation.
+```lean
+-- Define the same function using pipes
+def add1Times3FilterEven'' (xs : List Nat) :=
+  xs.map (· + 1) |>.map (· * 3) |>.filter (· % 2 == 0)
+
+#eval add1Times3FilterEven'' [1, 2, 3, 4]
+-- [6, 12]
+```
+
+For users familiar with the Haskell programming language,
+Lean also supports the notation `f $ a` for the backward pipeline `f <| a`.