chore: upstream List.modify, add lemmas, relate to Array.modify

This also requires us to expand the theory of `Int.bmod`.

---------

Co-authored-by: Alex Keizer <alex@keizer.dev>

.github/workflows/check-prelude.yml

@@ -11,7 +11,9 @@ jobs:
         with:
           # the default is to use a virtual merge commit between the PR and master: just use the PR
           ref: ${{ github.event.pull_request.head.sha }}
-          sparse-checkout: src/Lean
+          sparse-checkout: |
+            src/Lean
+            src/Std
       - name: Check Prelude
         run: |
           failed_files=""
@@ -19,8 +21,8 @@ jobs:
             if ! grep -q "^prelude$" "$file"; then
               failed_files="$failed_files$file\n"
             fi
-          done < <(find src/Lean -name '*.lean' -print0)
+          done < <(find src/Lean src/Std -name '*.lean' -print0)
           if [ -n "$failed_files" ]; then
             echo -e "The following files should use 'prelude':\n$failed_files"
             exit 1
-          fi
+          fi

CODEOWNERS

@@ -4,14 +4,14 @@
 # Listed persons will automatically be asked by GitHub to review a PR touching these paths.
 # If multiple names are listed, a review by any of them is considered sufficient by default.
 
-/.github/ @Kha @semorrison
-/RELEASES.md @semorrison
+/.github/ @Kha @kim-em
+/RELEASES.md @kim-em
 /src/kernel/ @leodemoura
 /src/lake/ @tydeu
 /src/Lean/Compiler/ @leodemoura
 /src/Lean/Data/Lsp/ @mhuisi
-/src/Lean/Elab/Deriving/ @semorrison
-/src/Lean/Elab/Tactic/ @semorrison
+/src/Lean/Elab/Deriving/ @kim-em
+/src/Lean/Elab/Tactic/ @kim-em
 /src/Lean/Language/ @Kha
 /src/Lean/Meta/Tactic/ @leodemoura
 /src/Lean/Parser/ @Kha
@@ -19,7 +19,7 @@
 /src/Lean/PrettyPrinter/Delaborator/ @kmill
 /src/Lean/Server/ @mhuisi
 /src/Lean/Widget/ @Vtec234
-/src/Init/Data/ @semorrison
+/src/Init/Data/ @kim-em
 /src/Init/Data/Array/Lemmas.lean @digama0
 /src/Init/Data/List/Lemmas.lean @digama0
 /src/Init/Data/List/BasicAux.lean @digama0
@@ -45,3 +45,4 @@
 /src/Std/ @TwoFX
 /src/Std/Tactic/BVDecide/ @hargoniX
 /src/Lean/Elab/Tactic/BVDecide/ @hargoniX
+/src/Std/Sat/ @hargoniX

src/Init.lean

@@ -35,3 +35,4 @@ import Init.Ext
 import Init.Omega
 import Init.MacroTrace
 import Init.Grind
+import Init.While

src/Init/Core.lean

@@ -1385,6 +1385,7 @@ gen_injective_theorems% Except
 gen_injective_theorems% EStateM.Result
 gen_injective_theorems% Lean.Name
 gen_injective_theorems% Lean.Syntax
+gen_injective_theorems% BitVec
 
 theorem Nat.succ.inj {m n : Nat} : m.succ = n.succ → m = n :=
   fun x => Nat.noConfusion x id
@@ -1936,15 +1937,6 @@ instance : Subsingleton (Squash α) where
     apply Quot.sound
     trivial
 
-/-! # Relations -/
-
-/--
-`Antisymm (·≤·)` says that `(·≤·)` is antisymmetric, that is, `a ≤ b → b ≤ a → a = b`.
--/
-class Antisymm {α : Sort u} (r : α → α → Prop) : Prop where
-  /-- An antisymmetric relation `(·≤·)` satisfies `a ≤ b → b ≤ a → a = b`. -/
-  antisymm {a b : α} : r a b → r b a → a = b
-
 namespace Lean
 /-! # Kernel reduction hints -/
 
@@ -2120,4 +2112,14 @@ instance : Commutative Or := ⟨fun _ _ => propext or_comm⟩
 instance : Commutative And := ⟨fun _ _ => propext and_comm⟩
 instance : Commutative Iff := ⟨fun _ _ => propext iff_comm⟩
 
+/--
+`Antisymm (·≤·)` says that `(·≤·)` is antisymmetric, that is, `a ≤ b → b ≤ a → a = b`.
+-/
+class Antisymm (r : α → α → Prop) : Prop where
+  /-- An antisymmetric relation `(·≤·)` satisfies `a ≤ b → b ≤ a → a = b`. -/
+  antisymm {a b : α} : r a b → r b a → a = b
+
+@[deprecated Antisymm (since := "2024-10-16"), inherit_doc Antisymm]
+abbrev _root_.Antisymm (r : α → α → Prop) : Prop := Std.Antisymm r
+
 end Std

src/Init/Data/Array.lean

@@ -16,3 +16,4 @@ import Init.Data.Array.Lemmas
 import Init.Data.Array.TakeDrop
 import Init.Data.Array.Bootstrap
 import Init.Data.Array.GetLit
+import Init.Data.Array.MapIdx

src/Init/Data/Array/Basic.lean

@@ -7,7 +7,7 @@ prelude
 import Init.WFTactics
 import Init.Data.Nat.Basic
 import Init.Data.Fin.Basic
-import Init.Data.UInt.Basic
+import Init.Data.UInt.BasicAux
 import Init.Data.Repr
 import Init.Data.ToString.Basic
 import Init.GetElem
@@ -25,6 +25,8 @@ variable {α : Type u}
 
 namespace Array
 
+@[deprecated size (since := "2024-10-13")] abbrev data := @toList
+
 /-! ### Preliminary theorems -/
 
 @[simp] theorem size_set (a : Array α) (i : Fin a.size) (v : α) : (set a i v).size = a.size :=
@@ -78,6 +80,26 @@ theorem ext' {as bs : Array α} (h : as.toList = bs.toList) : as = bs := by
 
 @[simp] theorem size_toArray (as : List α) : as.toArray.size = as.length := by simp [size]
 
+@[simp] theorem getElem_toList {a : Array α} {i : Nat} (h : i < a.size) : a.toList[i] = a[i] := rfl
+
+end Array
+
+namespace List
+
+@[simp] theorem toArray_toList (a : Array α) : a.toList.toArray = a := rfl
+
+@[simp] theorem getElem_toArray {a : List α} {i : Nat} (h : i < a.toArray.size) :
+    a.toArray[i] = a[i]'(by simpa using h) := rfl
+
+@[simp] theorem getElem?_toArray {a : List α} {i : Nat} : a.toArray[i]? = a[i]? := rfl
+
+@[simp] theorem getElem!_toArray [Inhabited α] {a : List α} {i : Nat} :
+    a.toArray[i]! = a[i]! := rfl
+
+end List
+
+namespace Array
+
 @[deprecated toList_toArray (since := "2024-09-09")] abbrev data_toArray := @toList_toArray
 
 @[deprecated Array.toList (since := "2024-09-10")] abbrev Array.data := @Array.toList
@@ -396,20 +418,25 @@ def mapM {α : Type u} {β : Type v} {m : Type v → Type w} [Monad m] (f : α
   decreasing_by simp_wf; decreasing_trivial_pre_omega
   map 0 (mkEmpty as.size)
 
+/-- Variant of `mapIdxM` which receives the index as a `Fin as.size`. -/
 @[inline]
-def mapIdxM {α : Type u} {β : Type v} {m : Type v → Type w} [Monad m] (as : Array α) (f : Fin as.size → α → m β) : m (Array β) :=
+def mapFinIdxM {α : Type u} {β : Type v} {m : Type v → Type w} [Monad m]
+    (as : Array α) (f : Fin as.size → α → m β) : m (Array β) :=
   let rec @[specialize] map (i : Nat) (j : Nat) (inv : i + j = as.size) (bs : Array β) : m (Array β) := do
     match i, inv with
     | 0,    _  => pure bs
     | i+1, inv =>
-      have : j < as.size := by
+      have j_lt : j < as.size := by
         rw [← inv, Nat.add_assoc, Nat.add_comm 1 j, Nat.add_comm]
         apply Nat.le_add_right
-      let idx : Fin as.size := ⟨j, this⟩
       have : i + (j + 1) = as.size := by rw [← inv, Nat.add_comm j 1, Nat.add_assoc]
-      map i (j+1) this (bs.push (← f idx (as.get idx)))
+      map i (j+1) this (bs.push (← f ⟨j, j_lt⟩ (as.get ⟨j, j_lt⟩)))
   map as.size 0 rfl (mkEmpty as.size)
 
+@[inline]
+def mapIdxM {α : Type u} {β : Type v} {m : Type v → Type w} [Monad m] (as : Array α) (f : Nat → α → m β) : m (Array β) :=
+  as.mapFinIdxM fun i a => f i a
+
 @[inline]
 def findSomeM? {α : Type u} {β : Type v} {m : Type v → Type w} [Monad m] (as : Array α) (f : α → m (Option β)) : m (Option β) := do
   for a in as do
@@ -515,8 +542,13 @@ def foldr {α : Type u} {β : Type v} (f : α → β → β) (init : β) (as : A
 def map {α : Type u} {β : Type v} (f : α → β) (as : Array α) : Array β :=
   Id.run <| as.mapM f
 
+/-- Variant of `mapIdx` which receives the index as a `Fin as.size`. -/
 @[inline]
-def mapIdx {α : Type u} {β : Type v} (as : Array α) (f : Fin as.size → α → β) : Array β :=
+def mapFinIdx {α : Type u} {β : Type v} (as : Array α) (f : Fin as.size → α → β) : Array β :=
+  Id.run <| as.mapFinIdxM f
+
+@[inline]
+def mapIdx {α : Type u} {β : Type v} (as : Array α) (f : Nat → α → β) : Array β :=
   Id.run <| as.mapIdxM f
 
 /-- Turns `#[a, b]` into `#[(a, 0), (b, 1)]`. -/
@@ -607,13 +639,17 @@ protected def appendList (as : Array α) (bs : List α) : Array α :=
 instance : HAppend (Array α) (List α) (Array α) := ⟨Array.appendList⟩
 
 @[inline]
-def concatMapM [Monad m] (f : α → m (Array β)) (as : Array α) : m (Array β) :=
+def flatMapM [Monad m] (f : α → m (Array β)) (as : Array α) : m (Array β) :=
   as.foldlM (init := empty) fun bs a => do return bs ++ (← f a)
 
+@[deprecated concatMapM (since := "2024-10-16")] abbrev concatMapM := @flatMapM
+
 @[inline]
-def concatMap (f : α → Array β) (as : Array α) : Array β :=
+def flatMap (f : α → Array β) (as : Array α) : Array β :=
   as.foldl (init := empty) fun bs a => bs ++ f a
 
+@[deprecated flatMap (since := "2024-10-16")] abbrev concatMap := @flatMap
+
 /-- Joins array of array into a single array.
 
 `flatten #[#[a₁, a₂, ⋯], #[b₁, b₂, ⋯], ⋯]` = `#[a₁, a₂, ⋯, b₁, b₂, ⋯]`
@@ -813,9 +849,15 @@ def split (as : Array α) (p : α → Bool) : Array α × Array α :=
 
 /-! ## Auxiliary functions used in metaprogramming.
 
-We do not intend to provide verification theorems for these functions.
+We do not currently intend to provide verification theorems for these functions.
 -/
 
+/- ### reduceOption -/
+
+/-- Drop `none`s from a Array, and replace each remaining `some a` with `a`. -/
+@[inline] def reduceOption (as : Array (Option α)) : Array α :=
+  as.filterMap id
+
 /-! ### eraseReps -/
 
 /--

src/Init/Data/Array/Bootstrap.lean

@@ -42,7 +42,7 @@ theorem foldrM_eq_reverse_foldlM_toList.aux [Monad m]
   unfold foldrM.fold
   match i with
   | 0 => simp [List.foldlM, List.take]
-  | i+1 => rw [← List.take_concat_get _ _ h]; simp [← (aux f arr · i)]; rfl
+  | i+1 => rw [← List.take_concat_get _ _ h]; simp [← (aux f arr · i)]
 
 theorem foldrM_eq_reverse_foldlM_toList [Monad m] (f : α → β → m β) (init : β) (arr : Array α) :
     arr.foldrM f init = arr.toList.reverse.foldlM (fun x y => f y x) init := by

src/Init/Data/Array/DecidableEq.lean

@@ -6,6 +6,8 @@ Authors: Leonardo de Moura
 prelude
 import Init.Data.Array.Basic
 import Init.Data.BEq
+import Init.Data.Nat.Lemmas
+import Init.Data.List.Nat.BEq
 import Init.ByCases
 
 namespace Array
@@ -26,6 +28,14 @@ theorem rel_of_isEqvAux
       subst hj'
       exact heqv.left
 
+theorem isEqvAux_of_rel (r : α → α → Bool) (a b : Array α) (hsz : a.size = b.size) (i : Nat) (hi : i ≤ a.size)
+    (w : ∀ j, (hj : j < i) → r (a[j]'(Nat.lt_of_lt_of_le hj hi)) (b[j]'(Nat.lt_of_lt_of_le hj (hsz ▸ hi)))) : Array.isEqvAux a b hsz r i hi := by
+  induction i with
+  | zero => simp [Array.isEqvAux]
+  | succ i ih =>
+    simp only [isEqvAux, Bool.and_eq_true]
+    exact ⟨w i (Nat.lt_add_one i), ih _ fun j hj => w j (Nat.lt_add_right 1 hj)⟩
+
 theorem rel_of_isEqv (r : α → α → Bool) (a b : Array α) :
     Array.isEqv a b r → ∃ h : a.size = b.size, ∀ (i : Nat) (h' : i < a.size), r (a[i]) (b[i]'(h ▸ h')) := by
   simp only [isEqv]
@@ -33,6 +43,29 @@ theorem rel_of_isEqv (r : α → α → Bool) (a b : Array α) :
   · exact fun h' => ⟨h, rel_of_isEqvAux r a b h a.size (Nat.le_refl ..) h'⟩
   · intro; contradiction
 
+theorem isEqv_iff_rel (a b : Array α) (r) :
+    Array.isEqv a b r ↔ ∃ h : a.size = b.size, ∀ (i : Nat) (h' : i < a.size), r (a[i]) (b[i]'(h ▸ h')) :=
+  ⟨rel_of_isEqv r a b, fun ⟨h, w⟩ => by
+    simp only [isEqv, ← h, ↓reduceDIte]
+    exact isEqvAux_of_rel r a b h a.size (by simp [h]) w⟩
+
+theorem isEqv_eq_decide (a b : Array α) (r) :
+    Array.isEqv a b r =
+      if h : a.size = b.size then decide (∀ (i : Nat) (h' : i < a.size), r (a[i]) (b[i]'(h ▸ h'))) else false := by
+  by_cases h : Array.isEqv a b r
+  · simp only [h, Bool.true_eq]
+    simp only [isEqv_iff_rel] at h
+    obtain ⟨h, w⟩ := h
+    simp [h, w]
+  · let h' := h
+    simp only [Bool.not_eq_true] at h
+    simp only [h, Bool.false_eq, dite_eq_right_iff, decide_eq_false_iff_not, Classical.not_forall,
+      Bool.not_eq_true]
+    simpa [isEqv_iff_rel] using h'
+
+@[simp] theorem isEqv_toList [BEq α] (a b : Array α) : (a.toList.isEqv b.toList r) = (a.isEqv b r) := by
+  simp [isEqv_eq_decide, List.isEqv_eq_decide]
+
 theorem eq_of_isEqv [DecidableEq α] (a b : Array α) (h : Array.isEqv a b (fun x y => x = y)) : a = b := by
   have ⟨h, h'⟩ := rel_of_isEqv (fun x y => x = y) a b h
   exact ext _ _ h (fun i lt _ => by simpa using h' i lt)
@@ -56,4 +89,22 @@ instance [DecidableEq α] : DecidableEq (Array α) :=
     | true  => isTrue (eq_of_isEqv a b h)
     | false => isFalse fun h' => by subst h'; rw [isEqv_self] at h; contradiction
 
+theorem beq_eq_decide [BEq α] (a b : Array α) :
+    (a == b) = if h : a.size = b.size then
+      decide (∀ (i : Nat) (h' : i < a.size), a[i] == b[i]'(h ▸ h')) else false := by
+  simp [BEq.beq, isEqv_eq_decide]
+
+@[simp] theorem beq_toList [BEq α] (a b : Array α) : (a.toList == b.toList) = (a == b) := by
+  simp [beq_eq_decide, List.beq_eq_decide]
+
 end Array
+
+namespace List
+
+@[simp] theorem isEqv_toArray [BEq α] (a b : List α) : (a.toArray.isEqv b.toArray r) = (a.isEqv b r) := by
+  simp [isEqv_eq_decide, Array.isEqv_eq_decide]
+
+@[simp] theorem beq_toArray [BEq α] (a b : List α) : (a.toArray == b.toArray) = (a == b) := by
+  simp [beq_eq_decide, Array.beq_eq_decide]
+
+end List

src/Init/Data/Array/GetLit.lean

@@ -41,6 +41,6 @@ where
   getLit_eq (as : Array α) (i : Nat) (h₁ : as.size = n) (h₂ : i < n) : as.getLit i h₁ h₂ = getElem as.toList i ((id (α := as.toList.length = n) h₁) ▸ h₂) :=
     rfl
   go (i : Nat) (hi : i ≤ as.size) : toListLitAux as n hsz i hi (as.toList.drop i) = as.toList := by
-    induction i <;> simp [getLit_eq, List.get_drop_eq_drop, toListLitAux, List.drop, *]
+    induction i <;> simp only [List.drop, toListLitAux, getLit_eq, List.get_drop_eq_drop, *]
 
 end Array

src/Init/Data/Array/Lemmas.lean

@@ -8,19 +8,17 @@ import Init.Data.Nat.Lemmas
 import Init.Data.List.Impl
 import Init.Data.List.Monadic
 import Init.Data.List.Range
+import Init.Data.List.Nat.TakeDrop
+import Init.Data.List.Nat.Modify
 import Init.Data.Array.Mem
 import Init.TacticsExtra
 
 /-!
-## Bootstrapping theorems about arrays
-
-This file contains some theorems about `Array` and `List` needed for `Init.Data.List.Impl`.
+## Theorems about `Array`.
 -/
 
 namespace Array
 
-@[simp] theorem getElem_toList {a : Array α} {i : Nat} (h : i < a.size) : a.toList[i] = a[i] := rfl
-
 @[simp] theorem getElem_mk {xs : List α} {i : Nat} (h : i < xs.length) : (Array.mk xs)[i] = xs[i] := rfl
 
 theorem getElem_eq_getElem_toList {a : Array α} (h : i < a.size) : a[i] = a.toList[i] := by
@@ -45,31 +43,32 @@ theorem getElem?_eq_getElem?_toList (a : Array α) (i : Nat) : a[i]? = a.toList[
   rw [getElem?_eq]
   split <;> simp_all
 
-@[deprecated getElem_eq_getElem_toList (since := "2024-09-25")]
-abbrev getElem_eq_toList_getElem := @getElem_eq_getElem_toList
-
-@[deprecated getElem_eq_toList_getElem (since := "2024-09-09")]
-abbrev getElem_eq_data_getElem := @getElem_eq_getElem_toList
-
-@[deprecated getElem_eq_toList_getElem (since := "2024-06-12")]
-theorem getElem_eq_toList_get (a : Array α) (h : i < a.size) : a[i] = a.toList.get ⟨i, h⟩ := by
-  simp
-
-theorem get_push_lt (a : Array α) (x : α) (i : Nat) (h : i < a.size) :
+theorem getElem_push_lt (a : Array α) (x : α) (i : Nat) (h : i < a.size) :
     have : i < (a.push x).size := by simp [*, Nat.lt_succ_of_le, Nat.le_of_lt]
     (a.push x)[i] = a[i] := by
   simp only [push, getElem_eq_getElem_toList, List.concat_eq_append, List.getElem_append_left, h]
 
-@[simp] theorem get_push_eq (a : Array α) (x : α) : (a.push x)[a.size] = x := by
+@[simp] theorem getElem_push_eq (a : Array α) (x : α) : (a.push x)[a.size] = x := by
   simp only [push, getElem_eq_getElem_toList, List.concat_eq_append]
   rw [List.getElem_append_right] <;> simp [getElem_eq_getElem_toList, Nat.zero_lt_one]
 
-theorem get_push (a : Array α) (x : α) (i : Nat) (h : i < (a.push x).size) :
+theorem getElem_push (a : Array α) (x : α) (i : Nat) (h : i < (a.push x).size) :
     (a.push x)[i] = if h : i < a.size then a[i] else x := by
   by_cases h' : i < a.size
-  · simp [get_push_lt, h']
+  · simp [getElem_push_lt, h']
   · simp at h
-    simp [get_push_lt, Nat.le_antisymm (Nat.le_of_lt_succ h) (Nat.ge_of_not_lt h')]
+    simp [getElem_push_lt, Nat.le_antisymm (Nat.le_of_lt_succ h) (Nat.ge_of_not_lt h')]
+
+@[deprecated getElem_push (since := "2024-10-21")] abbrev get_push := @getElem_push
+@[deprecated getElem_push_lt (since := "2024-10-21")] abbrev get_push_lt := @getElem_push_lt
+@[deprecated getElem_push_eq (since := "2024-10-21")] abbrev get_push_eq := @getElem_push_eq
+
+@[simp] theorem get!_eq_getElem! [Inhabited α] (a : Array α) (i : Nat) : a.get! i = a[i]! := by
+  simp [getElem!_def, get!, getD]
+  split <;> rename_i h
+  · simp [getElem?_eq_getElem h]
+    rfl
+  · simp [getElem?_eq_none_iff.2 (by simpa using h)]
 
 end Array
 
@@ -77,28 +76,15 @@ namespace List
 
 open Array
 
-/-! ### Lemmas about `List.toArray`. -/
+/-! ### Lemmas about `List.toArray`.
+
+We prefer to pull `List.toArray` outwards.
+-/
 
 @[simp] theorem size_toArrayAux {a : List α} {b : Array α} :
     (a.toArrayAux b).size = b.size + a.length := by
   simp [size]
 
-@[simp] theorem toArray_toList (a : Array α) : a.toList.toArray = a := rfl
-
-@[deprecated toArray_toList (since := "2024-09-09")]
-abbrev toArray_data := @toArray_toList
-
-@[simp] theorem getElem_toArray {a : List α} {i : Nat} (h : i < a.toArray.size) :
-    a.toArray[i] = a[i]'(by simpa using h) := rfl
-
-@[simp] theorem getElem?_toArray {a : List α} {i : Nat} : a.toArray[i]? = a[i]? := rfl
-
-@[deprecated "Use the reverse direction of `List.push_toArray`." (since := "2024-09-27")]
-theorem toArray_concat {as : List α} {x : α} :
-    (as ++ [x]).toArray = as.toArray.push x := by
-  apply ext'
-  simp
-
 @[simp] theorem push_toArray (l : List α) (a : α) : l.toArray.push a = (l ++ [a]).toArray := by
   apply ext'
   simp
@@ -108,6 +94,14 @@ theorem toArray_concat {as : List α} {x : α} :
   funext a
   simp
 
+@[simp] theorem isEmpty_toArray (l : List α) : l.toArray.isEmpty = l.isEmpty := by
+  cases l <;> simp
+
+@[simp] theorem toArray_singleton (a : α) : (List.singleton a).toArray = singleton a := rfl
+
+@[simp] theorem back_toArray [Inhabited α] (l : List α) : l.toArray.back = l.getLast! := by
+  simp only [back, size_toArray, Array.get!_eq_getElem!, getElem!_toArray, getLast!_eq_getElem!]
+
 theorem foldrM_toArray [Monad m] (f : α → β → m β) (init : β) (l : List α) :
     l.toArray.foldrM f init = l.foldrM f init := by
   rw [foldrM_eq_reverse_foldlM_toList]
@@ -163,20 +157,15 @@ end List
 
 namespace Array
 
-attribute [simp] uset
-
 @[simp] theorem singleton_def (v : α) : singleton v = #[v] := rfl
 
+-- This is a duplicate of `List.toArray_toList`.
+-- It's confusing to guess which namespace this theorem should live in,
+-- so we provide both.
 @[simp] theorem toArray_toList (a : Array α) : a.toList.toArray = a := rfl
 
-@[deprecated toArray_toList (since := "2024-09-09")]
-abbrev toArray_data := @toArray_toList
-
 @[simp] theorem length_toList {l : Array α} : l.toList.length = l.size := rfl
 
-@[deprecated length_toList (since := "2024-09-09")]
-abbrev data_length := @length_toList
-
 @[simp] theorem mkEmpty_eq (α n) : @mkEmpty α n = #[] := rfl
 
 @[simp] theorem size_mk (as : List α) : (Array.mk as).size = as.length := by simp [size]
@@ -225,9 +214,6 @@ where
     induction l generalizing arr <;> simp [*]
   simp [H]
 
-@[deprecated toList_map (since := "2024-09-09")]
-abbrev map_data := @toList_map
-
 @[simp] theorem size_map (f : α → β) (arr : Array α) : (arr.map f).size = arr.size := by
   simp only [← length_toList]
   simp
@@ -242,24 +228,16 @@ abbrev map_data := @toList_map
   cases arr
   simp
 
-theorem foldl_toList_eq_bind (l : List α) (acc : Array β)
+theorem foldl_toList_eq_flatMap (l : List α) (acc : Array β)
     (F : Array β → α → Array β) (G : α → List β)
     (H : ∀ acc a, (F acc a).toList = acc.toList ++ G a) :
-    (l.foldl F acc).toList = acc.toList ++ l.bind G := by
-  induction l generalizing acc <;> simp [*, List.bind]
-
-@[deprecated foldl_toList_eq_bind (since := "2024-09-09")]
-abbrev foldl_data_eq_bind := @foldl_toList_eq_bind
+    (l.foldl F acc).toList = acc.toList ++ l.flatMap G := by
+  induction l generalizing acc <;> simp [*, List.flatMap]
 
 theorem foldl_toList_eq_map (l : List α) (acc : Array β) (G : α → β) :
     (l.foldl (fun acc a => acc.push (G a)) acc).toList = acc.toList ++ l.map G := by
   induction l generalizing acc <;> simp [*]
 
-@[deprecated foldl_toList_eq_map (since := "2024-09-09")]
-abbrev foldl_data_eq_map := @foldl_toList_eq_map
-
-theorem size_uset (a : Array α) (v i h) : (uset a i v h).size = a.size := by simp
-
 theorem anyM_eq_anyM_loop [Monad m] (p : α → m Bool) (as : Array α) (start stop) :
     anyM p as start stop = anyM.loop p as (min stop as.size) (Nat.min_le_right ..) start := by
   simp only [anyM, Nat.min_def]; split <;> rfl
@@ -274,12 +252,18 @@ theorem mem_def {a : α} {as : Array α} : a ∈ as ↔ a ∈ as.toList :=
 @[simp] theorem not_mem_empty (a : α) : ¬(a ∈ #[]) := by
   simp [mem_def]
 
+/-! # uset -/
+
+attribute [simp] uset
+
+theorem size_uset (a : Array α) (v i h) : (uset a i v h).size = a.size := by simp
+
 /-! # get -/
 
 @[simp] theorem get_eq_getElem (a : Array α) (i : Fin _) : a.get i = a[i.1] := rfl
 
 theorem getElem?_lt
-    (a : Array α) {i : Nat} (h : i < a.size) : a[i]? = some (a[i]) := dif_pos h
+    (a : Array α) {i : Nat} (h : i < a.size) : a[i]? = some a[i] := dif_pos h
 
 theorem getElem?_ge
     (a : Array α) {i : Nat} (h : i ≥ a.size) : a[i]? = none := dif_neg (Nat.not_lt_of_le h)
@@ -302,8 +286,10 @@ theorem getD_get? (a : Array α) (i : Nat) (d : α) :
 
 theorem get!_eq_getD [Inhabited α] (a : Array α) : a.get! n = a.getD n default := rfl
 
-@[simp] theorem get!_eq_getElem? [Inhabited α] (a : Array α) (i : Nat) : a.get! i = (a.get? i).getD default := by
-  by_cases p : i < a.size <;> simp [getD_get?, get!_eq_getD, p]
+@[simp] theorem get!_eq_getElem? [Inhabited α] (a : Array α) (i : Nat) :
+    a.get! i = (a.get? i).getD default := by
+  by_cases p : i < a.size <;>
+  simp only [get!_eq_getD, getD_eq_get?, getD_get?, p, get?_eq_getElem?]
 
 /-! # set -/
 
@@ -383,8 +369,8 @@ theorem getElem_ofFn_go (f : Fin n → α) (i) {acc k}
     simp only [dif_pos hin]
     rw [getElem_ofFn_go f (i+1) _ hin (by simp [*]) (fun j hj => ?hacc)]
     cases (Nat.lt_or_eq_of_le <| Nat.le_of_lt_succ (by simpa using hj)) with
-    | inl hj => simp [get_push, hj, hacc j hj]
-    | inr hj => simp [get_push, *]
+    | inl hj => simp [getElem_push, hj, hacc j hj]
+    | inr hj => simp [getElem_push, *]
   else
     simp [hin, hacc k (Nat.lt_of_lt_of_le hki (Nat.le_of_not_lt (hi ▸ hin)))]
 termination_by n - i
@@ -393,6 +379,10 @@ termination_by n - i
     (ofFn f)[i] = f ⟨i, size_ofFn f ▸ h⟩ :=
   getElem_ofFn_go _ _ _ (by simp) (by simp) nofun
 
+theorem getElem?_ofFn (f : Fin n → α) (i : Nat) :
+    (ofFn f)[i]? = if h : i < n then some (f ⟨i, h⟩) else none := by
+  simp [getElem?_def]
+
 /-- # mkArray -/
 
 @[simp] theorem size_mkArray (n : Nat) (v : α) : (mkArray n v).size = n :=
@@ -400,19 +390,17 @@ termination_by n - i
 
 @[simp] theorem toList_mkArray (n : Nat) (v : α) : (mkArray n v).toList = List.replicate n v := rfl
 
-@[deprecated toList_mkArray (since := "2024-09-09")]
-abbrev mkArray_data := @toList_mkArray
-
 @[simp] theorem getElem_mkArray (n : Nat) (v : α) (h : i < (mkArray n v).size) :
     (mkArray n v)[i] = v := by simp [Array.getElem_eq_getElem_toList]
 
+theorem getElem?_mkArray (n : Nat) (v : α) (i : Nat) :
+    (mkArray n v)[i]? = if i < n then some v else none := by
+  simp [getElem?_def]
+
 /-- # mem -/
 
 theorem mem_toList {a : α} {l : Array α} : a ∈ l.toList ↔ a ∈ l := mem_def.symm
 
-@[deprecated mem_toList (since := "2024-09-09")]
-abbrev mem_data := @mem_toList
-
 theorem not_mem_nil (a : α) : ¬ a ∈ #[] := nofun
 
 theorem getElem_of_mem {a : α} {as : Array α} :
@@ -422,6 +410,12 @@ theorem getElem_of_mem {a : α} {as : Array α} :
   exists i
   exists hbound
 
+theorem getElem?_of_mem {a : α} {as : Array α} :
+    a ∈ as → ∃ (n : Nat), as[n]? = some a := by
+  intro ha
+  rcases List.getElem?_of_mem ha.val with ⟨i, hi⟩
+  exists i
+
 @[simp] theorem mem_dite_empty_left {x : α} [Decidable p] {l : ¬ p → Array α} :
     (x ∈ if h : p then #[] else l h) ↔ ∃ h : ¬ p, x ∈ l h := by
   split <;> simp_all [mem_def]
@@ -444,75 +438,60 @@ theorem lt_of_getElem {x : α} {a : Array α} {idx : Nat} {hidx : idx < a.size}
     idx < a.size :=
   hidx
 
-theorem getElem?_mem {l : Array α} {i : Fin l.size} : l[i] ∈ l := by
+@[simp] theorem getElem_mem {l : Array α} {i : Nat} (h : i < l.size) : l[i] ∈ l := by
   erw [Array.mem_def, getElem_eq_getElem_toList]
   apply List.get_mem
 
-theorem getElem_fin_eq_toList_get (a : Array α) (i : Fin _) : a[i] = a.toList.get i := rfl
-
-@[deprecated getElem_fin_eq_toList_get (since := "2024-09-09")]
-abbrev getElem_fin_eq_data_get := @getElem_fin_eq_toList_get
+theorem getElem_fin_eq_getElem_toList (a : Array α) (i : Fin a.size) : a[i] = a.toList[i] := rfl
 
 @[simp] theorem ugetElem_eq_getElem (a : Array α) {i : USize} (h : i.toNat < a.size) :
   a[i] = a[i.toNat] := rfl
 
-theorem get?_len_le (a : Array α) (i : Nat) (h : a.size ≤ i) : a[i]? = none := by
+theorem getElem?_size_le (a : Array α) (i : Nat) (h : a.size ≤ i) : a[i]? = none := by
   simp [getElem?_neg, h]
 
+@[deprecated getElem?_size_le (since := "2024-10-21")] abbrev get?_len_le := @getElem?_size_le
+
 theorem getElem_mem_toList (a : Array α) (h : i < a.size) : a[i] ∈ a.toList := by
   simp only [getElem_eq_getElem_toList, List.getElem_mem]
 
-@[deprecated getElem_mem_toList (since := "2024-09-09")]
-abbrev getElem_mem_data := @getElem_mem_toList
-
-theorem getElem?_eq_toList_getElem? (a : Array α) (i : Nat) : a[i]? = a.toList[i]? := by
-  by_cases i < a.size <;> simp_all [getElem?_pos, getElem?_neg]
-
-@[deprecated getElem?_eq_toList_getElem? (since := "2024-09-30")]
-theorem getElem?_eq_toList_get? (a : Array α) (i : Nat) : a[i]? = a.toList.get? i := by
-  by_cases i < a.size <;> simp_all [getElem?_pos, getElem?_neg, List.get?_eq_get, eq_comm]
-
-set_option linter.deprecated false in
-@[deprecated getElem?_eq_toList_getElem? (since := "2024-09-09")]
-abbrev getElem?_eq_data_get? := @getElem?_eq_toList_get?
-
-set_option linter.deprecated false in
-theorem get?_eq_toList_get? (a : Array α) (i : Nat) : a.get? i = a.toList.get? i :=
-  getElem?_eq_toList_get? ..
-
-@[deprecated get?_eq_toList_get? (since := "2024-09-09")]
-abbrev get?_eq_data_get? := @get?_eq_toList_get?
+theorem get?_eq_get?_toList (a : Array α) (i : Nat) : a.get? i = a.toList.get? i := by
+  simp [getElem?_eq_getElem?_toList]
 
 theorem get!_eq_get? [Inhabited α] (a : Array α) : a.get! n = (a.get? n).getD default := by
-  simp [get!_eq_getD]
+  simp only [get!_eq_getElem?, get?_eq_getElem?]
 
 theorem getElem?_eq_some_iff {as : Array α} : as[n]? = some a ↔ ∃ h : n < as.size, as[n] = a := by
   cases as
   simp [List.getElem?_eq_some_iff]
 
 @[simp] theorem back_eq_back? [Inhabited α] (a : Array α) : a.back = a.back?.getD default := by
-  simp [back, back?]
+  simp only [back, get!_eq_getElem?, get?_eq_getElem?, back?]
 
 @[simp] theorem back?_push (a : Array α) : (a.push x).back? = some x := by
-  simp [back?, getElem?_eq_toList_getElem?]
+  simp [back?, getElem?_eq_getElem?_toList]
 
 theorem back_push [Inhabited α] (a : Array α) : (a.push x).back = x := by simp
 
-theorem get?_push_lt (a : Array α) (x : α) (i : Nat) (h : i < a.size) :
+theorem getElem?_push_lt (a : Array α) (x : α) (i : Nat) (h : i < a.size) :
     (a.push x)[i]? = some a[i] := by
-  rw [getElem?_pos, get_push_lt]
+  rw [getElem?_pos, getElem_push_lt]
 
-theorem get?_push_eq (a : Array α) (x : α) : (a.push x)[a.size]? = some x := by
-  rw [getElem?_pos, get_push_eq]
+@[deprecated getElem?_push_lt (since := "2024-10-21")] abbrev get?_push_lt := @getElem?_push_lt
 
-theorem get?_push {a : Array α} : (a.push x)[i]? = if i = a.size then some x else a[i]? := by
+theorem getElem?_push_eq (a : Array α) (x : α) : (a.push x)[a.size]? = some x := by
+  rw [getElem?_pos, getElem_push_eq]
+
+@[deprecated getElem?_push_eq (since := "2024-10-21")] abbrev get?_push_eq := @getElem?_push_eq
+
+theorem getElem?_push {a : Array α} : (a.push x)[i]? = if i = a.size then some x else a[i]? := by
   match Nat.lt_trichotomy i a.size with
   | Or.inl g =>
     have h1 : i < a.size + 1 := by omega
     have h2 : i ≠ a.size := by omega
-    simp [getElem?_def, size_push, g, h1, h2, get_push_lt]
+    simp [getElem?_def, size_push, g, h1, h2, getElem_push_lt]
   | Or.inr (Or.inl heq) =>
-    simp [heq, getElem?_pos, get_push_eq]
+    simp [heq, getElem?_pos, getElem_push_eq]
   | Or.inr (Or.inr g) =>
     simp only [getElem?_def, size_push]
     have h1 : ¬ (i < a.size) := by omega
@@ -520,13 +499,14 @@ theorem get?_push {a : Array α} : (a.push x)[i]? = if i = a.size then some x el
     have h3 : i ≠ a.size := by omega
     simp [h1, h2, h3]
 
-@[simp] theorem get?_size {a : Array α} : a[a.size]? = none := by
+@[deprecated getElem?_push (since := "2024-10-21")] abbrev get?_push := @getElem?_push
+
+@[simp] theorem getElem?_size {a : Array α} : a[a.size]? = none := by
   simp only [getElem?_def, Nat.lt_irrefl, dite_false]
 
-@[simp] theorem toList_set (a : Array α) (i v) : (a.set i v).toList = a.toList.set i.1 v := rfl
+@[deprecated getElem?_size (since := "2024-10-21")] abbrev get?_size := @getElem?_size
 
-@[deprecated toList_set (since := "2024-09-09")]
-abbrev data_set := @toList_set
+@[simp] theorem toList_set (a : Array α) (i v) : (a.set i v).toList = a.toList.set i.1 v := rfl
 
 theorem get_set_eq (a : Array α) (i : Fin a.size) (v : α) :
     (a.set i v)[i.1] = v := by
@@ -568,16 +548,16 @@ theorem swap_def (a : Array α) (i j : Fin a.size) :
 @[simp] theorem toList_swap (a : Array α) (i j : Fin a.size) :
     (a.swap i j).toList = (a.toList.set i (a.get j)).set j (a.get i) := by simp [swap_def]
 
-@[deprecated toList_swap (since := "2024-09-09")]
-abbrev data_swap := @toList_swap
-
-theorem get?_swap (a : Array α) (i j : Fin a.size) (k : Nat) : (a.swap i j)[k]? =
+theorem getElem?_swap (a : Array α) (i j : Fin a.size) (k : Nat) : (a.swap i j)[k]? =
     if j = k then some a[i.1] else if i = k then some a[j.1] else a[k]? := by
-  simp [swap_def, get?_set, ← getElem_fin_eq_toList_get]
+  simp [swap_def, get?_set, ← getElem_fin_eq_getElem_toList]
 
 @[simp] theorem swapAt_def (a : Array α) (i : Fin a.size) (v : α) :
     a.swapAt i v = (a[i.1], a.set i v) := rfl
 
+@[simp] theorem size_swapAt (a : Array α) (i : Fin a.size) (v : α) :
+    (a.swapAt i v).2.size = a.size := by simp [swapAt_def]
+
 @[simp]
 theorem swapAt!_def (a : Array α) (i : Nat) (v : α) (h : i < a.size) :
     a.swapAt! i v = (a[i], a.set ⟨i, h⟩ v) := by simp [swapAt!, h]
@@ -591,9 +571,6 @@ theorem swapAt!_def (a : Array α) (i : Nat) (v : α) (h : i < a.size) :
 
 @[simp] theorem toList_pop (a : Array α) : a.pop.toList = a.toList.dropLast := by simp [pop]
 
-@[deprecated toList_pop (since := "2024-09-09")]
-abbrev data_pop := @toList_pop
-
 @[simp] theorem pop_empty : (#[] : Array α).pop = #[] := rfl
 
 @[simp] theorem pop_push (a : Array α) : (a.push x).pop = a := by simp [pop]
@@ -613,11 +590,11 @@ theorem eq_push_pop_back_of_size_ne_zero [Inhabited α] {as : Array α} (h : as.
   · simp [Nat.sub_add_cancel (Nat.zero_lt_of_ne_zero h)]
   · intros i h h'
     if hlt : i < as.pop.size then
-      rw [get_push_lt (h:=hlt), getElem_pop]
+      rw [getElem_push_lt (h:=hlt), getElem_pop]
     else
       have heq : i = as.pop.size :=
         Nat.le_antisymm (size_pop .. ▸ Nat.le_pred_of_lt h) (Nat.le_of_not_gt hlt)
-      cases heq; rw [get_push_eq, back, ←size_pop, get!_eq_getD, getD, dif_pos h]; rfl
+      cases heq; rw [getElem_push_eq, back, ←size_pop, get!_eq_getD, getD, dif_pos h]; rfl
 
 theorem eq_push_of_size_ne_zero {as : Array α} (h : as.size ≠ 0) :
     ∃ (bs : Array α) (c : α), as = bs.push c :=
@@ -626,9 +603,6 @@ theorem eq_push_of_size_ne_zero {as : Array α} (h : as.size ≠ 0) :
 
 theorem size_eq_length_toList (as : Array α) : as.size = as.toList.length := rfl
 
-@[deprecated size_eq_length_toList (since := "2024-09-09")]
-abbrev size_eq_length_data := @size_eq_length_toList
-
 @[simp] theorem size_swap! (a : Array α) (i j) :
     (a.swap! i j).size = a.size := by unfold swap!; split <;> (try split) <;> simp [size_swap]
 
@@ -653,14 +627,10 @@ abbrev size_eq_length_data := @size_eq_length_toList
 @[simp] theorem toList_range (n : Nat) : (range n).toList = List.range n := by
   induction n <;> simp_all [range, Nat.fold, flip, List.range_succ]
 
-@[deprecated toList_range (since := "2024-09-09")]
-abbrev data_range := @toList_range
-
 @[simp]
 theorem getElem_range {n : Nat} {x : Nat} (h : x < (Array.range n).size) : (Array.range n)[x] = x := by
   simp [getElem_eq_getElem_toList]
 
-set_option linter.deprecated false in
 @[simp] theorem toList_reverse (a : Array α) : a.reverse.toList = a.toList.reverse := by
   let rec go (as : Array α) (i j hj)
       (h : i + j + 1 = a.size) (h₂ : as.size = a.size)
@@ -673,9 +643,9 @@ set_option linter.deprecated false in
       · rwa [Nat.add_right_comm i]
       · simp [size_swap, h₂]
       · intro k
-        rw [← getElem?_eq_toList_getElem?, get?_swap]
+        rw [← getElem?_eq_getElem?_toList, getElem?_swap]
         simp only [H, getElem_eq_getElem_toList, ← List.getElem?_eq_getElem, Nat.le_of_lt h₁,
-          getElem?_eq_toList_getElem?]
+          getElem?_eq_getElem?_toList]
         split <;> rename_i h₂
         · simp only [← h₂, Nat.not_le.2 (Nat.lt_succ_self _), Nat.le_refl, and_false]
           exact (List.getElem?_reverse' (j+1) i (Eq.trans (by simp_arith) h)).symm
@@ -702,9 +672,6 @@ set_option linter.deprecated false in
         true_and, Nat.not_lt] at h
       rw [List.getElem?_eq_none_iff.2 ‹_›, List.getElem?_eq_none_iff.2 (a.toList.length_reverse ▸ ‹_›)]
 
-@[deprecated toList_reverse (since := "2024-09-30")]
-abbrev reverse_toList := @toList_reverse
-
 /-! ### foldl / foldr -/
 
 @[simp] theorem foldlM_loop_empty [Monad m] (f : β → α → m β) (init : β) (i j : Nat) :
@@ -733,7 +700,7 @@ abbrev reverse_toList := @toList_reverse
     foldrM f init #[] start stop = return init := by
   simp [foldrM]
 
--- This proof is the pure version of `Array.SatisfiesM_foldlM`,
+-- This proof is the pure version of `Array.SatisfiesM_foldlM` in Batteries,
 -- reproduced to avoid a dependency on `SatisfiesM`.
 theorem foldl_induction
     {as : Array α} (motive : Nat → β → Prop) {init : β} (h0 : motive 0 init) {f : β → α → β}
@@ -749,7 +716,7 @@ theorem foldl_induction
     · next hj => exact Nat.le_antisymm h₁ (Nat.ge_of_not_lt hj) ▸ H
   simpa [foldl, foldlM] using go (Nat.zero_le _) (Nat.le_refl _) h0
 
--- This proof is the pure version of `Array.SatisfiesM_foldrM`,
+-- This proof is the pure version of `Array.SatisfiesM_foldrM` in Batteries,
 -- reproduced to avoid a dependency on `SatisfiesM`.
 theorem foldr_induction
     {as : Array α} (motive : Nat → β → Prop) {init : β} (h0 : motive as.size init) {f : α → β → β}
@@ -795,9 +762,6 @@ theorem mapM_eq_mapM_toList [Monad m] [LawfulMonad m] (f : α → m β) (arr : A
     toList <$> arr.mapM f = arr.toList.mapM f := by
   simp [mapM_eq_mapM_toList]
 
-@[deprecated mapM_eq_mapM_toList (since := "2024-09-09")]
-abbrev mapM_eq_mapM_data := @mapM_eq_mapM_toList
-
 theorem mapM_map_eq_foldl (as : Array α) (f : α → β) (i) :
     mapM.map (m := Id) f as i b = as.foldl (start := i) (fun r a => r.push (f a)) b := by
   unfold mapM.map
@@ -839,9 +803,9 @@ theorem map_induction (as : Array α) (f : α → β) (motive : Nat → Prop) (h
     · intro j h
       simp at h ⊢
       by_cases h' : j < size b
-      · rw [get_push]
+      · rw [getElem_push]
         simp_all
-      · rw [get_push, dif_neg h']
+      · rw [getElem_push, dif_neg h']
         simp only [show j = i by omega]
         exact (hs _ m).1
 
@@ -866,59 +830,14 @@ theorem map_spec (as : Array α) (f : α → β) (p : Fin as.size → β → Pro
     (as.push x).map f = (as.map f).push (f x) := by
   ext
   · simp
-  · simp only [getElem_map, get_push, size_map]
+  · simp only [getElem_map, getElem_push, size_map]
     split <;> rfl
 
-/-! ### mapIdx -/
-
--- This could also be proved from `SatisfiesM_mapIdxM` in Batteries.
-theorem mapIdx_induction (as : Array α) (f : Fin as.size → α → β)
-    (motive : Nat → Prop) (h0 : motive 0)
-    (p : Fin as.size → β → Prop)
-    (hs : ∀ i, motive i.1 → p i (f i as[i]) ∧ motive (i + 1)) :
-    motive as.size ∧ ∃ eq : (Array.mapIdx as f).size = as.size,
-      ∀ i h, p ⟨i, h⟩ ((Array.mapIdx as f)[i]) := by
-  let rec go {bs i j h} (h₁ : j = bs.size) (h₂ : ∀ i h h', p ⟨i, h⟩ bs[i]) (hm : motive j) :
-    let arr : Array β := Array.mapIdxM.map (m := Id) as f i j h bs
-    motive as.size ∧ ∃ eq : arr.size = as.size, ∀ i h, p ⟨i, h⟩ arr[i] := by
-    induction i generalizing j bs with simp [mapIdxM.map]
-    | zero =>
-      have := (Nat.zero_add _).symm.trans h
-      exact ⟨this ▸ hm, h₁ ▸ this, fun _ _ => h₂ ..⟩
-    | succ i ih =>
-      apply @ih (bs.push (f ⟨j, by omega⟩ as[j])) (j + 1) (by omega) (by simp; omega)
-      · intro i i_lt h'
-        rw [get_push]
-        split
-        · apply h₂
-        · simp only [size_push] at h'
-          obtain rfl : i = j := by omega
-          apply (hs ⟨i, by omega⟩ hm).1
-      · exact (hs ⟨j, by omega⟩ hm).2
-  simp [mapIdx, mapIdxM]; exact go rfl nofun h0
-
-theorem mapIdx_spec (as : Array α) (f : Fin as.size → α → β)
-    (p : Fin as.size → β → Prop) (hs : ∀ i, p i (f i as[i])) :
-    ∃ eq : (Array.mapIdx as f).size = as.size,
-      ∀ i h, p ⟨i, h⟩ ((Array.mapIdx as f)[i]) :=
-  (mapIdx_induction _ _ (fun _ => True) trivial p fun _ _ => ⟨hs .., trivial⟩).2
-
-@[simp] theorem size_mapIdx (a : Array α) (f : Fin a.size → α → β) : (a.mapIdx f).size = a.size :=
-  (mapIdx_spec (p := fun _ _ => True) (hs := fun _ => trivial)).1
-
-@[simp] theorem size_zipWithIndex (as : Array α) : as.zipWithIndex.size = as.size :=
-  Array.size_mapIdx _ _
-
-@[simp] theorem getElem_mapIdx (a : Array α) (f : Fin a.size → α → β) (i : Nat)
-    (h : i < (mapIdx a f).size) :
-    (a.mapIdx f)[i] = f ⟨i, by simp_all⟩ (a[i]'(by simp_all)) :=
-  (mapIdx_spec _ _ (fun i b => b = f i a[i]) fun _ => rfl).2 i _
-
-@[simp] theorem getElem?_mapIdx (a : Array α) (f : Fin a.size → α → β) (i : Nat) :
-    (a.mapIdx f)[i]? =
-      a[i]?.pbind fun b h => f ⟨i, (getElem?_eq_some_iff.1 h).1⟩ b := by
-  simp only [getElem?_def, size_mapIdx, getElem_mapIdx]
-  split <;> simp_all
+@[simp] theorem map_pop {f : α → β} {as : Array α} :
+    as.pop.map f = (as.map f).pop := by
+  ext
+  · simp
+  · simp only [getElem_map, getElem_pop, size_map]
 
 /-! ### modify -/
 
@@ -933,6 +852,12 @@ theorem getElem_modify {as : Array α} {x i} (h : i < (as.modify x f).size) :
   · simp only [Id.bind_eq, get_set _ _ _ (by simpa using h)]; split <;> simp [*]
   · rw [if_neg (mt (by rintro rfl; exact h) (by simp_all))]
 
+@[simp] theorem toList_modify (as : Array α) (f : α → α) :
+    (as.modify x f).toList = as.toList.modify f x := by
+  apply List.ext_getElem
+  · simp
+  · simp [getElem_modify, List.getElem_modify]
+
 theorem getElem_modify_self {as : Array α} {i : Nat} (f : α → α) (h : i < (as.modify i f).size) :
     (as.modify i f)[i] = f (as[i]'(by simpa using h)) := by
   simp [getElem_modify h]
@@ -942,11 +867,10 @@ theorem getElem_modify_of_ne {as : Array α} {i : Nat} (h : i ≠ j)
     (as.modify i f)[j] = as[j]'(by simpa using hj) := by
   simp [getElem_modify hj, h]
 
-@[deprecated getElem_modify (since := "2024-08-08")]
-theorem get_modify {arr : Array α} {x i} (h : i < (arr.modify x f).size) :
-    (arr.modify x f).get ⟨i, h⟩ =
-    if x = i then f (arr.get ⟨i, by simpa using h⟩) else arr.get ⟨i, by simpa using h⟩ := by
-  simp [getElem_modify h]
+theorem getElem?_modify {as : Array α} {i : Nat} {f : α → α} {j : Nat} :
+    (as.modify i f)[j]? = if i = j then as[j]?.map f else as[j]? := by
+  simp only [getElem?_def, size_modify, getElem_modify, Option.map_dif]
+  split <;> split <;> rfl
 
 /-! ### filter -/
 
@@ -961,9 +885,6 @@ theorem get_modify {arr : Array α} {x i} (h : i < (arr.modify x f).size) :
   induction l with simp
   | cons => split <;> simp [*]
 
-@[deprecated toList_filter (since := "2024-09-09")]
-abbrev filter_data := @toList_filter
-
 @[simp] theorem filter_filter (q) (l : Array α) :
     filter p (filter q l) = filter (fun a => p a && q a) l := by
   apply ext'
@@ -997,9 +918,6 @@ theorem filter_congr {as bs : Array α} (h : as = bs)
   · simp_all [Id.run, List.filterMap_cons]
     split <;> simp_all
 
-@[deprecated toList_filterMap (since := "2024-09-09")]
-abbrev filterMap_data := @toList_filterMap
-
 @[simp] theorem mem_filterMap {f : α → Option β} {l : Array α} {b : β} :
     b ∈ filterMap f l ↔ ∃ a, a ∈ l ∧ f a = some b := by
   simp only [mem_def, toList_filterMap, List.mem_filterMap]
@@ -1015,10 +933,7 @@ theorem filterMap_congr {as bs : Array α} (h : as = bs)
 
 theorem size_empty : (#[] : Array α).size = 0 := rfl
 
-theorem toList_empty : (#[] : Array α).toList = [] := rfl
-
-@[deprecated toList_empty (since := "2024-09-09")]
-abbrev empty_data := @toList_empty
+@[simp] theorem toList_empty : (#[] : Array α).toList = [] := rfl
 
 /-! ### append -/
 
@@ -1042,9 +957,6 @@ theorem getElem_append_left {as bs : Array α} {h : i < (as ++ bs).size} (hlt :
   conv => rhs; rw [← List.getElem_append_left (bs := bs.toList) (h' := h')]
   apply List.get_of_eq; rw [toList_append]
 
-@[deprecated getElem_append_left (since := "2024-09-30")]
-abbrev get_append_left := @getElem_append_left
-
 theorem getElem_append_right {as bs : Array α} {h : i < (as ++ bs).size} (hle : as.size ≤ i)
     (hlt : i - as.size < bs.size := Nat.sub_lt_left_of_lt_add hle (size_append .. ▸ h)) :
     (as ++ bs)[i] = bs[i - as.size] := by
@@ -1053,9 +965,6 @@ theorem getElem_append_right {as bs : Array α} {h : i < (as ++ bs).size} (hle :
   conv => rhs; rw [← List.getElem_append_right (h₁ := hle) (h₂ := h')]
   apply List.get_of_eq; rw [toList_append]
 
-@[deprecated getElem_append_right (since := "2024-09-30")]
-abbrev get_append_right := @getElem_append_right
-
 @[simp] theorem append_nil (as : Array α) : as ++ #[] = as := by
   apply ext'; simp only [toList_append, toList_empty, List.append_nil]
 
@@ -1182,7 +1091,7 @@ theorem getElem_extract_loop_ge (as bs : Array α) (size start : Nat) (hge : i
       have h₂ : bs.size < (extract.loop as size (start+1) (bs.push as[start])).size := by
         rw [size_extract_loop]; apply Nat.lt_of_lt_of_le h₁; exact Nat.le_add_right ..
       have h : (extract.loop as size (start + 1) (push bs as[start]))[bs.size] = as[start] := by
-        rw [getElem_extract_loop_lt as (bs.push as[start]) size (start+1) h₁ h₂, get_push_eq]
+        rw [getElem_extract_loop_lt as (bs.push as[start]) size (start+1) h₁ h₂, getElem_push_eq]
       rw [h]; congr; rw [Nat.add_sub_cancel]
     else
       have hge : bs.size + 1 ≤ i := Nat.lt_of_le_of_ne hge hi
@@ -1209,6 +1118,14 @@ theorem getElem?_extract {as : Array α} {start stop : Nat} :
     · omega
   · rfl
 
+@[simp] theorem toList_extract (as : Array α) (start stop : Nat) :
+    (as.extract start stop).toList = (as.toList.drop start).take (stop - start) := by
+  apply List.ext_getElem
+  · simp only [length_toList, size_extract, List.length_take, List.length_drop]
+    omega
+  · intros n h₁ h₂
+    simp
+
 @[simp] theorem extract_all (as : Array α) : as.extract 0 as.size = as := by
   apply ext
   · rw [size_extract, Nat.min_self, Nat.sub_zero]
@@ -1298,9 +1215,6 @@ theorem any_toList {p : α → Bool} (as : Array α) : as.toList.any p = as.any
   rw [Bool.eq_iff_iff, any_eq_true, List.any_eq_true]; simp only [List.mem_iff_get]
   exact ⟨fun ⟨_, ⟨i, rfl⟩, h⟩ => ⟨i, h⟩, fun ⟨i, h⟩ => ⟨_, ⟨i, rfl⟩, h⟩⟩
 
-@[deprecated "Use the reverse direction of `Array.any_toList`" (since := "2024-09-30")]
-abbrev any_def := @any_toList
-
 /-! ### all -/
 
 theorem allM_eq_not_anyM_not [Monad m] [LawfulMonad m] (p : α → m Bool) (as : Array α) :
@@ -1340,9 +1254,6 @@ theorem all_toList {p : α → Bool} (as : Array α) : as.toList.all p = as.all
     rw [← getElem_eq_getElem_toList]
     exact w ⟨r, h⟩
 
-@[deprecated "Use the reverse direction of `Array.all_toList`" (since := "2024-09-30")]
-abbrev all_def := @all_toList
-
 theorem all_eq_true_iff_forall_mem {l : Array α} : l.all p ↔ ∀ x, x ∈ l → p x := by
   simp only [← all_toList, List.all_eq_true, mem_def]
 
@@ -1384,7 +1295,7 @@ open Fin
       · assumption
 
 theorem getElem_swap' (a : Array α) (i j : Fin a.size) (k : Nat) (hk : k < a.size) :
-    (a.swap i j)[k]'(by simp_all) = if k = i then a[j] else if k = j then a[i]  else a[k] := by
+    (a.swap i j)[k]'(by simp_all) = if k = i then a[j] else if k = j then a[i] else a[k] := by
   split
   · simp_all only [getElem_swap_left]
   · split <;> simp_all
@@ -1394,7 +1305,7 @@ theorem getElem_swap (a : Array α) (i j : Fin a.size) (k : Nat) (hk : k < (a.sw
   apply getElem_swap'
 
 @[simp] theorem swap_swap (a : Array α) {i j : Fin a.size} :
-    (a.swap i j).swap ⟨i.1, (a.size_swap ..).symm ▸i.2⟩ ⟨j.1, (a.size_swap ..).symm ▸j.2⟩ = a := by
+    (a.swap i j).swap ⟨i.1, (a.size_swap ..).symm ▸ i.2⟩ ⟨j.1, (a.size_swap ..).symm ▸ j.2⟩ = a := by
   apply ext
   · simp only [size_swap]
   · intros
@@ -1412,33 +1323,8 @@ theorem swap_comm (a : Array α) {i j : Fin a.size} : a.swap i j = a.swap j i :=
     · split <;> simp_all
     · split <;> simp_all
 
-@[deprecated getElem_extract_loop_lt_aux (since := "2024-09-30")]
-abbrev get_extract_loop_lt_aux := @getElem_extract_loop_lt_aux
-@[deprecated getElem_extract_loop_lt (since := "2024-09-30")]
-abbrev get_extract_loop_lt := @getElem_extract_loop_lt
-@[deprecated getElem_extract_loop_ge_aux (since := "2024-09-30")]
-abbrev get_extract_loop_ge_aux := @getElem_extract_loop_ge_aux
-@[deprecated getElem_extract_loop_ge (since := "2024-09-30")]
-abbrev get_extract_loop_ge := @getElem_extract_loop_ge
-@[deprecated getElem_extract_aux (since := "2024-09-30")]
-abbrev get_extract_aux := @getElem_extract_aux
-@[deprecated getElem_extract (since := "2024-09-30")]
-abbrev get_extract := @getElem_extract
-
-@[deprecated getElem_swap_right (since := "2024-09-30")]
-abbrev get_swap_right := @getElem_swap_right
-@[deprecated getElem_swap_left (since := "2024-09-30")]
-abbrev get_swap_left := @getElem_swap_left
-@[deprecated getElem_swap_of_ne (since := "2024-09-30")]
-abbrev get_swap_of_ne := @getElem_swap_of_ne
-@[deprecated getElem_swap (since := "2024-09-30")]
-abbrev get_swap := @getElem_swap
-@[deprecated getElem_swap' (since := "2024-09-30")]
-abbrev get_swap' := @getElem_swap'
-
 end Array
 
-
 open Array
 
 namespace List
@@ -1554,6 +1440,11 @@ theorem all_toArray (p : α → Bool) (l : List α) : l.toArray.all p = l.all p
   apply ext'
   simp
 
+@[simp] theorem modify_toArray (f : α → α) (l : List α) :
+    l.toArray.modify i f = (l.modify f i).toArray := by
+  apply ext'
+  simp
+
 @[simp] theorem filter_toArray' (p : α → Bool) (l : List α) (h : stop = l.toArray.size) :
     l.toArray.filter p 0 stop = (l.filter p).toArray := by
   subst h
@@ -1582,4 +1473,164 @@ theorem filterMap_toArray (f : α → Option β) (l : List α) :
   apply ext'
   simp
 
+@[simp] theorem toArray_extract (l : List α) (start stop : Nat) :
+    l.toArray.extract start stop = ((l.drop start).take (stop - start)).toArray := by
+  apply ext'
+  simp
+
 end List
+
+/-! ### Deprecations -/
+
+namespace List
+
+@[deprecated toArray_toList (since := "2024-09-09")]
+abbrev toArray_data := @toArray_toList
+
+@[deprecated "Use the reverse direction of `List.push_toArray`." (since := "2024-09-27")]
+theorem toArray_concat {as : List α} {x : α} :
+    (as ++ [x]).toArray = as.toArray.push x := by
+  apply ext'
+  simp
+
+end List
+
+namespace Array
+
+@[deprecated getElem_eq_getElem_toList (since := "2024-09-25")]
+abbrev getElem_eq_toList_getElem := @getElem_eq_getElem_toList
+
+@[deprecated getElem_eq_toList_getElem (since := "2024-09-09")]
+abbrev getElem_eq_data_getElem := @getElem_eq_getElem_toList
+
+@[deprecated getElem_eq_toList_getElem (since := "2024-06-12")]
+theorem getElem_eq_toList_get (a : Array α) (h : i < a.size) : a[i] = a.toList.get ⟨i, h⟩ := by
+  simp
+
+@[deprecated toArray_toList (since := "2024-09-09")]
+abbrev toArray_data := @toArray_toList
+
+@[deprecated length_toList (since := "2024-09-09")]
+abbrev data_length := @length_toList
+
+@[deprecated toList_map (since := "2024-09-09")]
+abbrev map_data := @toList_map
+
+@[deprecated foldl_toList_eq_flatMap (since := "2024-10-16")]
+abbrev foldl_toList_eq_bind := @foldl_toList_eq_flatMap
+
+@[deprecated foldl_toList_eq_flatMap (since := "2024-10-16")]
+abbrev foldl_data_eq_bind := @foldl_toList_eq_flatMap
+
+@[deprecated foldl_toList_eq_map (since := "2024-09-09")]
+abbrev foldl_data_eq_map := @foldl_toList_eq_map
+
+@[deprecated toList_mkArray (since := "2024-09-09")]
+abbrev mkArray_data := @toList_mkArray
+
+@[deprecated mem_toList (since := "2024-09-09")]
+abbrev mem_data := @mem_toList
+
+@[deprecated getElem_mem (since := "2024-10-17")]
+abbrev getElem?_mem := @getElem_mem
+
+@[deprecated getElem_fin_eq_getElem_toList (since := "2024-10-17")]
+abbrev getElem_fin_eq_toList_get := @getElem_fin_eq_getElem_toList
+
+@[deprecated getElem_fin_eq_getElem_toList (since := "2024-09-09")]
+abbrev getElem_fin_eq_data_get := @getElem_fin_eq_getElem_toList
+
+@[deprecated getElem_mem_toList (since := "2024-09-09")]
+abbrev getElem_mem_data := @getElem_mem_toList
+
+@[deprecated getElem?_eq_getElem?_toList (since := "2024-10-17")]
+abbrev getElem?_eq_toList_getElem? := @getElem?_eq_getElem?_toList
+
+@[deprecated getElem?_eq_toList_getElem? (since := "2024-09-30")]
+theorem getElem?_eq_toList_get? (a : Array α) (i : Nat) : a[i]? = a.toList.get? i := by
+  by_cases i < a.size <;> simp_all [getElem?_pos, getElem?_neg, List.get?_eq_get, eq_comm]
+
+set_option linter.deprecated false in
+@[deprecated getElem?_eq_toList_getElem? (since := "2024-09-09")]
+abbrev getElem?_eq_data_get? := @getElem?_eq_toList_get?
+
+@[deprecated get?_eq_get?_toList (since := "2024-10-17")]
+abbrev get?_eq_toList_get? := @get?_eq_get?_toList
+
+@[deprecated get?_eq_toList_get? (since := "2024-09-09")]
+abbrev get?_eq_data_get? := @get?_eq_get?_toList
+
+@[deprecated toList_set (since := "2024-09-09")]
+abbrev data_set := @toList_set
+
+@[deprecated toList_swap (since := "2024-09-09")]
+abbrev data_swap := @toList_swap
+
+@[deprecated getElem?_swap (since := "2024-10-17")] abbrev get?_swap := @getElem?_swap
+
+@[deprecated toList_pop (since := "2024-09-09")] abbrev data_pop := @toList_pop
+
+@[deprecated size_eq_length_toList (since := "2024-09-09")]
+abbrev size_eq_length_data := @size_eq_length_toList
+
+@[deprecated toList_range (since := "2024-09-09")]
+abbrev data_range := @toList_range
+
+@[deprecated toList_reverse (since := "2024-09-30")]
+abbrev reverse_toList := @toList_reverse
+
+@[deprecated mapM_eq_mapM_toList (since := "2024-09-09")]
+abbrev mapM_eq_mapM_data := @mapM_eq_mapM_toList
+
+@[deprecated getElem_modify (since := "2024-08-08")]
+theorem get_modify {arr : Array α} {x i} (h : i < (arr.modify x f).size) :
+    (arr.modify x f).get ⟨i, h⟩ =
+    if x = i then f (arr.get ⟨i, by simpa using h⟩) else arr.get ⟨i, by simpa using h⟩ := by
+  simp [getElem_modify h]
+
+@[deprecated toList_filter (since := "2024-09-09")]
+abbrev filter_data := @toList_filter
+
+@[deprecated toList_filterMap (since := "2024-09-09")]
+abbrev filterMap_data := @toList_filterMap
+
+@[deprecated toList_empty (since := "2024-09-09")]
+abbrev empty_data := @toList_empty
+
+@[deprecated getElem_append_left (since := "2024-09-30")]
+abbrev get_append_left := @getElem_append_left
+
+@[deprecated getElem_append_right (since := "2024-09-30")]
+abbrev get_append_right := @getElem_append_right
+
+@[deprecated "Use the reverse direction of `Array.any_toList`" (since := "2024-09-30")]
+abbrev any_def := @any_toList
+
+@[deprecated "Use the reverse direction of `Array.all_toList`" (since := "2024-09-30")]
+abbrev all_def := @all_toList
+
+@[deprecated getElem_extract_loop_lt_aux (since := "2024-09-30")]
+abbrev get_extract_loop_lt_aux := @getElem_extract_loop_lt_aux
+@[deprecated getElem_extract_loop_lt (since := "2024-09-30")]
+abbrev get_extract_loop_lt := @getElem_extract_loop_lt
+@[deprecated getElem_extract_loop_ge_aux (since := "2024-09-30")]
+abbrev get_extract_loop_ge_aux := @getElem_extract_loop_ge_aux
+@[deprecated getElem_extract_loop_ge (since := "2024-09-30")]
+abbrev get_extract_loop_ge := @getElem_extract_loop_ge
+@[deprecated getElem_extract_aux (since := "2024-09-30")]
+abbrev get_extract_aux := @getElem_extract_aux
+@[deprecated getElem_extract (since := "2024-09-30")]
+abbrev get_extract := @getElem_extract
+
+@[deprecated getElem_swap_right (since := "2024-09-30")]
+abbrev get_swap_right := @getElem_swap_right
+@[deprecated getElem_swap_left (since := "2024-09-30")]
+abbrev get_swap_left := @getElem_swap_left
+@[deprecated getElem_swap_of_ne (since := "2024-09-30")]
+abbrev get_swap_of_ne := @getElem_swap_of_ne
+@[deprecated getElem_swap (since := "2024-09-30")]
+abbrev get_swap := @getElem_swap
+@[deprecated getElem_swap' (since := "2024-09-30")]
+abbrev get_swap' := @getElem_swap'
+
+end Array

src/Init/Data/Array/MapIdx.lean

@@ -0,0 +1,92 @@
+/-
+Copyright (c) 2022 Mario Carneiro. All rights reserved.
+Released under Apache 2.0 license as described in the file LICENSE.
+Authors: Mario Carneiro, Kim Morrison
+-/
+prelude
+import Init.Data.Array.Lemmas
+import Init.Data.List.MapIdx
+
+namespace Array
+
+/-! ### mapFinIdx -/
+
+-- This could also be proved from `SatisfiesM_mapIdxM` in Batteries.
+theorem mapFinIdx_induction (as : Array α) (f : Fin as.size → α → β)
+    (motive : Nat → Prop) (h0 : motive 0)
+    (p : Fin as.size → β → Prop)
+    (hs : ∀ i, motive i.1 → p i (f i as[i]) ∧ motive (i + 1)) :
+    motive as.size ∧ ∃ eq : (Array.mapFinIdx as f).size = as.size,
+      ∀ i h, p ⟨i, h⟩ ((Array.mapFinIdx as f)[i]) := by
+  let rec go {bs i j h} (h₁ : j = bs.size) (h₂ : ∀ i h h', p ⟨i, h⟩ bs[i]) (hm : motive j) :
+    let arr : Array β := Array.mapFinIdxM.map (m := Id) as f i j h bs
+    motive as.size ∧ ∃ eq : arr.size = as.size, ∀ i h, p ⟨i, h⟩ arr[i] := by
+    induction i generalizing j bs with simp [mapFinIdxM.map]
+    | zero =>
+      have := (Nat.zero_add _).symm.trans h
+      exact ⟨this ▸ hm, h₁ ▸ this, fun _ _ => h₂ ..⟩
+    | succ i ih =>
+      apply @ih (bs.push (f ⟨j, by omega⟩ as[j])) (j + 1) (by omega) (by simp; omega)
+      · intro i i_lt h'
+        rw [getElem_push]
+        split
+        · apply h₂
+        · simp only [size_push] at h'
+          obtain rfl : i = j := by omega
+          apply (hs ⟨i, by omega⟩ hm).1
+      · exact (hs ⟨j, by omega⟩ hm).2
+  simp [mapFinIdx, mapFinIdxM]; exact go rfl nofun h0
+
+theorem mapFinIdx_spec (as : Array α) (f : Fin as.size → α → β)
+    (p : Fin as.size → β → Prop) (hs : ∀ i, p i (f i as[i])) :
+    ∃ eq : (Array.mapFinIdx as f).size = as.size,
+      ∀ i h, p ⟨i, h⟩ ((Array.mapFinIdx as f)[i]) :=
+  (mapFinIdx_induction _ _ (fun _ => True) trivial p fun _ _ => ⟨hs .., trivial⟩).2
+
+@[simp] theorem size_mapFinIdx (a : Array α) (f : Fin a.size → α → β) : (a.mapFinIdx f).size = a.size :=
+  (mapFinIdx_spec (p := fun _ _ => True) (hs := fun _ => trivial)).1
+
+@[simp] theorem size_zipWithIndex (as : Array α) : as.zipWithIndex.size = as.size :=
+  Array.size_mapFinIdx _ _
+
+@[simp] theorem getElem_mapFinIdx (a : Array α) (f : Fin a.size → α → β) (i : Nat)
+    (h : i < (mapFinIdx a f).size) :
+    (a.mapFinIdx f)[i] = f ⟨i, by simp_all⟩ (a[i]'(by simp_all)) :=
+  (mapFinIdx_spec _ _ (fun i b => b = f i a[i]) fun _ => rfl).2 i _
+
+@[simp] theorem getElem?_mapFinIdx (a : Array α) (f : Fin a.size → α → β) (i : Nat) :
+    (a.mapFinIdx f)[i]? =
+      a[i]?.pbind fun b h => f ⟨i, (getElem?_eq_some_iff.1 h).1⟩ b := by
+  simp only [getElem?_def, size_mapFinIdx, getElem_mapFinIdx]
+  split <;> simp_all
+
+/-! ### mapIdx -/
+
+theorem mapIdx_induction (as : Array α) (f : Nat → α → β)
+    (motive : Nat → Prop) (h0 : motive 0)
+    (p : Fin as.size → β → Prop)
+    (hs : ∀ i, motive i.1 → p i (f i as[i]) ∧ motive (i + 1)) :
+    motive as.size ∧ ∃ eq : (Array.mapIdx as f).size = as.size,
+      ∀ i h, p ⟨i, h⟩ ((Array.mapIdx as f)[i]) :=
+  mapFinIdx_induction as (fun i a => f i a) motive h0 p hs
+
+theorem mapIdx_spec (as : Array α) (f : Nat → α → β)
+    (p : Fin as.size → β → Prop) (hs : ∀ i, p i (f i as[i])) :
+    ∃ eq : (Array.mapIdx as f).size = as.size,
+      ∀ i h, p ⟨i, h⟩ ((Array.mapIdx as f)[i]) :=
+  (mapIdx_induction _ _ (fun _ => True) trivial p fun _ _ => ⟨hs .., trivial⟩).2
+
+@[simp] theorem size_mapIdx (a : Array α) (f : Nat → α → β) : (a.mapIdx f).size = a.size :=
+  (mapIdx_spec (p := fun _ _ => True) (hs := fun _ => trivial)).1
+
+@[simp] theorem getElem_mapIdx (a : Array α) (f : Nat → α → β) (i : Nat)
+    (h : i < (mapIdx a f).size) :
+    (a.mapIdx f)[i] = f i (a[i]'(by simp_all)) :=
+  (mapIdx_spec _ _ (fun i b => b = f i a[i]) fun _ => rfl).2 i (by simp_all)
+
+@[simp] theorem getElem?_mapIdx (a : Array α) (f : Nat → α → β) (i : Nat) :
+    (a.mapIdx f)[i]? =
+      a[i]?.map (f i) := by
+  simp [getElem?_def, size_mapIdx, getElem_mapIdx]
+
+end Array

src/Init/Data/BitVec/Basic.lean

@@ -8,12 +8,13 @@ import Init.Data.Fin.Basic
 import Init.Data.Nat.Bitwise.Lemmas
 import Init.Data.Nat.Power2
 import Init.Data.Int.Bitwise
+import Init.Data.BitVec.BasicAux
 
 /-!
-We define bitvectors. We choose the `Fin` representation over others for its relative efficiency
-(Lean has special support for `Nat`), alignment with `UIntXY` types which are also represented
-with `Fin`, and the fact that bitwise operations on `Fin` are already defined. Some other possible
-representations are `List Bool`, `{ l : List Bool // l.length = w }`, `Fin w → Bool`.
+We define the basic algebraic structure of bitvectors. We choose the `Fin` representation over
+others for its relative efficiency (Lean has special support for `Nat`),  and the fact that bitwise
+operations on `Fin` are already defined. Some other possible representations are `List Bool`,
+`{ l : List Bool // l.length = w }`, `Fin w → Bool`.
 
 We define many of the bitvector operations from the
 [`QF_BV` logic](https://smtlib.cs.uiowa.edu/logics-all.shtml#QF_BV).
@@ -22,60 +23,12 @@ of SMT-LIBv2.
 
 set_option linter.missingDocs true
 
-/--
-A bitvector of the specified width.
-
-This is represented as the underlying `Nat` number in both the runtime
-and the kernel, inheriting all the special support for `Nat`.
--/
-structure BitVec (w : Nat) where
-  /-- Construct a `BitVec w` from a number less than `2^w`.
-  O(1), because we use `Fin` as the internal representation of a bitvector. -/
-  ofFin ::
-  /-- Interpret a bitvector as a number less than `2^w`.
-  O(1), because we use `Fin` as the internal representation of a bitvector. -/
-  toFin : Fin (2^w)
-
-/--
-Bitvectors have decidable equality. This should be used via the instance `DecidableEq (BitVec n)`.
--/
--- We manually derive the `DecidableEq` instances for `BitVec` because
--- we want to have builtin support for bit-vector literals, and we
--- need a name for this function to implement `canUnfoldAtMatcher` at `WHNF.lean`.
-def BitVec.decEq (x y : BitVec n) : Decidable (x = y) :=
-  match x, y with
-  | ⟨n⟩, ⟨m⟩ =>
-    if h : n = m then
-      isTrue (h ▸ rfl)
-    else
-      isFalse (fun h' => BitVec.noConfusion h' (fun h' => absurd h' h))
-
-instance : DecidableEq (BitVec n) := BitVec.decEq
-
 namespace BitVec
 
 section Nat
 
-/-- The `BitVec` with value `i`, given a proof that `i < 2^n`. -/
-@[match_pattern]
-protected def ofNatLt {n : Nat} (i : Nat) (p : i < 2^n) : BitVec n where
-  toFin := ⟨i, p⟩
-
-/-- The `BitVec` with value `i mod 2^n`. -/
-@[match_pattern]
-protected def ofNat (n : Nat) (i : Nat) : BitVec n where
-  toFin := Fin.ofNat' (2^n) i
-
-instance instOfNat : OfNat (BitVec n) i where ofNat := .ofNat n i
 instance natCastInst : NatCast (BitVec w) := ⟨BitVec.ofNat w⟩
 
-/-- Given a bitvector `x`, return the underlying `Nat`. This is O(1) because `BitVec` is a
-(zero-cost) wrapper around a `Nat`. -/
-protected def toNat (x : BitVec n) : Nat := x.toFin.val
-
-/-- Return the bound in terms of toNat. -/
-theorem isLt (x : BitVec w) : x.toNat < 2^w := x.toFin.isLt
-
 @[deprecated isLt (since := "2024-03-12")]
 theorem toNat_lt (x : BitVec n) : x.toNat < 2^n := x.isLt
 
@@ -238,22 +191,6 @@ end repr_toString
 
 section arithmetic
 
-/--
-Addition for bit vectors. This can be interpreted as either signed or unsigned addition
-modulo `2^n`.
-
-SMT-Lib name: `bvadd`.
--/
-protected def add (x y : BitVec n) : BitVec n := .ofNat n (x.toNat + y.toNat)
-instance : Add (BitVec n) := ⟨BitVec.add⟩
-
-/--
-Subtraction for bit vectors. This can be interpreted as either signed or unsigned subtraction
-modulo `2^n`.
--/
-protected def sub (x y : BitVec n) : BitVec n := .ofNat n ((2^n - y.toNat) + x.toNat)
-instance : Sub (BitVec n) := ⟨BitVec.sub⟩
-
 /--
 Negation for bit vectors. This can be interpreted as either signed or unsigned negation
 modulo `2^n`.
@@ -387,10 +324,6 @@ SMT-Lib name: `bvult`.
 -/
 protected def ult (x y : BitVec n) : Bool := x.toNat < y.toNat
 
-instance : LT (BitVec n) where lt := (·.toNat < ·.toNat)
-instance (x y : BitVec n) : Decidable (x < y) :=
-  inferInstanceAs (Decidable (x.toNat < y.toNat))
-
 /--
 Unsigned less-than-or-equal-to for bit vectors.
 
@@ -398,10 +331,6 @@ SMT-Lib name: `bvule`.
 -/
 protected def ule (x y : BitVec n) : Bool := x.toNat ≤ y.toNat
 
-instance : LE (BitVec n) where le := (·.toNat ≤ ·.toNat)
-instance (x y : BitVec n) : Decidable (x ≤ y) :=
-  inferInstanceAs (Decidable (x.toNat ≤ y.toNat))
-
 /--
 Signed less-than for bit vectors.
 

src/Init/Data/BitVec/BasicAux.lean

@@ -0,0 +1,52 @@
+/-
+Copyright (c) 2024 Lean FRO, LLC. All rights reserved.
+Released under Apache 2.0 license as described in the file LICENSE.
+Authors: Joe Hendrix, Wojciech Nawrocki, Leonardo de Moura, Mario Carneiro, Alex Keizer, Harun Khan, Abdalrhman M Mohamed
+-/
+prelude
+import Init.Data.Fin.Basic
+
+set_option linter.missingDocs true
+
+/-!
+This module exists to provide the very basic `BitVec` definitions required for
+`Init.Data.UInt.BasicAux`.
+-/
+
+namespace BitVec
+
+section Nat
+
+/-- The `BitVec` with value `i mod 2^n`. -/
+@[match_pattern]
+protected def ofNat (n : Nat) (i : Nat) : BitVec n where
+  toFin := Fin.ofNat' (2^n) i
+
+instance instOfNat : OfNat (BitVec n) i where ofNat := .ofNat n i
+
+/-- Return the bound in terms of toNat. -/
+theorem isLt (x : BitVec w) : x.toNat < 2^w := x.toFin.isLt
+
+end Nat
+
+section arithmetic
+
+/--
+Addition for bit vectors. This can be interpreted as either signed or unsigned addition
+modulo `2^n`.
+
+SMT-Lib name: `bvadd`.
+-/
+protected def add (x y : BitVec n) : BitVec n := .ofNat n (x.toNat + y.toNat)
+instance : Add (BitVec n) := ⟨BitVec.add⟩
+
+/--
+Subtraction for bit vectors. This can be interpreted as either signed or unsigned subtraction
+modulo `2^n`.
+-/
+protected def sub (x y : BitVec n) : BitVec n := .ofNat n ((2^n - y.toNat) + x.toNat)
+instance : Sub (BitVec n) := ⟨BitVec.sub⟩
+
+end arithmetic
+
+end BitVec

src/Init/Data/BitVec/Bitblast.lean

@@ -267,6 +267,21 @@ theorem add_eq_adc (w : Nat) (x y : BitVec w) : x + y = (adc x y false).snd := b
 
 /-! ### add -/
 
+theorem getMsbD_add {i : Nat} {i_lt : i < w} {x y : BitVec w} :
+    getMsbD (x + y) i =
+      Bool.xor (getMsbD x i) (Bool.xor (getMsbD y i) (carry (w - 1 - i) x y false)) := by
+  simp [getMsbD, getLsbD_add, i_lt, show w - 1 - i < w by omega]
+
+theorem msb_add {w : Nat} {x y: BitVec w} :
+    (x + y).msb =
+      Bool.xor x.msb (Bool.xor y.msb (carry (w - 1) x y false)) := by
+  simp only [BitVec.msb, BitVec.getMsbD]
+  by_cases h : w ≤ 0
+  · simp [h, show w = 0 by omega]
+  · rw [getLsbD_add (x := x)]
+    simp [show w > 0 by omega]
+    omega
+
 /-- Adding a bitvector to its own complement yields the all ones bitpattern -/
 @[simp] theorem add_not_self (x : BitVec w) : x + ~~~x = allOnes w := by
   rw [add_eq_adc, adc, iunfoldr_replace (fun _ => false) (allOnes w)]
@@ -292,6 +307,26 @@ theorem add_eq_or_of_and_eq_zero {w : Nat} (x y : BitVec w)
       simp_all [hx]
     · by_cases hx : x.getLsbD i <;> simp_all [hx]
 
+/-! ### Sub-/
+
+theorem getLsbD_sub {i : Nat} {i_lt : i < w} {x y : BitVec w} :
+    (x - y).getLsbD i
+      = (x.getLsbD i ^^ ((~~~y + 1#w).getLsbD i ^^ carry i x (~~~y + 1#w) false)) := by
+  rw [sub_toAdd, BitVec.neg_eq_not_add, getLsbD_add]
+  omega
+
+theorem getMsbD_sub {i : Nat} {i_lt : i < w} {x y : BitVec w} :
+    (x - y).getMsbD i =
+      (x.getMsbD i ^^ ((~~~y + 1).getMsbD i ^^ carry (w - 1 - i) x (~~~y + 1) false)) := by
+  rw [sub_toAdd, neg_eq_not_add, getMsbD_add]
+  · rfl
+  · omega
+
+theorem msb_sub {x y: BitVec w} :
+    (x - y).msb
+      = (x.msb ^^ ((~~~y + 1#w).msb ^^ carry (w - 1 - 0) x (~~~y + 1#w) false)) := by
+  simp [sub_toAdd, BitVec.neg_eq_not_add, msb_add]
+
 /-! ### Negation -/
 
 theorem bit_not_testBit (x : BitVec w) (i : Fin w) :

src/Init/Data/BitVec/Lemmas.lean

@@ -316,6 +316,12 @@ theorem getLsbD_ofNat (n : Nat) (x : Nat) (i : Nat) :
   simp [Nat.sub_sub_eq_min, Nat.min_eq_right]
   omega
 
+@[simp] theorem sub_add_bmod_cancel {x y : BitVec w} :
+    ((((2 ^ w : Nat) - y.toNat) : Int) + x.toNat).bmod (2 ^ w) =
+      ((x.toNat : Int) - y.toNat).bmod (2 ^ w) := by
+  rw [Int.sub_eq_add_neg, Int.add_assoc, Int.add_comm, Int.bmod_add_cancel, Int.add_comm,
+    Int.sub_eq_add_neg]
+
 private theorem lt_two_pow_of_le {x m n : Nat} (lt : x < 2 ^ m) (le : m ≤ n) : x < 2 ^ n :=
   Nat.lt_of_lt_of_le lt (Nat.pow_le_pow_of_le_right (by trivial : 0 < 2) le)
 
@@ -1974,6 +1980,10 @@ theorem sub_def {n} (x y : BitVec n) : x - y = .ofNat n ((2^n - y.toNat) + x.toN
 @[simp] theorem toNat_sub {n} (x y : BitVec n) :
     (x - y).toNat = (((2^n - y.toNat) + x.toNat) % 2^n) := rfl
 
+@[simp, bv_toNat] theorem toInt_sub {x y : BitVec w} :
+    (x - y).toInt = (x.toInt - y.toInt).bmod (2 ^ w) := by
+  simp [toInt_eq_toNat_bmod, @Int.ofNat_sub y.toNat (2 ^ w) (by omega)]
+
 -- We prefer this lemma to `toNat_sub` for the `bv_toNat` simp set.
 -- For reasons we don't yet understand, unfolding via `toNat_sub` sometimes
 -- results in `omega` generating proof terms that are very slow in the kernel.
@@ -1996,6 +2006,8 @@ theorem ofNat_sub_ofNat {n} (x y : Nat) : BitVec.ofNat n x - BitVec.ofNat n y =
 
 @[simp] protected theorem sub_zero (x : BitVec n) : x - 0#n = x := by apply eq_of_toNat_eq ; simp
 
+@[simp] protected theorem zero_sub (x : BitVec n) : 0#n - x = -x := rfl
+
 @[simp] protected theorem sub_self (x : BitVec n) : x - x = 0#n := by
   apply eq_of_toNat_eq
   simp only [toNat_sub]
@@ -2008,18 +2020,8 @@ theorem ofNat_sub_ofNat {n} (x y : Nat) : BitVec.ofNat n x - BitVec.ofNat n y =
 
 theorem toInt_neg {x : BitVec w} :
     (-x).toInt = (-x.toInt).bmod (2 ^ w) := by
-  simp only [toInt_eq_toNat_bmod, toNat_neg, Int.ofNat_emod, Int.emod_bmod_congr]
-  rw [← Int.subNatNat_of_le (by omega), Int.subNatNat_eq_coe, Int.sub_eq_add_neg, Int.add_comm,
-    Int.bmod_add_cancel]
-  by_cases h : x.toNat < ((2 ^ w) + 1) / 2
-  · rw [Int.bmod_pos (x := x.toNat)]
-    all_goals simp only [toNat_mod_cancel']
-    norm_cast
-  · rw [Int.bmod_neg (x := x.toNat)]
-    · simp only [toNat_mod_cancel']
-      rw_mod_cast [Int.neg_sub, Int.sub_eq_add_neg, Int.add_comm, Int.bmod_add_cancel]
-    · norm_cast
-      simp_all
+  rw [← BitVec.zero_sub, toInt_sub]
+  simp [BitVec.toInt_ofNat]
 
 @[simp] theorem toFin_neg (x : BitVec n) :
     (-x).toFin = Fin.ofNat' (2^n) (2^n - x.toNat) :=

src/Init/Data/Char/Basic.lean

@@ -4,7 +4,7 @@ Released under Apache 2.0 license as described in the file LICENSE.
 Author: Leonardo de Moura
 -/
 prelude
-import Init.Data.UInt.Basic
+import Init.Data.UInt.BasicAux
 
 /-- Determines if the given integer is a valid [Unicode scalar value](https://www.unicode.org/glossary/#unicode_scalar_value).
 
@@ -42,8 +42,10 @@ theorem isValidUInt32 (n : Nat) (h : isValidCharNat n) : n < UInt32.size := by
 
 theorem isValidChar_of_isValidCharNat (n : Nat) (h : isValidCharNat n) : isValidChar (UInt32.ofNat' n (isValidUInt32 n h)) :=
   match h with
-  | Or.inl h        => Or.inl h
-  | Or.inr ⟨h₁, h₂⟩ => Or.inr ⟨h₁, h₂⟩
+  | Or.inl h =>
+    Or.inl (UInt32.ofNat'_lt_of_lt _ (by decide) h)
+  | Or.inr ⟨h₁, h₂⟩ =>
+    Or.inr ⟨UInt32.lt_ofNat'_of_lt _ (by decide) h₁, UInt32.ofNat'_lt_of_lt _ (by decide) h₂⟩
 
 theorem isValidChar_zero : isValidChar 0 :=
   Or.inl (by decide)
@@ -57,7 +59,7 @@ theorem isValidChar_zero : isValidChar 0 :=
   c.val.toUInt8
 
 /-- The numbers from 0 to 256 are all valid UTF-8 characters, so we can embed one in the other. -/
-def ofUInt8 (n : UInt8) : Char := ⟨n.toUInt32, .inl (Nat.lt_trans n.1.2 (by decide))⟩
+def ofUInt8 (n : UInt8) : Char := ⟨n.toUInt32, .inl (Nat.lt_trans n.toBitVec.isLt (by decide))⟩
 
 instance : Inhabited Char where
   default := 'A'

src/Init/Data/Hashable.lean

@@ -51,6 +51,9 @@ instance : Hashable USize where
 instance : Hashable (Fin n) where
   hash v := v.val.toUInt64
 
+instance : Hashable Char where
+  hash c := c.val.toUInt64
+
 instance : Hashable Int where
   hash
     | Int.ofNat n => UInt64.ofNat (2 * n)

src/Init/Data/Int/DivModLemmas.lean

@@ -1125,6 +1125,17 @@ theorem emod_add_bmod_congr (x : Int) (n : Nat) : Int.bmod (x%n + y) n = Int.bmo
   simp [Int.emod_def, Int.sub_eq_add_neg]
   rw [←Int.mul_neg, Int.add_right_comm,  Int.bmod_add_mul_cancel]
 
+@[simp]
+theorem emod_sub_bmod_congr (x : Int) (n : Nat) : Int.bmod (x%n - y) n = Int.bmod (x - y) n := by
+  simp only [emod_def, Int.sub_eq_add_neg]
+  rw [←Int.mul_neg, Int.add_right_comm,  Int.bmod_add_mul_cancel]
+
+@[simp]
+theorem sub_emod_bmod_congr (x : Int) (n : Nat) : Int.bmod (x - y%n) n = Int.bmod (x - y) n := by
+  simp only [emod_def]
+  rw [Int.sub_eq_add_neg, Int.neg_sub, Int.sub_eq_add_neg, ← Int.add_assoc, Int.add_right_comm,
+    Int.bmod_add_mul_cancel, Int.sub_eq_add_neg]
+
 @[simp]
 theorem emod_mul_bmod_congr (x : Int) (n : Nat) : Int.bmod (x%n * y) n = Int.bmod (x * y) n := by
   simp [Int.emod_def, Int.sub_eq_add_neg]
@@ -1140,9 +1151,28 @@ theorem bmod_add_bmod_congr : Int.bmod (Int.bmod x n + y) n = Int.bmod (x + y) n
     rw [Int.sub_eq_add_neg, Int.add_right_comm, ←Int.sub_eq_add_neg]
     simp
 
+@[simp]
+theorem bmod_sub_bmod_congr : Int.bmod (Int.bmod x n - y) n = Int.bmod (x - y) n := by
+  rw [Int.bmod_def x n]
+  split
+  next p =>
+    simp only [emod_sub_bmod_congr]
+  next p =>
+    rw [Int.sub_eq_add_neg, Int.sub_eq_add_neg, Int.add_right_comm, ←Int.sub_eq_add_neg, ← Int.sub_eq_add_neg]
+    simp [emod_sub_bmod_congr]
+
 @[simp] theorem add_bmod_bmod : Int.bmod (x + Int.bmod y n) n = Int.bmod (x + y) n := by
   rw [Int.add_comm x, Int.bmod_add_bmod_congr, Int.add_comm y]
 
+@[simp] theorem sub_bmod_bmod : Int.bmod (x - Int.bmod y n) n = Int.bmod (x - y) n := by
+  rw [Int.bmod_def y n]
+  split
+  next p =>
+    simp [sub_emod_bmod_congr]
+  next p =>
+    rw [Int.sub_eq_add_neg, Int.sub_eq_add_neg, Int.neg_add, Int.neg_neg, ← Int.add_assoc, ← Int.sub_eq_add_neg]
+    simp [sub_emod_bmod_congr]
+
 @[simp]
 theorem bmod_mul_bmod : Int.bmod (Int.bmod x n * y) n = Int.bmod (x * y) n := by
   rw [bmod_def x n]

src/Init/Data/List/Attach.lean

@@ -639,14 +639,16 @@ and simplifies these to the function directly taking the value.
   | nil => simp
   | cons a l ih => simp [ih, hf, filterMap_cons]
 
-@[simp] theorem bind_subtype {p : α → Prop} {l : List { x // p x }}
+@[simp] theorem flatMap_subtype {p : α → Prop} {l : List { x // p x }}
     {f : { x // p x } → List β} {g : α → List β} {hf : ∀ x h, f ⟨x, h⟩ = g x} :
-    (l.bind f) = l.unattach.bind g := by
+    (l.flatMap f) = l.unattach.flatMap g := by
   unfold unattach
   induction l with
   | nil => simp
   | cons a l ih => simp [ih, hf]
 
+@[deprecated flatMap_subtype (since := "2024-10-16")] abbrev bind_subtype := @flatMap_subtype
+
 @[simp] theorem unattach_filter {p : α → Prop} {l : List { x // p x }}
     {f : { x // p x } → Bool} {g : α → Bool} {hf : ∀ x h, f ⟨x, h⟩ = g x} :
     (l.filter f).unattach = l.unattach.filter g := by

src/Init/Data/List/Basic.lean

@@ -38,7 +38,7 @@ The operations are organized as follow:
 * Sublists: `take`, `drop`, `takeWhile`, `dropWhile`, `partition`, `dropLast`,
   `isPrefixOf`, `isPrefixOf?`, `isSuffixOf`, `isSuffixOf?`, `Subset`, `Sublist`,
   `rotateLeft` and `rotateRight`.
-* Manipulating elements: `replace`, `insert`, `erase`, `eraseP`, `eraseIdx`.
+* Manipulating elements: `replace`, `insert`, `modify`, `erase`, `eraseP`, `eraseIdx`.
 * Finding elements: `find?`, `findSome?`, `findIdx`, `indexOf`, `findIdx?`, `indexOf?`,
  `countP`, `count`, and `lookup`.
 * Logic: `any`, `all`, `or`, and `and`.
@@ -122,6 +122,11 @@ protected def beq [BEq α] : List α → List α → Bool
   | a::as, b::bs => a == b && List.beq as bs
   | _,     _     => false
 
+@[simp] theorem beq_nil_nil [BEq α] : List.beq ([] : List α) ([] : List α) = true := rfl
+@[simp] theorem beq_cons_nil [BEq α] (a : α) (as : List α) : List.beq (a::as) [] = false := rfl
+@[simp] theorem beq_nil_cons [BEq α] (a : α) (as : List α) : List.beq [] (a::as) = false := rfl
+theorem beq_cons₂ [BEq α] (a b : α) (as bs : List α) : List.beq (a::as) (b::bs) = (a == b && List.beq as bs) := rfl
+
 instance [BEq α] : BEq (List α) := ⟨List.beq⟩
 
 instance [BEq α] [LawfulBEq α] : LawfulBEq (List α) where
@@ -558,28 +563,38 @@ def flatten : List (List α) → List α
 
 @[deprecated flatten (since := "2024-10-14"), inherit_doc flatten] abbrev join := @flatten
 
-/-! ### pure -/
+/-! ### singleton -/
 
-/-- `pure x = [x]` is the `pure` operation of the list monad. -/
-@[inline] protected def pure {α : Type u} (a : α) : List α := [a]
+/-- `singleton x = [x]`. -/
+@[inline] protected def singleton {α : Type u} (a : α) : List α := [a]
 
-/-! ### bind -/
+set_option linter.missingDocs false in
+@[deprecated singleton (since := "2024-10-16")] protected abbrev pure := @singleton
+
+/-! ### flatMap -/
 
 /--
-`bind xs f` is the bind operation of the list monad. It applies `f` to each element of `xs`
+`flatMap xs f` applies `f` to each element of `xs`
 to get a list of lists, and then concatenates them all together.
 * `[2, 3, 2].bind range = [0, 1, 0, 1, 2, 0, 1]`
 -/
-@[inline] protected def bind {α : Type u} {β : Type v} (a : List α) (b : α → List β) : List β := flatten (map b a)
+@[inline] def flatMap {α : Type u} {β : Type v} (a : List α) (b : α → List β) : List β := flatten (map b a)
 
-@[simp] theorem bind_nil (f : α → List β) : List.bind [] f = [] := by simp [flatten, List.bind]
-@[simp] theorem bind_cons x xs (f : α → List β) :
-  List.bind (x :: xs) f = f x ++ List.bind xs f := by simp [flatten, List.bind]
+@[simp] theorem flatMap_nil (f : α → List β) : List.flatMap [] f = [] := by simp [flatten, List.flatMap]
+@[simp] theorem flatMap_cons x xs (f : α → List β) :
+  List.flatMap (x :: xs) f = f x ++ List.flatMap xs f := by simp [flatten, List.flatMap]
 
 set_option linter.missingDocs false in
-@[deprecated bind_nil (since := "2024-06-15")] abbrev nil_bind := @bind_nil
+@[deprecated flatMap (since := "2024-10-16")] abbrev bind := @flatMap
 set_option linter.missingDocs false in
-@[deprecated bind_cons (since := "2024-06-15")] abbrev cons_bind := @bind_cons
+@[deprecated flatMap_nil (since := "2024-10-16")] abbrev nil_flatMap := @flatMap_nil
+set_option linter.missingDocs false in
+@[deprecated flatMap_cons (since := "2024-10-16")] abbrev cons_flatMap := @flatMap_cons
+
+set_option linter.missingDocs false in
+@[deprecated flatMap_nil (since := "2024-06-15")] abbrev nil_bind := @flatMap_nil
+set_option linter.missingDocs false in
+@[deprecated flatMap_cons (since := "2024-06-15")] abbrev cons_bind := @flatMap_cons
 
 /-! ### replicate -/
 
@@ -1104,6 +1119,35 @@ theorem replace_cons [BEq α] {a : α} :
 @[inline] protected def insert [BEq α] (a : α) (l : List α) : List α :=
   if l.elem a then l else a :: l
 
+/-! ### modify -/
+
+/--
+Apply a function to the nth tail of `l`. Returns the input without
+using `f` if the index is larger than the length of the List.
+```
+modifyTailIdx f 2 [a, b, c] = [a, b] ++ f [c]
+```
+-/
+@[simp] def modifyTailIdx (f : List α → List α) : Nat → List α → List α
+  | 0, l => f l
+  | _+1, [] => []
+  | n+1, a :: l => a :: modifyTailIdx f n l
+
+/-- Apply `f` to the head of the list, if it exists. -/
+@[inline] def modifyHead (f : α → α) : List α → List α
+  | [] => []
+  | a :: l => f a :: l
+
+@[simp] theorem modifyHead_nil (f : α → α) : [].modifyHead f = [] := by rw [modifyHead]
+@[simp] theorem modifyHead_cons (a : α) (l : List α) (f : α → α) :
+    (a :: l).modifyHead f = f a :: l := by rw [modifyHead]
+
+/--
+Apply `f` to the nth element of the list, if it exists, replacing that element with the result.
+-/
+def modify (f : α → α) : Nat → List α → List α :=
+  modifyTailIdx (modifyHead f)
+
 /-! ### erase -/
 
 /--
@@ -1408,11 +1452,15 @@ def sum {α} [Add α] [Zero α] : List α → α :=
 @[simp] theorem sum_cons [Add α] [Zero α] {a : α} {l : List α} : (a::l).sum = a + l.sum := rfl
 
 /-- Sum of a list of natural numbers. -/
--- We intend to subsequently deprecate this in favor of `List.sum`.
+@[deprecated List.sum (since := "2024-10-17")]
 protected def _root_.Nat.sum (l : List Nat) : Nat := l.foldr (·+·) 0
 
-@[simp] theorem _root_.Nat.sum_nil : Nat.sum ([] : List Nat) = 0 := rfl
-@[simp] theorem _root_.Nat.sum_cons (a : Nat) (l : List Nat) :
+set_option linter.deprecated false in
+@[simp, deprecated sum_nil (since := "2024-10-17")]
+theorem _root_.Nat.sum_nil : Nat.sum ([] : List Nat) = 0 := rfl
+set_option linter.deprecated false in
+@[simp, deprecated sum_cons (since := "2024-10-17")]
+theorem _root_.Nat.sum_cons (a : Nat) (l : List Nat) :
     Nat.sum (a::l) = a + Nat.sum l := rfl
 
 /-! ### range -/

src/Init/Data/List/BasicAux.lean

@@ -232,7 +232,8 @@ theorem sizeOf_get [SizeOf α] (as : List α) (i : Fin as.length) : sizeOf (as.g
     apply Nat.lt_trans ih
     simp_arith
 
-theorem le_antisymm [LT α] [s : Antisymm (¬ · < · : α → α → Prop)] {as bs : List α} (h₁ : as ≤ bs) (h₂ : bs ≤ as) : as = bs :=
+theorem le_antisymm [LT α] [s : Std.Antisymm (¬ · < · : α → α → Prop)]
+    {as bs : List α} (h₁ : as ≤ bs) (h₂ : bs ≤ as) : as = bs :=
   match as, bs with
   | [],    []    => rfl
   | [],    _::_ => False.elim <| h₂ (List.lt.nil ..)
@@ -248,7 +249,8 @@ theorem le_antisymm [LT α] [s : Antisymm (¬ · < · : α → α → Prop)] {as
         have : a = b := s.antisymm hab hba
         simp [this, ih]
 
-instance [LT α] [Antisymm (¬ · < · : α → α → Prop)] : Antisymm (· ≤ · : List α → List α → Prop) where
+instance [LT α] [Std.Antisymm (¬ · < · : α → α → Prop)] :
+    Std.Antisymm (· ≤ · : List α → List α → Prop) where
   antisymm h₁ h₂ := le_antisymm h₁ h₂
 
 end List

src/Init/Data/List/Find.lean

@@ -378,14 +378,18 @@ theorem find?_flatten_eq_some {xs : List (List α)} {p : α → Bool} {a : α} :
     · exact h₁ l ml a m
     · exact h₂ a m
 
-@[simp] theorem find?_bind (xs : List α) (f : α → List β) (p : β → Bool) :
-    (xs.bind f).find? p = xs.findSome? (fun x => (f x).find? p) := by
-  simp [bind_def, findSome?_map]; rfl
+@[simp] theorem find?_flatMap (xs : List α) (f : α → List β) (p : β → Bool) :
+    (xs.flatMap f).find? p = xs.findSome? (fun x => (f x).find? p) := by
+  simp [flatMap_def, findSome?_map]; rfl
 
-theorem find?_bind_eq_none {xs : List α} {f : α → List β} {p : β → Bool} :
-    (xs.bind f).find? p = none ↔ ∀ x ∈ xs, ∀ y ∈ f x, !p y := by
+@[deprecated find?_flatMap (since := "2024-10-16")] abbrev find?_bind := @find?_flatMap
+
+theorem find?_flatMap_eq_none {xs : List α} {f : α → List β} {p : β → Bool} :
+    (xs.flatMap f).find? p = none ↔ ∀ x ∈ xs, ∀ y ∈ f x, !p y := by
   simp
 
+@[deprecated find?_flatMap_eq_none (since := "2024-10-16")] abbrev find?_bind_eq_none := @find?_flatMap_eq_none
+
 theorem find?_replicate : find? p (replicate n a) = if n = 0 then none else if p a then some a else none := by
   cases n
   · simp

src/Init/Data/List/Impl.lean

@@ -38,7 +38,7 @@ The following operations were already given `@[csimp]` replacements in `Init/Dat
 
 The following operations are given `@[csimp]` replacements below:
 `set`, `filterMap`, `foldr`, `append`, `bind`, `join`,
-`take`, `takeWhile`, `dropLast`, `replace`, `erase`, `eraseIdx`, `zipWith`,
+`take`, `takeWhile`, `dropLast`, `replace`, `modify`, `erase`, `eraseIdx`, `zipWith`,
 `enumFrom`, and `intercalate`.
 
 -/
@@ -93,29 +93,29 @@ The following operations are given `@[csimp]` replacements below:
 @[csimp] theorem foldr_eq_foldrTR : @foldr = @foldrTR := by
   funext α β f init l; simp [foldrTR, Array.foldr_eq_foldr_toList, -Array.size_toArray]
 
-/-! ### bind  -/
+/-! ### flatMap  -/
 
-/-- Tail recursive version of `List.bind`. -/
-@[inline] def bindTR (as : List α) (f : α → List β) : List β := go as #[] where
-  /-- Auxiliary for `bind`: `bind.go f as = acc.toList ++ bind f as` -/
+/-- Tail recursive version of `List.flatMap`. -/
+@[inline] def flatMapTR (as : List α) (f : α → List β) : List β := go as #[] where
+  /-- Auxiliary for `flatMap`: `flatMap.go f as = acc.toList ++ bind f as` -/
   @[specialize] go : List α → Array β → List β
   | [], acc => acc.toList
   | x::xs, acc => go xs (acc ++ f x)
 
-@[csimp] theorem bind_eq_bindTR : @List.bind = @bindTR := by
+@[csimp] theorem flatMap_eq_flatMapTR : @List.flatMap = @flatMapTR := by
   funext α β as f
-  let rec go : ∀ as acc, bindTR.go f as acc = acc.toList ++ as.bind f
-    | [], acc => by simp [bindTR.go, bind]
-    | x::xs, acc => by simp [bindTR.go, bind, go xs]
+  let rec go : ∀ as acc, flatMapTR.go f as acc = acc.toList ++ as.flatMap f
+    | [], acc => by simp [flatMapTR.go, flatMap]
+    | x::xs, acc => by simp [flatMapTR.go, flatMap, go xs]
   exact (go as #[]).symm
 
 /-! ### flatten -/
 
 /-- Tail recursive version of `List.flatten`. -/
-@[inline] def flattenTR (l : List (List α)) : List α := bindTR l id
+@[inline] def flattenTR (l : List (List α)) : List α := flatMapTR l id
 
 @[csimp] theorem flatten_eq_flattenTR : @flatten = @flattenTR := by
-  funext α l; rw [← List.bind_id, List.bind_eq_bindTR]; rfl
+  funext α l; rw [← List.flatMap_id, List.flatMap_eq_flatMapTR]; rfl
 
 /-! ## Sublists -/
 
@@ -197,6 +197,24 @@ The following operations are given `@[csimp]` replacements below:
     · simp [*]
     · intro h; rw [IH] <;> simp_all
 
+/-! ### modify -/
+
+/-- Tail-recursive version of `modify`. -/
+def modifyTR (f : α → α) (n : Nat) (l : List α) : List α := go l n #[] where
+  /-- Auxiliary for `modifyTR`: `modifyTR.go f l n acc = acc.toList ++ modify f n l`. -/
+  go : List α → Nat → Array α → List α
+  | [], _, acc => acc.toList
+  | a :: l, 0, acc => acc.toListAppend (f a :: l)
+  | a :: l, n+1, acc => go l n (acc.push a)
+
+theorem modifyTR_go_eq : ∀ l n, modifyTR.go f l n acc = acc.toList ++ modify f n l
+  | [], n => by cases n <;> simp [modifyTR.go, modify]
+  | a :: l, 0 => by simp [modifyTR.go, modify]
+  | a :: l, n+1 => by simp [modifyTR.go, modify, modifyTR_go_eq l]
+
+@[csimp] theorem modify_eq_modifyTR : @modify = @modifyTR := by
+  funext α f n l; simp [modifyTR, modifyTR_go_eq]
+
 /-! ### erase -/
 
 /-- Tail recursive version of `List.erase`. -/

src/Init/Data/List/Lemmas.lean

@@ -1047,9 +1047,6 @@ theorem get_cons_length (x : α) (xs : List α) (n : Nat) (h : n = xs.length) :
 
 @[simp] theorem getLast?_singleton (a : α) : getLast? [a] = a := rfl
 
-theorem getLast!_of_getLast? [Inhabited α] : ∀ {l : List α}, getLast? l = some a → getLast! l = a
-  | _ :: _, rfl => rfl
-
 theorem getLast?_eq_getLast : ∀ l h, @getLast? α l = some (getLast l h)
   | [], h => nomatch h rfl
   | _ :: _, _ => rfl
@@ -1083,6 +1080,21 @@ theorem getLast?_concat (l : List α) : getLast? (l ++ [a]) = some a := by
 theorem getLastD_concat (a b l) : @getLastD α (l ++ [b]) a = b := by
   rw [getLastD_eq_getLast?, getLast?_concat]; rfl
 
+/-! ### getLast! -/
+
+@[simp] theorem getLast!_nil [Inhabited α] : ([] : List α).getLast! = default := rfl
+
+theorem getLast!_of_getLast? [Inhabited α] : ∀ {l : List α}, getLast? l = some a → getLast! l = a
+  | _ :: _, rfl => rfl
+
+theorem getLast!_eq_getElem! [Inhabited α] {l : List α} : l.getLast! = l[l.length - 1]! := by
+  cases l with
+  | nil => simp
+  | cons _ _ =>
+    apply getLast!_of_getLast?
+    rw [getElem!_pos, getElem_cons_length (h := by simp)]
+    rfl
+
 /-! ## Head and tail -/
 
 /-! ### head -/
@@ -2097,8 +2109,8 @@ theorem forall_mem_flatten {p : α → Prop} {L : List (List α)} :
   simp only [mem_flatten, forall_exists_index, and_imp]
   constructor <;> (intros; solve_by_elim)
 
-theorem flatten_eq_bind {L : List (List α)} : flatten L = L.bind id := by
-  induction L <;> simp [List.bind]
+theorem flatten_eq_flatMap {L : List (List α)} : flatten L = L.flatMap id := by
+  induction L <;> simp [List.flatMap]
 
 theorem head?_flatten {L : List (List α)} : (flatten L).head? = L.findSome? fun l => l.head? := by
   induction L with
@@ -2215,86 +2227,86 @@ theorem eq_iff_flatten_eq : ∀ {L L' : List (List α)},
       obtain ⟨rfl, h⟩ := append_inj h₁ h₂
       exact ⟨rfl, h, h₃⟩
 
-/-! ### bind -/
+/-! ### flatMap -/
 
-theorem bind_def (l : List α) (f : α → List β) : l.bind f = flatten (map f l) := by rfl
+theorem flatMap_def (l : List α) (f : α → List β) : l.flatMap f = flatten (map f l) := by rfl
 
-@[simp] theorem bind_id (l : List (List α)) : List.bind l id = l.flatten := by simp [bind_def]
+@[simp] theorem flatMap_id (l : List (List α)) : List.flatMap l id = l.flatten := by simp [flatMap_def]
 
-@[simp] theorem mem_bind {f : α → List β} {b} {l : List α} : b ∈ l.bind f ↔ ∃ a, a ∈ l ∧ b ∈ f a := by
-  simp [bind_def, mem_flatten]
+@[simp] theorem mem_flatMap {f : α → List β} {b} {l : List α} : b ∈ l.flatMap f ↔ ∃ a, a ∈ l ∧ b ∈ f a := by
+  simp [flatMap_def, mem_flatten]
   exact ⟨fun ⟨_, ⟨a, h₁, rfl⟩, h₂⟩ => ⟨a, h₁, h₂⟩, fun ⟨a, h₁, h₂⟩ => ⟨_, ⟨a, h₁, rfl⟩, h₂⟩⟩
 
-theorem exists_of_mem_bind {b : β} {l : List α} {f : α → List β} :
-    b ∈ l.bind f → ∃ a, a ∈ l ∧ b ∈ f a := mem_bind.1
+theorem exists_of_mem_flatMap {b : β} {l : List α} {f : α → List β} :
+    b ∈ l.flatMap f → ∃ a, a ∈ l ∧ b ∈ f a := mem_flatMap.1
 
-theorem mem_bind_of_mem {b : β} {l : List α} {f : α → List β} {a} (al : a ∈ l) (h : b ∈ f a) :
-    b ∈ l.bind f := mem_bind.2 ⟨a, al, h⟩
+theorem mem_flatMap_of_mem {b : β} {l : List α} {f : α → List β} {a} (al : a ∈ l) (h : b ∈ f a) :
+    b ∈ l.flatMap f := mem_flatMap.2 ⟨a, al, h⟩
 
 @[simp]
-theorem bind_eq_nil_iff {l : List α} {f : α → List β} : List.bind l f = [] ↔ ∀ x ∈ l, f x = [] :=
+theorem flatMap_eq_nil_iff {l : List α} {f : α → List β} : List.flatMap l f = [] ↔ ∀ x ∈ l, f x = [] :=
   flatten_eq_nil_iff.trans <| by
     simp only [mem_map, forall_exists_index, and_imp, forall_apply_eq_imp_iff₂]
 
-@[deprecated bind_eq_nil_iff (since := "2024-09-05")] abbrev bind_eq_nil := @bind_eq_nil_iff
+@[deprecated flatMap_eq_nil_iff (since := "2024-09-05")] abbrev bind_eq_nil := @flatMap_eq_nil_iff
 
-theorem forall_mem_bind {p : β → Prop} {l : List α} {f : α → List β} :
-    (∀ (x) (_ : x ∈ l.bind f), p x) ↔ ∀ (a) (_ : a ∈ l) (b) (_ : b ∈ f a), p b := by
-  simp only [mem_bind, forall_exists_index, and_imp]
+theorem forall_mem_flatMap {p : β → Prop} {l : List α} {f : α → List β} :
+    (∀ (x) (_ : x ∈ l.flatMap f), p x) ↔ ∀ (a) (_ : a ∈ l) (b) (_ : b ∈ f a), p b := by
+  simp only [mem_flatMap, forall_exists_index, and_imp]
   constructor <;> (intros; solve_by_elim)
 
-theorem bind_singleton (f : α → List β) (x : α) : [x].bind f = f x :=
+theorem flatMap_singleton (f : α → List β) (x : α) : [x].flatMap f = f x :=
   append_nil (f x)
 
-@[simp] theorem bind_singleton' (l : List α) : (l.bind fun x => [x]) = l := by
+@[simp] theorem flatMap_singleton' (l : List α) : (l.flatMap fun x => [x]) = l := by
   induction l <;> simp [*]
 
-theorem head?_bind {l : List α} {f : α → List β} :
-    (l.bind f).head? = l.findSome? fun a => (f a).head? := by
+theorem head?_flatMap {l : List α} {f : α → List β} :
+    (l.flatMap f).head? = l.findSome? fun a => (f a).head? := by
   induction l with
   | nil => rfl
   | cons =>
     simp only [findSome?_cons]
     split <;> simp_all
 
-@[simp] theorem bind_append (xs ys : List α) (f : α → List β) :
-    (xs ++ ys).bind f = xs.bind f ++ ys.bind f := by
-  induction xs; {rfl}; simp_all [bind_cons, append_assoc]
+@[simp] theorem flatMap_append (xs ys : List α) (f : α → List β) :
+    (xs ++ ys).flatMap f = xs.flatMap f ++ ys.flatMap f := by
+  induction xs; {rfl}; simp_all [flatMap_cons, append_assoc]
 
-@[deprecated bind_append (since := "2024-07-24")] abbrev append_bind := @bind_append
+@[deprecated flatMap_append (since := "2024-07-24")] abbrev append_bind := @flatMap_append
 
-theorem bind_assoc {α β} (l : List α) (f : α → List β) (g : β → List γ) :
-    (l.bind f).bind g = l.bind fun x => (f x).bind g := by
+theorem flatMap_assoc {α β} (l : List α) (f : α → List β) (g : β → List γ) :
+    (l.flatMap f).flatMap g = l.flatMap fun x => (f x).flatMap g := by
   induction l <;> simp [*]
 
-theorem map_bind (f : β → γ) (g : α → List β) :
-    ∀ l : List α, (l.bind g).map f = l.bind fun a => (g a).map f
+theorem map_flatMap (f : β → γ) (g : α → List β) :
+    ∀ l : List α, (l.flatMap g).map f = l.flatMap fun a => (g a).map f
   | [] => rfl
-  | a::l => by simp only [bind_cons, map_append, map_bind _ _ l]
+  | a::l => by simp only [flatMap_cons, map_append, map_flatMap _ _ l]
 
-theorem bind_map (f : α → β) (g : β → List γ) (l : List α) :
-    (map f l).bind g = l.bind (fun a => g (f a)) := by
-  induction l <;> simp [bind_cons, *]
+theorem flatMap_map (f : α → β) (g : β → List γ) (l : List α) :
+    (map f l).flatMap g = l.flatMap (fun a => g (f a)) := by
+  induction l <;> simp [flatMap_cons, *]
 
-theorem map_eq_bind {α β} (f : α → β) (l : List α) : map f l = l.bind fun x => [f x] := by
+theorem map_eq_flatMap {α β} (f : α → β) (l : List α) : map f l = l.flatMap fun x => [f x] := by
   simp only [← map_singleton]
-  rw [← bind_singleton' l, map_bind, bind_singleton']
+  rw [← flatMap_singleton' l, map_flatMap, flatMap_singleton']
 
-theorem filterMap_bind {β γ} (l : List α) (g : α → List β) (f : β → Option γ) :
-    (l.bind g).filterMap f = l.bind fun a => (g a).filterMap f := by
+theorem filterMap_flatMap {β γ} (l : List α) (g : α → List β) (f : β → Option γ) :
+    (l.flatMap g).filterMap f = l.flatMap fun a => (g a).filterMap f := by
   induction l <;> simp [*]
 
-theorem filter_bind (l : List α) (g : α → List β) (f : β → Bool) :
-    (l.bind g).filter f = l.bind fun a => (g a).filter f := by
+theorem filter_flatMap (l : List α) (g : α → List β) (f : β → Bool) :
+    (l.flatMap g).filter f = l.flatMap fun a => (g a).filter f := by
   induction l <;> simp [*]
 
-theorem bind_eq_foldl (f : α → List β) (l : List α) :
-    l.bind f = l.foldl (fun acc a => acc ++ f a) [] := by
-  suffices ∀ l', l' ++ l.bind f = l.foldl (fun acc a => acc ++ f a) l' by simpa using this []
+theorem flatMap_eq_foldl (f : α → List β) (l : List α) :
+    l.flatMap f = l.foldl (fun acc a => acc ++ f a) [] := by
+  suffices ∀ l', l' ++ l.flatMap f = l.foldl (fun acc a => acc ++ f a) l' by simpa using this []
   intro l'
   induction l generalizing l'
   · simp
-  · next ih => rw [bind_cons, ← append_assoc, ih, foldl_cons]
+  · next ih => rw [flatMap_cons, ← append_assoc, ih, foldl_cons]
 
 /-! ### replicate -/
 
@@ -2484,10 +2496,10 @@ theorem filterMap_replicate_of_some {f : α → Option β} (h : f a = some b) :
     simp only [replicate_succ, flatten_cons, ih, append_replicate_replicate, replicate_inj, or_true,
       and_true, add_one_mul, Nat.add_comm]
 
-theorem bind_replicate {β} (f : α → List β) : (replicate n a).bind f = (replicate n (f a)).flatten := by
+theorem flatMap_replicate {β} (f : α → List β) : (replicate n a).flatMap f = (replicate n (f a)).flatten := by
   induction n with
   | zero => simp
-  | succ n ih => simp only [replicate_succ, bind_cons, ih, flatten_cons]
+  | succ n ih => simp only [replicate_succ, flatMap_cons, ih, flatten_cons]
 
 @[simp] theorem isEmpty_replicate : (replicate n a).isEmpty = decide (n = 0) := by
   cases n <;> simp [replicate_succ]
@@ -2672,10 +2684,10 @@ theorem flatten_reverse (L : List (List α)) :
     L.reverse.flatten = (L.map reverse).flatten.reverse := by
   induction L <;> simp_all
 
-theorem reverse_bind {β} (l : List α) (f : α → List β) : (l.bind f).reverse = l.reverse.bind (reverse ∘ f) := by
+theorem reverse_flatMap {β} (l : List α) (f : α → List β) : (l.flatMap f).reverse = l.reverse.flatMap (reverse ∘ f) := by
   induction l <;> simp_all
 
-theorem bind_reverse {β} (l : List α) (f : α → List β) : (l.reverse.bind f) = (l.bind (reverse ∘ f)).reverse := by
+theorem flatMap_reverse {β} (l : List α) (f : α → List β) : (l.reverse.flatMap f) = (l.flatMap (reverse ∘ f)).reverse := by
   induction l <;> simp_all
 
 @[simp] theorem reverseAux_eq (as bs : List α) : reverseAux as bs = reverse as ++ bs :=
@@ -2783,15 +2795,15 @@ theorem getLast_filterMap_of_eq_some {f : α → Option β} {l : List α} {w : l
   rw [head_filterMap_of_eq_some (by simp_all)]
   simp_all
 
-theorem getLast?_bind {L : List α} {f : α → List β} :
-    (L.bind f).getLast? = L.reverse.findSome? fun a => (f a).getLast? := by
-  simp only [← head?_reverse, reverse_bind]
-  rw [head?_bind]
+theorem getLast?_flatMap {L : List α} {f : α → List β} :
+    (L.flatMap f).getLast? = L.reverse.findSome? fun a => (f a).getLast? := by
+  simp only [← head?_reverse, reverse_flatMap]
+  rw [head?_flatMap]
   rfl
 
 theorem getLast?_flatten {L : List (List α)} :
     (flatten L).getLast? = L.reverse.findSome? fun l => l.getLast? := by
-  simp [← bind_id, getLast?_bind]
+  simp [← flatMap_id, getLast?_flatMap]
 
 theorem getLast?_replicate (a : α) (n : Nat) : (replicate n a).getLast? = if n = 0 then none else some a := by
   simp only [← head?_reverse, reverse_replicate, head?_replicate]
@@ -3300,12 +3312,12 @@ theorem all_eq_not_any_not (l : List α) (p : α → Bool) : l.all p = !l.any (!
 
 @[deprecated all_flatten (since := "2024-10-14")] abbrev all_join := @all_flatten
 
-@[simp] theorem any_bind {l : List α} {f : α → List β} :
-    (l.bind f).any p = l.any fun a => (f a).any p := by
+@[simp] theorem any_flatMap {l : List α} {f : α → List β} :
+    (l.flatMap f).any p = l.any fun a => (f a).any p := by
   induction l <;> simp_all
 
-@[simp] theorem all_bind {l : List α} {f : α → List β} :
-    (l.bind f).all p = l.all fun a => (f a).all p := by
+@[simp] theorem all_flatMap {l : List α} {f : α → List β} :
+    (l.flatMap f).all p = l.all fun a => (f a).all p := by
   induction l <;> simp_all
 
 @[simp] theorem any_reverse {l : List α} : l.reverse.any f = l.any f := by
@@ -3345,7 +3357,7 @@ theorem all_eq_not_any_not (l : List α) (p : α → Bool) : l.all p = !l.any (!
 @[deprecated exists_of_mem_flatten (since := "2024-10-14")] abbrev exists_of_mem_join := @exists_of_mem_flatten
 @[deprecated mem_flatten_of_mem (since := "2024-10-14")] abbrev mem_join_of_mem := @mem_flatten_of_mem
 @[deprecated forall_mem_flatten (since := "2024-10-14")] abbrev forall_mem_join := @forall_mem_flatten
-@[deprecated flatten_eq_bind (since := "2024-10-14")] abbrev join_eq_bind := @flatten_eq_bind
+@[deprecated flatten_eq_flatMap (since := "2024-10-14")] abbrev join_eq_bind := @flatten_eq_flatMap
 @[deprecated head?_flatten (since := "2024-10-14")] abbrev head?_join := @head?_flatten
 @[deprecated foldl_flatten (since := "2024-10-14")] abbrev foldl_join := @foldl_flatten
 @[deprecated foldr_flatten (since := "2024-10-14")] abbrev foldr_join := @foldr_flatten
@@ -3372,5 +3384,30 @@ theorem join_map_filter (p : α → Bool) (l : List (List α)) :
 @[deprecated reverse_flatten (since := "2024-10-14")] abbrev reverse_join := @reverse_flatten
 @[deprecated flatten_reverse (since := "2024-10-14")] abbrev join_reverse := @flatten_reverse
 @[deprecated getLast?_flatten (since := "2024-10-14")] abbrev getLast?_join := @getLast?_flatten
+@[deprecated flatten_eq_flatMap (since := "2024-10-16")] abbrev flatten_eq_bind := @flatten_eq_flatMap
+@[deprecated flatMap_def (since := "2024-10-16")] abbrev bind_def := @flatMap_def
+@[deprecated flatMap_id (since := "2024-10-16")] abbrev bind_id := @flatMap_id
+@[deprecated mem_flatMap (since := "2024-10-16")] abbrev mem_bind := @mem_flatMap
+@[deprecated exists_of_mem_flatMap (since := "2024-10-16")] abbrev exists_of_mem_bind := @exists_of_mem_flatMap
+@[deprecated mem_flatMap_of_mem (since := "2024-10-16")] abbrev mem_bind_of_mem := @mem_flatMap_of_mem
+@[deprecated flatMap_eq_nil_iff (since := "2024-10-16")] abbrev bind_eq_nil_iff := @flatMap_eq_nil_iff
+@[deprecated forall_mem_flatMap (since := "2024-10-16")] abbrev forall_mem_bind := @forall_mem_flatMap
+@[deprecated flatMap_singleton (since := "2024-10-16")] abbrev bind_singleton := @flatMap_singleton
+@[deprecated flatMap_singleton' (since := "2024-10-16")] abbrev bind_singleton' := @flatMap_singleton'
+@[deprecated head?_flatMap (since := "2024-10-16")] abbrev head_bind := @head?_flatMap
+@[deprecated flatMap_append (since := "2024-10-16")] abbrev bind_append := @flatMap_append
+@[deprecated flatMap_assoc (since := "2024-10-16")] abbrev bind_assoc := @flatMap_assoc
+@[deprecated map_flatMap (since := "2024-10-16")] abbrev map_bind := @map_flatMap
+@[deprecated flatMap_map (since := "2024-10-16")] abbrev bind_map := @flatMap_map
+@[deprecated map_eq_flatMap (since := "2024-10-16")] abbrev map_eq_bind := @map_eq_flatMap
+@[deprecated filterMap_flatMap (since := "2024-10-16")] abbrev filterMap_bind := @filterMap_flatMap
+@[deprecated filter_flatMap (since := "2024-10-16")] abbrev filter_bind := @filter_flatMap
+@[deprecated flatMap_eq_foldl (since := "2024-10-16")] abbrev bind_eq_foldl := @flatMap_eq_foldl
+@[deprecated flatMap_replicate (since := "2024-10-16")] abbrev bind_replicate := @flatMap_replicate
+@[deprecated reverse_flatMap (since := "2024-10-16")] abbrev reverse_bind := @reverse_flatMap
+@[deprecated flatMap_reverse (since := "2024-10-16")] abbrev bind_reverse := @flatMap_reverse
+@[deprecated getLast?_flatMap (since := "2024-10-16")] abbrev getLast?_bind := @getLast?_flatMap
+@[deprecated any_flatMap (since := "2024-10-16")] abbrev any_bind := @any_flatMap
+@[deprecated all_flatMap (since := "2024-10-16")] abbrev all_bind := @all_flatMap
 
 end List

src/Init/Data/List/MinMax.lean

@@ -75,7 +75,7 @@ theorem le_min?_iff [Min α] [LE α]
 
 -- This could be refactored by designing appropriate typeclasses to replace `le_refl`, `min_eq_or`,
 -- and `le_min_iff`.
-theorem min?_eq_some_iff [Min α] [LE α] [anti : Antisymm ((· : α) ≤ ·)]
+theorem min?_eq_some_iff [Min α] [LE α] [anti : Std.Antisymm ((· : α) ≤ ·)]
     (le_refl : ∀ a : α, a ≤ a)
     (min_eq_or : ∀ a b : α, min a b = a ∨ min a b = b)
     (le_min_iff : ∀ a b c : α, a ≤ min b c ↔ a ≤ b ∧ a ≤ c) {xs : List α} :
@@ -146,7 +146,7 @@ theorem max?_le_iff [Max α] [LE α]
 
 -- This could be refactored by designing appropriate typeclasses to replace `le_refl`, `max_eq_or`,
 -- and `le_min_iff`.
-theorem max?_eq_some_iff [Max α] [LE α] [anti : Antisymm ((· : α) ≤ ·)]
+theorem max?_eq_some_iff [Max α] [LE α] [anti : Std.Antisymm ((· : α) ≤ ·)]
     (le_refl : ∀ a : α, a ≤ a)
     (max_eq_or : ∀ a b : α, max a b = a ∨ max a b = b)
     (max_le_iff : ∀ a b c : α, max b c ≤ a ↔ b ≤ a ∧ c ≤ a) {xs : List α} :

src/Init/Data/List/Monadic.lean

@@ -99,4 +99,14 @@ theorem allM_eq_not_anyM_not [Monad m] [LawfulMonad m] (p : α → m Bool) (as :
     funext b
     split <;> simp_all
 
+/-! ### foldlM and foldrM -/
+
+theorem foldlM_map [Monad m] (f : β₁ → β₂) (g : α → β₂ → m α) (l : List β₁) (init : α) :
+    (l.map f).foldlM g init = l.foldlM (fun x y => g x (f y)) init := by
+  induction l generalizing g init <;> simp [*]
+
+theorem foldrM_map [Monad m] [LawfulMonad m] (f : β₁ → β₂) (g : β₂ → α → m α) (l : List β₁)
+    (init : α) : (l.map f).foldrM g init = l.foldrM (fun x y => g (f x) y) init := by
+  induction l generalizing g init <;> simp [*]
+
 end List

src/Init/Data/List/Nat.lean

@@ -12,3 +12,5 @@ import Init.Data.List.Nat.TakeDrop
 import Init.Data.List.Nat.Count
 import Init.Data.List.Nat.Erase
 import Init.Data.List.Nat.Find
+import Init.Data.List.Nat.BEq
+import Init.Data.List.Nat.Modify

src/Init/Data/List/Nat/BEq.lean

@@ -0,0 +1,47 @@
+/-
+Copyright (c) 2024 Lean FRO All rights reserved.
+Released under Apache 2.0 license as described in the file LICENSE.
+Authors: Kim Morrison
+-/
+prelude
+import Init.Data.Nat.Lemmas
+import Init.Data.List.Basic
+
+namespace List
+
+/-! ### isEqv-/
+
+theorem isEqv_eq_decide (a b : List α) (r) :
+    isEqv a b r = if h : a.length = b.length then
+      decide (∀ (i : Nat) (h' : i < a.length), r (a[i]'(h ▸ h')) (b[i]'(h ▸ h'))) else false := by
+  induction a generalizing b with
+  | nil =>
+    cases b <;> simp
+  | cons a as ih =>
+    cases b with
+    | nil => simp
+    | cons b bs =>
+      simp only [isEqv, ih, length_cons, Nat.add_right_cancel_iff]
+      split <;> simp [Nat.forall_lt_succ_left']
+
+/-! ### beq -/
+
+theorem beq_eq_isEqv [BEq α] (a b : List α) : a.beq b = isEqv a b (· == ·) := by
+  induction a generalizing b with
+  | nil =>
+    cases b <;> simp
+  | cons a as ih =>
+    cases b with
+    | nil => simp
+    | cons b bs =>
+      simp only [beq_cons₂, ih, isEqv_eq_decide, length_cons, Nat.add_right_cancel_iff,
+        Nat.forall_lt_succ_left', getElem_cons_zero, getElem_cons_succ, Bool.decide_and,
+        Bool.decide_eq_true]
+      split <;> simp
+
+theorem beq_eq_decide [BEq α] (a b : List α) :
+    (a == b) = if h : a.length = b.length then
+      decide (∀ (i : Nat) (h' : i < a.length), a[i] == b[i]'(h ▸ h')) else false := by
+  simp [BEq.beq, beq_eq_isEqv, isEqv_eq_decide]
+
+end List

src/Init/Data/List/Nat/Modify.lean

@@ -0,0 +1,102 @@
+/-
+Copyright (c) 2014 Parikshit Khanna. All rights reserved.
+Released under Apache 2.0 license as described in the file LICENSE.
+Authors: Parikshit Khanna, Jeremy Avigad, Leonardo de Moura, Floris van Doorn, Mario Carneiro
+-/
+
+prelude
+import Init.Data.List.Nat.TakeDrop
+
+namespace List
+
+/-! ### modifyHead -/
+
+@[simp] theorem modifyHead_modifyHead (l : List α) (f g : α → α) :
+    (l.modifyHead f).modifyHead g = l.modifyHead (g ∘ f) := by cases l <;> simp [modifyHead]
+
+/-! ### modify -/
+
+@[simp] theorem modify_nil (f : α → α) (n) : [].modify f n = [] := by cases n <;> rfl
+
+@[simp] theorem modify_zero_cons (f : α → α) (a : α) (l : List α) :
+    (a :: l).modify f 0 = f a :: l := rfl
+
+@[simp] theorem modify_succ_cons (f : α → α) (a : α) (l : List α) (n) :
+    (a :: l).modify f (n + 1) = a :: l.modify f n := by rfl
+
+theorem modifyTailIdx_id : ∀ n (l : List α), l.modifyTailIdx id n = l
+  | 0, _ => rfl
+  | _+1, [] => rfl
+  | n+1, a :: l => congrArg (cons a) (modifyTailIdx_id n l)
+
+theorem eraseIdx_eq_modifyTailIdx : ∀ n (l : List α), eraseIdx l n = modifyTailIdx tail n l
+  | 0, l => by cases l <;> rfl
+  | _+1, [] => rfl
+  | _+1, _ :: _ => congrArg (cons _) (eraseIdx_eq_modifyTailIdx _ _)
+
+theorem getElem?_modify (f : α → α) :
+    ∀ n (l : List α) m, (modify f n l)[m]? = (fun a => if n = m then f a else a) <$> l[m]?
+  | n, l, 0 => by cases l <;> cases n <;> simp
+  | n, [], _+1 => by cases n <;> rfl
+  | 0, _ :: l, m+1 => by cases h : l[m]? <;> simp [h, modify, m.succ_ne_zero.symm]
+  | n+1, a :: l, m+1 => by
+    simp only [modify_succ_cons, getElem?_cons_succ, Nat.reduceEqDiff, Option.map_eq_map]
+    refine (getElem?_modify f n l m).trans ?_
+    cases h' : l[m]? <;> by_cases h : n = m <;>
+      simp [h, if_pos, if_neg, Option.map, mt Nat.succ.inj, not_false_iff, h']
+
+@[simp] theorem length_modifyTailIdx (f : List α → List α) (H : ∀ l, length (f l) = length l) :
+    ∀ n l, length (modifyTailIdx f n l) = length l
+  | 0, _ => H _
+  | _+1, [] => rfl
+  | _+1, _ :: _ => congrArg (·+1) (length_modifyTailIdx _ H _ _)
+
+theorem modifyTailIdx_add (f : List α → List α) (n) (l₁ l₂ : List α) :
+    modifyTailIdx f (l₁.length + n) (l₁ ++ l₂) = l₁ ++ modifyTailIdx f n l₂ := by
+  induction l₁ <;> simp [*, Nat.succ_add]
+
+@[simp] theorem length_modify (f : α → α) : ∀ n l, length (modify f n l) = length l :=
+  length_modifyTailIdx _ fun l => by cases l <;> rfl
+
+@[simp] theorem getElem?_modify_eq (f : α → α) (n) (l : List α) :
+    (modify f n l)[n]? = f <$> l[n]? := by
+  simp only [getElem?_modify, if_pos]
+
+@[simp] theorem getElem?_modify_ne (f : α → α) {m n} (l : List α) (h : m ≠ n) :
+    (modify f m l)[n]? = l[n]? := by
+  simp only [getElem?_modify, if_neg h, id_map']
+
+theorem getElem_modify (f : α → α) (n) (l : List α) (m) (h : m < (modify f n l).length) :
+    (modify f n l)[m] =
+      if n = m then f (l[m]'(by simp at h; omega)) else l[m]'(by simp at h; omega) := by
+  rw [getElem_eq_iff, getElem?_modify]
+  simp at h
+  simp [h]
+
+theorem modifyTailIdx_eq_take_drop (f : List α → List α) (H : f [] = []) :
+    ∀ n l, modifyTailIdx f n l = take n l ++ f (drop n l)
+  | 0, _ => rfl
+  | _ + 1, [] => H.symm
+  | n + 1, b :: l => congrArg (cons b) (modifyTailIdx_eq_take_drop f H n l)
+
+theorem modify_eq_take_drop (f : α → α) :
+    ∀ n l, modify f n l = take n l ++ modifyHead f (drop n l) :=
+  modifyTailIdx_eq_take_drop _ rfl
+
+theorem modify_eq_take_cons_drop (f : α → α) {n l} (h : n < length l) :
+    modify f n l = take n l ++ f l[n] :: drop (n + 1) l := by
+  rw [modify_eq_take_drop, drop_eq_getElem_cons h]; rfl
+
+theorem exists_of_modifyTailIdx (f : List α → List α) {n} {l : List α} (h : n ≤ l.length) :
+    ∃ l₁ l₂, l = l₁ ++ l₂ ∧ l₁.length = n ∧ modifyTailIdx f n l = l₁ ++ f l₂ :=
+  have ⟨_, _, eq, hl⟩ : ∃ l₁ l₂, l = l₁ ++ l₂ ∧ l₁.length = n :=
+    ⟨_, _, (take_append_drop n l).symm, length_take_of_le h⟩
+  ⟨_, _, eq, hl, hl ▸ eq ▸ modifyTailIdx_add (n := 0) ..⟩
+
+theorem exists_of_modify (f : α → α) {n} {l : List α} (h : n < l.length) :
+    ∃ l₁ a l₂, l = l₁ ++ a :: l₂ ∧ l₁.length = n ∧ modify f n l = l₁ ++ f a :: l₂ :=
+  match exists_of_modifyTailIdx _ (Nat.le_of_lt h) with
+  | ⟨_, _::_, eq, hl, H⟩ => ⟨_, _, _, eq, hl, H⟩
+  | ⟨_, [], eq, hl, _⟩ => nomatch Nat.ne_of_gt h (eq ▸ append_nil _ ▸ hl)
+
+end List

src/Init/Data/List/Pairwise.lean

@@ -173,10 +173,12 @@ theorem pairwise_flatten {L : List (List α)} :
 
 @[deprecated pairwise_flatten (since := "2024-10-14")] abbrev pairwise_join := @pairwise_flatten
 
-theorem pairwise_bind {R : β → β → Prop} {l : List α} {f : α → List β} :
-    List.Pairwise R (l.bind f) ↔
+theorem pairwise_flatMap {R : β → β → Prop} {l : List α} {f : α → List β} :
+    List.Pairwise R (l.flatMap f) ↔
       (∀ a ∈ l, Pairwise R (f a)) ∧ Pairwise (fun a₁ a₂ => ∀ x ∈ f a₁, ∀ y ∈ f a₂, R x y) l := by
-  simp [List.bind, pairwise_flatten, pairwise_map]
+  simp [List.flatMap, pairwise_flatten, pairwise_map]
+
+@[deprecated pairwise_flatMap (since := "2024-10-14")] abbrev pairwise_bind := @pairwise_flatMap
 
 theorem pairwise_reverse {l : List α} :
     l.reverse.Pairwise R ↔ l.Pairwise (fun a b => R b a) := by

src/Init/Data/List/Perm.lean

@@ -470,9 +470,11 @@ theorem Perm.flatten {l₁ l₂ : List (List α)} (h : l₁ ~ l₂) : l₁.flatt
 
 @[deprecated Perm.flatten (since := "2024-10-14")] abbrev Perm.join := @Perm.flatten
 
-theorem Perm.bind_right {l₁ l₂ : List α} (f : α → List β) (p : l₁ ~ l₂) : l₁.bind f ~ l₂.bind f :=
+theorem Perm.flatMap_right {l₁ l₂ : List α} (f : α → List β) (p : l₁ ~ l₂) : l₁.flatMap f ~ l₂.flatMap f :=
   (p.map _).flatten
 
+@[deprecated Perm.flatMap_right (since := "2024-10-16")] abbrev Perm.bind_right := @Perm.flatMap_right
+
 theorem Perm.eraseP (f : α → Bool) {l₁ l₂ : List α}
     (H : Pairwise (fun a b => f a → f b → False) l₁) (p : l₁ ~ l₂) : eraseP f l₁ ~ eraseP f l₂ := by
   induction p with

src/Init/Data/Nat/Basic.lean

@@ -131,7 +131,7 @@ theorem or_exists_add_one : p 0 ∨ (Exists fun n => p (n + 1)) ↔ Exists p :=
 @[simp] theorem blt_eq : (Nat.blt x y = true) = (x < y) := propext <| Iff.intro Nat.le_of_ble_eq_true Nat.ble_eq_true_of_le
 
 instance : LawfulBEq Nat where
-  eq_of_beq h := Nat.eq_of_beq_eq_true h
+  eq_of_beq h := by simpa using h
   rfl := by simp [BEq.beq]
 
 theorem beq_eq_true_eq (a b : Nat) : ((a == b) = true) = (a = b) := by simp
@@ -490,10 +490,10 @@ protected theorem le_antisymm_iff {a b : Nat} : a = b ↔ a ≤ b ∧ b ≤ a :=
             (fun ⟨hle, hge⟩ => Nat.le_antisymm hle hge)
 protected theorem eq_iff_le_and_ge : ∀{a b : Nat}, a = b ↔ a ≤ b ∧ b ≤ a := @Nat.le_antisymm_iff
 
-instance : Antisymm ( . ≤ . : Nat → Nat → Prop) where
+instance : Std.Antisymm ( . ≤ . : Nat → Nat → Prop) where
   antisymm h₁ h₂ := Nat.le_antisymm h₁ h₂
 
-instance : Antisymm (¬ . < . : Nat → Nat → Prop) where
+instance : Std.Antisymm (¬ . < . : Nat → Nat → Prop) where
   antisymm h₁ h₂ := Nat.le_antisymm (Nat.ge_of_not_lt h₂) (Nat.ge_of_not_lt h₁)
 
 protected theorem add_le_add_left {n m : Nat} (h : n ≤ m) (k : Nat) : k + n ≤ k + m :=
@@ -796,6 +796,8 @@ theorem pos_pow_of_pos {n : Nat} (m : Nat) (h : 0 < n) : 0 < n^m :=
   | zero => cases h
   | succ n => simp [Nat.pow_succ]
 
+protected theorem two_pow_pos (w : Nat) : 0 < 2^w := Nat.pos_pow_of_pos _ (by decide)
+
 instance {n m : Nat} [NeZero n] : NeZero (n^m) :=
   ⟨Nat.ne_zero_iff_zero_lt.mpr (Nat.pos_pow_of_pos m (pos_of_neZero _))⟩
 

src/Init/Data/Nat/Lemmas.lean

@@ -32,6 +32,77 @@ namespace Nat
 @[simp] theorem exists_add_one_eq : (∃ n, n + 1 = a) ↔ 0 < a :=
   ⟨fun ⟨n, h⟩ => by omega, fun h => ⟨a - 1, by omega⟩⟩
 
+/-- Dependent variant of `forall_lt_succ_right`. -/
+theorem forall_lt_succ_right' {p : (m : Nat) → (m < n + 1) → Prop} :
+    (∀ m (h : m < n + 1), p m h) ↔ (∀ m (h : m < n), p m (by omega)) ∧ p n (by omega) := by
+  simp only [Nat.lt_succ_iff, Nat.le_iff_lt_or_eq]
+  constructor
+  · intro w
+    constructor
+    · intro m h
+      exact w _ (.inl h)
+    · exact w _ (.inr rfl)
+  · rintro w m (h|rfl)
+    · exact w.1 _ h
+    · exact w.2
+
+/-- See `forall_lt_succ_right'` for a variant where `p` takes the bound as an argument. -/
+theorem forall_lt_succ_right {p : Nat → Prop} :
+    (∀ m, m < n + 1 → p m) ↔ (∀ m, m < n → p m) ∧ p n := by
+  simpa using forall_lt_succ_right' (p := fun m _ => p m)
+
+/-- Dependent variant of `forall_lt_succ_left`. -/
+theorem forall_lt_succ_left' {p : (m : Nat) → (m < n + 1) → Prop} :
+    (∀ m (h : m < n + 1), p m h) ↔ p 0 (by omega) ∧ (∀ m (h : m < n), p (m + 1) (by omega)) := by
+  constructor
+  · intro w
+    constructor
+    · exact w 0 (by omega)
+    · intro m h
+      exact w (m + 1) (by omega)
+  · rintro ⟨h₀, h₁⟩ m h
+    cases m with
+    | zero => exact h₀
+    | succ m => exact h₁ m (by omega)
+
+/-- See `forall_lt_succ_left'` for a variant where `p` takes the bound as an argument. -/
+theorem forall_lt_succ_left {p : Nat → Prop} :
+    (∀ m, m < n + 1 → p m) ↔ p 0 ∧ (∀ m, m < n → p (m + 1)) := by
+  simpa using forall_lt_succ_left' (p := fun m _ => p m)
+
+/-- Dependent variant of `exists_lt_succ_right`. -/
+theorem exists_lt_succ_right' {p : (m : Nat) → (m < n + 1) → Prop} :
+    (∃ m, ∃ (h : m < n + 1), p m h) ↔ (∃ m, ∃ (h : m < n), p m (by omega)) ∨ p n (by omega) := by
+  simp only [Nat.lt_succ_iff, Nat.le_iff_lt_or_eq]
+  constructor
+  · rintro ⟨m, (h|rfl), w⟩
+    · exact .inl ⟨m, h, w⟩
+    · exact .inr w
+  · rintro (⟨m, h, w⟩ | w)
+    · exact ⟨m, by omega, w⟩
+    · exact ⟨n, by omega, w⟩
+
+/-- See `exists_lt_succ_right'` for a variant where `p` takes the bound as an argument. -/
+theorem exists_lt_succ_right {p : Nat → Prop} :
+    (∃ m, m < n + 1 ∧ p m) ↔ (∃ m, m < n ∧ p m) ∨ p n := by
+  simpa using exists_lt_succ_right' (p := fun m _ => p m)
+
+/-- Dependent variant of `exists_lt_succ_left`. -/
+theorem exists_lt_succ_left' {p : (m : Nat) → (m < n + 1) → Prop} :
+    (∃ m, ∃ (h : m < n + 1), p m h) ↔ p 0 (by omega) ∨ (∃ m, ∃ (h : m < n), p (m + 1) (by omega)) := by
+  constructor
+  · rintro ⟨_|m, h, w⟩
+    · exact .inl w
+    · exact .inr ⟨m, by omega, w⟩
+  · rintro (w|⟨m, h, w⟩)
+    · exact ⟨0, by omega, w⟩
+    · exact ⟨m + 1, by omega, w⟩
+
+/-- See `exists_lt_succ_left'` for a variant where `p` takes the bound as an argument. -/
+theorem exists_lt_succ_left {p : Nat → Prop} :
+    (∃ m, m < n + 1 ∧ p m) ↔ p 0 ∨ (∃ m, m < n ∧ p (m + 1)) := by
+  simpa using exists_lt_succ_left' (p := fun m _ => p m)
+
 /-! ## add -/
 
 protected theorem add_add_add_comm (a b c d : Nat) : (a + b) + (c + d) = (a + c) + (b + d) := by

src/Init/Data/Nat/Power2.lean

@@ -8,8 +8,6 @@ import Init.Data.Nat.Linear
 
 namespace Nat
 
-protected theorem two_pow_pos (w : Nat) : 0 < 2^w := Nat.pos_pow_of_pos _ (by decide)
-
 theorem nextPowerOfTwo_dec {n power : Nat} (h₁ : power > 0) (h₂ : power < n) : n - power * 2 < n - power := by
   have : power * 2 = power + power := by simp_arith
   rw [this, Nat.sub_add_eq]

src/Init/Data/OfScientific.lean

@@ -10,8 +10,10 @@ import Init.Data.Nat.Log2
 
 /-- For decimal and scientific numbers (e.g., `1.23`, `3.12e10`).
    Examples:
-   - `OfScientific.ofScientific 123 true 2`    represents `1.23`
-   - `OfScientific.ofScientific 121 false 100` represents `121e100`
+   - `1.23` is syntax for `OfScientific.ofScientific (nat_lit 123) true (nat_lit 2)`
+   - `121e100` is syntax for `OfScientific.ofScientific (nat_lit 121) false (nat_lit 100)`
+
+   Note the use of `nat_lit`; there is no wrapping `OfNat.ofNat` in the resulting term.
 -/
 class OfScientific (α : Type u) where
   ofScientific (mantissa : Nat) (exponentSign : Bool) (decimalExponent : Nat) : α

src/Init/Data/Option/Attach.lean

@@ -44,7 +44,7 @@ theorem attach_congr {o₁ o₂ : Option α} (h : o₁ = o₂) :
   simp
 
 theorem attachWith_congr {o₁ o₂ : Option α} (w : o₁ = o₂) {P : α → Prop} {H : ∀ x ∈ o₁, P x} :
-    o₁.attachWith P H = o₂.attachWith P fun x h => H _ (w ▸ h) := by
+    o₁.attachWith P H = o₂.attachWith P fun _ h => H _ (w ▸ h) := by
   subst w
   simp
 
@@ -128,12 +128,12 @@ theorem attach_map {o : Option α} (f : α → β) :
   cases o <;> simp
 
 theorem attachWith_map {o : Option α} (f : α → β) {P : β → Prop} {H : ∀ (b : β), b ∈ o.map f → P b} :
-    (o.map f).attachWith P H = (o.attachWith (P ∘ f) (fun a h => H _ (mem_map_of_mem f h))).map
+    (o.map f).attachWith P H = (o.attachWith (P ∘ f) (fun _ h => H _ (mem_map_of_mem f h))).map
       fun ⟨x, h⟩ => ⟨f x, h⟩ := by
   cases o <;> simp
 
 theorem map_attach {o : Option α} (f : { x // x ∈ o } → β) :
-    o.attach.map f = o.pmap (fun a (h : a ∈ o) => f ⟨a, h⟩) (fun a h => h) := by
+    o.attach.map f = o.pmap (fun a (h : a ∈ o) => f ⟨a, h⟩) (fun _ h => h) := by
   cases o <;> simp
 
 theorem map_attachWith {o : Option α} {P : α → Prop} {H : ∀ (a : α), a ∈ o → P a}

src/Init/Data/Prod.lean

@@ -7,6 +7,8 @@ prelude
 import Init.SimpLemmas
 import Init.NotationExtra
 
+namespace Prod
+
 instance [BEq α] [BEq β] [LawfulBEq α] [LawfulBEq β] : LawfulBEq (α × β) where
   eq_of_beq {a b} (h : a.1 == b.1 && a.2 == b.2) := by
     cases a; cases b
@@ -14,9 +16,65 @@ instance [BEq α] [BEq β] [LawfulBEq α] [LawfulBEq β] : LawfulBEq (α × β)
   rfl {a} := by cases a; simp [BEq.beq, LawfulBEq.rfl]
 
 @[simp]
-protected theorem Prod.forall {p : α × β → Prop} : (∀ x, p x) ↔ ∀ a b, p (a, b) :=
+protected theorem «forall» {p : α × β → Prop} : (∀ x, p x) ↔ ∀ a b, p (a, b) :=
   ⟨fun h a b ↦ h (a, b), fun h ⟨a, b⟩ ↦ h a b⟩
 
 @[simp]
-protected theorem Prod.exists {p : α × β → Prop} : (∃ x, p x) ↔ ∃ a b, p (a, b) :=
+protected theorem «exists» {p : α × β → Prop} : (∃ x, p x) ↔ ∃ a b, p (a, b) :=
   ⟨fun ⟨⟨a, b⟩, h⟩ ↦ ⟨a, b, h⟩, fun ⟨a, b, h⟩ ↦ ⟨⟨a, b⟩, h⟩⟩
+
+@[simp] theorem map_id : Prod.map (@id α) (@id β) = id := rfl
+
+@[simp] theorem map_id' : Prod.map (fun a : α => a) (fun b : β => b) = fun x ↦ x := rfl
+
+/--
+Composing a `Prod.map` with another `Prod.map` is equal to
+a single `Prod.map` of composed functions.
+-/
+theorem map_comp_map (f : α → β) (f' : γ → δ) (g : β → ε) (g' : δ → ζ) :
+    Prod.map g g' ∘ Prod.map f f' = Prod.map (g ∘ f) (g' ∘ f') :=
+  rfl
+
+/--
+Composing a `Prod.map` with another `Prod.map` is equal to
+a single `Prod.map` of composed functions, fully applied.
+-/
+theorem map_map (f : α → β) (f' : γ → δ) (g : β → ε) (g' : δ → ζ) (x : α × γ) :
+    Prod.map g g' (Prod.map f f' x) = Prod.map (g ∘ f) (g' ∘ f') x :=
+  rfl
+
+/-- Swap the factors of a product. `swap (a, b) = (b, a)` -/
+def swap : α × β → β × α := fun p => (p.2, p.1)
+
+@[simp]
+theorem swap_swap : ∀ x : α × β, swap (swap x) = x
+  | ⟨_, _⟩ => rfl
+
+@[simp]
+theorem fst_swap {p : α × β} : (swap p).1 = p.2 :=
+  rfl
+
+@[simp]
+theorem snd_swap {p : α × β} : (swap p).2 = p.1 :=
+  rfl
+
+@[simp]
+theorem swap_prod_mk {a : α} {b : β} : swap (a, b) = (b, a) :=
+  rfl
+
+@[simp]
+theorem swap_swap_eq : swap ∘ swap = @id (α × β) :=
+  funext swap_swap
+
+@[simp]
+theorem swap_inj {p q : α × β} : swap p = swap q ↔ p = q := by
+  cases p; cases q; simp [and_comm]
+
+/--
+For two functions `f` and `g`, the composition of `Prod.map f g` with `Prod.swap`
+is equal to the composition of `Prod.swap` with `Prod.map g f`.
+-/
+theorem map_comp_swap (f : α → β) (g : γ → δ) :
+    Prod.map f g ∘ Prod.swap = Prod.swap ∘ Prod.map g f := rfl
+
+end Prod

src/Init/Data/Repr.lean

@@ -7,7 +7,7 @@ prelude
 import Init.Data.Format.Basic
 import Init.Data.Int.Basic
 import Init.Data.Nat.Div
-import Init.Data.UInt.Basic
+import Init.Data.UInt.BasicAux
 import Init.Control.Id
 open Sum Subtype Nat
 

src/Init/Data/String/Basic.lean

@@ -1148,23 +1148,23 @@ namespace String
 /--
 If `pre` is a prefix of `s`, i.e. `s = pre ++ t`, returns the remainder `t`.
 -/
-def dropPrefix? (s : String) (pre : Substring) : Option Substring :=
-  s.toSubstring.dropPrefix? pre
+def dropPrefix? (s : String) (pre : String) : Option Substring :=
+  s.toSubstring.dropPrefix? pre.toSubstring
 
 /--
 If `suff` is a suffix of `s`, i.e. `s = t ++ suff`, returns the remainder `t`.
 -/
-def dropSuffix? (s : String) (suff : Substring) : Option Substring :=
-  s.toSubstring.dropSuffix? suff
+def dropSuffix? (s : String) (suff : String) : Option Substring :=
+  s.toSubstring.dropSuffix? suff.toSubstring
 
 /-- `s.stripPrefix pre` will remove `pre` from the beginning of `s` if it occurs there,
 or otherwise return `s`. -/
-def stripPrefix (s : String) (pre : Substring) : String :=
+def stripPrefix (s : String) (pre : String) : String :=
   s.dropPrefix? pre |>.map Substring.toString |>.getD s
 
 /-- `s.stripSuffix suff` will remove `suff` from the end of `s` if it occurs there,
 or otherwise return `s`. -/
-def stripSuffix (s : String) (suff : Substring) : String :=
+def stripSuffix (s : String) (suff : String) : String :=
   s.dropSuffix? suff |>.map Substring.toString |>.getD s
 
 end String

src/Init/Data/String/Extra.lean

@@ -5,6 +5,7 @@ Author: Leonardo de Moura
 -/
 prelude
 import Init.Data.ByteArray
+import Init.Data.UInt.Lemmas
 
 namespace String
 
@@ -20,14 +21,14 @@ def toNat! (s : String) : Nat :=
 def utf8DecodeChar? (a : ByteArray) (i : Nat) : Option Char := do
   let c ← a[i]?
   if c &&& 0x80 == 0 then
-    some ⟨c.toUInt32, .inl (Nat.lt_trans c.1.2 (by decide))⟩
+    some ⟨c.toUInt32, .inl (Nat.lt_trans c.toBitVec.isLt (by decide))⟩
   else if c &&& 0xe0 == 0xc0 then
     let c1 ← a[i+1]?
     guard (c1 &&& 0xc0 == 0x80)
     let r := ((c &&& 0x1f).toUInt32 <<< 6) ||| (c1 &&& 0x3f).toUInt32
     guard (0x80 ≤ r)
     -- TODO: Prove h from the definition of r once we have the necessary lemmas
-    if h : r < 0xd800 then some ⟨r, .inl h⟩ else none
+    if h : r < 0xd800 then some ⟨r, .inl (UInt32.toNat_lt_of_lt (by decide) h)⟩ else none
   else if c &&& 0xf0 == 0xe0 then
     let c1 ← a[i+1]?
     let c2 ← a[i+2]?
@@ -38,7 +39,14 @@ def utf8DecodeChar? (a : ByteArray) (i : Nat) : Option Char := do
       (c2 &&& 0x3f).toUInt32
     guard (0x800 ≤ r)
     -- TODO: Prove `r < 0x110000` from the definition of r once we have the necessary lemmas
-    if h : r < 0xd800 ∨ 0xdfff < r ∧ r < 0x110000 then some ⟨r, h⟩ else none
+    if h : r < 0xd800 ∨ 0xdfff < r ∧ r < 0x110000 then
+      have :=
+        match h with
+        | .inl h => Or.inl (UInt32.toNat_lt_of_lt (by decide) h)
+        | .inr h => Or.inr ⟨UInt32.lt_toNat_of_lt (by decide) h.left, UInt32.toNat_lt_of_lt (by decide) h.right⟩
+      some ⟨r, this⟩
+    else
+      none
   else if c &&& 0xf8 == 0xf0 then
     let c1 ← a[i+1]?
     let c2 ← a[i+2]?
@@ -50,7 +58,7 @@ def utf8DecodeChar? (a : ByteArray) (i : Nat) : Option Char := do
       ((c2 &&& 0x3f).toUInt32 <<< 6) |||
       (c3 &&& 0x3f).toUInt32
     if h : 0x10000 ≤ r ∧ r < 0x110000 then
-      some ⟨r, .inr ⟨Nat.lt_of_lt_of_le (by decide) h.1, h.2⟩⟩
+      some ⟨r, .inr ⟨Nat.lt_of_lt_of_le (by decide) (UInt32.le_toNat_of_le (by decide) h.left), UInt32.toNat_lt_of_lt (by decide) h.right⟩⟩
     else none
   else
     none
@@ -117,10 +125,10 @@ def utf8EncodeChar (c : Char) : List UInt8 :=
 /-- Converts the given `String` to a [UTF-8](https://en.wikipedia.org/wiki/UTF-8) encoded byte array. -/
 @[extern "lean_string_to_utf8"]
 def toUTF8 (a : @& String) : ByteArray :=
-  ⟨⟨a.data.bind utf8EncodeChar⟩⟩
+  ⟨⟨a.data.flatMap utf8EncodeChar⟩⟩
 
 @[simp] theorem size_toUTF8 (s : String) : s.toUTF8.size = s.utf8ByteSize := by
-  simp [toUTF8, ByteArray.size, Array.size, utf8ByteSize, List.bind]
+  simp [toUTF8, ByteArray.size, Array.size, utf8ByteSize, List.flatMap]
   induction s.data <;> simp [List.map, List.flatten, utf8ByteSize.go, Nat.add_comm, *]
 
 /-- Accesses a byte in the UTF-8 encoding of the `String`. O(1) -/

src/Init/Data/Sum.lean

@@ -4,21 +4,5 @@ Released under Apache 2.0 license as described in the file LICENSE.
 Authors: Mario Carneiro, Yury G. Kudryashov
 -/
 prelude
-import Init.Core
-
-namespace Sum
-
-deriving instance DecidableEq for Sum
-deriving instance BEq for Sum
-
-/-- Check if a sum is `inl` and if so, retrieve its contents. -/
-def getLeft? : α ⊕ β → Option α
-  | inl a => some a
-  | inr _ => none
-
-/-- Check if a sum is `inr` and if so, retrieve its contents. -/
-def getRight? : α ⊕ β → Option β
-  | inr b => some b
-  | inl _ => none
-
-end Sum
+import Init.Data.Sum.Basic
+import Init.Data.Sum.Lemmas

src/Init/Data/Sum/Basic.lean

@@ -0,0 +1,178 @@
+/-
+Copyright (c) 2017 Mario Carneiro. All rights reserved.
+Released under Apache 2.0 license as described in the file LICENSE.
+Authors: Mario Carneiro, Yury G. Kudryashov
+-/
+prelude
+import Init.PropLemmas
+
+/-!
+# Disjoint union of types
+
+This file defines basic operations on the the sum type `α ⊕ β`.
+
+`α ⊕ β` is the type made of a copy of `α` and a copy of `β`. It is also called *disjoint union*.
+
+## Main declarations
+
+* `Sum.isLeft`: Returns whether `x : α ⊕ β` comes from the left component or not.
+* `Sum.isRight`: Returns whether `x : α ⊕ β` comes from the right component or not.
+* `Sum.getLeft`: Retrieves the left content of a `x : α ⊕ β` that is known to come from the left.
+* `Sum.getRight`: Retrieves the right content of `x : α ⊕ β` that is known to come from the right.
+* `Sum.getLeft?`: Retrieves the left content of `x : α ⊕ β` as an option type or returns `none`
+  if it's coming from the right.
+* `Sum.getRight?`: Retrieves the right content of `x : α ⊕ β` as an option type or returns `none`
+  if it's coming from the left.
+* `Sum.map`: Maps `α ⊕ β` to `γ ⊕ δ` component-wise.
+* `Sum.elim`: Nondependent eliminator/induction principle for `α ⊕ β`.
+* `Sum.swap`: Maps `α ⊕ β` to `β ⊕ α` by swapping components.
+* `Sum.LiftRel`: The disjoint union of two relations.
+* `Sum.Lex`: Lexicographic order on `α ⊕ β` induced by a relation on `α` and a relation on `β`.
+
+## Further material
+
+See `Batteries.Data.Sum.Lemmas` for theorems about these definitions.
+
+## Notes
+
+The definition of `Sum` takes values in `Type _`. This effectively forbids `Prop`- valued sum types.
+To this effect, we have `PSum`, which takes value in `Sort _` and carries a more complicated
+universe signature in consequence. The `Prop` version is `Or`.
+-/
+
+namespace Sum
+
+deriving instance DecidableEq for Sum
+deriving instance BEq for Sum
+
+section get
+
+/-- Check if a sum is `inl`. -/
+def isLeft : α ⊕ β → Bool
+  | inl _ => true
+  | inr _ => false
+
+/-- Check if a sum is `inr`. -/
+def isRight : α ⊕ β → Bool
+  | inl _ => false
+  | inr _ => true
+
+/-- Retrieve the contents from a sum known to be `inl`.-/
+def getLeft : (ab : α ⊕ β) → ab.isLeft → α
+  | inl a, _ => a
+
+/-- Retrieve the contents from a sum known to be `inr`.-/
+def getRight : (ab : α ⊕ β) → ab.isRight → β
+  | inr b, _ => b
+
+/-- Check if a sum is `inl` and if so, retrieve its contents. -/
+def getLeft? : α ⊕ β → Option α
+  | inl a => some a
+  | inr _ => none
+
+/-- Check if a sum is `inr` and if so, retrieve its contents. -/
+def getRight? : α ⊕ β → Option β
+  | inr b => some b
+  | inl _ => none
+
+@[simp] theorem isLeft_inl : (inl x : α ⊕ β).isLeft = true := rfl
+@[simp] theorem isLeft_inr : (inr x : α ⊕ β).isLeft = false := rfl
+@[simp] theorem isRight_inl : (inl x : α ⊕ β).isRight = false := rfl
+@[simp] theorem isRight_inr : (inr x : α ⊕ β).isRight = true := rfl
+
+@[simp] theorem getLeft_inl (h : (inl x : α ⊕ β).isLeft) : (inl x).getLeft h = x := rfl
+@[simp] theorem getRight_inr (h : (inr x : α ⊕ β).isRight) : (inr x).getRight h = x := rfl
+
+@[simp] theorem getLeft?_inl : (inl x : α ⊕ β).getLeft? = some x := rfl
+@[simp] theorem getLeft?_inr : (inr x : α ⊕ β).getLeft? = none := rfl
+@[simp] theorem getRight?_inl : (inl x : α ⊕ β).getRight? = none := rfl
+@[simp] theorem getRight?_inr : (inr x : α ⊕ β).getRight? = some x := rfl
+
+end get
+
+/-- Define a function on `α ⊕ β` by giving separate definitions on `α` and `β`. -/
+protected def elim {α β γ} (f : α → γ) (g : β → γ) : α ⊕ β → γ :=
+  fun x => Sum.casesOn x f g
+
+@[simp] theorem elim_inl (f : α → γ) (g : β → γ) (x : α) :
+    Sum.elim f g (inl x) = f x := rfl
+
+@[simp] theorem elim_inr (f : α → γ) (g : β → γ) (x : β) :
+    Sum.elim f g (inr x) = g x := rfl
+
+/-- Map `α ⊕ β` to `α' ⊕ β'` sending `α` to `α'` and `β` to `β'`. -/
+protected def map (f : α → α') (g : β → β') : α ⊕ β → α' ⊕ β' :=
+  Sum.elim (inl ∘ f) (inr ∘ g)
+
+@[simp] theorem map_inl (f : α → α') (g : β → β') (x : α) : (inl x).map f g = inl (f x) := rfl
+
+@[simp] theorem map_inr (f : α → α') (g : β → β') (x : β) : (inr x).map f g = inr (g x) := rfl
+
+/-- Swap the factors of a sum type -/
+def swap : α ⊕ β → β ⊕ α := Sum.elim inr inl
+
+@[simp] theorem swap_inl : swap (inl x : α ⊕ β) = inr x := rfl
+
+@[simp] theorem swap_inr : swap (inr x : α ⊕ β) = inl x := rfl
+
+section LiftRel
+
+/-- Lifts pointwise two relations between `α` and `γ` and between `β` and `δ` to a relation between
+`α ⊕ β` and `γ ⊕ δ`. -/
+inductive LiftRel (r : α → γ → Prop) (s : β → δ → Prop) : α ⊕ β → γ ⊕ δ → Prop
+  /-- `inl a` and `inl c` are related via `LiftRel r s` if `a` and `c` are related via `r`. -/
+  | protected inl {a c} : r a c → LiftRel r s (inl a) (inl c)
+  /-- `inr b` and `inr d` are related via `LiftRel r s` if `b` and `d` are related via `s`. -/
+  | protected inr {b d} : s b d → LiftRel r s (inr b) (inr d)
+
+@[simp] theorem liftRel_inl_inl : LiftRel r s (inl a) (inl c) ↔ r a c :=
+  ⟨fun h => by cases h; assumption, LiftRel.inl⟩
+
+@[simp] theorem not_liftRel_inl_inr : ¬LiftRel r s (inl a) (inr d) := nofun
+
+@[simp] theorem not_liftRel_inr_inl : ¬LiftRel r s (inr b) (inl c) := nofun
+
+@[simp] theorem liftRel_inr_inr : LiftRel r s (inr b) (inr d) ↔ s b d :=
+  ⟨fun h => by cases h; assumption, LiftRel.inr⟩
+
+instance {r : α → γ → Prop} {s : β → δ → Prop}
+    [∀ a c, Decidable (r a c)] [∀ b d, Decidable (s b d)] :
+    ∀ (ab : α ⊕ β) (cd : γ ⊕ δ), Decidable (LiftRel r s ab cd)
+  | inl _, inl _ => decidable_of_iff' _ liftRel_inl_inl
+  | inl _, inr _ => Decidable.isFalse not_liftRel_inl_inr
+  | inr _, inl _ => Decidable.isFalse not_liftRel_inr_inl
+  | inr _, inr _ => decidable_of_iff' _ liftRel_inr_inr
+
+end LiftRel
+
+section Lex
+
+/-- Lexicographic order for sum. Sort all the `inl a` before the `inr b`, otherwise use the
+respective order on `α` or `β`. -/
+inductive Lex (r : α → α → Prop) (s : β → β → Prop) : α ⊕ β → α ⊕ β → Prop
+  /-- `inl a₁` and `inl a₂` are related via `Lex r s` if `a₁` and `a₂` are related via `r`. -/
+  | protected inl {a₁ a₂} (h : r a₁ a₂) : Lex r s (inl a₁) (inl a₂)
+  /-- `inr b₁` and `inr b₂` are related via `Lex r s` if `b₁` and `b₂` are related via `s`. -/
+  | protected inr {b₁ b₂} (h : s b₁ b₂) : Lex r s (inr b₁) (inr b₂)
+  /-- `inl a` and `inr b` are always related via `Lex r s`. -/
+  | sep (a b) : Lex r s (inl a) (inr b)
+
+attribute [simp] Lex.sep
+
+@[simp] theorem lex_inl_inl : Lex r s (inl a₁) (inl a₂) ↔ r a₁ a₂ :=
+  ⟨fun h => by cases h; assumption, Lex.inl⟩
+
+@[simp] theorem lex_inr_inr : Lex r s (inr b₁) (inr b₂) ↔ s b₁ b₂ :=
+  ⟨fun h => by cases h; assumption, Lex.inr⟩
+
+@[simp] theorem lex_inr_inl : ¬Lex r s (inr b) (inl a) := nofun
+
+instance instDecidableRelSumLex [DecidableRel r] [DecidableRel s] : DecidableRel (Lex r s)
+  | inl _, inl _ => decidable_of_iff' _ lex_inl_inl
+  | inl _, inr _ => Decidable.isTrue (Lex.sep _ _)
+  | inr _, inl _ => Decidable.isFalse lex_inr_inl
+  | inr _, inr _ => decidable_of_iff' _ lex_inr_inr
+
+end Lex
+
+end Sum

src/Init/Data/Sum/Lemmas.lean

@@ -0,0 +1,251 @@
+/-
+Copyright (c) 2017 Mario Carneiro. All rights reserved.
+Released under Apache 2.0 license as described in the file LICENSE.
+Authors: Mario Carneiro, Yury G. Kudryashov
+-/
+prelude
+import Init.Data.Sum.Basic
+import Init.Ext
+
+/-!
+# Disjoint union of types
+
+Theorems about the definitions introduced in `Init.Data.Sum.Basic`.
+-/
+
+open Function
+
+namespace Sum
+
+@[simp] protected theorem «forall» {p : α ⊕ β → Prop} :
+    (∀ x, p x) ↔ (∀ a, p (inl a)) ∧ ∀ b, p (inr b) :=
+  ⟨fun h => ⟨fun _ => h _, fun _ => h _⟩, fun ⟨h₁, h₂⟩ => Sum.rec h₁ h₂⟩
+
+@[simp] protected theorem «exists» {p : α ⊕ β → Prop} :
+    (∃ x, p x) ↔ (∃ a, p (inl a)) ∨ ∃ b, p (inr b) :=
+  ⟨ fun
+    | ⟨inl a, h⟩ => Or.inl ⟨a, h⟩
+    | ⟨inr b, h⟩ => Or.inr ⟨b, h⟩,
+    fun
+    | Or.inl ⟨a, h⟩ => ⟨inl a, h⟩
+    | Or.inr ⟨b, h⟩ => ⟨inr b, h⟩⟩
+
+theorem forall_sum {γ : α ⊕ β → Sort _} (p : (∀ ab, γ ab) → Prop) :
+    (∀ fab, p fab) ↔ (∀ fa fb, p (Sum.rec fa fb)) := by
+  refine ⟨fun h fa fb => h _, fun h fab => ?_⟩
+  have h1 : fab = Sum.rec (fun a => fab (Sum.inl a)) (fun b => fab (Sum.inr b)) := by
+    apply funext
+    rintro (_ | _) <;> rfl
+  rw [h1]; exact h _ _
+
+section get
+
+@[simp] theorem inl_getLeft : ∀ (x : α ⊕ β) (h : x.isLeft), inl (x.getLeft h) = x
+  | inl _, _ => rfl
+@[simp] theorem inr_getRight : ∀ (x : α ⊕ β) (h : x.isRight), inr (x.getRight h) = x
+  | inr _, _ => rfl
+
+@[simp] theorem getLeft?_eq_none_iff {x : α ⊕ β} : x.getLeft? = none ↔ x.isRight := by
+  cases x <;> simp only [getLeft?, isRight, eq_self_iff_true, reduceCtorEq]
+
+@[simp] theorem getRight?_eq_none_iff {x : α ⊕ β} : x.getRight? = none ↔ x.isLeft := by
+  cases x <;> simp only [getRight?, isLeft, eq_self_iff_true, reduceCtorEq]
+
+theorem eq_left_getLeft_of_isLeft : ∀ {x : α ⊕ β} (h : x.isLeft), x = inl (x.getLeft h)
+  | inl _, _ => rfl
+
+@[simp] theorem getLeft_eq_iff (h : x.isLeft) : x.getLeft h = a ↔ x = inl a := by
+  cases x <;> simp at h ⊢
+
+theorem eq_right_getRight_of_isRight : ∀ {x : α ⊕ β} (h : x.isRight), x = inr (x.getRight h)
+  | inr _, _ => rfl
+
+@[simp] theorem getRight_eq_iff (h : x.isRight) : x.getRight h = b ↔ x = inr b := by
+  cases x <;> simp at h ⊢
+
+@[simp] theorem getLeft?_eq_some_iff : x.getLeft? = some a ↔ x = inl a := by
+  cases x <;> simp only [getLeft?, Option.some.injEq, inl.injEq, reduceCtorEq]
+
+@[simp] theorem getRight?_eq_some_iff : x.getRight? = some b ↔ x = inr b := by
+  cases x <;> simp only [getRight?, Option.some.injEq, inr.injEq, reduceCtorEq]
+
+@[simp] theorem bnot_isLeft (x : α ⊕ β) : !x.isLeft = x.isRight := by cases x <;> rfl
+
+@[simp] theorem isLeft_eq_false {x : α ⊕ β} : x.isLeft = false ↔ x.isRight := by cases x <;> simp
+
+theorem not_isLeft {x : α ⊕ β} : ¬x.isLeft ↔ x.isRight := by simp
+
+@[simp] theorem bnot_isRight (x : α ⊕ β) : !x.isRight = x.isLeft := by cases x <;> rfl
+
+@[simp] theorem isRight_eq_false {x : α ⊕ β} : x.isRight = false ↔ x.isLeft := by cases x <;> simp
+
+theorem not_isRight {x : α ⊕ β} : ¬x.isRight ↔ x.isLeft := by simp
+
+theorem isLeft_iff : x.isLeft ↔ ∃ y, x = Sum.inl y := by cases x <;> simp
+
+theorem isRight_iff : x.isRight ↔ ∃ y, x = Sum.inr y := by cases x <;> simp
+
+end get
+
+theorem inl.inj_iff : (inl a : α ⊕ β) = inl b ↔ a = b := ⟨inl.inj, congrArg _⟩
+
+theorem inr.inj_iff : (inr a : α ⊕ β) = inr b ↔ a = b := ⟨inr.inj, congrArg _⟩
+
+theorem inl_ne_inr : inl a ≠ inr b := nofun
+
+theorem inr_ne_inl : inr b ≠ inl a := nofun
+
+/-! ### `Sum.elim` -/
+
+@[simp] theorem elim_comp_inl (f : α → γ) (g : β → γ) : Sum.elim f g ∘ inl = f :=
+  rfl
+
+@[simp] theorem elim_comp_inr (f : α → γ) (g : β → γ) : Sum.elim f g ∘ inr = g :=
+  rfl
+
+@[simp] theorem elim_inl_inr : @Sum.elim α β _ inl inr = id :=
+  funext fun x => Sum.casesOn x (fun _ => rfl) fun _ => rfl
+
+theorem comp_elim (f : γ → δ) (g : α → γ) (h : β → γ) :
+    f ∘ Sum.elim g h = Sum.elim (f ∘ g) (f ∘ h) :=
+  funext fun x => Sum.casesOn x (fun _ => rfl) fun _ => rfl
+
+@[simp] theorem elim_comp_inl_inr (f : α ⊕ β → γ) :
+    Sum.elim (f ∘ inl) (f ∘ inr) = f :=
+  funext fun x => Sum.casesOn x (fun _ => rfl) fun _ => rfl
+
+theorem elim_eq_iff {u u' : α → γ} {v v' : β → γ} :
+    Sum.elim u v = Sum.elim u' v' ↔ u = u' ∧ v = v' := by
+  simp [funext_iff]
+
+/-! ### `Sum.map` -/
+
+@[simp] theorem map_map (f' : α' → α'') (g' : β' → β'') (f : α → α') (g : β → β') :
+    ∀ x : Sum α β, (x.map f g).map f' g' = x.map (f' ∘ f) (g' ∘ g)
+  | inl _ => rfl
+  | inr _ => rfl
+
+@[simp] theorem map_comp_map (f' : α' → α'') (g' : β' → β'') (f : α → α') (g : β → β') :
+    Sum.map f' g' ∘ Sum.map f g = Sum.map (f' ∘ f) (g' ∘ g) :=
+  funext <| map_map f' g' f g
+
+@[simp] theorem map_id_id : Sum.map (@id α) (@id β) = id :=
+  funext fun x => Sum.recOn x (fun _ => rfl) fun _ => rfl
+
+theorem elim_map {f₁ : α → β} {f₂ : β → ε} {g₁ : γ → δ} {g₂ : δ → ε} {x} :
+    Sum.elim f₂ g₂ (Sum.map f₁ g₁ x) = Sum.elim (f₂ ∘ f₁) (g₂ ∘ g₁) x := by
+  cases x <;> rfl
+
+theorem elim_comp_map {f₁ : α → β} {f₂ : β → ε} {g₁ : γ → δ} {g₂ : δ → ε} :
+    Sum.elim f₂ g₂ ∘ Sum.map f₁ g₁ = Sum.elim (f₂ ∘ f₁) (g₂ ∘ g₁) :=
+  funext fun _ => elim_map
+
+@[simp] theorem isLeft_map (f : α → β) (g : γ → δ) (x : α ⊕ γ) :
+    isLeft (x.map f g) = isLeft x := by
+  cases x <;> rfl
+
+@[simp] theorem isRight_map (f : α → β) (g : γ → δ) (x : α ⊕ γ) :
+    isRight (x.map f g) = isRight x := by
+  cases x <;> rfl
+
+@[simp] theorem getLeft?_map (f : α → β) (g : γ → δ) (x : α ⊕ γ) :
+    (x.map f g).getLeft? = x.getLeft?.map f := by
+  cases x <;> rfl
+
+@[simp] theorem getRight?_map (f : α → β) (g : γ → δ) (x : α ⊕ γ) :
+    (x.map f g).getRight? = x.getRight?.map g := by cases x <;> rfl
+
+/-! ### `Sum.swap` -/
+
+@[simp] theorem swap_swap (x : α ⊕ β) : swap (swap x) = x := by cases x <;> rfl
+
+@[simp] theorem swap_swap_eq : swap ∘ swap = @id (α ⊕ β) := funext <| swap_swap
+
+@[simp] theorem isLeft_swap (x : α ⊕ β) : x.swap.isLeft = x.isRight := by cases x <;> rfl
+
+@[simp] theorem isRight_swap (x : α ⊕ β) : x.swap.isRight = x.isLeft := by cases x <;> rfl
+
+@[simp] theorem getLeft?_swap (x : α ⊕ β) : x.swap.getLeft? = x.getRight? := by cases x <;> rfl
+
+@[simp] theorem getRight?_swap (x : α ⊕ β) : x.swap.getRight? = x.getLeft? := by cases x <;> rfl
+
+section LiftRel
+
+theorem LiftRel.mono (hr : ∀ a b, r₁ a b → r₂ a b) (hs : ∀ a b, s₁ a b → s₂ a b)
+  (h : LiftRel r₁ s₁ x y) : LiftRel r₂ s₂ x y := by
+  cases h
+  · exact LiftRel.inl (hr _ _ ‹_›)
+  · exact LiftRel.inr (hs _ _ ‹_›)
+
+theorem LiftRel.mono_left (hr : ∀ a b, r₁ a b → r₂ a b) (h : LiftRel r₁ s x y) :
+    LiftRel r₂ s x y :=
+  (h.mono hr) fun _ _ => id
+
+theorem LiftRel.mono_right (hs : ∀ a b, s₁ a b → s₂ a b) (h : LiftRel r s₁ x y) :
+    LiftRel r s₂ x y :=
+  h.mono (fun _ _ => id) hs
+
+protected theorem LiftRel.swap (h : LiftRel r s x y) : LiftRel s r x.swap y.swap := by
+  cases h
+  · exact LiftRel.inr ‹_›
+  · exact LiftRel.inl ‹_›
+
+@[simp] theorem liftRel_swap_iff : LiftRel s r x.swap y.swap ↔ LiftRel r s x y :=
+  ⟨fun h => by rw [← swap_swap x, ← swap_swap y]; exact h.swap, LiftRel.swap⟩
+
+end LiftRel
+
+section Lex
+
+protected theorem LiftRel.lex {a b : α ⊕ β} (h : LiftRel r s a b) : Lex r s a b := by
+  cases h
+  · exact Lex.inl ‹_›
+  · exact Lex.inr ‹_›
+
+theorem liftRel_subrelation_lex : Subrelation (LiftRel r s) (Lex r s) := LiftRel.lex
+
+theorem Lex.mono (hr : ∀ a b, r₁ a b → r₂ a b) (hs : ∀ a b, s₁ a b → s₂ a b) (h : Lex r₁ s₁ x y) :
+    Lex r₂ s₂ x y := by
+  cases h
+  · exact Lex.inl (hr _ _ ‹_›)
+  · exact Lex.inr (hs _ _ ‹_›)
+  · exact Lex.sep _ _
+
+theorem Lex.mono_left (hr : ∀ a b, r₁ a b → r₂ a b) (h : Lex r₁ s x y) : Lex r₂ s x y :=
+  (h.mono hr) fun _ _ => id
+
+theorem Lex.mono_right (hs : ∀ a b, s₁ a b → s₂ a b) (h : Lex r s₁ x y) : Lex r s₂ x y :=
+  h.mono (fun _ _ => id) hs
+
+theorem lex_acc_inl (aca : Acc r a) : Acc (Lex r s) (inl a) := by
+  induction aca with
+  | intro _ _ IH =>
+    constructor
+    intro y h
+    cases h with
+    | inl h' => exact IH _ h'
+
+theorem lex_acc_inr (aca : ∀ a, Acc (Lex r s) (inl a)) {b} (acb : Acc s b) :
+    Acc (Lex r s) (inr b) := by
+  induction acb with
+  | intro _ _ IH =>
+    constructor
+    intro y h
+    cases h with
+    | inr h' => exact IH _ h'
+    | sep => exact aca _
+
+theorem lex_wf (ha : WellFounded r) (hb : WellFounded s) : WellFounded (Lex r s) :=
+  have aca : ∀ a, Acc (Lex r s) (inl a) := fun a => lex_acc_inl (ha.apply a)
+  ⟨fun x => Sum.recOn x aca fun b => lex_acc_inr aca (hb.apply b)⟩
+
+end Lex
+
+theorem elim_const_const (c : γ) :
+    Sum.elim (const _ c : α → γ) (const _ c : β → γ) = const _ c := by
+  apply funext
+  rintro (_ | _) <;> rfl
+
+@[simp] theorem elim_lam_const_lam_const (c : γ) :
+    Sum.elim (fun _ : α => c) (fun _ : β => c) = fun _ => c :=
+  Sum.elim_const_const c

src/Init/Data/ToString/Basic.lean

@@ -5,7 +5,7 @@ Author: Leonardo de Moura
 -/
 prelude
 import Init.Data.String.Basic
-import Init.Data.UInt.Basic
+import Init.Data.UInt.BasicAux
 import Init.Data.Nat.Div
 import Init.Data.Repr
 import Init.Data.Int.Basic

src/Init/Data/UInt.lean

@@ -4,6 +4,7 @@ Released under Apache 2.0 license as described in the file LICENSE.
 Authors: Henrik Böving
 -/
 prelude
+import Init.Data.UInt.BasicAux
 import Init.Data.UInt.Basic
 import Init.Data.UInt.Log2
 import Init.Data.UInt.Lemmas

src/Init/Data/UInt/Basic.lean

@@ -4,52 +4,50 @@ Released under Apache 2.0 license as described in the file LICENSE.
 Authors: Leonardo de Moura
 -/
 prelude
-import Init.Data.Fin.Basic
+import Init.Data.UInt.BasicAux
+import Init.Data.BitVec.Basic
 
 open Nat
 
-@[extern "lean_uint8_of_nat"]
-def UInt8.ofNat (n : @& Nat) : UInt8 := ⟨Fin.ofNat n⟩
-abbrev Nat.toUInt8 := UInt8.ofNat
-@[extern "lean_uint8_to_nat"]
-def UInt8.toNat (n : UInt8) : Nat := n.val.val
 @[extern "lean_uint8_add"]
-def UInt8.add (a b : UInt8) : UInt8 := ⟨a.val + b.val⟩
+def UInt8.add (a b : UInt8) : UInt8 := ⟨a.toBitVec + b.toBitVec⟩
 @[extern "lean_uint8_sub"]
-def UInt8.sub (a b : UInt8) : UInt8 := ⟨a.val - b.val⟩
+def UInt8.sub (a b : UInt8) : UInt8 := ⟨a.toBitVec - b.toBitVec⟩
 @[extern "lean_uint8_mul"]
-def UInt8.mul (a b : UInt8) : UInt8 := ⟨a.val * b.val⟩
+def UInt8.mul (a b : UInt8) : UInt8 := ⟨a.toBitVec * b.toBitVec⟩
 @[extern "lean_uint8_div"]
-def UInt8.div (a b : UInt8) : UInt8 := ⟨a.val / b.val⟩
+def UInt8.div (a b : UInt8) : UInt8 := ⟨BitVec.udiv a.toBitVec b.toBitVec⟩
 @[extern "lean_uint8_mod"]
-def UInt8.mod (a b : UInt8) : UInt8 := ⟨a.val % b.val⟩
-@[extern "lean_uint8_modn"]
+def UInt8.mod (a b : UInt8) : UInt8 := ⟨BitVec.umod a.toBitVec b.toBitVec⟩
+@[extern "lean_uint8_modn", deprecated UInt8.mod (since := "2024-09-23")]
 def UInt8.modn (a : UInt8) (n : @& Nat) : UInt8 := ⟨Fin.modn a.val n⟩
 @[extern "lean_uint8_land"]
-def UInt8.land (a b : UInt8) : UInt8 := ⟨Fin.land a.val b.val⟩
+def UInt8.land (a b : UInt8) : UInt8 := ⟨a.toBitVec &&& b.toBitVec⟩
 @[extern "lean_uint8_lor"]
-def UInt8.lor (a b : UInt8) : UInt8 := ⟨Fin.lor a.val b.val⟩
+def UInt8.lor (a b : UInt8) : UInt8 := ⟨a.toBitVec ||| b.toBitVec⟩
 @[extern "lean_uint8_xor"]
-def UInt8.xor (a b : UInt8) : UInt8 := ⟨Fin.xor a.val b.val⟩
+def UInt8.xor (a b : UInt8) : UInt8 := ⟨a.toBitVec ^^^ b.toBitVec⟩
 @[extern "lean_uint8_shift_left"]
-def UInt8.shiftLeft (a b : UInt8) : UInt8 := ⟨a.val <<< (modn b 8).val⟩
+def UInt8.shiftLeft (a b : UInt8) : UInt8 := ⟨a.toBitVec <<< (mod b 8).toBitVec⟩
 @[extern "lean_uint8_shift_right"]
-def UInt8.shiftRight (a b : UInt8) : UInt8 := ⟨a.val >>> (modn b 8).val⟩
-def UInt8.lt (a b : UInt8) : Prop := a.val < b.val
-def UInt8.le (a b : UInt8) : Prop := a.val ≤ b.val
+def UInt8.shiftRight (a b : UInt8) : UInt8 := ⟨a.toBitVec >>> (mod b 8).toBitVec⟩
+def UInt8.lt (a b : UInt8) : Prop := a.toBitVec < b.toBitVec
+def UInt8.le (a b : UInt8) : Prop := a.toBitVec ≤ b.toBitVec
 
-instance UInt8.instOfNat : OfNat UInt8 n := ⟨UInt8.ofNat n⟩
 instance : Add UInt8       := ⟨UInt8.add⟩
 instance : Sub UInt8       := ⟨UInt8.sub⟩
 instance : Mul UInt8       := ⟨UInt8.mul⟩
 instance : Mod UInt8       := ⟨UInt8.mod⟩
+
+set_option linter.deprecated false in
 instance : HMod UInt8 Nat UInt8 := ⟨UInt8.modn⟩
+
 instance : Div UInt8       := ⟨UInt8.div⟩
 instance : LT UInt8        := ⟨UInt8.lt⟩
 instance : LE UInt8        := ⟨UInt8.le⟩
 
 @[extern "lean_uint8_complement"]
-def UInt8.complement (a:UInt8) : UInt8 := 0-(a+1)
+def UInt8.complement (a : UInt8) : UInt8 := ⟨~~~a.toBitVec⟩
 
 instance : Complement UInt8 := ⟨UInt8.complement⟩
 instance : AndOp UInt8     := ⟨UInt8.land⟩
@@ -58,69 +56,58 @@ instance : Xor UInt8       := ⟨UInt8.xor⟩
 instance : ShiftLeft UInt8  := ⟨UInt8.shiftLeft⟩
 instance : ShiftRight UInt8 := ⟨UInt8.shiftRight⟩
 
-set_option bootstrap.genMatcherCode false in
 @[extern "lean_uint8_dec_lt"]
 def UInt8.decLt (a b : UInt8) : Decidable (a < b) :=
-  match a, b with
-  | ⟨n⟩, ⟨m⟩ => inferInstanceAs (Decidable (n < m))
+  inferInstanceAs (Decidable (a.toBitVec < b.toBitVec))
 
-set_option bootstrap.genMatcherCode false in
 @[extern "lean_uint8_dec_le"]
 def UInt8.decLe (a b : UInt8) : Decidable (a ≤ b) :=
-  match a, b with
-  | ⟨n⟩, ⟨m⟩ => inferInstanceAs (Decidable (n <= m))
+  inferInstanceAs (Decidable (a.toBitVec ≤ b.toBitVec))
 
 instance (a b : UInt8) : Decidable (a < b) := UInt8.decLt a b
 instance (a b : UInt8) : Decidable (a ≤ b) := UInt8.decLe a b
 instance : Max UInt8 := maxOfLe
 instance : Min UInt8 := minOfLe
 
-@[extern "lean_uint16_of_nat"]
-def UInt16.ofNat (n : @& Nat) : UInt16 := ⟨Fin.ofNat n⟩
-abbrev Nat.toUInt16 := UInt16.ofNat
-@[extern "lean_uint16_to_nat"]
-def UInt16.toNat (n : UInt16) : Nat := n.val.val
 @[extern "lean_uint16_add"]
-def UInt16.add (a b : UInt16) : UInt16 := ⟨a.val + b.val⟩
+def UInt16.add (a b : UInt16) : UInt16 := ⟨a.toBitVec + b.toBitVec⟩
 @[extern "lean_uint16_sub"]
-def UInt16.sub (a b : UInt16) : UInt16 := ⟨a.val - b.val⟩
+def UInt16.sub (a b : UInt16) : UInt16 := ⟨a.toBitVec - b.toBitVec⟩
 @[extern "lean_uint16_mul"]
-def UInt16.mul (a b : UInt16) : UInt16 := ⟨a.val * b.val⟩
+def UInt16.mul (a b : UInt16) : UInt16 := ⟨a.toBitVec * b.toBitVec⟩
 @[extern "lean_uint16_div"]
-def UInt16.div (a b : UInt16) : UInt16 := ⟨a.val / b.val⟩
+def UInt16.div (a b : UInt16) : UInt16 := ⟨BitVec.udiv a.toBitVec b.toBitVec⟩
 @[extern "lean_uint16_mod"]
-def UInt16.mod (a b : UInt16) : UInt16 := ⟨a.val % b.val⟩
-@[extern "lean_uint16_modn"]
+def UInt16.mod (a b : UInt16) : UInt16 := ⟨BitVec.umod a.toBitVec b.toBitVec⟩
+@[extern "lean_uint16_modn", deprecated UInt16.mod (since := "2024-09-23")]
 def UInt16.modn (a : UInt16) (n : @& Nat) : UInt16 := ⟨Fin.modn a.val n⟩
 @[extern "lean_uint16_land"]
-def UInt16.land (a b : UInt16) : UInt16 := ⟨Fin.land a.val b.val⟩
+def UInt16.land (a b : UInt16) : UInt16 := ⟨a.toBitVec &&& b.toBitVec⟩
 @[extern "lean_uint16_lor"]
-def UInt16.lor (a b : UInt16) : UInt16 := ⟨Fin.lor a.val b.val⟩
+def UInt16.lor (a b : UInt16) : UInt16 := ⟨a.toBitVec ||| b.toBitVec⟩
 @[extern "lean_uint16_xor"]
-def UInt16.xor (a b : UInt16) : UInt16 := ⟨Fin.xor a.val b.val⟩
+def UInt16.xor (a b : UInt16) : UInt16 := ⟨a.toBitVec ^^^ b.toBitVec⟩
 @[extern "lean_uint16_shift_left"]
-def UInt16.shiftLeft (a b : UInt16) : UInt16 := ⟨a.val <<< (modn b 16).val⟩
-@[extern "lean_uint16_to_uint8"]
-def UInt16.toUInt8 (a : UInt16) : UInt8 := a.toNat.toUInt8
-@[extern "lean_uint8_to_uint16"]
-def UInt8.toUInt16 (a : UInt8) : UInt16 := ⟨a.val, Nat.lt_trans a.1.2 (by decide)⟩
+def UInt16.shiftLeft (a b : UInt16) : UInt16 := ⟨a.toBitVec <<< (mod b 16).toBitVec⟩
 @[extern "lean_uint16_shift_right"]
-def UInt16.shiftRight (a b : UInt16) : UInt16 := ⟨a.val >>> (modn b 16).val⟩
-def UInt16.lt (a b : UInt16) : Prop := a.val < b.val
-def UInt16.le (a b : UInt16) : Prop := a.val ≤ b.val
+def UInt16.shiftRight (a b : UInt16) : UInt16 := ⟨a.toBitVec >>> (mod b 16).toBitVec⟩
+def UInt16.lt (a b : UInt16) : Prop := a.toBitVec < b.toBitVec
+def UInt16.le (a b : UInt16) : Prop := a.toBitVec ≤ b.toBitVec
 
-instance UInt16.instOfNat : OfNat UInt16 n := ⟨UInt16.ofNat n⟩
 instance : Add UInt16       := ⟨UInt16.add⟩
 instance : Sub UInt16       := ⟨UInt16.sub⟩
 instance : Mul UInt16       := ⟨UInt16.mul⟩
 instance : Mod UInt16       := ⟨UInt16.mod⟩
+
+set_option linter.deprecated false in
 instance : HMod UInt16 Nat UInt16 := ⟨UInt16.modn⟩
+
 instance : Div UInt16       := ⟨UInt16.div⟩
 instance : LT UInt16        := ⟨UInt16.lt⟩
 instance : LE UInt16        := ⟨UInt16.le⟩
 
 @[extern "lean_uint16_complement"]
-def UInt16.complement (a:UInt16) : UInt16 := 0-(a+1)
+def UInt16.complement (a : UInt16) : UInt16 := ⟨~~~a.toBitVec⟩
 
 instance : Complement UInt16 := ⟨UInt16.complement⟩
 instance : AndOp UInt16     := ⟨UInt16.land⟩
@@ -132,74 +119,53 @@ instance : ShiftRight UInt16 := ⟨UInt16.shiftRight⟩
 set_option bootstrap.genMatcherCode false in
 @[extern "lean_uint16_dec_lt"]
 def UInt16.decLt (a b : UInt16) : Decidable (a < b) :=
-  match a, b with
-  | ⟨n⟩, ⟨m⟩ => inferInstanceAs (Decidable (n < m))
+  inferInstanceAs (Decidable (a.toBitVec < b.toBitVec))
 
 set_option bootstrap.genMatcherCode false in
 @[extern "lean_uint16_dec_le"]
 def UInt16.decLe (a b : UInt16) : Decidable (a ≤ b) :=
-  match a, b with
-  | ⟨n⟩, ⟨m⟩ => inferInstanceAs (Decidable (n <= m))
+  inferInstanceAs (Decidable (a.toBitVec ≤ b.toBitVec))
 
 instance (a b : UInt16) : Decidable (a < b) := UInt16.decLt a b
 instance (a b : UInt16) : Decidable (a ≤ b) := UInt16.decLe a b
 instance : Max UInt16 := maxOfLe
 instance : Min UInt16 := minOfLe
 
-@[extern "lean_uint32_of_nat"]
-def UInt32.ofNat (n : @& Nat) : UInt32 := ⟨Fin.ofNat n⟩
-@[extern "lean_uint32_of_nat"]
-def UInt32.ofNat' (n : Nat) (h : n < UInt32.size) : UInt32 := ⟨⟨n, h⟩⟩
-/--
-Converts the given natural number to `UInt32`, but returns `2^32 - 1` for natural numbers `>= 2^32`.
--/
-def UInt32.ofNatTruncate (n : Nat) : UInt32 :=
-  if h : n < UInt32.size then
-    UInt32.ofNat' n h
-  else
-    UInt32.ofNat' (UInt32.size - 1) (by decide)
-abbrev Nat.toUInt32 := UInt32.ofNat
 @[extern "lean_uint32_add"]
-def UInt32.add (a b : UInt32) : UInt32 := ⟨a.val + b.val⟩
+def UInt32.add (a b : UInt32) : UInt32 := ⟨a.toBitVec + b.toBitVec⟩
 @[extern "lean_uint32_sub"]
-def UInt32.sub (a b : UInt32) : UInt32 := ⟨a.val - b.val⟩
+def UInt32.sub (a b : UInt32) : UInt32 := ⟨a.toBitVec - b.toBitVec⟩
 @[extern "lean_uint32_mul"]
-def UInt32.mul (a b : UInt32) : UInt32 := ⟨a.val * b.val⟩
+def UInt32.mul (a b : UInt32) : UInt32 := ⟨a.toBitVec * b.toBitVec⟩
 @[extern "lean_uint32_div"]
-def UInt32.div (a b : UInt32) : UInt32 := ⟨a.val / b.val⟩
+def UInt32.div (a b : UInt32) : UInt32 := ⟨BitVec.udiv a.toBitVec b.toBitVec⟩
 @[extern "lean_uint32_mod"]
-def UInt32.mod (a b : UInt32) : UInt32 := ⟨a.val % b.val⟩
-@[extern "lean_uint32_modn"]
+def UInt32.mod (a b : UInt32) : UInt32 := ⟨BitVec.umod a.toBitVec b.toBitVec⟩
+@[extern "lean_uint32_modn", deprecated UInt32.mod (since := "2024-09-23")]
 def UInt32.modn (a : UInt32) (n : @& Nat) : UInt32 := ⟨Fin.modn a.val n⟩
 @[extern "lean_uint32_land"]
-def UInt32.land (a b : UInt32) : UInt32 := ⟨Fin.land a.val b.val⟩
+def UInt32.land (a b : UInt32) : UInt32 := ⟨a.toBitVec &&& b.toBitVec⟩
 @[extern "lean_uint32_lor"]
-def UInt32.lor (a b : UInt32) : UInt32 := ⟨Fin.lor a.val b.val⟩
+def UInt32.lor (a b : UInt32) : UInt32 := ⟨a.toBitVec ||| b.toBitVec⟩
 @[extern "lean_uint32_xor"]
-def UInt32.xor (a b : UInt32) : UInt32 := ⟨Fin.xor a.val b.val⟩
+def UInt32.xor (a b : UInt32) : UInt32 := ⟨a.toBitVec ^^^ b.toBitVec⟩
 @[extern "lean_uint32_shift_left"]
-def UInt32.shiftLeft (a b : UInt32) : UInt32 := ⟨a.val <<< (modn b 32).val⟩
+def UInt32.shiftLeft (a b : UInt32) : UInt32 := ⟨a.toBitVec <<< (mod b 32).toBitVec⟩
 @[extern "lean_uint32_shift_right"]
-def UInt32.shiftRight (a b : UInt32) : UInt32 := ⟨a.val >>> (modn b 32).val⟩
-@[extern "lean_uint32_to_uint8"]
-def UInt32.toUInt8 (a : UInt32) : UInt8 := a.toNat.toUInt8
-@[extern "lean_uint32_to_uint16"]
-def UInt32.toUInt16 (a : UInt32) : UInt16 := a.toNat.toUInt16
-@[extern "lean_uint8_to_uint32"]
-def UInt8.toUInt32 (a : UInt8) : UInt32 := ⟨a.val, Nat.lt_trans a.1.2 (by decide)⟩
-@[extern "lean_uint16_to_uint32"]
-def UInt16.toUInt32 (a : UInt16) : UInt32 := ⟨a.val, Nat.lt_trans a.1.2 (by decide)⟩
+def UInt32.shiftRight (a b : UInt32) : UInt32 := ⟨a.toBitVec >>> (mod b 32).toBitVec⟩
 
-instance UInt32.instOfNat : OfNat UInt32 n := ⟨UInt32.ofNat n⟩
 instance : Add UInt32       := ⟨UInt32.add⟩
 instance : Sub UInt32       := ⟨UInt32.sub⟩
 instance : Mul UInt32       := ⟨UInt32.mul⟩
 instance : Mod UInt32       := ⟨UInt32.mod⟩
+
+set_option linter.deprecated false in
 instance : HMod UInt32 Nat UInt32 := ⟨UInt32.modn⟩
+
 instance : Div UInt32       := ⟨UInt32.div⟩
 
 @[extern "lean_uint32_complement"]
-def UInt32.complement (a:UInt32) : UInt32 := 0-(a+1)
+def UInt32.complement (a : UInt32) : UInt32 := ⟨~~~a.toBitVec⟩
 
 instance : Complement UInt32 := ⟨UInt32.complement⟩
 instance : AndOp UInt32     := ⟨UInt32.land⟩
@@ -208,60 +174,45 @@ instance : Xor UInt32       := ⟨UInt32.xor⟩
 instance : ShiftLeft UInt32  := ⟨UInt32.shiftLeft⟩
 instance : ShiftRight UInt32 := ⟨UInt32.shiftRight⟩
 
-@[extern "lean_uint64_of_nat"]
-def UInt64.ofNat (n : @& Nat) : UInt64 := ⟨Fin.ofNat n⟩
-abbrev Nat.toUInt64 := UInt64.ofNat
-@[extern "lean_uint64_to_nat"]
-def UInt64.toNat (n : UInt64) : Nat := n.val.val
 @[extern "lean_uint64_add"]
-def UInt64.add (a b : UInt64) : UInt64 := ⟨a.val + b.val⟩
+def UInt64.add (a b : UInt64) : UInt64 := ⟨a.toBitVec + b.toBitVec⟩
 @[extern "lean_uint64_sub"]
-def UInt64.sub (a b : UInt64) : UInt64 := ⟨a.val - b.val⟩
+def UInt64.sub (a b : UInt64) : UInt64 := ⟨a.toBitVec - b.toBitVec⟩
 @[extern "lean_uint64_mul"]
-def UInt64.mul (a b : UInt64) : UInt64 := ⟨a.val * b.val⟩
+def UInt64.mul (a b : UInt64) : UInt64 := ⟨a.toBitVec * b.toBitVec⟩
 @[extern "lean_uint64_div"]
-def UInt64.div (a b : UInt64) : UInt64 := ⟨a.val / b.val⟩
+def UInt64.div (a b : UInt64) : UInt64 := ⟨BitVec.udiv a.toBitVec b.toBitVec⟩
 @[extern "lean_uint64_mod"]
-def UInt64.mod (a b : UInt64) : UInt64 := ⟨a.val % b.val⟩
-@[extern "lean_uint64_modn"]
+def UInt64.mod (a b : UInt64) : UInt64 := ⟨BitVec.umod a.toBitVec b.toBitVec⟩
+@[extern "lean_uint64_modn", deprecated UInt64.mod (since := "2024-09-23")]
 def UInt64.modn (a : UInt64) (n : @& Nat) : UInt64 := ⟨Fin.modn a.val n⟩
 @[extern "lean_uint64_land"]
-def UInt64.land (a b : UInt64) : UInt64 := ⟨Fin.land a.val b.val⟩
+def UInt64.land (a b : UInt64) : UInt64 := ⟨a.toBitVec &&& b.toBitVec⟩
 @[extern "lean_uint64_lor"]
-def UInt64.lor (a b : UInt64) : UInt64 := ⟨Fin.lor a.val b.val⟩
+def UInt64.lor (a b : UInt64) : UInt64 := ⟨a.toBitVec ||| b.toBitVec⟩
 @[extern "lean_uint64_xor"]
-def UInt64.xor (a b : UInt64) : UInt64 := ⟨Fin.xor a.val b.val⟩
+def UInt64.xor (a b : UInt64) : UInt64 := ⟨a.toBitVec ^^^ b.toBitVec⟩
 @[extern "lean_uint64_shift_left"]
-def UInt64.shiftLeft (a b : UInt64) : UInt64 := ⟨a.val <<< (modn b 64).val⟩
+def UInt64.shiftLeft (a b : UInt64) : UInt64 := ⟨a.toBitVec <<< (mod b 64).toBitVec⟩
 @[extern "lean_uint64_shift_right"]
-def UInt64.shiftRight (a b : UInt64) : UInt64 := ⟨a.val >>> (modn b 64).val⟩
-def UInt64.lt (a b : UInt64) : Prop := a.val < b.val
-def UInt64.le (a b : UInt64) : Prop := a.val ≤ b.val
-@[extern "lean_uint64_to_uint8"]
-def UInt64.toUInt8 (a : UInt64) : UInt8 := a.toNat.toUInt8
-@[extern "lean_uint64_to_uint16"]
-def UInt64.toUInt16 (a : UInt64) : UInt16 := a.toNat.toUInt16
-@[extern "lean_uint64_to_uint32"]
-def UInt64.toUInt32 (a : UInt64) : UInt32 := a.toNat.toUInt32
-@[extern "lean_uint8_to_uint64"]
-def UInt8.toUInt64 (a : UInt8) : UInt64 := ⟨a.val, Nat.lt_trans a.1.2 (by decide)⟩
-@[extern "lean_uint16_to_uint64"]
-def UInt16.toUInt64 (a : UInt16) : UInt64 := ⟨a.val, Nat.lt_trans a.1.2 (by decide)⟩
-@[extern "lean_uint32_to_uint64"]
-def UInt32.toUInt64 (a : UInt32) : UInt64 := ⟨a.val, Nat.lt_trans a.1.2 (by decide)⟩
+def UInt64.shiftRight (a b : UInt64) : UInt64 := ⟨a.toBitVec >>> (mod b 64).toBitVec⟩
+def UInt64.lt (a b : UInt64) : Prop := a.toBitVec < b.toBitVec
+def UInt64.le (a b : UInt64) : Prop := a.toBitVec ≤ b.toBitVec
 
-instance UInt64.instOfNat : OfNat UInt64 n := ⟨UInt64.ofNat n⟩
 instance : Add UInt64       := ⟨UInt64.add⟩
 instance : Sub UInt64       := ⟨UInt64.sub⟩
 instance : Mul UInt64       := ⟨UInt64.mul⟩
 instance : Mod UInt64       := ⟨UInt64.mod⟩
+
+set_option linter.deprecated false in
 instance : HMod UInt64 Nat UInt64 := ⟨UInt64.modn⟩
+
 instance : Div UInt64       := ⟨UInt64.div⟩
 instance : LT UInt64        := ⟨UInt64.lt⟩
 instance : LE UInt64        := ⟨UInt64.le⟩
 
 @[extern "lean_uint64_complement"]
-def UInt64.complement (a:UInt64) : UInt64 := 0-(a+1)
+def UInt64.complement (a : UInt64) : UInt64 := ⟨~~~a.toBitVec⟩
 
 instance : Complement UInt64 := ⟨UInt64.complement⟩
 instance : AndOp UInt64     := ⟨UInt64.land⟩
@@ -273,79 +224,52 @@ instance : ShiftRight UInt64 := ⟨UInt64.shiftRight⟩
 @[extern "lean_bool_to_uint64"]
 def Bool.toUInt64 (b : Bool) : UInt64 := if b then 1 else 0
 
-set_option bootstrap.genMatcherCode false in
 @[extern "lean_uint64_dec_lt"]
 def UInt64.decLt (a b : UInt64) : Decidable (a < b) :=
-  match a, b with
-  | ⟨n⟩, ⟨m⟩ => inferInstanceAs (Decidable (n < m))
+  inferInstanceAs (Decidable (a.toBitVec < b.toBitVec))
 
-set_option bootstrap.genMatcherCode false in
 @[extern "lean_uint64_dec_le"]
 def UInt64.decLe (a b : UInt64) : Decidable (a ≤ b) :=
-  match a, b with
-  | ⟨n⟩, ⟨m⟩ => inferInstanceAs (Decidable (n <= m))
+  inferInstanceAs (Decidable (a.toBitVec ≤ b.toBitVec))
 
 instance (a b : UInt64) : Decidable (a < b) := UInt64.decLt a b
 instance (a b : UInt64) : Decidable (a ≤ b) := UInt64.decLe a b
 instance : Max UInt64 := maxOfLe
 instance : Min UInt64 := minOfLe
 
--- This instance would interfere with the global instance `NeZero (n + 1)`,
--- so we only enable it locally.
-@[local instance]
-private def instNeZeroUSizeSize : NeZero USize.size := ⟨add_one_ne_zero _⟩
-
-@[deprecated (since := "2024-09-16")]
-theorem usize_size_gt_zero : USize.size > 0 :=
-  Nat.zero_lt_succ ..
-
-@[extern "lean_usize_of_nat"]
-def USize.ofNat (n : @& Nat) : USize := ⟨Fin.ofNat'  _ n⟩
-abbrev Nat.toUSize := USize.ofNat
-@[extern "lean_usize_to_nat"]
-def USize.toNat (n : USize) : Nat := n.val.val
-@[extern "lean_usize_add"]
-def USize.add (a b : USize) : USize := ⟨a.val + b.val⟩
-@[extern "lean_usize_sub"]
-def USize.sub (a b : USize) : USize := ⟨a.val - b.val⟩
 @[extern "lean_usize_mul"]
-def USize.mul (a b : USize) : USize := ⟨a.val * b.val⟩
+def USize.mul (a b : USize) : USize := ⟨a.toBitVec * b.toBitVec⟩
 @[extern "lean_usize_div"]
-def USize.div (a b : USize) : USize := ⟨a.val / b.val⟩
+def USize.div (a b : USize) : USize := ⟨a.toBitVec / b.toBitVec⟩
 @[extern "lean_usize_mod"]
-def USize.mod (a b : USize) : USize := ⟨a.val % b.val⟩
-@[extern "lean_usize_modn"]
+def USize.mod (a b : USize) : USize := ⟨a.toBitVec % b.toBitVec⟩
+@[extern "lean_usize_modn", deprecated USize.mod (since := "2024-09-23")]
 def USize.modn (a : USize) (n : @& Nat) : USize := ⟨Fin.modn a.val n⟩
 @[extern "lean_usize_land"]
-def USize.land (a b : USize) : USize := ⟨Fin.land a.val b.val⟩
+def USize.land (a b : USize) : USize := ⟨a.toBitVec &&& b.toBitVec⟩
 @[extern "lean_usize_lor"]
-def USize.lor (a b : USize) : USize := ⟨Fin.lor a.val b.val⟩
+def USize.lor (a b : USize) : USize := ⟨a.toBitVec ||| b.toBitVec⟩
 @[extern "lean_usize_xor"]
-def USize.xor (a b : USize) : USize := ⟨Fin.xor a.val b.val⟩
+def USize.xor (a b : USize) : USize := ⟨a.toBitVec ^^^ b.toBitVec⟩
 @[extern "lean_usize_shift_left"]
-def USize.shiftLeft (a b : USize) : USize := ⟨a.val <<< (modn b System.Platform.numBits).val⟩
+def USize.shiftLeft (a b : USize) : USize := ⟨a.toBitVec <<< (mod b (USize.ofNat System.Platform.numBits)).toBitVec⟩
 @[extern "lean_usize_shift_right"]
-def USize.shiftRight (a b : USize) : USize := ⟨a.val >>> (modn b System.Platform.numBits).val⟩
+def USize.shiftRight (a b : USize) : USize := ⟨a.toBitVec >>> (mod b (USize.ofNat System.Platform.numBits)).toBitVec⟩
 @[extern "lean_uint32_to_usize"]
-def UInt32.toUSize (a : UInt32) : USize := USize.ofNat32 a.val a.1.2
+def UInt32.toUSize (a : UInt32) : USize := USize.ofNat32 a.toBitVec.toNat a.toBitVec.isLt
 @[extern "lean_usize_to_uint32"]
 def USize.toUInt32 (a : USize) : UInt32 := a.toNat.toUInt32
 
-def USize.lt (a b : USize) : Prop := a.val < b.val
-def USize.le (a b : USize) : Prop := a.val ≤ b.val
-
-instance USize.instOfNat : OfNat USize n := ⟨USize.ofNat n⟩
-instance : Add USize       := ⟨USize.add⟩
-instance : Sub USize       := ⟨USize.sub⟩
 instance : Mul USize       := ⟨USize.mul⟩
 instance : Mod USize       := ⟨USize.mod⟩
+
+set_option linter.deprecated false in
 instance : HMod USize Nat USize := ⟨USize.modn⟩
+
 instance : Div USize       := ⟨USize.div⟩
-instance : LT USize        := ⟨USize.lt⟩
-instance : LE USize        := ⟨USize.le⟩
 
 @[extern "lean_usize_complement"]
-def USize.complement (a:USize) : USize := 0-(a+1)
+def USize.complement (a : USize) : USize := ⟨~~~a.toBitVec⟩
 
 instance : Complement USize := ⟨USize.complement⟩
 instance : AndOp USize      := ⟨USize.land⟩
@@ -354,19 +278,5 @@ instance : Xor USize        := ⟨USize.xor⟩
 instance : ShiftLeft USize  := ⟨USize.shiftLeft⟩
 instance : ShiftRight USize := ⟨USize.shiftRight⟩
 
-set_option bootstrap.genMatcherCode false in
-@[extern "lean_usize_dec_lt"]
-def USize.decLt (a b : USize) : Decidable (a < b) :=
-  match a, b with
-  | ⟨n⟩, ⟨m⟩ => inferInstanceAs (Decidable (n < m))
-
-set_option bootstrap.genMatcherCode false in
-@[extern "lean_usize_dec_le"]
-def USize.decLe (a b : USize) : Decidable (a ≤ b) :=
-  match a, b with
-  | ⟨n⟩, ⟨m⟩ => inferInstanceAs (Decidable (n <= m))
-
-instance (a b : USize) : Decidable (a < b) := USize.decLt a b
-instance (a b : USize) : Decidable (a ≤ b) := USize.decLe a b
 instance : Max USize := maxOfLe
 instance : Min USize := minOfLe

src/Init/Data/UInt/BasicAux.lean

@@ -0,0 +1,132 @@
+/-
+Copyright (c) 2018 Microsoft Corporation. All rights reserved.
+Released under Apache 2.0 license as described in the file LICENSE.
+Authors: Leonardo de Moura
+-/
+prelude
+import Init.Data.Fin.Basic
+import Init.Data.BitVec.BasicAux
+
+/-!
+This module exists to provide the very basic `UInt8` etc. definitions required for
+`Init.Data.Char.Basic` and `Init.Data.Array.Basic`. These are very important as they are used in
+meta code that is then (transitively) used in `Init.Data.UInt.Basic` and `Init.Data.BitVec.Basic`.
+This file thus breaks the import cycle that would be created by this dependency.
+-/
+
+open Nat
+
+def UInt8.val (x : UInt8) : Fin UInt8.size := x.toBitVec.toFin
+@[extern "lean_uint8_of_nat"]
+def UInt8.ofNat (n : @& Nat) : UInt8 := ⟨BitVec.ofNat 8 n⟩
+abbrev Nat.toUInt8 := UInt8.ofNat
+@[extern "lean_uint8_to_nat"]
+def UInt8.toNat (n : UInt8) : Nat := n.toBitVec.toNat
+
+instance UInt8.instOfNat : OfNat UInt8 n := ⟨UInt8.ofNat n⟩
+
+def UInt16.val (x : UInt16) : Fin UInt16.size := x.toBitVec.toFin
+@[extern "lean_uint16_of_nat"]
+def UInt16.ofNat (n : @& Nat) : UInt16 := ⟨BitVec.ofNat 16 n⟩
+abbrev Nat.toUInt16 := UInt16.ofNat
+@[extern "lean_uint16_to_nat"]
+def UInt16.toNat (n : UInt16) : Nat := n.toBitVec.toNat
+@[extern "lean_uint16_to_uint8"]
+def UInt16.toUInt8 (a : UInt16) : UInt8 := a.toNat.toUInt8
+@[extern "lean_uint8_to_uint16"]
+def UInt8.toUInt16 (a : UInt8) : UInt16 := ⟨⟨a.toNat, Nat.lt_trans a.toBitVec.isLt (by decide)⟩⟩
+
+instance UInt16.instOfNat : OfNat UInt16 n := ⟨UInt16.ofNat n⟩
+
+def UInt32.val (x : UInt32) : Fin UInt32.size := x.toBitVec.toFin
+@[extern "lean_uint32_of_nat"]
+def UInt32.ofNat (n : @& Nat) : UInt32 := ⟨BitVec.ofNat 32 n⟩
+@[extern "lean_uint32_of_nat"]
+def UInt32.ofNat' (n : Nat) (h : n < UInt32.size) : UInt32 := ⟨BitVec.ofNatLt n h⟩
+/--
+Converts the given natural number to `UInt32`, but returns `2^32 - 1` for natural numbers `>= 2^32`.
+-/
+def UInt32.ofNatTruncate (n : Nat) : UInt32 :=
+  if h : n < UInt32.size then
+    UInt32.ofNat' n h
+  else
+    UInt32.ofNat' (UInt32.size - 1) (by decide)
+abbrev Nat.toUInt32 := UInt32.ofNat
+@[extern "lean_uint32_to_uint8"]
+def UInt32.toUInt8 (a : UInt32) : UInt8 := a.toNat.toUInt8
+@[extern "lean_uint32_to_uint16"]
+def UInt32.toUInt16 (a : UInt32) : UInt16 := a.toNat.toUInt16
+@[extern "lean_uint8_to_uint32"]
+def UInt8.toUInt32 (a : UInt8) : UInt32 := ⟨⟨a.toNat, Nat.lt_trans a.toBitVec.isLt (by decide)⟩⟩
+@[extern "lean_uint16_to_uint32"]
+def UInt16.toUInt32 (a : UInt16) : UInt32 := ⟨⟨a.toNat, Nat.lt_trans a.toBitVec.isLt (by decide)⟩⟩
+
+instance UInt32.instOfNat : OfNat UInt32 n := ⟨UInt32.ofNat n⟩
+
+theorem UInt32.ofNat'_lt_of_lt {n m : Nat} (h1 : n < UInt32.size) (h2 : m < UInt32.size) :
+     n < m → UInt32.ofNat' n h1 < UInt32.ofNat m := by
+  simp only [(· < ·), BitVec.toNat, ofNat', BitVec.ofNatLt, ofNat, BitVec.ofNat, Fin.ofNat',
+    Nat.mod_eq_of_lt h2, imp_self]
+
+theorem UInt32.lt_ofNat'_of_lt {n m : Nat} (h1 : n < UInt32.size) (h2 : m < UInt32.size) :
+     m < n → UInt32.ofNat m < UInt32.ofNat' n h1  := by
+  simp only [(· < ·), BitVec.toNat, ofNat', BitVec.ofNatLt, ofNat, BitVec.ofNat, Fin.ofNat',
+    Nat.mod_eq_of_lt h2, imp_self]
+
+def UInt64.val (x : UInt64) : Fin UInt64.size := x.toBitVec.toFin
+@[extern "lean_uint64_of_nat"]
+def UInt64.ofNat (n : @& Nat) : UInt64 := ⟨BitVec.ofNat 64 n⟩
+abbrev Nat.toUInt64 := UInt64.ofNat
+@[extern "lean_uint64_to_nat"]
+def UInt64.toNat (n : UInt64) : Nat := n.toBitVec.toNat
+@[extern "lean_uint64_to_uint8"]
+def UInt64.toUInt8 (a : UInt64) : UInt8 := a.toNat.toUInt8
+@[extern "lean_uint64_to_uint16"]
+def UInt64.toUInt16 (a : UInt64) : UInt16 := a.toNat.toUInt16
+@[extern "lean_uint64_to_uint32"]
+def UInt64.toUInt32 (a : UInt64) : UInt32 := a.toNat.toUInt32
+@[extern "lean_uint8_to_uint64"]
+def UInt8.toUInt64 (a : UInt8) : UInt64 := ⟨⟨a.toNat, Nat.lt_trans a.toBitVec.isLt (by decide)⟩⟩
+@[extern "lean_uint16_to_uint64"]
+def UInt16.toUInt64 (a : UInt16) : UInt64 := ⟨⟨a.toNat, Nat.lt_trans a.toBitVec.isLt (by decide)⟩⟩
+@[extern "lean_uint32_to_uint64"]
+def UInt32.toUInt64 (a : UInt32) : UInt64 := ⟨⟨a.toNat, Nat.lt_trans a.toBitVec.isLt (by decide)⟩⟩
+
+instance UInt64.instOfNat : OfNat UInt64 n := ⟨UInt64.ofNat n⟩
+
+theorem usize_size_gt_zero : USize.size > 0 := by
+  cases usize_size_eq with
+  | inl h => rw [h]; decide
+  | inr h => rw [h]; decide
+
+def USize.val (x : USize) : Fin USize.size := x.toBitVec.toFin
+@[extern "lean_usize_of_nat"]
+def USize.ofNat (n : @& Nat) : USize := ⟨BitVec.ofNat _ n⟩
+abbrev Nat.toUSize := USize.ofNat
+@[extern "lean_usize_to_nat"]
+def USize.toNat (n : USize) : Nat := n.toBitVec.toNat
+@[extern "lean_usize_add"]
+def USize.add (a b : USize) : USize := ⟨a.toBitVec + b.toBitVec⟩
+@[extern "lean_usize_sub"]
+def USize.sub (a b : USize) : USize := ⟨a.toBitVec - b.toBitVec⟩
+
+def USize.lt (a b : USize) : Prop := a.toBitVec < b.toBitVec
+def USize.le (a b : USize) : Prop := a.toBitVec ≤ b.toBitVec
+
+instance USize.instOfNat : OfNat USize n := ⟨USize.ofNat n⟩
+
+instance : Add USize       := ⟨USize.add⟩
+instance : Sub USize       := ⟨USize.sub⟩
+instance : LT USize        := ⟨USize.lt⟩
+instance : LE USize        := ⟨USize.le⟩
+
+@[extern "lean_usize_dec_lt"]
+def USize.decLt (a b : USize) : Decidable (a < b) :=
+  inferInstanceAs (Decidable (a.toBitVec < b.toBitVec))
+
+@[extern "lean_usize_dec_le"]
+def USize.decLe (a b : USize) : Decidable (a ≤ b) :=
+  inferInstanceAs (Decidable (a.toBitVec ≤ b.toBitVec))
+
+instance (a b : USize) : Decidable (a < b) := USize.decLt a b
+instance (a b : USize) : Decidable (a ≤ b) := USize.decLe a b

src/Init/Data/UInt/Bitwise.lean

@@ -6,13 +6,14 @@ Authors: Markus Himmel
 prelude
 import Init.Data.UInt.Basic
 import Init.Data.Fin.Bitwise
+import Init.Data.BitVec.Lemmas
 
 set_option hygiene false in
 macro "declare_bitwise_uint_theorems" typeName:ident : command =>
 `(
 namespace $typeName
 
-@[simp] protected theorem and_toNat (a b : $typeName) : (a &&& b).toNat = a.toNat &&& b.toNat := Fin.and_val ..
+@[simp] protected theorem and_toNat (a b : $typeName) : (a &&& b).toNat = a.toNat &&& b.toNat := BitVec.toNat_and ..
 
 end $typeName
 )

src/Init/Data/UInt/Lemmas.lean

@@ -6,6 +6,8 @@ Authors: Leonardo de Moura
 prelude
 import Init.Data.UInt.Basic
 import Init.Data.Fin.Lemmas
+import Init.Data.BitVec.Lemmas
+import Init.Data.BitVec.Bitblast
 
 set_option hygiene false in
 macro "declare_uint_theorems" typeName:ident : command =>
@@ -17,50 +19,111 @@ instance : Inhabited $typeName where
 
 theorem zero_def : (0 : $typeName) = ⟨0⟩ := rfl
 theorem one_def : (1 : $typeName) = ⟨1⟩ := rfl
-theorem sub_def (a b : $typeName) : a - b = ⟨a.val - b.val⟩ := rfl
-theorem mul_def (a b : $typeName) : a * b = ⟨a.val * b.val⟩ := rfl
-theorem mod_def (a b : $typeName) : a % b = ⟨a.val % b.val⟩ := rfl
-theorem add_def (a b : $typeName) : a + b = ⟨a.val + b.val⟩ := rfl
+theorem sub_def (a b : $typeName) : a - b = ⟨a.toBitVec - b.toBitVec⟩ := rfl
+theorem mul_def (a b : $typeName) : a * b = ⟨a.toBitVec * b.toBitVec⟩ := rfl
+theorem mod_def (a b : $typeName) : a % b = ⟨a.toBitVec % b.toBitVec⟩ := rfl
+theorem add_def (a b : $typeName) : a + b = ⟨a.toBitVec + b.toBitVec⟩ := rfl
 
-@[simp] theorem mk_val_eq : ∀ (a : $typeName), mk a.val = a
+@[simp] theorem mk_toBitVec_eq : ∀ (a : $typeName), mk a.toBitVec = a
   | ⟨_, _⟩ => rfl
-theorem val_eq_of_lt {a : Nat} : a < size → ((ofNat a).val : Nat) = a :=
-  Nat.mod_eq_of_lt
-theorem toNat_ofNat_of_lt {n : Nat} (h : n < size) : (ofNat n).toNat = n := by
-  rw [toNat, val_eq_of_lt h]
 
-theorem le_def {a b : $typeName} : a ≤ b ↔ a.1 ≤ b.1 := .rfl
-theorem lt_def {a b : $typeName} : a < b ↔ a.1 < b.1 := .rfl
-theorem lt_iff_val_lt_val {a b : $typeName} : a < b ↔ a.val < b.val := .rfl
-@[simp] protected theorem not_le {a b : $typeName} : ¬ a ≤ b ↔ b < a := Fin.not_le
-@[simp] protected theorem not_lt {a b : $typeName} : ¬ a < b ↔ b ≤ a := Fin.not_lt
+theorem toBitVec_eq_of_lt {a : Nat} : a < size → (ofNat a).toBitVec.toNat = a :=
+  Nat.mod_eq_of_lt
+
+theorem toNat_ofNat_of_lt {n : Nat} (h : n < size) : (ofNat n).toNat = n := by
+  rw [toNat, toBitVec_eq_of_lt h]
+
+theorem le_def {a b : $typeName} : a ≤ b ↔ a.toBitVec ≤ b.toBitVec := .rfl
+
+theorem lt_def {a b : $typeName} : a < b ↔ a.toBitVec < b.toBitVec := .rfl
+
+@[simp] protected theorem not_le {a b : $typeName} : ¬ a ≤ b ↔ b < a := by simp [le_def, lt_def]
+
+@[simp] protected theorem not_lt {a b : $typeName} : ¬ a < b ↔ b ≤ a := by simp [le_def, lt_def]
+
 @[simp] protected theorem le_refl (a : $typeName) : a ≤ a := by simp [le_def]
+
 @[simp] protected theorem lt_irrefl (a : $typeName) : ¬ a < a := by simp
-protected theorem le_trans {a b c : $typeName} : a ≤ b → b ≤ c → a ≤ c := Fin.le_trans
-protected theorem lt_trans {a b c : $typeName} : a < b → b < c → a < c := Fin.lt_trans
-protected theorem le_total (a b : $typeName) : a ≤ b ∨ b ≤ a := Fin.le_total a.1 b.1
-protected theorem lt_asymm {a b : $typeName} (h : a < b) : ¬ b < a := Fin.lt_asymm h
-protected theorem val_eq_of_eq {a b : $typeName} (h : a = b) : a.val = b.val := h ▸ rfl
-protected theorem eq_of_val_eq {a b : $typeName} (h : a.val = b.val) : a = b := by cases a; cases b; simp at h; simp [h]
-open $typeName (val_eq_of_eq) in
-protected theorem ne_of_val_ne {a b : $typeName} (h : a.val ≠ b.val) : a ≠ b := fun h' => absurd (val_eq_of_eq h') h
-open $typeName (ne_of_val_ne) in
-protected theorem ne_of_lt {a b : $typeName} (h : a < b) : a ≠ b := ne_of_val_ne (Fin.ne_of_lt h)
+
+protected theorem le_trans {a b c : $typeName} : a ≤ b → b ≤ c → a ≤ c := BitVec.le_trans
+
+protected theorem lt_trans {a b c : $typeName} : a < b → b < c → a < c := BitVec.lt_trans
+
+protected theorem le_total (a b : $typeName) : a ≤ b ∨ b ≤ a := BitVec.le_total ..
+
+protected theorem lt_asymm {a b : $typeName} : a < b → ¬ b < a := BitVec.lt_asymm
+
+protected theorem toBitVec_eq_of_eq {a b : $typeName} (h : a = b) : a.toBitVec = b.toBitVec := h ▸ rfl
+
+protected theorem eq_of_toBitVec_eq {a b : $typeName} (h : a.toBitVec = b.toBitVec) : a = b := by
+  cases a; cases b; simp_all
+
+open $typeName (eq_of_toBitVec_eq) in
+protected theorem eq_of_val_eq {a b : $typeName} (h : a.val = b.val) : a = b := by
+  rcases a with ⟨⟨_⟩⟩; rcases b with ⟨⟨_⟩⟩; simp_all [val]
+
+open $typeName (toBitVec_eq_of_eq) in
+protected theorem ne_of_toBitVec_ne {a b : $typeName} (h : a.toBitVec ≠ b.toBitVec) : a ≠ b :=
+  fun h' => absurd (toBitVec_eq_of_eq h') h
+
+open $typeName (ne_of_toBitVec_ne) in
+protected theorem ne_of_lt {a b : $typeName} (h : a < b) : a ≠ b := by
+  apply ne_of_toBitVec_ne
+  apply BitVec.ne_of_lt
+  simpa [lt_def] using h
 
 @[simp] protected theorem toNat_zero : (0 : $typeName).toNat = 0 := Nat.zero_mod _
-@[simp] protected theorem toNat_mod (a b : $typeName) : (a % b).toNat = a.toNat % b.toNat := Fin.mod_val ..
-@[simp] protected theorem toNat_div (a b : $typeName) : (a / b).toNat = a.toNat / b.toNat := Fin.div_val ..
-@[simp] protected theorem toNat_sub_of_le (a b : $typeName) : b ≤ a → (a - b).toNat = a.toNat - b.toNat := Fin.sub_val_of_le
-@[simp] protected theorem toNat_modn (a : $typeName) (b : Nat) : (a.modn b).toNat = a.toNat % b := Fin.modn_val ..
-protected theorem modn_lt {m : Nat} : ∀ (u : $typeName), m > 0 → toNat (u % m) < m
-  | ⟨u⟩, h => Fin.modn_lt u h
-open $typeName (modn_lt) in
-protected theorem mod_lt (a b : $typeName) (h : 0 < b) : a % b < b := modn_lt _ (by simp [lt_def] at h; exact h)
+
+@[simp] protected theorem toNat_mod (a b : $typeName) : (a % b).toNat = a.toNat % b.toNat := BitVec.toNat_umod ..
+
+@[simp] protected theorem toNat_div (a b : $typeName) : (a / b).toNat = a.toNat / b.toNat := BitVec.toNat_udiv  ..
+
+@[simp] protected theorem toNat_sub_of_le (a b : $typeName) : b ≤ a → (a - b).toNat = a.toNat - b.toNat := BitVec.toNat_sub_of_le
+
+protected theorem toNat_lt_size (a : $typeName) : a.toNat < size := a.toBitVec.isLt
+
+open $typeName (toNat_mod toNat_lt_size) in
+protected theorem toNat_mod_lt {m : Nat} : ∀ (u : $typeName), m > 0 → toNat (u % ofNat m) < m := by
+  intro u h1
+  by_cases h2 : m < size
+  · rw [toNat_mod, toNat_ofNat_of_lt h2]
+    apply Nat.mod_lt _ h1
+  · apply Nat.lt_of_lt_of_le
+    · apply toNat_lt_size
+    · simpa using h2
+
+open $typeName (toNat_mod_lt) in
+set_option linter.deprecated false in
+@[deprecated toNat_mod_lt (since := "2024-09-24")]
+protected theorem modn_lt {m : Nat} : ∀ (u : $typeName), m > 0 → toNat (u % m) < m := by
+  intro u
+  simp only [(· % ·)]
+  simp only [gt_iff_lt, toNat, modn, Fin.modn_val, BitVec.natCast_eq_ofNat, BitVec.toNat_ofNat,
+    Nat.reducePow]
+  rw [Nat.mod_eq_of_lt]
+  · apply Nat.mod_lt
+  · apply Nat.lt_of_le_of_lt
+    · apply Nat.mod_le
+    · apply Fin.is_lt
+
+protected theorem mod_lt (a : $typeName) {b : $typeName} : 0 < b → a % b < b := by
+  simp only [lt_def, mod_def]
+  apply BitVec.umod_lt
+
 protected theorem toNat.inj : ∀ {a b : $typeName}, a.toNat = b.toNat → a = b
   | ⟨_, _⟩, ⟨_, _⟩, rfl => rfl
-protected theorem toNat_lt_size (a : $typeName) : a.toNat < size := a.1.2
+
 @[simp] protected theorem ofNat_one : ofNat 1 = 1 := rfl
 
+@[simp]
+theorem val_ofNat (n : Nat) : val (no_index (OfNat.ofNat n)) = OfNat.ofNat n := rfl
+
+@[simp]
+theorem toBitVec_ofNat (n : Nat) : toBitVec (no_index (OfNat.ofNat n)) = BitVec.ofNat _ n := rfl
+
+@[simp]
+theorem mk_ofNat (n : Nat) : mk (BitVec.ofNat _ n) = OfNat.ofNat n := rfl
+
 end $typeName
 )
 
@@ -70,27 +133,34 @@ declare_uint_theorems UInt32
 declare_uint_theorems UInt64
 declare_uint_theorems USize
 
+theorem UInt32.toNat_lt_of_lt {n : UInt32} {m : Nat} (h : m < size) : n < ofNat m → n.toNat < m := by
+  simp [lt_def, BitVec.lt_def, UInt32.toNat, toBitVec_eq_of_lt h]
+
+theorem UInt32.lt_toNat_of_lt {n : UInt32} {m : Nat} (h : m < size) : ofNat m < n → m < n.toNat := by
+  simp [lt_def, BitVec.lt_def, UInt32.toNat, toBitVec_eq_of_lt h]
+
+theorem UInt32.toNat_le_of_le {n : UInt32} {m : Nat} (h : m < size) : n ≤ ofNat m → n.toNat ≤ m := by
+  simp [le_def, BitVec.le_def, UInt32.toNat, toBitVec_eq_of_lt h]
+
+theorem UInt32.le_toNat_of_le {n : UInt32} {m : Nat} (h : m < size) : ofNat m ≤ n → m ≤ n.toNat := by
+  simp [le_def, BitVec.le_def, UInt32.toNat, toBitVec_eq_of_lt h]
+
 @[deprecated (since := "2024-06-23")] protected abbrev UInt8.zero_toNat := @UInt8.toNat_zero
 @[deprecated (since := "2024-06-23")] protected abbrev UInt8.div_toNat := @UInt8.toNat_div
 @[deprecated (since := "2024-06-23")] protected abbrev UInt8.mod_toNat := @UInt8.toNat_mod
-@[deprecated (since := "2024-06-23")] protected abbrev UInt8.modn_toNat := @UInt8.toNat_modn
 
 @[deprecated (since := "2024-06-23")] protected abbrev UInt16.zero_toNat := @UInt16.toNat_zero
 @[deprecated (since := "2024-06-23")] protected abbrev UInt16.div_toNat := @UInt16.toNat_div
 @[deprecated (since := "2024-06-23")] protected abbrev UInt16.mod_toNat := @UInt16.toNat_mod
-@[deprecated (since := "2024-06-23")] protected abbrev UInt16.modn_toNat := @UInt16.toNat_modn
 
 @[deprecated (since := "2024-06-23")] protected abbrev UInt32.zero_toNat := @UInt32.toNat_zero
 @[deprecated (since := "2024-06-23")] protected abbrev UInt32.div_toNat := @UInt32.toNat_div
 @[deprecated (since := "2024-06-23")] protected abbrev UInt32.mod_toNat := @UInt32.toNat_mod
-@[deprecated (since := "2024-06-23")] protected abbrev UInt32.modn_toNat := @UInt32.toNat_modn
 
 @[deprecated (since := "2024-06-23")] protected abbrev UInt64.zero_toNat := @UInt64.toNat_zero
 @[deprecated (since := "2024-06-23")] protected abbrev UInt64.div_toNat := @UInt64.toNat_div
 @[deprecated (since := "2024-06-23")] protected abbrev UInt64.mod_toNat := @UInt64.toNat_mod
-@[deprecated (since := "2024-06-23")] protected abbrev UInt64.modn_toNat := @UInt64.toNat_modn
 
 @[deprecated (since := "2024-06-23")] protected abbrev USize.zero_toNat := @USize.toNat_zero
 @[deprecated (since := "2024-06-23")] protected abbrev USize.div_toNat := @USize.toNat_div
 @[deprecated (since := "2024-06-23")] protected abbrev USize.mod_toNat := @USize.toNat_mod
-@[deprecated (since := "2024-06-23")] protected abbrev USize.modn_toNat := @USize.toNat_modn

src/Init/Data/UInt/Log2.lean

@@ -7,16 +7,16 @@ prelude
 import Init.Data.Fin.Log2
 
 @[extern "lean_uint8_log2"]
-def UInt8.log2 (a : UInt8) : UInt8 := ⟨Fin.log2 a.val⟩
+def UInt8.log2 (a : UInt8) : UInt8 := ⟨⟨Fin.log2 a.val⟩⟩
 
 @[extern "lean_uint16_log2"]
-def UInt16.log2 (a : UInt16) : UInt16 := ⟨Fin.log2 a.val⟩
+def UInt16.log2 (a : UInt16) : UInt16 := ⟨⟨Fin.log2 a.val⟩⟩
 
 @[extern "lean_uint32_log2"]
-def UInt32.log2 (a : UInt32) : UInt32 := ⟨Fin.log2 a.val⟩
+def UInt32.log2 (a : UInt32) : UInt32 := ⟨⟨Fin.log2 a.val⟩⟩
 
 @[extern "lean_uint64_log2"]
-def UInt64.log2 (a : UInt64) : UInt64 := ⟨Fin.log2 a.val⟩
+def UInt64.log2 (a : UInt64) : UInt64 := ⟨⟨Fin.log2 a.val⟩⟩
 
 @[extern "lean_usize_log2"]
-def USize.log2 (a : USize) : USize := ⟨Fin.log2 a.val⟩
+def USize.log2 (a : USize) : USize := ⟨⟨Fin.log2 a.val⟩⟩

src/Init/MetaTypes.lean

@@ -224,11 +224,7 @@ structure Config where
   -/
   index             : Bool := true
   /--
-  When `true` (default: `true`), `simp` will **not** create a proof for a rewriting rule associated
-  with an `rfl`-theorem.
-  Rewriting rules are provided by users by annotating theorems with the attribute `@[simp]`.
-  If the proof of the theorem is just `rfl` (reflexivity), and `implicitDefEqProofs := true`, `simp`
-  will **not** create a proof term which is an application of the annotated theorem.
+  This option does not have any effect (yet).
   -/
   implicitDefEqProofs : Bool := true
   deriving Inhabited, BEq

src/Init/NotationExtra.lean

@@ -10,6 +10,7 @@ import Init.Data.ToString.Basic
 import Init.Data.Array.Subarray
 import Init.Conv
 import Init.Meta
+import Init.While
 
 namespace Lean
 
@@ -168,9 +169,9 @@ end Lean
   | _                => throw ()
 
 @[app_unexpander sorryAx] def unexpandSorryAx : Lean.PrettyPrinter.Unexpander
-  | `($(_) _)   => `(sorry)
-  | `($(_) _ _) => `(sorry)
-  | _           => throw ()
+  | `($(_) $_)    => `(sorry)
+  | `($(_) $_ $_) => `(sorry)
+  | _             => throw ()
 
 @[app_unexpander Eq.ndrec] def unexpandEqNDRec : Lean.PrettyPrinter.Unexpander
   | `($(_) $m $h) => `($h ▸ $m)
@@ -344,42 +345,6 @@ syntax (name := solveTactic) "solve" withPosition((ppDedent(ppLine) colGe "| " t
 macro_rules
   | `(tactic| solve $[| $ts]* ) => `(tactic| focus first $[| ($ts); done]*)
 
-/-! # `repeat` and `while` notation -/
-
-inductive Loop where
-  | mk
-
-@[inline]
-partial def Loop.forIn {β : Type u} {m : Type u → Type v} [Monad m] (_ : Loop) (init : β) (f : Unit → β → m (ForInStep β)) : m β :=
-  let rec @[specialize] loop (b : β) : m β := do
-    match ← f () b with
-      | ForInStep.done b  => pure b
-      | ForInStep.yield b => loop b
-  loop init
-
-instance : ForIn m Loop Unit where
-  forIn := Loop.forIn
-
-syntax "repeat " doSeq : doElem
-
-macro_rules
-  | `(doElem| repeat $seq) => `(doElem| for _ in Loop.mk do $seq)
-
-syntax "while " ident " : " termBeforeDo " do " doSeq : doElem
-
-macro_rules
-  | `(doElem| while $h : $cond do $seq) => `(doElem| repeat if $h : $cond then $seq else break)
-
-syntax "while " termBeforeDo " do " doSeq : doElem
-
-macro_rules
-  | `(doElem| while $cond do $seq) => `(doElem| repeat if $cond then $seq else break)
-
-syntax "repeat " doSeq ppDedent(ppLine) "until " term : doElem
-
-macro_rules
-  | `(doElem| repeat $seq until $cond) => `(doElem| repeat do $seq:doSeq; if $cond then break)
-
 macro:50 e:term:51 " matches " p:sepBy1(term:51, " | ") : term =>
   `(((match $e:term with | $[$p:term]|* => true | _ => false) : Bool))
 

src/Init/Prelude.lean

@@ -1592,9 +1592,6 @@ def Nat.beq : (@& Nat) → (@& Nat) → Bool
   | succ _, zero   => false
   | succ n, succ m => beq n m
 
-instance : BEq Nat where
-  beq := Nat.beq
-
 theorem Nat.eq_of_beq_eq_true : {n m : Nat} → Eq (beq n m) true → Eq n m
   | zero,   zero,   _ => rfl
   | zero,   succ _, h => Bool.noConfusion h
@@ -1869,6 +1866,52 @@ instance {n} : LE (Fin n) where
 instance Fin.decLt {n} (a b : Fin n) : Decidable (LT.lt a b) := Nat.decLt ..
 instance Fin.decLe {n} (a b : Fin n) : Decidable (LE.le a b) := Nat.decLe ..
 
+/--
+A bitvector of the specified width.
+
+This is represented as the underlying `Nat` number in both the runtime
+and the kernel, inheriting all the special support for `Nat`.
+-/
+structure BitVec (w : Nat) where
+  /-- Construct a `BitVec w` from a number less than `2^w`.
+  O(1), because we use `Fin` as the internal representation of a bitvector. -/
+  ofFin ::
+  /-- Interpret a bitvector as a number less than `2^w`.
+  O(1), because we use `Fin` as the internal representation of a bitvector. -/
+  toFin : Fin (hPow 2 w)
+
+/--
+Bitvectors have decidable equality. This should be used via the instance `DecidableEq (BitVec n)`.
+-/
+-- We manually derive the `DecidableEq` instances for `BitVec` because
+-- we want to have builtin support for bit-vector literals, and we
+-- need a name for this function to implement `canUnfoldAtMatcher` at `WHNF.lean`.
+def BitVec.decEq (x y : BitVec n) : Decidable (Eq x y) :=
+  match x, y with
+  | ⟨n⟩, ⟨m⟩ =>
+    dite (Eq n m)
+      (fun h => isTrue (h ▸ rfl))
+      (fun h => isFalse (fun h' => BitVec.noConfusion h' (fun h' => absurd h' h)))
+
+instance : DecidableEq (BitVec n) := BitVec.decEq
+
+/-- The `BitVec` with value `i`, given a proof that `i < 2^n`. -/
+@[match_pattern]
+protected def BitVec.ofNatLt {n : Nat} (i : Nat) (p : LT.lt i (hPow 2 n)) : BitVec n where
+  toFin := ⟨i, p⟩
+
+/-- Given a bitvector `x`, return the underlying `Nat`. This is O(1) because `BitVec` is a
+(zero-cost) wrapper around a `Nat`. -/
+protected def BitVec.toNat (x : BitVec n) : Nat := x.toFin.val
+
+instance : LT (BitVec n) where lt := (LT.lt ·.toNat ·.toNat)
+instance (x y : BitVec n) : Decidable (LT.lt x y) :=
+  inferInstanceAs (Decidable (LT.lt x.toNat y.toNat))
+
+instance : LE (BitVec n) where le := (LE.le ·.toNat ·.toNat)
+instance (x y : BitVec n) : Decidable (LE.le x y) :=
+  inferInstanceAs (Decidable (LE.le x.toNat y.toNat))
+
 /-- The size of type `UInt8`, that is, `2^8 = 256`. -/
 abbrev UInt8.size : Nat := 256
 
@@ -1877,12 +1920,12 @@ The type of unsigned 8-bit integers. This type has special support in the
 compiler to make it actually 8 bits rather than wrapping a `Nat`.
 -/
 structure UInt8 where
-  /-- Unpack a `UInt8` as a `Nat` less than `2^8`.
+  /-- Unpack a `UInt8` as a `BitVec 8`.
   This function is overridden with a native implementation. -/
-  val : Fin UInt8.size
+  toBitVec : BitVec 8
 
 attribute [extern "lean_uint8_of_nat_mk"] UInt8.mk
-attribute [extern "lean_uint8_to_nat"] UInt8.val
+attribute [extern "lean_uint8_to_nat"] UInt8.toBitVec
 
 /--
 Pack a `Nat` less than `2^8` into a `UInt8`.
@@ -1890,7 +1933,7 @@ This function is overridden with a native implementation.
 -/
 @[extern "lean_uint8_of_nat"]
 def UInt8.ofNatCore (n : @& Nat) (h : LT.lt n UInt8.size) : UInt8 where
-  val := { val := n, isLt := h }
+  toBitVec := BitVec.ofNatLt n h
 
 set_option bootstrap.genMatcherCode false in
 /--
@@ -1901,7 +1944,9 @@ This function is overridden with a native implementation.
 def UInt8.decEq (a b : UInt8) : Decidable (Eq a b) :=
   match a, b with
   | ⟨n⟩, ⟨m⟩ =>
-    dite (Eq n m) (fun h => isTrue (h ▸ rfl)) (fun h => isFalse (fun h' => UInt8.noConfusion h' (fun h' => absurd h' h)))
+    dite (Eq n m)
+      (fun h => isTrue (h ▸ rfl))
+      (fun h => isFalse (fun h' => UInt8.noConfusion h' (fun h' => absurd h' h)))
 
 instance : DecidableEq UInt8 := UInt8.decEq
 
@@ -1916,12 +1961,12 @@ The type of unsigned 16-bit integers. This type has special support in the
 compiler to make it actually 16 bits rather than wrapping a `Nat`.
 -/
 structure UInt16 where
-  /-- Unpack a `UInt16` as a `Nat` less than `2^16`.
+  /-- Unpack a `UInt16` as a `BitVec 16`.
   This function is overridden with a native implementation. -/
-  val : Fin UInt16.size
+  toBitVec : BitVec 16
 
 attribute [extern "lean_uint16_of_nat_mk"] UInt16.mk
-attribute [extern "lean_uint16_to_nat"] UInt16.val
+attribute [extern "lean_uint16_to_nat"] UInt16.toBitVec
 
 /--
 Pack a `Nat` less than `2^16` into a `UInt16`.
@@ -1929,7 +1974,7 @@ This function is overridden with a native implementation.
 -/
 @[extern "lean_uint16_of_nat"]
 def UInt16.ofNatCore (n : @& Nat) (h : LT.lt n UInt16.size) : UInt16 where
-  val := { val := n, isLt := h }
+  toBitVec := BitVec.ofNatLt n h
 
 set_option bootstrap.genMatcherCode false in
 /--
@@ -1940,7 +1985,9 @@ This function is overridden with a native implementation.
 def UInt16.decEq (a b : UInt16) : Decidable (Eq a b) :=
   match a, b with
   | ⟨n⟩, ⟨m⟩ =>
-    dite (Eq n m) (fun h => isTrue (h ▸ rfl)) (fun h => isFalse (fun h' => UInt16.noConfusion h' (fun h' => absurd h' h)))
+    dite (Eq n m)
+      (fun h => isTrue (h ▸ rfl))
+      (fun h => isFalse (fun h' => UInt16.noConfusion h' (fun h' => absurd h' h)))
 
 instance : DecidableEq UInt16 := UInt16.decEq
 
@@ -1955,12 +2002,12 @@ The type of unsigned 32-bit integers. This type has special support in the
 compiler to make it actually 32 bits rather than wrapping a `Nat`.
 -/
 structure UInt32 where
-  /-- Unpack a `UInt32` as a `Nat` less than `2^32`.
+  /-- Unpack a `UInt32` as a `BitVec 32.
   This function is overridden with a native implementation. -/
-  val : Fin UInt32.size
+  toBitVec : BitVec 32
 
 attribute [extern "lean_uint32_of_nat_mk"] UInt32.mk
-attribute [extern "lean_uint32_to_nat"] UInt32.val
+attribute [extern "lean_uint32_to_nat"] UInt32.toBitVec
 
 /--
 Pack a `Nat` less than `2^32` into a `UInt32`.
@@ -1968,14 +2015,14 @@ This function is overridden with a native implementation.
 -/
 @[extern "lean_uint32_of_nat"]
 def UInt32.ofNatCore (n : @& Nat) (h : LT.lt n UInt32.size) : UInt32 where
-  val := { val := n, isLt := h }
+  toBitVec := BitVec.ofNatLt n h
 
 /--
 Unpack a `UInt32` as a `Nat`.
 This function is overridden with a native implementation.
 -/
 @[extern "lean_uint32_to_nat"]
-def UInt32.toNat (n : UInt32) : Nat := n.val.val
+def UInt32.toNat (n : UInt32) : Nat := n.toBitVec.toNat
 
 set_option bootstrap.genMatcherCode false in
 /--
@@ -1994,30 +2041,26 @@ instance : Inhabited UInt32 where
   default := UInt32.ofNatCore 0 (by decide)
 
 instance : LT UInt32 where
-  lt a b := LT.lt a.val b.val
+  lt a b := LT.lt a.toBitVec b.toBitVec
 
 instance : LE UInt32 where
-  le a b := LE.le a.val b.val
+  le a b := LE.le a.toBitVec b.toBitVec
 
-set_option bootstrap.genMatcherCode false in
 /--
 Decides less-equal on `UInt32`.
 This function is overridden with a native implementation.
 -/
 @[extern "lean_uint32_dec_lt"]
 def UInt32.decLt (a b : UInt32) : Decidable (LT.lt a b) :=
-  match a, b with
-  | ⟨n⟩, ⟨m⟩ => inferInstanceAs (Decidable (LT.lt n m))
+  inferInstanceAs (Decidable (LT.lt a.toBitVec b.toBitVec))
 
-set_option bootstrap.genMatcherCode false in
 /--
 Decides less-than on `UInt32`.
 This function is overridden with a native implementation.
 -/
 @[extern "lean_uint32_dec_le"]
 def UInt32.decLe (a b : UInt32) : Decidable (LE.le a b) :=
-  match a, b with
-  | ⟨n⟩, ⟨m⟩ => inferInstanceAs (Decidable (LE.le n m))
+  inferInstanceAs (Decidable (LE.le a.toBitVec b.toBitVec))
 
 instance (a b : UInt32) : Decidable (LT.lt a b) := UInt32.decLt a b
 instance (a b : UInt32) : Decidable (LE.le a b) := UInt32.decLe a b
@@ -2031,12 +2074,12 @@ The type of unsigned 64-bit integers. This type has special support in the
 compiler to make it actually 64 bits rather than wrapping a `Nat`.
 -/
 structure UInt64 where
-  /-- Unpack a `UInt64` as a `Nat` less than `2^64`.
+  /-- Unpack a `UInt64` as a `BitVec 64`.
   This function is overridden with a native implementation. -/
-  val : Fin UInt64.size
+  toBitVec: BitVec 64
 
 attribute [extern "lean_uint64_of_nat_mk"] UInt64.mk
-attribute [extern "lean_uint64_to_nat"] UInt64.val
+attribute [extern "lean_uint64_to_nat"] UInt64.toBitVec
 
 /--
 Pack a `Nat` less than `2^64` into a `UInt64`.
@@ -2044,7 +2087,7 @@ This function is overridden with a native implementation.
 -/
 @[extern "lean_uint64_of_nat"]
 def UInt64.ofNatCore (n : @& Nat) (h : LT.lt n UInt64.size) : UInt64 where
-  val := { val := n, isLt := h }
+  toBitVec := BitVec.ofNatLt n h
 
 set_option bootstrap.genMatcherCode false in
 /--
@@ -2055,36 +2098,20 @@ This function is overridden with a native implementation.
 def UInt64.decEq (a b : UInt64) : Decidable (Eq a b) :=
   match a, b with
   | ⟨n⟩, ⟨m⟩ =>
-    dite (Eq n m) (fun h => isTrue (h ▸ rfl)) (fun h => isFalse (fun h' => UInt64.noConfusion h' (fun h' => absurd h' h)))
+    dite (Eq n m)
+      (fun h => isTrue (h ▸ rfl))
+      (fun h => isFalse (fun h' => UInt64.noConfusion h' (fun h' => absurd h' h)))
 
 instance : DecidableEq UInt64 := UInt64.decEq
 
 instance : Inhabited UInt64 where
   default := UInt64.ofNatCore 0 (by decide)
 
-/--
-The size of type `USize`, that is, `2^System.Platform.numBits`, which may
-be either `2^32` or `2^64` depending on the platform's architecture.
-
-Remark: we define `USize.size` using `(2^numBits - 1) + 1` to ensure the
-Lean unifier can solve constraints such as `?m + 1 = USize.size`. Recall that
-`numBits` does not reduce to a numeral in the Lean kernel since it is platform
-specific. Without this trick, the following definition would be rejected by the
-Lean type checker.
-```
-def one: Fin USize.size := 1
-```
-Because Lean would fail to synthesize instance `OfNat (Fin USize.size) 1`.
-Recall that the `OfNat` instance for `Fin` is
-```
-instance : OfNat (Fin (n+1)) i where
-  ofNat := Fin.ofNat i
-```
--/
-abbrev USize.size : Nat := hAdd (hSub (hPow 2 System.Platform.numBits) 1) 1
+/-- The size of type `USize`, that is, `2^System.Platform.numBits`. -/
+abbrev USize.size : Nat := (hPow 2 System.Platform.numBits)
 
 theorem usize_size_eq : Or (Eq USize.size 4294967296) (Eq USize.size 18446744073709551616) :=
-  show Or (Eq (Nat.succ (Nat.sub (hPow 2 System.Platform.numBits) 1)) 4294967296) (Eq (Nat.succ (Nat.sub (hPow 2 System.Platform.numBits) 1)) 18446744073709551616) from
+  show Or (Eq (hPow 2 System.Platform.numBits) 4294967296) (Eq (hPow 2 System.Platform.numBits) 18446744073709551616) from
   match System.Platform.numBits, System.Platform.numBits_eq with
   | _, Or.inl rfl => Or.inl (by decide)
   | _, Or.inr rfl => Or.inr (by decide)
@@ -2097,21 +2124,20 @@ For example, if running on a 32-bit machine, USize is equivalent to UInt32.
 Or on a 64-bit machine, UInt64.
 -/
 structure USize where
-  /-- Unpack a `USize` as a `Nat` less than `USize.size`.
+  /-- Unpack a `USize` as a `BitVec System.Platform.numBits`.
   This function is overridden with a native implementation. -/
-  val : Fin USize.size
+  toBitVec : BitVec System.Platform.numBits
 
 attribute [extern "lean_usize_of_nat_mk"] USize.mk
-attribute [extern "lean_usize_to_nat"] USize.val
+attribute [extern "lean_usize_to_nat"] USize.toBitVec
 
 /--
 Pack a `Nat` less than `USize.size` into a `USize`.
 This function is overridden with a native implementation.
 -/
 @[extern "lean_usize_of_nat"]
-def USize.ofNatCore (n : @& Nat) (h : LT.lt n USize.size) : USize := {
-  val := { val := n, isLt := h }
-}
+def USize.ofNatCore (n : @& Nat) (h : LT.lt n USize.size) : USize where
+  toBitVec := BitVec.ofNatLt n h
 
 set_option bootstrap.genMatcherCode false in
 /--
@@ -2122,7 +2148,9 @@ This function is overridden with a native implementation.
 def USize.decEq (a b : USize) : Decidable (Eq a b) :=
   match a, b with
   | ⟨n⟩, ⟨m⟩ =>
-    dite (Eq n m) (fun h =>isTrue (h ▸ rfl)) (fun h => isFalse (fun h' => USize.noConfusion h' (fun h' => absurd h' h)))
+    dite (Eq n m)
+      (fun h => isTrue (h ▸ rfl))
+      (fun h => isFalse (fun h' => USize.noConfusion h' (fun h' => absurd h' h)))
 
 instance : DecidableEq USize := USize.decEq
 
@@ -2138,12 +2166,12 @@ This function is overridden with a native implementation.
 -/
 @[extern "lean_usize_of_nat"]
 def USize.ofNat32 (n : @& Nat) (h : LT.lt n 4294967296) : USize where
-  val := {
-    val  := n
-    isLt := match USize.size, usize_size_eq with
+  toBitVec :=
+    BitVec.ofNatLt n (
+      match System.Platform.numBits, System.Platform.numBits_eq with
       | _, Or.inl rfl => h
       | _, Or.inr rfl => Nat.lt_trans h (by decide)
-  }
+    )
 
 /--
 A `Nat` denotes a valid unicode codepoint if it is less than `0x110000`, and
@@ -2178,7 +2206,7 @@ This function is overridden with a native implementation.
 -/
 @[extern "lean_uint32_of_nat"]
 def Char.ofNatAux (n : @& Nat) (h : n.isValidChar) : Char :=
-  { val := ⟨{ val := n, isLt := isValidChar_UInt32 h }⟩, valid := h }
+  { val := ⟨BitVec.ofNatLt n (isValidChar_UInt32 h)⟩, valid := h }
 
 /--
 Convert a `Nat` into a `Char`. If the `Nat` does not encode a valid unicode scalar value,
@@ -2188,7 +2216,7 @@ Convert a `Nat` into a `Char`. If the `Nat` does not encode a valid unicode scal
 def Char.ofNat (n : Nat) : Char :=
   dite (n.isValidChar)
     (fun h => Char.ofNatAux n h)
-    (fun _ => { val := ⟨{ val := 0, isLt := by decide }⟩, valid := Or.inl (by decide) })
+    (fun _ => { val := ⟨BitVec.ofNatLt 0 (by decide)⟩, valid := Or.inl (by decide) })
 
 theorem Char.eq_of_val_eq : ∀ {c d : Char}, Eq c.val d.val → Eq c d
   | ⟨_, _⟩, ⟨_, _⟩, rfl => rfl
@@ -3448,15 +3476,13 @@ This function is overridden with a native implementation.
 -/
 @[extern "lean_usize_to_uint64"]
 def USize.toUInt64 (u : USize) : UInt64 where
-  val := {
-    val  := u.val.val
-    isLt :=
-      let ⟨n, h⟩ := u
-      show LT.lt n _ from
-      match USize.size, usize_size_eq, h with
-      | _, Or.inl rfl, h => Nat.lt_trans h (by decide)
-      | _, Or.inr rfl, h => h
-  }
+  toBitVec := BitVec.ofNatLt u.toBitVec.toNat (
+        let ⟨⟨n, h⟩⟩ := u
+        show LT.lt n _ from
+        match System.Platform.numBits, System.Platform.numBits_eq, h with
+        | _, Or.inl rfl, h => Nat.lt_trans h (by decide)
+        | _, Or.inr rfl, h => h
+      )
 
 /-- An opaque hash mixing operation, used to implement hashing for tuples. -/
 @[extern "lean_uint64_mix_hash"]

src/Init/PropLemmas.lean

@@ -135,6 +135,10 @@ Both reduce to `b = false ∧ c = false` via `not_or`.
 
 theorem not_and_of_not_or_not (h : ¬a ∨ ¬b) : ¬(a ∧ b) := h.elim (mt (·.1)) (mt (·.2))
 
+/-! ## not equal -/
+
+theorem ne_of_apply_ne {α β : Sort _} (f : α → β) {x y : α} : f x ≠ f y → x ≠ y :=
+  mt <| congrArg _
 
 /-! ## Ite -/
 
@@ -384,6 +388,17 @@ theorem forall_prop_of_false {p : Prop} {q : p → Prop} (hn : ¬p) : (∀ h' :
 
 end quantifiers
 
+/-! ## membership -/
+
+section Mem
+variable [Membership α β] {s t : β} {a b : α}
+
+theorem ne_of_mem_of_not_mem (h : a ∈ s) : b ∉ s → a ≠ b := mt fun e => e ▸ h
+
+theorem ne_of_mem_of_not_mem' (h : a ∈ s) : a ∉ t → s ≠ t := mt fun e => e ▸ h
+
+end Mem
+
 /-! ## Nonempty -/
 
 @[simp] theorem nonempty_prop {p : Prop} : Nonempty p ↔ p :=

src/Init/SizeOf.lean

@@ -67,6 +67,7 @@ deriving instance SizeOf for PLift
 deriving instance SizeOf for ULift
 deriving instance SizeOf for Decidable
 deriving instance SizeOf for Fin
+deriving instance SizeOf for BitVec
 deriving instance SizeOf for UInt8
 deriving instance SizeOf for UInt16
 deriving instance SizeOf for UInt32

src/Init/SizeOfLemmas.lean

@@ -11,22 +11,25 @@ import Init.Data.Nat.Linear
 @[simp] protected theorem Fin.sizeOf (a : Fin n) : sizeOf a = a.val + 1 := by
   cases a; simp_arith
 
-@[simp] protected theorem UInt8.sizeOf (a : UInt8) : sizeOf a = a.toNat + 2 := by
-  cases a; simp_arith [UInt8.toNat]
+@[simp] protected theorem BitVec.sizeOf (a : BitVec w) : sizeOf a = sizeOf a.toFin + 1 := by
+  cases a; simp_arith
 
-@[simp] protected theorem UInt16.sizeOf (a : UInt16) : sizeOf a = a.toNat + 2 := by
-  cases a; simp_arith [UInt16.toNat]
+@[simp] protected theorem UInt8.sizeOf (a : UInt8) : sizeOf a = a.toNat + 3 := by
+  cases a; simp_arith [UInt8.toNat, BitVec.toNat]
 
-@[simp] protected theorem UInt32.sizeOf (a : UInt32) : sizeOf a = a.toNat + 2 := by
-  cases a; simp_arith [UInt32.toNat]
+@[simp] protected theorem UInt16.sizeOf (a : UInt16) : sizeOf a = a.toNat + 3 := by
+  cases a; simp_arith [UInt16.toNat, BitVec.toNat]
 
-@[simp] protected theorem UInt64.sizeOf (a : UInt64) : sizeOf a = a.toNat + 2 := by
-  cases a; simp_arith [UInt64.toNat]
+@[simp] protected theorem UInt32.sizeOf (a : UInt32) : sizeOf a = a.toNat + 3 := by
+  cases a; simp_arith [UInt32.toNat, BitVec.toNat]
 
-@[simp] protected theorem USize.sizeOf (a : USize) : sizeOf a = a.toNat + 2 := by
-  cases a; simp_arith [USize.toNat]
+@[simp] protected theorem UInt64.sizeOf (a : UInt64) : sizeOf a = a.toNat + 3 := by
+  cases a; simp_arith [UInt64.toNat, BitVec.toNat]
 
-@[simp] protected theorem Char.sizeOf (a : Char) : sizeOf a = a.toNat + 3 := by
+@[simp] protected theorem USize.sizeOf (a : USize) : sizeOf a = a.toNat + 3 := by
+  cases a; simp_arith [USize.toNat, BitVec.toNat]
+
+@[simp] protected theorem Char.sizeOf (a : Char) : sizeOf a = a.toNat + 4 := by
   cases a; simp_arith [Char.toNat]
 
 @[simp] protected theorem Subtype.sizeOf {α : Sort u_1} {p : α → Prop} (s : Subtype p) : sizeOf s = sizeOf s.val + 1 := by

src/Init/Tactics.lean

@@ -268,9 +268,9 @@ syntax (name := case') "case' " sepBy1(caseArg, " | ") " => " tacticSeq : tactic
 `next x₁ ... xₙ => tac` additionally renames the `n` most recent hypotheses with
 inaccessible names to the given names.
 -/
-macro "next " args:binderIdent* arrowTk:" => " tac:tacticSeq : tactic =>
+macro nextTk:"next " args:binderIdent* arrowTk:" => " tac:tacticSeq : tactic =>
   -- Limit ref variability for incrementality; see Note [Incremental Macros]
-  withRef arrowTk `(tactic| case _ $args* =>%$arrowTk $tac)
+  withRef arrowTk `(tactic| case%$nextTk _ $args* =>%$arrowTk $tac)
 
 /-- `all_goals tac` runs `tac` on each goal, concatenating the resulting goals, if any. -/
 syntax (name := allGoals) "all_goals " tacticSeq : tactic

src/Init/While.lean

@@ -0,0 +1,51 @@
+/-
+Copyright (c) 2020 Microsoft Corporation. All rights reserved.
+Released under Apache 2.0 license as described in the file LICENSE.
+Authors: Leonardo de Moura
+-/
+prelude
+import Init.Core
+
+/-!
+# Notation for `while` and `repeat` loops.
+-/
+
+namespace Lean
+
+/-! # `repeat` and `while` notation -/
+
+inductive Loop where
+  | mk
+
+@[inline]
+partial def Loop.forIn {β : Type u} {m : Type u → Type v} [Monad m] (_ : Loop) (init : β) (f : Unit → β → m (ForInStep β)) : m β :=
+  let rec @[specialize] loop (b : β) : m β := do
+    match ← f () b with
+      | ForInStep.done b  => pure b
+      | ForInStep.yield b => loop b
+  loop init
+
+instance : ForIn m Loop Unit where
+  forIn := Loop.forIn
+
+syntax "repeat " doSeq : doElem
+
+macro_rules
+  | `(doElem| repeat $seq) => `(doElem| for _ in Loop.mk do $seq)
+
+syntax "while " ident " : " termBeforeDo " do " doSeq : doElem
+
+macro_rules
+  | `(doElem| while $h : $cond do $seq) => `(doElem| repeat if $h : $cond then $seq else break)
+
+syntax "while " termBeforeDo " do " doSeq : doElem
+
+macro_rules
+  | `(doElem| while $cond do $seq) => `(doElem| repeat if $cond then $seq else break)
+
+syntax "repeat " doSeq ppDedent(ppLine) "until " term : doElem
+
+macro_rules
+  | `(doElem| repeat $seq until $cond) => `(doElem| repeat do $seq:doSeq; if $cond then break)
+
+end Lean

src/Lean.lean

@@ -29,7 +29,6 @@ import Lean.Server
 import Lean.ScopedEnvExtension
 import Lean.DocString
 import Lean.DeclarationRange
-import Lean.LazyInitExtension
 import Lean.LoadDynlib
 import Lean.Widget
 import Lean.Log

src/Lean/Data/HashMap.lean

@@ -46,7 +46,7 @@ private def mkIdx {sz : Nat} (hash : UInt64) (h : sz.isPowerOfTwo) : { u : USize
   if h' : u.toNat < sz then
     ⟨u, h'⟩
   else
-    ⟨0, by simp [USize.toNat, OfNat.ofNat, USize.ofNat]; apply Nat.pos_of_isPowerOfTwo h⟩
+    ⟨0, by simp; apply Nat.pos_of_isPowerOfTwo h⟩
 
 @[inline] def reinsertAux (hashFn : α → UInt64) (data : HashMapBucket α β) (a : α) (b : β) : HashMapBucket α β :=
   let ⟨i, h⟩ := mkIdx (hashFn a) data.property

src/Lean/Data/HashSet.lean

@@ -42,7 +42,7 @@ private def mkIdx {sz : Nat} (hash : UInt64) (h : sz.isPowerOfTwo) : { u : USize
   if h' : u.toNat < sz then
     ⟨u, h'⟩
   else
-    ⟨0, by simp [USize.toNat, OfNat.ofNat, USize.ofNat]; apply Nat.pos_of_isPowerOfTwo h⟩
+    ⟨0, by simp; apply Nat.pos_of_isPowerOfTwo h⟩
 
 @[inline] def reinsertAux (hashFn : α → UInt64) (data : HashSetBucket α) (a : α) : HashSetBucket α :=
   let ⟨i, h⟩ := mkIdx (hashFn a) data.property

src/Lean/Data/Lsp/Capabilities.lean

@@ -54,7 +54,7 @@ structure WorkspaceEditClientCapabilities where
   deriving ToJson, FromJson
 
 structure WorkspaceClientCapabilities where
-  applyEdit: Bool
+  applyEdit? : Option Bool := none
   workspaceEdit? : Option WorkspaceEditClientCapabilities := none
   deriving ToJson, FromJson
 

src/Lean/Data/PersistentArray.lean

@@ -7,6 +7,7 @@ prelude
 import Init.Data.Array.Basic
 import Init.NotationExtra
 import Init.Data.ToString.Macro
+import Init.Data.UInt.Basic
 
 universe u v w
 

src/Lean/Data/PersistentHashMap.lean

@@ -6,6 +6,7 @@ Authors: Leonardo de Moura
 prelude
 import Init.Data.Array.BasicAux
 import Init.Data.ToString.Macro
+import Init.Data.UInt.Basic
 
 namespace Lean
 universe u v w w'

src/Lean/Data/Xml/Parser.lean

@@ -459,7 +459,7 @@ mutual
 
       let z ← optional (Content.Character <$> CharData)
       pure #[y, z]
-    let xs := #[x] ++ xs.concatMap id |>.filterMap id
+    let xs := #[x] ++ xs.flatMap id |>.filterMap id
     let mut res := #[]
     for x in xs do
       if res.size > 0 then

src/Lean/Declaration.lean

@@ -369,8 +369,13 @@ def RecursorVal.getFirstIndexIdx (v : RecursorVal) : Nat :=
 def RecursorVal.getFirstMinorIdx (v : RecursorVal) : Nat :=
   v.numParams + v.numMotives
 
-def RecursorVal.getInduct (v : RecursorVal) : Name :=
-  v.name.getPrefix
+/-- The inductive type of the major argument of the recursor. -/
+def RecursorVal.getMajorInduct (v : RecursorVal) : Name :=
+  go v.getMajorIdx v.type
+where
+  go
+  | 0, e => e.bindingDomain!.getAppFn.constName!
+  | n+1, e => go n e.bindingBody!
 
 inductive QuotKind where
   | type  -- `Quot`

src/Lean/Elab/BuiltinCommand.lean

@@ -12,16 +12,18 @@ import Lean.Elab.Eval
 import Lean.Elab.Command
 import Lean.Elab.Open
 import Lean.Elab.SetOption
+import Init.System.Platform
 
 namespace Lean.Elab.Command
 
 @[builtin_command_elab moduleDoc] def elabModuleDoc : CommandElab := fun stx => do
-   match stx[1] with
-   | Syntax.atom _ val =>
-     let doc := val.extract 0 (val.endPos - ⟨2⟩)
-     let range ← Elab.getDeclarationRange stx
-     modifyEnv fun env => addMainModuleDoc env ⟨doc, range⟩
-   | _ => throwErrorAt stx "unexpected module doc string{indentD stx[1]}"
+  match stx[1] with
+  | Syntax.atom _ val =>
+    let doc := val.extract 0 (val.endPos - ⟨2⟩)
+    let some range ← Elab.getDeclarationRange? stx
+      | return  -- must be from partial syntax, ignore
+    modifyEnv fun env => addMainModuleDoc env ⟨doc, range⟩
+  | _ => throwErrorAt stx "unexpected module doc string{indentD stx[1]}"
 
 private def addScope (isNewNamespace : Bool) (isNoncomputable : Bool) (header : String) (newNamespace : Name) : CommandElabM Unit := do
   modify fun s => { s with
@@ -229,7 +231,7 @@ private def replaceBinderAnnotation (binder : TSyntax ``Parser.Term.bracketedBin
 
 @[builtin_command_elab «variable»] def elabVariable : CommandElab
   | `(variable $binders*) => do
-    let binders ← binders.concatMapM replaceBinderAnnotation
+    let binders ← binders.flatMapM replaceBinderAnnotation
     -- Try to elaborate `binders` for sanity checking
     runTermElabM fun _ => Term.withSynthesize <| Term.withAutoBoundImplicit <|
       Term.elabBinders binders fun _ => pure ()
@@ -348,7 +350,7 @@ def failIfSucceeds (x : CommandElabM Unit) : CommandElabM Unit := do
 @[builtin_command_elab Lean.Parser.Command.include] def elabInclude : CommandElab
   | `(Lean.Parser.Command.include| include $ids*) => do
     let sc ← getScope
-    let vars ← sc.varDecls.concatMapM getBracketedBinderIds
+    let vars ← sc.varDecls.flatMapM getBracketedBinderIds
     let mut uids := #[]
     for id in ids do
       if let some idx := vars.findIdx? (· == id.getId) then
@@ -403,6 +405,16 @@ def failIfSucceeds (x : CommandElabM Unit) : CommandElabM Unit := do
       includedVars := sc.includedVars.filter (!omittedVars.contains ·) }
   | _ => throwUnsupportedSyntax
 
+@[builtin_command_elab version] def elabVersion : CommandElab := fun _ => do
+  let mut target := System.Platform.target
+  if target.isEmpty then target := "unknown"
+  -- Only one should be set, but good to know if multiple are set in error.
+  let platforms :=
+    (if System.Platform.isWindows then [" Windows"] else [])
+    ++ (if System.Platform.isOSX then [" macOS"] else [])
+    ++ (if System.Platform.isEmscripten then [" Emscripten"] else [])
+  logInfo m!"Lean {Lean.versionString}\nTarget: {target}{String.join platforms}"
+
 @[builtin_command_elab Parser.Command.exit] def elabExit : CommandElab := fun _ =>
   logWarning "using 'exit' to interrupt Lean"
 

src/Lean/Elab/BuiltinEvalCommand.lean

@@ -84,7 +84,7 @@ private def addAndCompileExprForEval (declName : Name) (value : Expr) (allowSorr
   -- An alternative design would be to make `elabTermForEval` into a term elaborator and elaborate the command all at once
   -- with `unsafe def _eval := term_for_eval% $t`, which we did try, but unwanted error messages
   -- such as "failed to infer definition type" can surface.
-  let defView := mkDefViewOfDef { isUnsafe := true }
+  let defView := mkDefViewOfDef { isUnsafe := true, stx := ⟨.missing⟩ }
     (← `(Parser.Command.definition|
           def $(mkIdent <| `_root_ ++ declName) := $(← Term.exprToSyntax value)))
   Term.elabMutualDef #[] { header := "" } #[defView]

src/Lean/Elab/BuiltinNotation.lean

@@ -135,13 +135,21 @@ open Meta
   | _                                                => Macro.throwUnsupported
 
 @[builtin_macro Lean.Parser.Term.suffices] def expandSuffices : Macro
-  | `(suffices%$tk $x:ident      : $type from $val; $body)            => `(have%$tk $x : $type := $body; $val)
-  | `(suffices%$tk _%$x          : $type from $val; $body)            => `(have%$tk _%$x : $type := $body; $val)
-  | `(suffices%$tk $hy:hygieneInfo $type from $val; $body)            => `(have%$tk $hy:hygieneInfo : $type := $body; $val)
-  | `(suffices%$tk $x:ident      : $type by%$b $tac:tacticSeq; $body) => `(have%$tk $x : $type := $body; by%$b $tac)
-  | `(suffices%$tk _%$x          : $type by%$b $tac:tacticSeq; $body) => `(have%$tk _%$x : $type := $body; by%$b $tac)
-  | `(suffices%$tk $hy:hygieneInfo $type by%$b $tac:tacticSeq; $body) => `(have%$tk $hy:hygieneInfo : $type := $body; by%$b $tac)
-  | _                                                                 => Macro.throwUnsupported
+  | `(suffices%$tk $x:ident      : $type from $val; $body)   => `(have%$tk $x : $type := $body; $val)
+  | `(suffices%$tk _%$x          : $type from $val; $body)   => `(have%$tk _%$x : $type := $body; $val)
+  | `(suffices%$tk $hy:hygieneInfo $type from $val; $body)   => `(have%$tk $hy:hygieneInfo : $type := $body; $val)
+  | `(suffices%$tk $x:ident      : $type $b:byTactic'; $body) =>
+    -- Pass on `SourceInfo` of `b` to `have`. This is necessary to display the goal state in the
+    -- trailing whitespace of `by` and sound since `byTactic` and `byTactic'` are identical.
+    let b := ⟨b.raw.setKind `Lean.Parser.Term.byTactic⟩
+    `(have%$tk $x : $type := $body; $b:byTactic)
+  | `(suffices%$tk _%$x          : $type $b:byTactic'; $body) =>
+    let b := ⟨b.raw.setKind `Lean.Parser.Term.byTactic⟩
+    `(have%$tk _%$x : $type := $body; $b:byTactic)
+  | `(suffices%$tk $hy:hygieneInfo $type $b:byTactic'; $body) =>
+    let b := ⟨b.raw.setKind `Lean.Parser.Term.byTactic⟩
+    `(have%$tk $hy:hygieneInfo : $type := $body; $b:byTactic)
+  | _ => Macro.throwUnsupported
 
 open Lean.Parser in
 private def elabParserMacroAux (prec e : Term) (withAnonymousAntiquot : Bool) : TermElabM Syntax := do

src/Lean/Elab/Command.lean

@@ -532,11 +532,12 @@ def elabCommandTopLevel (stx : Syntax) : CommandElabM Unit := withRef stx do pro
     let mut msgs := (← get).messages
     for tree in (← getInfoTrees) do
       trace[Elab.info] (← tree.format)
-    if let some snap := (← read).snap? then
-      -- We can assume that the root command snapshot is not involved in parallelism yet, so this
-      -- should be true iff the command supports incrementality
-      if (← IO.hasFinished snap.new.result) then
-        liftCoreM <| Language.ToSnapshotTree.toSnapshotTree snap.new.result.get |>.trace
+    if (← isTracingEnabledFor `Elab.snapshotTree) then
+      if let some snap := (← read).snap? then
+        -- We can assume that the root command snapshot is not involved in parallelism yet, so this
+        -- should be true iff the command supports incrementality
+        if (← IO.hasFinished snap.new.result) then
+          liftCoreM <| Language.ToSnapshotTree.toSnapshotTree snap.new.result.get |>.trace
     modify fun st => { st with
       messages := initMsgs ++ msgs
       infoState := { st.infoState with trees := initInfoTrees ++ st.infoState.trees }
@@ -571,7 +572,7 @@ def getBracketedBinderIds : Syntax → CommandElabM (Array Name)
 private def mkTermContext (ctx : Context) (s : State) : CommandElabM Term.Context := do
   let scope      := s.scopes.head!
   let mut sectionVars := {}
-  for id in (← scope.varDecls.concatMapM getBracketedBinderIds), uid in scope.varUIds do
+  for id in (← scope.varDecls.flatMapM getBracketedBinderIds), uid in scope.varUIds do
     sectionVars := sectionVars.insert id uid
   return {
     macroStack             := ctx.macroStack
@@ -714,7 +715,7 @@ def expandDeclId (declId : Syntax) (modifiers : Modifiers) : CommandElabM Expand
   let currNamespace ← getCurrNamespace
   let currLevelNames ← getLevelNames
   let r ← Elab.expandDeclId currNamespace currLevelNames declId modifiers
-  for id in (← (← getScope).varDecls.concatMapM getBracketedBinderIds) do
+  for id in (← (← getScope).varDecls.flatMapM getBracketedBinderIds) do
     if id == r.shortName then
       throwError "invalid declaration name '{r.shortName}', there is a section variable with the same name"
   return r

src/Lean/Elab/DeclModifiers.lean

@@ -57,6 +57,7 @@ inductive RecKind where
 
 /-- Flags and data added to declarations (eg docstrings, attributes, `private`, `unsafe`, `partial`, ...). -/
 structure Modifiers where
+  stx             : TSyntax ``Parser.Command.declModifiers
   docString?      : Option String := none
   visibility      : Visibility := Visibility.regular
   isNoncomputable : Bool := false
@@ -121,16 +122,16 @@ section Methods
 variable [Monad m] [MonadEnv m] [MonadResolveName m] [MonadError m] [MonadMacroAdapter m] [MonadRecDepth m] [MonadTrace m] [MonadOptions m] [AddMessageContext m] [MonadLog m] [MonadInfoTree m] [MonadLiftT IO m]
 
 /-- Elaborate declaration modifiers (i.e., attributes, `partial`, `private`, `protected`, `unsafe`, `noncomputable`, doc string)-/
-def elabModifiers (stx : Syntax) : m Modifiers := do
-  let docCommentStx := stx[0]
-  let attrsStx      := stx[1]
-  let visibilityStx := stx[2]
-  let noncompStx    := stx[3]
-  let unsafeStx     := stx[4]
+def elabModifiers (stx : TSyntax ``Parser.Command.declModifiers) : m Modifiers := do
+  let docCommentStx := stx.raw[0]
+  let attrsStx      := stx.raw[1]
+  let visibilityStx := stx.raw[2]
+  let noncompStx    := stx.raw[3]
+  let unsafeStx     := stx.raw[4]
   let recKind       :=
-    if stx[5].isNone then
+    if stx.raw[5].isNone then
       RecKind.default
-    else if stx[5][0].getKind == ``Parser.Command.partial then
+    else if stx.raw[5][0].getKind == ``Parser.Command.partial then
       RecKind.partial
     else
       RecKind.nonrec
@@ -148,7 +149,7 @@ def elabModifiers (stx : Syntax) : m Modifiers := do
     | none       => pure #[]
     | some attrs => elabDeclAttrs attrs
   return {
-    docString?, visibility, recKind, attrs,
+    stx, docString?, visibility, recKind, attrs,
     isUnsafe        := !unsafeStx.isNone
     isNoncomputable := !noncompStx.isNone
   }

src/Lean/Elab/Declaration.lean

@@ -104,7 +104,7 @@ def elabAxiom (modifiers : Modifiers) (stx : Syntax) : CommandElabM Unit := do
   let (binders, typeStx) := expandDeclSig stx[2]
   let scopeLevelNames ← getLevelNames
   let ⟨_, declName, allUserLevelNames⟩ ← expandDeclId declId modifiers
-  addDeclarationRanges declName stx
+  addDeclarationRanges declName modifiers.stx stx
   runTermElabM fun vars =>
     Term.withDeclName declName <| Term.withLevelNames allUserLevelNames <| Term.elabBinders binders.getArgs fun xs => do
       Term.applyAttributesAt declName modifiers.attrs AttributeApplicationTime.beforeElaboration
@@ -144,10 +144,10 @@ private def inductiveSyntaxToView (modifiers : Modifiers) (decl : Syntax) : Comm
   let (binders, type?) := expandOptDeclSig decl[2]
   let declId           := decl[1]
   let ⟨name, declName, levelNames⟩ ← expandDeclId declId modifiers
-  addDeclarationRanges declName decl
+  addDeclarationRanges declName modifiers.stx decl
   let ctors      ← decl[4].getArgs.mapM fun ctor => withRef ctor do
     -- def ctor := leading_parser optional docComment >> "\n| " >> declModifiers >> rawIdent >> optDeclSig
-    let mut ctorModifiers ← elabModifiers ctor[2]
+    let mut ctorModifiers ← elabModifiers ⟨ctor[2]⟩
     if let some leadingDocComment := ctor[0].getOptional? then
       if ctorModifiers.docString?.isSome then
         logErrorAt leadingDocComment "duplicate doc string"
@@ -214,17 +214,18 @@ def elabDeclaration : CommandElab := fun stx => do
     -- only case implementing incrementality currently
     elabMutualDef #[stx]
   else withoutCommandIncrementality true do
+    let modifiers : TSyntax ``Parser.Command.declModifiers := ⟨stx[0]⟩
     if declKind == ``Lean.Parser.Command.«axiom» then
-      let modifiers ← elabModifiers stx[0]
+      let modifiers ← elabModifiers modifiers
       elabAxiom modifiers decl
     else if declKind == ``Lean.Parser.Command.«inductive» then
-      let modifiers ← elabModifiers stx[0]
+      let modifiers ← elabModifiers modifiers
       elabInductive modifiers decl
     else if declKind == ``Lean.Parser.Command.classInductive then
-      let modifiers ← elabModifiers stx[0]
+      let modifiers ← elabModifiers modifiers
       elabClassInductive modifiers decl
     else if declKind == ``Lean.Parser.Command.«structure» then
-      let modifiers ← elabModifiers stx[0]
+      let modifiers ← elabModifiers modifiers
       elabStructure modifiers decl
     else
       throwError "unexpected declaration"
@@ -238,7 +239,7 @@ private def isMutualInductive (stx : Syntax) : Bool :=
 
 private def elabMutualInductive (elems : Array Syntax) : CommandElabM Unit := do
   let views ← elems.mapM fun stx => do
-     let modifiers ← elabModifiers stx[0]
+     let modifiers ← elabModifiers ⟨stx[0]⟩
      inductiveSyntaxToView modifiers stx[1]
   elabInductiveViews views
 
@@ -399,7 +400,7 @@ def elabMutual : CommandElab := fun stx => do
       -- We need to add `id`'s ranges *before* elaborating `initFn` (and then `id` itself) as
       -- otherwise the info context created by `with_decl_name` will be incomplete and break the
       -- call hierarchy
-      addDeclarationRanges fullId defStx
+      addDeclarationRanges fullId ⟨defStx.raw[0]⟩ defStx.raw[1]
       elabCommand (← `(
         $[unsafe%$unsafe?]? def initFn : IO $type := with_decl_name% $(mkIdent fullId) do $doSeq
         $defStx:command))

src/Lean/Elab/DeclarationRange.lean

@@ -11,12 +11,14 @@ import Lean.Data.Lsp.Utf16
 
 namespace Lean.Elab
 
-def getDeclarationRange [Monad m] [MonadFileMap m] (stx : Syntax) : m DeclarationRange := do
+def getDeclarationRange? [Monad m] [MonadFileMap m] (stx : Syntax) : m (Option DeclarationRange) := do
+  let some range := stx.getRange?
+    | return none
   let fileMap ← getFileMap
-  let pos    := stx.getPos?.getD 0
-  let endPos := stx.getTailPos?.getD pos |> fileMap.toPosition
-  let pos    := pos |> fileMap.toPosition
-  return {
+  --let range := fileMap.utf8RangeToLspRange
+  let pos    := fileMap.toPosition range.start
+  let endPos := fileMap.toPosition range.stop
+  return some {
     pos          := pos
     charUtf16    := fileMap.leanPosToLspPos pos |>.character
     endPos       := endPos
@@ -49,23 +51,27 @@ def getDeclarationSelectionRef (stx : Syntax) : Syntax :=
 
 
 /--
-  Store the `range` and `selectionRange` for `declName` where `stx` is the whole syntax object describing `declName`.
-  This method is for the builtin declarations only.
-  User-defined commands should use `Lean.addDeclarationRanges` to store this information for their commands. -/
-def addDeclarationRanges [Monad m] [MonadEnv m] [MonadFileMap m] (declName : Name) (stx : Syntax) : m Unit := do
-  if stx.getKind == ``Parser.Command.«example» then
+Stores the `range` and `selectionRange` for `declName` where `modsStx` is the modifier part and
+`cmdStx` the remaining part of the syntax tree for `declName`.
+
+This method is for the builtin declarations only. User-defined commands should use
+`Lean.addDeclarationRanges` to store this information for their commands.
+-/
+def addDeclarationRanges [Monad m] [MonadEnv m] [MonadFileMap m] (declName : Name)
+    (modsStx : TSyntax ``Parser.Command.declModifiers) (declStx : Syntax) : m Unit := do
+  if declStx.getKind == ``Parser.Command.«example» then
     return ()
-  else
-    Lean.addDeclarationRanges declName {
-      range          := (← getDeclarationRange stx)
-      selectionRange := (← getDeclarationRange (getDeclarationSelectionRef stx))
-    }
+  let stx := mkNullNode #[modsStx, declStx]
+  -- may fail on partial syntax, ignore in that case
+  let some range ← getDeclarationRange? stx | return
+  let some selectionRange ← getDeclarationRange? (getDeclarationSelectionRef declStx) | return
+  Lean.addDeclarationRanges declName { range, selectionRange }
 
 /-- Auxiliary method for recording ranges for auxiliary declarations (e.g., fields, nested declarations, etc. -/
 def addAuxDeclarationRanges [Monad m] [MonadEnv m] [MonadFileMap m] (declName : Name) (stx : Syntax) (header : Syntax) : m Unit := do
-  Lean.addDeclarationRanges declName {
-    range          := (← getDeclarationRange stx)
-    selectionRange := (← getDeclarationRange header)
-  }
+  -- may fail on partial syntax, ignore in that case
+  let some range ← getDeclarationRange? stx | return
+  let some selectionRange ← getDeclarationRange? header | return
+  Lean.addDeclarationRanges declName { range, selectionRange }
 
 end Lean.Elab

src/Lean/Elab/Frontend.lean

@@ -102,7 +102,7 @@ partial def IO.processCommandsIncrementally (inputCtx : Parser.InputContext)
 where
   go initialSnap t commands :=
     let snap := t.get
-    let commands := commands.push snap.data.stx
+    let commands := commands.push snap.data
     if let some next := snap.nextCmdSnap? then
       go initialSnap next.task commands
     else
@@ -111,13 +111,15 @@ where
       let messages := toSnapshotTree initialSnap
         |>.getAll.map (·.diagnostics.msgLog)
         |>.foldl (· ++ ·) {}
-      let trees := toSnapshotTree initialSnap
-        |>.getAll.map (·.infoTree?) |>.filterMap id |>.toPArray'
+      -- In contrast to messages, we should collect info trees only from the top-level command
+      -- snapshots as they subsume any info trees reported incrementally by their children.
+      let trees := commands.map (·.finishedSnap.get.infoTree?) |>.filterMap id |>.toPArray'
       return {
         commandState := { snap.data.finishedSnap.get.cmdState with messages, infoState.trees := trees }
         parserState := snap.data.parserState
         cmdPos := snap.data.parserState.pos
-        inputCtx, initialSnap, commands
+        commands := commands.map (·.stx)
+        inputCtx, initialSnap
       }
 
 def IO.processCommands (inputCtx : Parser.InputContext) (parserState : Parser.ModuleParserState)
@@ -151,7 +153,7 @@ def runFrontend
   snaps.runAndReport opts jsonOutput
 
   if let some ileanFileName := ileanFileName? then
-    let trees := snaps.getAll.concatMap (match ·.infoTree? with | some t => #[t] | _ => #[])
+    let trees := snaps.getAll.flatMap (match ·.infoTree? with | some t => #[t] | _ => #[])
     let references := Lean.Server.findModuleRefs inputCtx.fileMap trees (localVars := false)
     let ilean := { module := mainModuleName, references := ← references.toLspModuleRefs : Lean.Server.Ilean }
     IO.FS.writeFile ileanFileName $ Json.compress $ toJson ilean

src/Lean/Elab/LetRec.lean

@@ -90,6 +90,7 @@ private def elabLetRecDeclValues (view : LetRecView) : TermElabM (Array Expr) :=
       for i in [0:view.binderIds.size] do
         addLocalVarInfo view.binderIds[i]! xs[i]!
       withDeclName view.declName do
+        withInfoContext' view.valStx (mkInfo := mkTermInfo `MutualDef.body view.valStx) do
          let value ← elabTermEnsuringType view.valStx type
          mkLambdaFVars xs value
 

src/Lean/Elab/MutualDef.lean

@@ -410,11 +410,15 @@ private def elabFunValues (headers : Array DefViewElabHeader) (vars : Array Expr
           -- skip auto-bound prefix in `xs`
           addLocalVarInfo header.binderIds[i] xs[header.numParams - header.binderIds.size + i]!
         let val ← withReader ({ · with tacSnap? := header.tacSnap? }) do
-          -- synthesize mvars here to force the top-level tactic block (if any) to run
-          elabTermEnsuringType valStx type <* synthesizeSyntheticMVarsNoPostponing
-        -- NOTE: without this `instantiatedMVars`, `mkLambdaFVars` may leave around a redex that
-        -- leads to more section variables being included than necessary
-        let val ← instantiateMVarsProfiling val
+          -- Store instantiated body in info tree for the benefit of the unused variables linter
+          -- and other metaprograms that may want to inspect it without paying for the instantiation
+          -- again
+          withInfoContext' valStx (mkInfo := mkTermInfo `MutualDef.body valStx) do
+            -- synthesize mvars here to force the top-level tactic block (if any) to run
+            let val ← elabTermEnsuringType valStx type <* synthesizeSyntheticMVarsNoPostponing
+            -- NOTE: without this `instantiatedMVars`, `mkLambdaFVars` may leave around a redex that
+            -- leads to more section variables being included than necessary
+            instantiateMVarsProfiling val
         let val ← mkLambdaFVars xs val
         if linter.unusedSectionVars.get (← getOptions) && !header.type.hasSorry && !val.hasSorry then
           let unusedVars ← vars.filterMapM fun var => do
@@ -883,6 +887,7 @@ def getKindForLetRecs (mainHeaders : Array DefViewElabHeader) : DefKind :=
   else DefKind.«def»
 
 def getModifiersForLetRecs (mainHeaders : Array DefViewElabHeader) : Modifiers := {
+  stx             := ⟨mkNullNode #[]⟩  -- ignore when computing declaration range
   isNoncomputable := mainHeaders.any fun h => h.modifiers.isNoncomputable
   recKind         := if mainHeaders.any fun h => h.modifiers.isPartial then RecKind.partial else RecKind.default
   isUnsafe        := mainHeaders.any fun h => h.modifiers.isUnsafe
@@ -993,7 +998,7 @@ where
       for view in views, header in headers do
         -- NOTE: this should be the full `ref`, and thus needs to be done after any snapshotting
         -- that depends only on a part of the ref
-        addDeclarationRanges header.declName view.ref
+        addDeclarationRanges header.declName view.modifiers.stx view.ref
 
 
   processDeriving (headers : Array DefViewElabHeader) := do
@@ -1017,7 +1022,7 @@ def elabMutualDef (ds : Array Syntax) : CommandElabM Unit := do
     let mut reusedAllHeaders := true
     for h : i in [0:ds.size], headerPromise in headerPromises do
       let d := ds[i]
-      let modifiers ← elabModifiers d[0]
+      let modifiers ← elabModifiers ⟨d[0]⟩
       if ds.size > 1 && modifiers.isNonrec then
         throwErrorAt d "invalid use of 'nonrec' modifier in 'mutual' block"
       let mut view ← mkDefView modifiers d[1]

src/Lean/Elab/PreDefinition/Basic.lean

@@ -221,7 +221,7 @@ def addAndCompilePartialRec (preDefs : Array PreDefinition) : TermElabM Unit :=
               else
                 none
             | _ => none
-          modifiers := {} }
+          modifiers := default }
 
 private def containsRecFn (recFnNames : Array Name) (e : Expr) : Bool :=
   (e.find? fun e => e.isConst && recFnNames.contains e.constName!).isSome

src/Lean/Elab/PreDefinition/Structural/BRecOn.lean

@@ -212,21 +212,21 @@ def mkBRecOnMotive (recArgInfo : RecArgInfo) (value : Expr) : M Expr := do
 /--
 Calculates the `.brecOn` functional argument corresponding to one structural recursive function.
 The `value` is the function with (only) the fixed parameters moved into the context,
-The `type` is the expected type of the argument.
+The `FType` is the expected type of the argument.
 The `recArgInfos` is used to transform the body of the function to replace recursive calls with
 uses of the `below` induction hypothesis.
 -/
 def mkBRecOnF (recArgInfos : Array RecArgInfo) (positions : Positions)
     (recArgInfo : RecArgInfo) (value : Expr) (FType : Expr) : M Expr := do
   lambdaTelescope value fun xs value => do
-    let (indexMajorArgs, otherArgs) := recArgInfo.pickIndicesMajor xs
-    let FType ← instantiateForall FType indexMajorArgs
+    let (indicesMajorArgs, otherArgs) := recArgInfo.pickIndicesMajor xs
+    let FType ← instantiateForall FType indicesMajorArgs
     forallBoundedTelescope FType (some 1) fun below _ => do
       -- TODO: `below` user name is `f`, and it will make a global `f` to be pretty printed as `_root_.f` in error messages.
       -- We should add an option to `forallBoundedTelescope` to ensure fresh names are used.
       let below := below[0]!
-      let valueNew   ← replaceRecApps recArgInfos positions below value
-      mkLambdaFVars (indexMajorArgs ++ #[below] ++ otherArgs) valueNew
+      let valueNew ← replaceRecApps recArgInfos positions below value
+      mkLambdaFVars (indicesMajorArgs ++ #[below] ++ otherArgs) valueNew
 
 /--
 Given the `motives`, figures out whether to use `.brecOn` or `.binductionOn`, pass
@@ -264,7 +264,7 @@ def inferBRecOnFTypes (recArgInfos : Array RecArgInfo) (positions : Positions)
     (brecOnConst : Nat → Expr) : MetaM (Array Expr) := do
   let numTypeFormers := positions.size
   let recArgInfo := recArgInfos[0]! -- pick an arbitrary one
-  let brecOn := brecOnConst 0
+  let brecOn := brecOnConst recArgInfo.indIdx
   check brecOn
   let brecOnType ← inferType brecOn
   -- Skip the indices and major argument

src/Lean/Elab/PreDefinition/Structural/FindRecArg.lean

@@ -77,7 +77,7 @@ def getRecArgInfo (fnName : Name) (numFixed : Nat) (xs : Array Expr) (i : Nat) :
       if !indIndices.all Expr.isFVar then
         throwError "its type {indInfo.name} is an inductive family and indices are not variables{indentExpr xType}"
       else if !indIndices.allDiff then
-        throwError " its type {indInfo.name} is an inductive family and indices are not pairwise distinct{indentExpr xType}"
+        throwError "its type {indInfo.name} is an inductive family and indices are not pairwise distinct{indentExpr xType}"
       else
         let indexMinPos := getIndexMinPos xs indIndices
         let numFixed    := if indexMinPos < numFixed then indexMinPos else numFixed
@@ -226,7 +226,7 @@ def allCombinations (xss : Array (Array α)) : Option (Array (Array α)) :=
   else
     let rec go i acc : Array (Array α):=
       if h : i < xss.size then
-        xss[i].concatMap fun x => go (i + 1) (acc.push x)
+        xss[i].flatMap fun x => go (i + 1) (acc.push x)
       else
         #[acc]
     some (go 0 #[])

src/Lean/Elab/PreDefinition/Structural/Main.lean

@@ -107,9 +107,9 @@ private def elimMutualRecursion (preDefs : Array PreDefinition) (xs : Array Expr
     check valueNew
     return #[{ preDef with value := valueNew }]
 
-  -- Sort the (indices of the) definitions by their position in indInfo.all
+  -- Groups the (indices of the) definitions by their position in indInfo.all
   let positions : Positions := .groupAndSort (·.indIdx) recArgInfos (Array.range indInfo.numTypeFormers)
-  trace[Elab.definition.structural] "positions: {positions}"
+  trace[Elab.definition.structural] "assignments of type formers of {indInfo.name} to functions: {positions}"
 
   -- Construct the common `.brecOn` arguments
   let motives ← (Array.zip recArgInfos values).mapM fun (r, v) => mkBRecOnMotive r v
@@ -117,7 +117,7 @@ private def elimMutualRecursion (preDefs : Array PreDefinition) (xs : Array Expr
   let brecOnConst ← mkBRecOnConst recArgInfos positions motives
   let FTypes ← inferBRecOnFTypes recArgInfos positions brecOnConst
   trace[Elab.definition.structural] "FTypes: {FTypes}"
-  let FArgs ← (recArgInfos.zip  (values.zip FTypes)).mapM fun (r, (v, t)) =>
+  let FArgs ← (recArgInfos.zip (values.zip FTypes)).mapM fun (r, (v, t)) =>
     mkBRecOnF recArgInfos positions r v t
   trace[Elab.definition.structural] "FArgs: {FArgs}"
   -- Assemble the individual `.brecOn` applications

src/Lean/Elab/PreDefinition/Structural/SmartUnfolding.lean

@@ -15,7 +15,7 @@ partial def addSmartUnfoldingDefAux (preDef : PreDefinition) (recArgPos : Nat) :
   return { preDef with
     declName  := mkSmartUnfoldingNameFor preDef.declName
     value     := (← visit preDef.value)
-    modifiers := {}
+    modifiers := default
   }
 where
   /--

src/Lean/Elab/Structure.lean

@@ -95,7 +95,7 @@ private def expandCtor (structStx : Syntax) (structModifiers : Modifiers) (struc
     let declName := structDeclName ++ defaultCtorName
     let ref := structStx[1].mkSynthetic
     addAuxDeclarationRanges declName ref ref
-    pure { ref, modifiers := {}, name := defaultCtorName, declName }
+    pure { ref, modifiers := default, name := defaultCtorName, declName }
   if structStx[5].isNone then
     useDefault
   else
@@ -912,7 +912,7 @@ def elabStructure (modifiers : Modifiers) (stx : Syntax) : CommandElabM Unit :=
       let scopeLevelNames ← Term.getLevelNames
       let ⟨name, declName, allUserLevelNames⟩ ← Elab.expandDeclId (← getCurrNamespace) scopeLevelNames declId modifiers
       Term.withAutoBoundImplicitForbiddenPred (fun n => name == n) do
-        addDeclarationRanges declName stx
+        addDeclarationRanges declName modifiers.stx stx
         Term.withDeclName declName do
           let ctor ← expandCtor stx modifiers declName
           let fields ← expandFields stx modifiers declName

src/Lean/Elab/Syntax.lean

@@ -146,7 +146,7 @@ where
       let args ← args.mapM fun arg => withNestedParser do process arg
       mkParserSeq args
     else
-      let args ← args.mapIdxM fun i arg => withReader (fun ctx => { ctx with first := ctx.first && i.val == 0 }) do process arg
+      let args ← args.mapIdxM fun i arg => withReader (fun ctx => { ctx with first := ctx.first && i == 0 }) do process arg
       mkParserSeq args
 
   ensureNoPrec (stx : Syntax) :=

src/Lean/Elab/Tactic/BVDecide/Frontend/BVDecide/ReifiedBVExpr.lean

@@ -65,202 +65,218 @@ def getNatOrBvValue? (ty : Expr) (expr : Expr) : M (Option Nat) := do
   | _ => return none
 
 /--
-Reify an `Expr` that's a `BitVec`.
+Construct an uninterpreted `BitVec` atom from `x`.
+-/
+def bitVecAtom (x : Expr) : M (Option ReifiedBVExpr) := do
+  let t ← instantiateMVars (← whnfR (← inferType x))
+  let_expr BitVec widthExpr := t | return none
+  let some width ← getNatValue? widthExpr | return none
+  let atom ← mkAtom x width
+  return some atom
+
+/--
+Reify an `Expr` that's a constant-width `BitVec`.
+Unless this function is called on something that is not a constant-width `BitVec` it is always
+going to return `some`.
 -/
 partial def of (x : Expr) : M (Option ReifiedBVExpr) := do
-  match_expr x with
-  | BitVec.ofNat _ _ => goBvLit x
-  | HAnd.hAnd _ _ _ _ lhsExpr rhsExpr =>
-    binaryReflection lhsExpr rhsExpr .and ``Std.Tactic.BVDecide.Reflect.BitVec.and_congr
-  | HOr.hOr _ _ _ _ lhsExpr rhsExpr =>
-    binaryReflection lhsExpr rhsExpr .or ``Std.Tactic.BVDecide.Reflect.BitVec.or_congr
-  | HXor.hXor _ _ _ _ lhsExpr rhsExpr =>
-    binaryReflection lhsExpr rhsExpr .xor ``Std.Tactic.BVDecide.Reflect.BitVec.xor_congr
-  | HAdd.hAdd _ _ _ _ lhsExpr rhsExpr =>
-    binaryReflection lhsExpr rhsExpr .add ``Std.Tactic.BVDecide.Reflect.BitVec.add_congr
-  | HMul.hMul _ _ _ _ lhsExpr rhsExpr =>
-    binaryReflection lhsExpr rhsExpr .mul ``Std.Tactic.BVDecide.Reflect.BitVec.mul_congr
-  | HDiv.hDiv _ _ _ _ lhsExpr rhsExpr =>
-    binaryReflection lhsExpr rhsExpr .udiv ``Std.Tactic.BVDecide.Reflect.BitVec.udiv_congr
-  | HMod.hMod _ _ _ _ lhsExpr rhsExpr =>
-    binaryReflection lhsExpr rhsExpr .umod ``Std.Tactic.BVDecide.Reflect.BitVec.umod_congr
-  | Complement.complement _ _ innerExpr =>
-    unaryReflection innerExpr .not ``Std.Tactic.BVDecide.Reflect.BitVec.not_congr
-  | HShiftLeft.hShiftLeft _ β _ _ innerExpr distanceExpr =>
-    let distance? ← getNatOrBvValue? β distanceExpr
-    if distance?.isSome then
-      shiftConstReflection
-        β
-        distanceExpr
+  goOrAtom x
+where
+  /--
+  Reify `x`, returns `none` if the reification procedure failed.
+  -/
+  go (x : Expr) : M (Option ReifiedBVExpr) := do
+    match_expr x with
+    | BitVec.ofNat _ _ => goBvLit x
+    | HAnd.hAnd _ _ _ _ lhsExpr rhsExpr =>
+      binaryReflection lhsExpr rhsExpr .and ``Std.Tactic.BVDecide.Reflect.BitVec.and_congr
+    | HOr.hOr _ _ _ _ lhsExpr rhsExpr =>
+      binaryReflection lhsExpr rhsExpr .or ``Std.Tactic.BVDecide.Reflect.BitVec.or_congr
+    | HXor.hXor _ _ _ _ lhsExpr rhsExpr =>
+      binaryReflection lhsExpr rhsExpr .xor ``Std.Tactic.BVDecide.Reflect.BitVec.xor_congr
+    | HAdd.hAdd _ _ _ _ lhsExpr rhsExpr =>
+      binaryReflection lhsExpr rhsExpr .add ``Std.Tactic.BVDecide.Reflect.BitVec.add_congr
+    | HMul.hMul _ _ _ _ lhsExpr rhsExpr =>
+      binaryReflection lhsExpr rhsExpr .mul ``Std.Tactic.BVDecide.Reflect.BitVec.mul_congr
+    | HDiv.hDiv _ _ _ _ lhsExpr rhsExpr =>
+      binaryReflection lhsExpr rhsExpr .udiv ``Std.Tactic.BVDecide.Reflect.BitVec.udiv_congr
+    | HMod.hMod _ _ _ _ lhsExpr rhsExpr =>
+      binaryReflection lhsExpr rhsExpr .umod ``Std.Tactic.BVDecide.Reflect.BitVec.umod_congr
+    | Complement.complement _ _ innerExpr =>
+      unaryReflection innerExpr .not ``Std.Tactic.BVDecide.Reflect.BitVec.not_congr
+    | HShiftLeft.hShiftLeft _ β _ _ innerExpr distanceExpr =>
+      let distance? ← getNatOrBvValue? β distanceExpr
+      if distance?.isSome then
+        shiftConstReflection
+          β
+          distanceExpr
+          innerExpr
+          .shiftLeftConst
+          ``BVUnOp.shiftLeftConst
+          ``Std.Tactic.BVDecide.Reflect.BitVec.shiftLeftNat_congr
+      else
+        shiftReflection
+          β
+          distanceExpr
+          innerExpr
+          .shiftLeft
+          ``BVExpr.shiftLeft
+          ``Std.Tactic.BVDecide.Reflect.BitVec.shiftLeft_congr
+    | HShiftRight.hShiftRight _ β _ _ innerExpr distanceExpr =>
+      let distance? ← getNatOrBvValue? β distanceExpr
+      if distance?.isSome then
+        shiftConstReflection
+          β
+          distanceExpr
+          innerExpr
+          .shiftRightConst
+          ``BVUnOp.shiftRightConst
+          ``Std.Tactic.BVDecide.Reflect.BitVec.shiftRightNat_congr
+      else
+        shiftReflection
+          β
+          distanceExpr
+          innerExpr
+          .shiftRight
+          ``BVExpr.shiftRight
+          ``Std.Tactic.BVDecide.Reflect.BitVec.shiftRight_congr
+    | BitVec.sshiftRight _ innerExpr distanceExpr =>
+      let some distance ← getNatValue? distanceExpr | return none
+      shiftConstLikeReflection
+        distance
         innerExpr
-        .shiftLeftConst
-        ``BVUnOp.shiftLeftConst
-        ``Std.Tactic.BVDecide.Reflect.BitVec.shiftLeftNat_congr
-    else
-      shiftReflection
-        β
-        distanceExpr
-        innerExpr
-        .shiftLeft
-        ``BVExpr.shiftLeft
-        ``Std.Tactic.BVDecide.Reflect.BitVec.shiftLeft_congr
-  | HShiftRight.hShiftRight _ β _ _ innerExpr distanceExpr =>
-    let distance? ← getNatOrBvValue? β distanceExpr
-    if distance?.isSome then
-      shiftConstReflection
-        β
-        distanceExpr
-        innerExpr
-        .shiftRightConst
-        ``BVUnOp.shiftRightConst
-        ``Std.Tactic.BVDecide.Reflect.BitVec.shiftRightNat_congr
-    else
-      shiftReflection
-        β
-        distanceExpr
-        innerExpr
-        .shiftRight
-        ``BVExpr.shiftRight
-        ``Std.Tactic.BVDecide.Reflect.BitVec.shiftRight_congr
-  | BitVec.sshiftRight _ innerExpr distanceExpr =>
-    let some distance ← getNatValue? distanceExpr | return ← ofAtom x
-    shiftConstLikeReflection
-      distance
-      innerExpr
-      .arithShiftRightConst
-      ``BVUnOp.arithShiftRightConst
-      ``Std.Tactic.BVDecide.Reflect.BitVec.arithShiftRight_congr
-  | BitVec.zeroExtend _ newWidthExpr innerExpr =>
-    let some newWidth ← getNatValue? newWidthExpr | return ← ofAtom x
-    let some inner ← ofOrAtom innerExpr | return none
-    let bvExpr := .zeroExtend newWidth inner.bvExpr
-    let expr :=
-      mkApp3
-        (mkConst ``BVExpr.zeroExtend)
+        .arithShiftRightConst
+        ``BVUnOp.arithShiftRightConst
+        ``Std.Tactic.BVDecide.Reflect.BitVec.arithShiftRight_congr
+    | BitVec.zeroExtend _ newWidthExpr innerExpr =>
+      let some newWidth ← getNatValue? newWidthExpr | return none
+      let some inner ← goOrAtom innerExpr | return none
+      let bvExpr := .zeroExtend newWidth inner.bvExpr
+      let expr :=
+        mkApp3
+          (mkConst ``BVExpr.zeroExtend)
+          (toExpr inner.width)
+          newWidthExpr
+          inner.expr
+      let proof := do
+        let innerEval ← mkEvalExpr inner.width inner.expr
+        let innerProof ← inner.evalsAtAtoms
+        return mkApp5 (mkConst ``Std.Tactic.BVDecide.Reflect.BitVec.zeroExtend_congr)
+          newWidthExpr
+          (toExpr inner.width)
+          innerExpr
+          innerEval
+          innerProof
+      return some ⟨newWidth, bvExpr, proof, expr⟩
+    | BitVec.signExtend _ newWidthExpr innerExpr =>
+      let some newWidth ← getNatValue? newWidthExpr | return none
+      let some inner ← goOrAtom innerExpr | return none
+      let bvExpr := .signExtend newWidth inner.bvExpr
+      let expr :=
+        mkApp3
+          (mkConst ``BVExpr.signExtend)
+          (toExpr inner.width)
+          newWidthExpr
+          inner.expr
+      let proof := do
+        let innerEval ← mkEvalExpr inner.width inner.expr
+        let innerProof ← inner.evalsAtAtoms
+        return mkApp5 (mkConst ``Std.Tactic.BVDecide.Reflect.BitVec.signExtend_congr)
+          newWidthExpr
+          (toExpr inner.width)
+          innerExpr
+          innerEval
+          innerProof
+      return some ⟨newWidth, bvExpr, proof, expr⟩
+    | HAppend.hAppend _ _ _ _ lhsExpr rhsExpr =>
+      let some lhs ← goOrAtom lhsExpr | return none
+      let some rhs ← goOrAtom rhsExpr | return none
+      let bvExpr := .append lhs.bvExpr rhs.bvExpr
+      let expr := mkApp4 (mkConst ``BVExpr.append)
+        (toExpr lhs.width)
+        (toExpr rhs.width)
+        lhs.expr rhs.expr
+      let proof := do
+        let lhsEval ← mkEvalExpr lhs.width lhs.expr
+        let lhsProof ← lhs.evalsAtAtoms
+        let rhsProof ← rhs.evalsAtAtoms
+        let rhsEval ← mkEvalExpr rhs.width rhs.expr
+        return mkApp8 (mkConst ``Std.Tactic.BVDecide.Reflect.BitVec.append_congr)
+          (toExpr lhs.width) (toExpr rhs.width)
+          lhsExpr lhsEval
+          rhsExpr rhsEval
+          lhsProof rhsProof
+      return some ⟨lhs.width + rhs.width, bvExpr, proof, expr⟩
+    | BitVec.replicate _ nExpr innerExpr =>
+      let some inner ← goOrAtom innerExpr | return none
+      let some n ← getNatValue? nExpr | return none
+      let bvExpr := .replicate n inner.bvExpr
+      let expr := mkApp3 (mkConst ``BVExpr.replicate)
         (toExpr inner.width)
-        newWidthExpr
-        inner.expr
-    let proof := do
-      let innerEval ← mkEvalExpr inner.width inner.expr
-      let innerProof ← inner.evalsAtAtoms
-      return mkApp5 (mkConst ``Std.Tactic.BVDecide.Reflect.BitVec.zeroExtend_congr)
-        newWidthExpr
-        (toExpr inner.width)
-        innerExpr
-        innerEval
-        innerProof
-    return some ⟨newWidth, bvExpr, proof, expr⟩
-  | BitVec.signExtend _ newWidthExpr innerExpr =>
-    let some newWidth ← getNatValue? newWidthExpr | return ← ofAtom x
-    let some inner ← ofOrAtom innerExpr | return none
-    let bvExpr := .signExtend newWidth inner.bvExpr
-    let expr :=
-      mkApp3
-        (mkConst ``BVExpr.signExtend)
-        (toExpr inner.width)
-        newWidthExpr
-        inner.expr
-    let proof := do
-      let innerEval ← mkEvalExpr inner.width inner.expr
-      let innerProof ← inner.evalsAtAtoms
-      return mkApp5 (mkConst ``Std.Tactic.BVDecide.Reflect.BitVec.signExtend_congr)
-        newWidthExpr
-        (toExpr inner.width)
-        innerExpr
-        innerEval
-        innerProof
-    return some ⟨newWidth, bvExpr, proof, expr⟩
-  | HAppend.hAppend _ _ _ _ lhsExpr rhsExpr =>
-    let some lhs ← ofOrAtom lhsExpr | return none
-    let some rhs ← ofOrAtom rhsExpr | return none
-    let bvExpr := .append lhs.bvExpr rhs.bvExpr
-    let expr := mkApp4 (mkConst ``BVExpr.append)
-      (toExpr lhs.width)
-      (toExpr rhs.width)
-      lhs.expr rhs.expr
-    let proof := do
-      let lhsEval ← mkEvalExpr lhs.width lhs.expr
-      let lhsProof ← lhs.evalsAtAtoms
-      let rhsProof ← rhs.evalsAtAtoms
-      let rhsEval ← mkEvalExpr rhs.width rhs.expr
-      return mkApp8 (mkConst ``Std.Tactic.BVDecide.Reflect.BitVec.append_congr)
-        (toExpr lhs.width) (toExpr rhs.width)
-        lhsExpr lhsEval
-        rhsExpr rhsEval
-        lhsProof rhsProof
-    return some ⟨lhs.width + rhs.width, bvExpr, proof, expr⟩
-  | BitVec.replicate _ nExpr innerExpr =>
-    let some inner ← ofOrAtom innerExpr | return none
-    let some n ← getNatValue? nExpr | return ← ofAtom x
-    let bvExpr := .replicate n inner.bvExpr
-    let expr := mkApp3 (mkConst ``BVExpr.replicate)
-      (toExpr inner.width)
-      (toExpr n)
-      inner.expr
-    let proof := do
-      let innerEval ← mkEvalExpr inner.width inner.expr
-      let innerProof ← inner.evalsAtAtoms
-      return mkApp5 (mkConst ``Std.Tactic.BVDecide.Reflect.BitVec.replicate_congr)
         (toExpr n)
+        inner.expr
+      let proof := do
+        let innerEval ← mkEvalExpr inner.width inner.expr
+        let innerProof ← inner.evalsAtAtoms
+        return mkApp5 (mkConst ``Std.Tactic.BVDecide.Reflect.BitVec.replicate_congr)
+          (toExpr n)
+          (toExpr inner.width)
+          innerExpr
+          innerEval
+          innerProof
+      return some ⟨inner.width * n, bvExpr, proof, expr⟩
+    | BitVec.extractLsb' _ startExpr lenExpr innerExpr =>
+      let some start ← getNatValue? startExpr | return none
+      let some len ← getNatValue? lenExpr | return none
+      let some inner ← goOrAtom innerExpr | return none
+      let bvExpr := .extract start len inner.bvExpr
+      let expr := mkApp4 (mkConst ``BVExpr.extract)
         (toExpr inner.width)
-        innerExpr
-        innerEval
-        innerProof
-    return some ⟨inner.width * n, bvExpr, proof, expr⟩
-  | BitVec.extractLsb' _ startExpr lenExpr innerExpr =>
-    let some start ← getNatValue? startExpr | return ← ofAtom x
-    let some len ← getNatValue? lenExpr | return ← ofAtom x
-    let some inner ← ofOrAtom innerExpr | return none
-    let bvExpr := .extract start len inner.bvExpr
-    let expr := mkApp4 (mkConst ``BVExpr.extract)
-      (toExpr inner.width)
-      startExpr
-      lenExpr
-      inner.expr
-    let proof := do
-      let innerEval ← mkEvalExpr inner.width inner.expr
-      let innerProof ← inner.evalsAtAtoms
-      return mkApp6 (mkConst ``Std.Tactic.BVDecide.Reflect.BitVec.extract_congr)
         startExpr
         lenExpr
-        (toExpr inner.width)
+        inner.expr
+      let proof := do
+        let innerEval ← mkEvalExpr inner.width inner.expr
+        let innerProof ← inner.evalsAtAtoms
+        return mkApp6 (mkConst ``Std.Tactic.BVDecide.Reflect.BitVec.extract_congr)
+          startExpr
+          lenExpr
+          (toExpr inner.width)
+          innerExpr
+          innerEval
+          innerProof
+      return some ⟨len, bvExpr, proof, expr⟩
+    | BitVec.rotateLeft _ innerExpr distanceExpr =>
+      rotateReflection
+        distanceExpr
         innerExpr
-        innerEval
-        innerProof
-    return some ⟨len, bvExpr, proof, expr⟩
-  | BitVec.rotateLeft _ innerExpr distanceExpr =>
-    rotateReflection
-      distanceExpr
-      innerExpr
-      .rotateLeft
-      ``BVUnOp.rotateLeft
-      ``Std.Tactic.BVDecide.Reflect.BitVec.rotateLeft_congr
-  | BitVec.rotateRight _ innerExpr distanceExpr =>
-    rotateReflection
-      distanceExpr
-      innerExpr
-      .rotateRight
-      ``BVUnOp.rotateRight
-      ``Std.Tactic.BVDecide.Reflect.BitVec.rotateRight_congr
-  | _ => ofAtom x
-where
-  ofAtom (x : Expr) : M (Option ReifiedBVExpr) := do
-    let t ← instantiateMVars (← whnfR (← inferType x))
-    let_expr BitVec widthExpr := t | return none
-    let some width ← getNatValue? widthExpr | return none
-    let atom ← mkAtom x width
-    return some atom
+        .rotateLeft
+        ``BVUnOp.rotateLeft
+        ``Std.Tactic.BVDecide.Reflect.BitVec.rotateLeft_congr
+    | BitVec.rotateRight _ innerExpr distanceExpr =>
+      rotateReflection
+        distanceExpr
+        innerExpr
+        .rotateRight
+        ``BVUnOp.rotateRight
+        ``Std.Tactic.BVDecide.Reflect.BitVec.rotateRight_congr
+    | _ => return none
 
-  ofOrAtom (x : Expr) : M (Option ReifiedBVExpr) := do
-    let res ← of x
+  /--
+  Reify `x` or abstract it as an atom.
+  Unless this function is called on something that is not a fixed-width `BitVec` it is always going
+  to return `some`.
+  -/
+  goOrAtom (x : Expr) : M (Option ReifiedBVExpr) := do
+    let res ← go x
     match res with
     | some exp => return some exp
-    | none => ofAtom x
+    | none => bitVecAtom x
 
   shiftConstLikeReflection (distance : Nat) (innerExpr : Expr) (shiftOp : Nat → BVUnOp)
       (shiftOpName : Name) (congrThm : Name) :
       M (Option ReifiedBVExpr) := do
-    let some inner ← ofOrAtom innerExpr | return none
+    let some inner ← goOrAtom innerExpr | return none
     let bvExpr : BVExpr inner.width := .un (shiftOp distance) inner.bvExpr
     let expr :=
       mkApp3
@@ -278,24 +294,22 @@ where
   rotateReflection (distanceExpr : Expr) (innerExpr : Expr) (rotateOp : Nat → BVUnOp)
       (rotateOpName : Name) (congrThm : Name) :
       M (Option ReifiedBVExpr) := do
-    -- Either the shift values are constant or we abstract the entire term as atoms
-    let some distance ← getNatValue? distanceExpr | return ← ofAtom x
+    let some distance ← getNatValue? distanceExpr | return none
     shiftConstLikeReflection distance innerExpr rotateOp rotateOpName congrThm
 
   shiftConstReflection (β : Expr) (distanceExpr : Expr) (innerExpr : Expr) (shiftOp : Nat → BVUnOp)
       (shiftOpName : Name) (congrThm : Name) :
       M (Option ReifiedBVExpr) := do
-    -- Either the shift values are constant or we abstract the entire term as atoms
-    let some distance ← getNatOrBvValue? β distanceExpr | return ← ofAtom x
+    let some distance ← getNatOrBvValue? β distanceExpr | return none
     shiftConstLikeReflection distance innerExpr shiftOp shiftOpName congrThm
 
   shiftReflection (β : Expr) (distanceExpr : Expr) (innerExpr : Expr)
       (shiftOp : {m n : Nat} → BVExpr m → BVExpr n → BVExpr m) (shiftOpName : Name)
       (congrThm : Name) :
       M (Option ReifiedBVExpr) := do
-    let_expr BitVec _ ← β | return ← ofAtom x
-    let some inner ← of innerExpr | return none
-    let some distance ← of distanceExpr | return none
+    let_expr BitVec _ ← β | return none
+    let some inner ← goOrAtom innerExpr | return none
+    let some distance ← goOrAtom distanceExpr | return none
     let bvExpr : BVExpr inner.width := shiftOp inner.bvExpr distance.bvExpr
     let expr :=
       mkApp4
@@ -314,8 +328,8 @@ where
 
   binaryReflection (lhsExpr rhsExpr : Expr) (op : BVBinOp) (congrThm : Name) :
       M (Option ReifiedBVExpr) := do
-    let some lhs ← ofOrAtom lhsExpr | return none
-    let some rhs ← ofOrAtom rhsExpr | return none
+    let some lhs ← goOrAtom lhsExpr | return none
+    let some rhs ← goOrAtom rhsExpr | return none
     if h : rhs.width = lhs.width then
       let bvExpr : BVExpr lhs.width := .bin lhs.bvExpr op (h ▸ rhs.bvExpr)
       let expr := mkApp4 (mkConst ``BVExpr.bin) (toExpr lhs.width) lhs.expr (toExpr op) rhs.expr
@@ -335,7 +349,7 @@ where
 
   unaryReflection (innerExpr : Expr) (op : BVUnOp) (congrThm : Name) :
       M (Option ReifiedBVExpr) := do
-    let some inner ← ofOrAtom innerExpr | return none
+    let some inner ← goOrAtom innerExpr | return none
     let bvExpr := .un op inner.bvExpr
     let expr := mkApp3 (mkConst ``BVExpr.un) (toExpr inner.width) (toExpr op) inner.expr
     let proof := unaryCongrProof inner innerExpr (mkConst congrThm)
@@ -347,7 +361,7 @@ where
     return mkApp4 congrProof (toExpr inner.width) innerExpr innerEval innerProof
 
   goBvLit (x : Expr) : M (Option ReifiedBVExpr) := do
-    let some ⟨width, bvVal⟩ ← getBitVecValue? x | return ← ofAtom x
+    let some ⟨width, bvVal⟩ ← getBitVecValue? x | return ← bitVecAtom x
     let bvExpr : BVExpr width := .const bvVal
     let expr := mkApp2 (mkConst ``BVExpr.const) (toExpr width) (toExpr bvVal)
     let proof := do

src/Lean/Elab/Tactic/BVDecide/Frontend/BVDecide/ReifiedBVLogical.lean

@@ -44,40 +44,75 @@ def mkTrans (x y z : Expr) (hxy hyz : Expr) : Expr :=
 def mkEvalExpr (expr : Expr) : M Expr := do
   return mkApp2 (mkConst ``BVLogicalExpr.eval) (← M.atomsAssignment) expr
 
+/--
+Construct a `ReifiedBVLogical` from `ReifiedBVPred` by wrapping it as an atom.
+-/
+def ofPred  (bvPred : ReifiedBVPred) : M (Option ReifiedBVLogical) := do
+  let boolExpr := .literal bvPred.bvPred
+  let expr := mkApp2 (mkConst ``BoolExpr.literal) (mkConst ``BVPred) bvPred.expr
+  let proof := bvPred.evalsAtAtoms
+  return some ⟨boolExpr, proof, expr⟩
+
+/--
+Construct an uninterrpeted `Bool` atom from `t`.
+-/
+def boolAtom (t : Expr) : M (Option ReifiedBVLogical) := do
+  let some pred ← ReifiedBVPred.boolAtom t | return none
+  ofPred pred
+
+/--
+Reify an `Expr` that is a boolean expression containing predicates about `BitVec` as atoms.
+Unless this function is called on something that is not a `Bool` it is always going to return `some`.
+-/
 partial def of (t : Expr) : M (Option ReifiedBVLogical) := do
-  match_expr t with
-  | Bool.true =>
-    let boolExpr := .const true
-    let expr := mkApp2 (mkConst ``BoolExpr.const) (mkConst ``BVPred) (toExpr Bool.true)
-    let proof := return mkRefl (mkConst ``Bool.true)
-    return some ⟨boolExpr, proof, expr⟩
-  | Bool.false =>
-    let boolExpr := .const false
-    let expr := mkApp2 (mkConst ``BoolExpr.const) (mkConst ``BVPred) (toExpr Bool.false)
-    let proof := return mkRefl (mkConst ``Bool.false)
-    return some ⟨boolExpr, proof, expr⟩
-  | Bool.not subExpr =>
-    let some sub ← of subExpr | return none
-    let boolExpr := .not sub.bvExpr
-    let expr := mkApp2 (mkConst ``BoolExpr.not) (mkConst ``BVPred) sub.expr
-    let proof := do
-      let subEvalExpr ← mkEvalExpr sub.expr
-      let subProof ← sub.evalsAtAtoms
-      return mkApp3 (mkConst ``Std.Tactic.BVDecide.Reflect.Bool.not_congr) subExpr subEvalExpr subProof
-    return some ⟨boolExpr, proof, expr⟩
-  | Bool.and lhsExpr rhsExpr => gateReflection lhsExpr rhsExpr .and ``Std.Tactic.BVDecide.Reflect.Bool.and_congr
-  | Bool.xor lhsExpr rhsExpr => gateReflection lhsExpr rhsExpr .xor ``Std.Tactic.BVDecide.Reflect.Bool.xor_congr
-  | BEq.beq α _ lhsExpr rhsExpr =>
-    match_expr α with
-    | Bool => gateReflection lhsExpr rhsExpr .beq ``Std.Tactic.BVDecide.Reflect.Bool.beq_congr
-    | BitVec _ => goPred t
-    | _ => return none
-  | _ => goPred t
+  goOrAtom t
 where
+  /--
+  Reify `t`, returns `none` if the reification procedure failed.
+  -/
+  go (t : Expr) : M (Option ReifiedBVLogical) := do
+    match_expr t with
+    | Bool.true =>
+      let boolExpr := .const true
+      let expr := mkApp2 (mkConst ``BoolExpr.const) (mkConst ``BVPred) (toExpr Bool.true)
+      let proof := pure <| mkRefl (mkConst ``Bool.true)
+      return some ⟨boolExpr, proof, expr⟩
+    | Bool.false =>
+      let boolExpr := .const false
+      let expr := mkApp2 (mkConst ``BoolExpr.const) (mkConst ``BVPred) (toExpr Bool.false)
+      let proof := pure <| mkRefl (mkConst ``Bool.false)
+      return some ⟨boolExpr, proof, expr⟩
+    | Bool.not subExpr =>
+      let some sub ← goOrAtom subExpr | return none
+      let boolExpr := .not sub.bvExpr
+      let expr := mkApp2 (mkConst ``BoolExpr.not) (mkConst ``BVPred) sub.expr
+      let proof := do
+        let subEvalExpr ← mkEvalExpr sub.expr
+        let subProof ← sub.evalsAtAtoms
+        return mkApp3 (mkConst ``Std.Tactic.BVDecide.Reflect.Bool.not_congr) subExpr subEvalExpr subProof
+      return some ⟨boolExpr, proof, expr⟩
+    | Bool.and lhsExpr rhsExpr => gateReflection lhsExpr rhsExpr .and ``Std.Tactic.BVDecide.Reflect.Bool.and_congr
+    | Bool.xor lhsExpr rhsExpr => gateReflection lhsExpr rhsExpr .xor ``Std.Tactic.BVDecide.Reflect.Bool.xor_congr
+    | BEq.beq α _ lhsExpr rhsExpr =>
+      match_expr α with
+      | Bool => gateReflection lhsExpr rhsExpr .beq ``Std.Tactic.BVDecide.Reflect.Bool.beq_congr
+      | BitVec _ => goPred t
+      | _ => return none
+    | _ => goPred t
+
+  /--
+  Reify `t` or abstract it as an atom.
+  Unless this function is called on something that is not a `Bool` it is always going to return `some`.
+  -/
+  goOrAtom (t : Expr) : M (Option ReifiedBVLogical) := do
+    match ← go t with
+    | some boolExpr => return some boolExpr
+    | none => boolAtom t
+
   gateReflection (lhsExpr rhsExpr : Expr) (gate : Gate) (congrThm : Name) :
       M (Option ReifiedBVLogical) := do
-    let some lhs ← of lhsExpr | return none
-    let some rhs ← of rhsExpr | return none
+    let some lhs ← goOrAtom lhsExpr | return none
+    let some rhs ← goOrAtom rhsExpr | return none
     let boolExpr := .gate  gate lhs.bvExpr rhs.bvExpr
     let expr :=
       mkApp4
@@ -99,11 +134,8 @@ where
     return some ⟨boolExpr, proof, expr⟩
 
   goPred (t : Expr) : M (Option ReifiedBVLogical) := do
-    let some bvPred ← ReifiedBVPred.of t | return none
-    let boolExpr := .literal bvPred.bvPred
-    let expr := mkApp2 (mkConst ``BoolExpr.literal) (mkConst ``BVPred) bvPred.expr
-    let proof := bvPred.evalsAtAtoms
-    return some ⟨boolExpr, proof, expr⟩
+    let some pred ← ReifiedBVPred.of t | return none
+    ofPred pred
 
 end ReifiedBVLogical
 

src/Lean/Elab/Tactic/BVDecide/Frontend/BVDecide/ReifiedBVPred.lean

@@ -37,54 +37,68 @@ structure ReifiedBVPred where
 namespace ReifiedBVPred
 
 /--
-Reify an `Expr` that is a proof of a predicate about `BitVec`.
+Construct an uninterpreted `Bool` atom from `t`.
 -/
-def of (t : Expr) : M (Option ReifiedBVPred) := do
-  match_expr t with
-  | BEq.beq α _ lhsExpr rhsExpr =>
-    let_expr BitVec _ := α | return none
-    binaryReflection lhsExpr rhsExpr .eq ``Std.Tactic.BVDecide.Reflect.BitVec.beq_congr
-  | BitVec.ult _ lhsExpr rhsExpr =>
-    binaryReflection lhsExpr rhsExpr .ult ``Std.Tactic.BVDecide.Reflect.BitVec.ult_congr
-  | BitVec.getLsbD _ subExpr idxExpr =>
-    let some sub ← ReifiedBVExpr.of subExpr | return none
-    let some idx ← getNatValue? idxExpr | return none
-    let bvExpr : BVPred := .getLsbD sub.bvExpr idx
-    let expr := mkApp3 (mkConst ``BVPred.getLsbD) (toExpr sub.width) sub.expr idxExpr
-    let proof := do
-      let subEval ← ReifiedBVExpr.mkEvalExpr sub.width sub.expr
-      let subProof ← sub.evalsAtAtoms
-      return mkApp5
-        (mkConst ``Std.Tactic.BVDecide.Reflect.BitVec.getLsbD_congr)
-        idxExpr
-        (toExpr sub.width)
-        subExpr
-        subEval
-        subProof
-    return some ⟨bvExpr, proof, expr⟩
-  | _ =>
-    /-
-    Idea: we have t : Bool here, let's construct:
-      BitVec.ofBool t : BitVec 1
-    as an atom. Then construct the BVPred corresponding to
-      BitVec.getLsb (BitVec.ofBool t) 0 : Bool
-    We can prove that this is equivalent to `t`. This allows us to have boolean variables in BVPred.
-    -/
-    let ty ← inferType t
-    let_expr Bool := ty | return none
-    let atom ← ReifiedBVExpr.mkAtom (mkApp (mkConst ``BitVec.ofBool) t) 1
-    let bvExpr : BVPred := .getLsbD atom.bvExpr 0
-    let expr := mkApp3 (mkConst ``BVPred.getLsbD) (toExpr 1) atom.expr (toExpr 0)
-    let proof := do
-      let atomEval ← ReifiedBVExpr.mkEvalExpr atom.width atom.expr
-      let atomProof ← atom.evalsAtAtoms
-      return mkApp3
-        (mkConst ``Std.Tactic.BVDecide.Reflect.BitVec.ofBool_congr)
-        t
-        atomEval
-        atomProof
-    return some ⟨bvExpr, proof, expr⟩
+def boolAtom (t : Expr) : M (Option ReifiedBVPred) := do
+  /-
+  Idea: we have t : Bool here, let's construct:
+    BitVec.ofBool t : BitVec 1
+  as an atom. Then construct the BVPred corresponding to
+    BitVec.getLsb (BitVec.ofBool t) 0 : Bool
+  We can prove that this is equivalent to `t`. This allows us to have boolean variables in BVPred.
+  -/
+  let ty ← inferType t
+  let_expr Bool := ty | return none
+  let atom ← ReifiedBVExpr.mkAtom (mkApp (mkConst ``BitVec.ofBool) t) 1
+  let bvExpr : BVPred := .getLsbD atom.bvExpr 0
+  let expr := mkApp3 (mkConst ``BVPred.getLsbD) (toExpr 1) atom.expr (toExpr 0)
+  let proof := do
+    let atomEval ← ReifiedBVExpr.mkEvalExpr atom.width atom.expr
+    let atomProof ← atom.evalsAtAtoms
+    return mkApp3
+      (mkConst ``Std.Tactic.BVDecide.Reflect.BitVec.ofBool_congr)
+      t
+      atomEval
+      atomProof
+  return some ⟨bvExpr, proof, expr⟩
+
+/--
+Reify an `Expr` that is a predicate about `BitVec`.
+Unless this function is called on something that is not a `Bool` it is always going to return `some`.
+-/
+partial def of (t : Expr) : M (Option ReifiedBVPred) := do
+  match ← go t with
+  | some pred => return some pred
+  | none => boolAtom t
 where
+  /--
+  Reify `t`, returns `none` if the reification procedure failed.
+  -/
+  go (t : Expr) : M (Option ReifiedBVPred) := do
+    match_expr t with
+    | BEq.beq α _ lhsExpr rhsExpr =>
+      let_expr BitVec _ := α | return none
+      binaryReflection lhsExpr rhsExpr .eq ``Std.Tactic.BVDecide.Reflect.BitVec.beq_congr
+    | BitVec.ult _ lhsExpr rhsExpr =>
+      binaryReflection lhsExpr rhsExpr .ult ``Std.Tactic.BVDecide.Reflect.BitVec.ult_congr
+    | BitVec.getLsbD _ subExpr idxExpr =>
+      let some sub ← ReifiedBVExpr.of subExpr | return none
+      let some idx ← getNatValue? idxExpr | return none
+      let bvExpr : BVPred := .getLsbD sub.bvExpr idx
+      let expr := mkApp3 (mkConst ``BVPred.getLsbD) (toExpr sub.width) sub.expr idxExpr
+      let proof := do
+        let subEval ← ReifiedBVExpr.mkEvalExpr sub.width sub.expr
+        let subProof ← sub.evalsAtAtoms
+        return mkApp5
+          (mkConst ``Std.Tactic.BVDecide.Reflect.BitVec.getLsbD_congr)
+          idxExpr
+          (toExpr sub.width)
+          subExpr
+          subEval
+          subProof
+      return some ⟨bvExpr, proof, expr⟩
+    | _ => return none
+
   binaryReflection (lhsExpr rhsExpr : Expr) (pred : BVBinPred) (congrThm : Name) :
       M (Option ReifiedBVPred) := do
     let some lhs ← ReifiedBVExpr.of lhsExpr | return none

src/Lean/Elab/Tactic/Basic.lean

@@ -52,6 +52,7 @@ instance : Monad TacticM :=
 instance : Inhabited (TacticM α) where
   default := fun _ _ => default
 
+/-- Returns the list of goals. Goals may or may not already be assigned. -/
 def getGoals : TacticM (List MVarId) :=
   return (← get).goals
 
@@ -300,13 +301,22 @@ instance : MonadBacktrack SavedState TacticM where
   saveState := Tactic.saveState
   restoreState b := b.restore
 
+/--
+Non-backtracking `try`/`catch`.
+-/
 @[inline] protected def tryCatch {α} (x : TacticM α) (h : Exception → TacticM α) : TacticM α := do
+  try x catch ex => h ex
+
+/--
+Backtracking `try`/`catch`. This is used for the `MonadExcept` instance for `TacticM`.
+-/
+@[inline] protected def tryCatchRestore {α} (x : TacticM α) (h : Exception → TacticM α) : TacticM α := do
   let b ← saveState
   try x catch ex => b.restore; h ex
 
 instance : MonadExcept Exception TacticM where
   throw    := throw
-  tryCatch := Tactic.tryCatch
+  tryCatch := Tactic.tryCatchRestore
 
 /-- Execute `x` with error recovery disabled -/
 def withoutRecover (x : TacticM α) : TacticM α :=
@@ -342,12 +352,26 @@ def adaptExpander (exp : Syntax → TacticM Syntax) : Tactic := fun stx => do
   let stx' ← exp stx
   withMacroExpansion stx stx' $ evalTactic stx'
 
-/-- Add the given goals at the end of the current goals collection. -/
+/-- Add the given goal to the front of the current list of goals. -/
+def pushGoal (mvarId : MVarId) : TacticM Unit :=
+  modify fun s => { s with goals := mvarId :: s.goals }
+
+/-- Add the given goals to the front of the current list of goals. -/
+def pushGoals (mvarIds : List MVarId) : TacticM Unit :=
+  modify fun s => { s with goals := mvarIds ++ s.goals }
+
+/-- Add the given goals at the end of the current list of goals. -/
 def appendGoals (mvarIds : List MVarId) : TacticM Unit :=
   modify fun s => { s with goals := s.goals ++ mvarIds }
 
-/-- Discard the first goal and replace it by the given list of goals,
-keeping the other goals. -/
+/--
+Discard the first goal and replace it by the given list of goals,
+keeping the other goals. This is used in conjunction with `getMainGoal`.
+
+Contract: between `getMainGoal` and `replaceMainGoal`, nothing manipulates the goal list.
+
+See also `Lean.Elab.Tactic.popMainGoal` and `Lean.Elab.Tactic.pushGoal`/`Lean.Elab.Tactic.pushGoal` for another interface.
+-/
 def replaceMainGoal (mvarIds : List MVarId) : TacticM Unit := do
   let (_ :: mvarIds') ← getGoals | throwNoGoalsToBeSolved
   modify fun _ => { goals := mvarIds ++ mvarIds' }
@@ -365,6 +389,16 @@ where
         setGoals (mvarId :: mvarIds)
         return mvarId
 
+/--
+Return the first goal, and remove it from the goal list.
+
+See also: `Lean.Elab.Tactic.pushGoal` and `Lean.Elab.Tactic.pushGoals`.
+-/
+def popMainGoal : TacticM MVarId := do
+  let mvarId ← getMainGoal
+  replaceMainGoal []
+  return mvarId
+
 /-- Return the main goal metavariable declaration. -/
 def getMainDecl : TacticM MetavarDecl := do
   (← getMainGoal).getDecl

src/Lean/Elab/Tactic/BuiltinTactic.lean

@@ -520,7 +520,7 @@ where
 
 @[builtin_tactic «case», builtin_incremental]
 def evalCase : Tactic
-  | stx@`(tactic| case $[$tag $hs*]|* =>%$arr $tac:tacticSeq1Indented) =>
+  | stx@`(tactic| case%$caseTk $[$tag $hs*]|* =>%$arr $tac:tacticSeq1Indented) =>
     -- disable incrementality if body is run multiple times
     Term.withoutTacticIncrementality (tag.size > 1) do
       for tag in tag, hs in hs do
@@ -528,20 +528,20 @@ def evalCase : Tactic
         let g ← renameInaccessibles g hs
         setGoals [g]
         g.setTag Name.anonymous
-        withCaseRef arr tac <| closeUsingOrAdmit <| withTacticInfoContext stx <|
+        withCaseRef arr tac <| closeUsingOrAdmit <| withTacticInfoContext (mkNullNode #[caseTk, arr]) <|
           Term.withNarrowedArgTacticReuse (argIdx := 3) (evalTactic ·) stx
         setGoals gs
   | _ => throwUnsupportedSyntax
 
 @[builtin_tactic «case'»] def evalCase' : Tactic
-  | `(tactic| case' $[$tag $hs*]|* =>%$arr $tac:tacticSeq) => do
+  | `(tactic| case'%$caseTk $[$tag $hs*]|* =>%$arr $tac:tacticSeq) => do
     let mut acc := #[]
     for tag in tag, hs in hs do
       let (g, gs) ← getCaseGoals tag
       let g ← renameInaccessibles g hs
       let mvarTag ← g.getTag
       setGoals [g]
-      withCaseRef arr tac (evalTactic tac)
+      withCaseRef arr tac <| withTacticInfoContext (mkNullNode #[caseTk, arr]) <| evalTactic tac
       let gs' ← getUnsolvedGoals
       if let [g'] := gs' then
         g'.setTag mvarTag

src/Lean/Elab/Tactic/Calc.lean

@@ -14,9 +14,9 @@ open Meta
 @[builtin_tactic Lean.calcTactic]
 def evalCalc : Tactic := fun stx => withMainContext do
   let steps : TSyntax ``calcSteps := ⟨stx[1]⟩
-  let (val, mvarIds) ← withCollectingNewGoalsFrom (tagSuffix := `calc) do
-    let target := (← getMainTarget).consumeMData
-    let tag ← getMainTag
+  let target := (← getMainTarget).consumeMData
+  let tag ← getMainTag
+  let (val, mvarIds) ← withCollectingNewGoalsFrom (parentTag := tag) (tagSuffix := `calc) do
     runTermElab do
     let mut val ← Term.elabCalcSteps steps
     let mut valType ← instantiateMVars (← inferType val)

src/Lean/Elab/Tactic/Conv/Pattern.lean

@@ -119,7 +119,7 @@ private def pre (pattern : AbstractMVarsResult) (state : IO.Ref PatternMatchStat
         let ids ← ids.mapIdxM fun i id =>
           match id.getNat with
           | 0 => throwErrorAt id "positive integer expected"
-          | n+1 => pure (n, i.1)
+          | n+1 => pure (n, i)
         let ids := ids.qsort (·.1 < ·.1)
         unless @Array.allDiff _ ⟨(·.1 == ·.1)⟩ ids do
           throwError "occurrence list is not distinct"

src/Lean/Elab/Tactic/ElabTerm.lean

@@ -56,11 +56,6 @@ def elabTermEnsuringType (stx : Syntax) (expectedType? : Option Expr) (mayPostpo
       Term.throwTypeMismatchError none expectedType eType e
     return e
 
-/-- Try to close main goal using `x target`, where `target` is the type of the main goal.  -/
-def closeMainGoalUsing (tacName : Name) (x : Expr → TacticM Expr) (checkUnassigned := true) : TacticM Unit :=
-  withMainContext do
-    closeMainGoal (tacName := tacName) (checkUnassigned := checkUnassigned) (← x (← getMainTarget))
-
 def logUnassignedAndAbort (mvarIds : Array MVarId) : TacticM Unit := do
    if (← Term.logUnassignedUsingErrorInfos mvarIds) then
      throwAbortTactic
@@ -69,14 +64,37 @@ def filterOldMVars (mvarIds : Array MVarId) (mvarCounterSaved : Nat) : MetaM (Ar
   let mctx ← getMCtx
   return mvarIds.filter fun mvarId => (mctx.getDecl mvarId |>.index) >= mvarCounterSaved
 
+/--
+Try to close main goal using `x target tag`, where `target` is the type of the main goal and `tag` is its user name.
+
+If `checkNewUnassigned` is true, then throws an error if the resulting value has metavariables that were created during the execution of `x`.
+If it is false, then it is the responsibility of `x` to add such metavariables to the goal list.
+
+During the execution of `x`:
+* The local context is that of the main goal.
+* The goal list has the main goal removed.
+* It is allowable to modify the goal list, for example with `Lean.Elab.Tactic.pushGoals`.
+
+On failure, the main goal remains at the front of the goal list.
+-/
+def closeMainGoalUsing (tacName : Name) (x : Expr → Name → TacticM Expr) (checkNewUnassigned := true) : TacticM Unit := do
+  let mvarCounterSaved := (← getMCtx).mvarCounter
+  let mvarId ← popMainGoal
+  Tactic.tryCatch
+    (mvarId.withContext do
+      let val ← x (← mvarId.getType) (← mvarId.getTag)
+      if checkNewUnassigned then
+        let mvars ← filterOldMVars (← getMVars val) mvarCounterSaved
+        logUnassignedAndAbort mvars
+      unless (← mvarId.checkedAssign val) do
+        throwTacticEx tacName mvarId m!"attempting to close the goal using{indentExpr val}\nthis is often due occurs-check failure")
+    (fun ex => do
+      pushGoal mvarId
+      throw ex)
+
 @[builtin_tactic «exact»] def evalExact : Tactic := fun stx => do
   match stx with
-  | `(tactic| exact $e) =>
-    closeMainGoalUsing `exact (checkUnassigned := false) fun type => do
-      let mvarCounterSaved := (← getMCtx).mvarCounter
-      let r ← elabTermEnsuringType e type
-      logUnassignedAndAbort (← filterOldMVars (← getMVars r) mvarCounterSaved)
-      return r
+  | `(tactic| exact $e) => closeMainGoalUsing `exact fun type _ => elabTermEnsuringType e type
   | _ => throwUnsupportedSyntax
 
 def sortMVarIdArrayByIndex [MonadMCtx m] [Monad m] (mvarIds : Array MVarId) : m (Array MVarId) := do
@@ -93,9 +111,12 @@ def sortMVarIdsByIndex [MonadMCtx m] [Monad m] (mvarIds : List MVarId) : m (List
   return (← sortMVarIdArrayByIndex mvarIds.toArray).toList
 
 /--
-  Execute `k`, and collect new "holes" in the resulting expression.
+Execute `k`, and collect new "holes" in the resulting expression.
+
+* `parentTag` and `tagSuffix` are used to tag untagged goals with `Lean.Elab.Tactic.tagUntaggedGoals`.
+* If `allowNaturalHoles` is true, then `_`'s are allowed and create new goals.
 -/
-def withCollectingNewGoalsFrom (k : TacticM Expr) (tagSuffix : Name) (allowNaturalHoles := false) : TacticM (Expr × List MVarId) :=
+def withCollectingNewGoalsFrom (k : TacticM Expr) (parentTag : Name) (tagSuffix : Name) (allowNaturalHoles := false) : TacticM (Expr × List MVarId) :=
   /-
   When `allowNaturalHoles = true`, unassigned holes should become new metavariables, including `_`s.
   Thus, we set `holesAsSyntheticOpaque` to true if it is not already set to `true`.
@@ -144,7 +165,7 @@ where
     appear in the `.lean` file. We should tell users to prefer tagged goals.
     -/
     let newMVarIds ← sortMVarIdsByIndex newMVarIds.toList
-    tagUntaggedGoals (← getMainTag) tagSuffix newMVarIds
+    tagUntaggedGoals parentTag tagSuffix newMVarIds
     return (val, newMVarIds)
 
 /-- Elaborates `stx` and collects the `MVarId`s of any holes that were created during elaboration.
@@ -153,8 +174,8 @@ With `allowNaturalHoles := false` (the default), any new natural holes (`_`) whi
 be synthesized during elaboration cause `elabTermWithHoles` to fail. (Natural goals appearing in
 `stx` which were created prior to elaboration are permitted.)
 
-Unnamed `MVarId`s are renamed to share the main goal's tag. If multiple unnamed goals are
-encountered, `tagSuffix` is appended to the main goal's tag along with a numerical index.
+Unnamed `MVarId`s are renamed to share the tag `parentTag?` (or the main goal's tag if `parentTag?` is `none`).
+If multiple unnamed goals are encountered, `tagSuffix` is appended to this tag along with a numerical index.
 
 Note:
 * Previously-created `MVarId`s which appear in `stx` are not returned.
@@ -163,8 +184,8 @@ metavariables.
 * When `allowNaturalHoles := true`, `stx` is elaborated under `withAssignableSyntheticOpaque`,
 meaning that `.syntheticOpaque` metavariables might be assigned during elaboration. This is a
 consequence of the implementation. -/
-def elabTermWithHoles (stx : Syntax) (expectedType? : Option Expr) (tagSuffix : Name) (allowNaturalHoles := false) : TacticM (Expr × List MVarId) := do
-  withCollectingNewGoalsFrom (elabTermEnsuringType stx expectedType?) tagSuffix allowNaturalHoles
+def elabTermWithHoles (stx : Syntax) (expectedType? : Option Expr) (tagSuffix : Name) (allowNaturalHoles := false) (parentTag? : Option Name := none) : TacticM (Expr × List MVarId) := do
+  withCollectingNewGoalsFrom (elabTermEnsuringType stx expectedType?) (← parentTag?.getDM getMainTag) tagSuffix allowNaturalHoles
 
 /-- If `allowNaturalHoles == true`, then we allow the resultant expression to contain unassigned "natural" metavariables.
    Recall that "natutal" metavariables are created for explicit holes `_` and implicit arguments. They are meant to be
@@ -395,7 +416,7 @@ private partial def blameDecideReductionFailure (inst : Expr) : MetaM Expr := wi
   return inst
 
 def evalDecideCore (tacticName : Name) (kernelOnly : Bool) : TacticM Unit :=
-  closeMainGoalUsing tacticName fun expectedType => do
+  closeMainGoalUsing tacticName fun expectedType _ => do
     let expectedType ← preprocessPropToDecide expectedType
     let pf ← mkDecideProof expectedType
     -- Get instance from `pf`
@@ -501,7 +522,7 @@ private def mkNativeAuxDecl (baseName : Name) (type value : Expr) : TermElabM Na
   pure auxName
 
 @[builtin_tactic Lean.Parser.Tactic.nativeDecide] def evalNativeDecide : Tactic := fun _ =>
-  closeMainGoalUsing `nativeDecide fun expectedType => do
+  closeMainGoalUsing `nativeDecide fun expectedType _ => do
     let expectedType ← preprocessPropToDecide expectedType
     let d ← mkDecide expectedType
     let auxDeclName ← mkNativeAuxDecl `_nativeDecide (Lean.mkConst `Bool) d

src/Lean/Elab/Tactic/Ext.lean

@@ -123,9 +123,7 @@ def realizeExtTheorem (structName : Name) (flat : Bool) : Elab.Command.CommandEl
           levelParams := info.levelParams
         }
         modifyEnv fun env => addProtected env extName
-        Lean.addDeclarationRanges extName {
-          range := ← getDeclarationRange (← getRef)
-          selectionRange := ← getDeclarationRange (← getRef) }
+        addAuxDeclarationRanges extName (← getRef) (← getRef)
     catch e =>
       throwError m!"\
         Failed to generate an 'ext' theorem for '{MessageData.ofConstName structName}': {e.toMessageData}"
@@ -163,9 +161,7 @@ def realizeExtIffTheorem (extName : Name) : Elab.Command.CommandElabM Name := do
         -- Only declarations in a namespace can be protected:
         unless extIffName.isAtomic do
           modifyEnv fun env => addProtected env extIffName
-        Lean.addDeclarationRanges extIffName {
-          range := ← getDeclarationRange (← getRef)
-          selectionRange := ← getDeclarationRange (← getRef) }
+        addAuxDeclarationRanges extName (← getRef) (← getRef)
     catch e =>
       throwError m!"\
         Failed to generate an 'ext_iff' theorem from '{MessageData.ofConstName extName}': {e.toMessageData}\n\

src/Lean/Elab/Tactic/Induction.lean

@@ -27,8 +27,10 @@ open Meta
   syntax inductionAlt  := ppDedent(ppLine) inductionAltLHS+ " => " (hole <|> syntheticHole <|> tacticSeq)
   ```
 -/
+private def getAltLhses (alt : Syntax) : Syntax :=
+  alt[0]
 private def getFirstAltLhs (alt : Syntax) : Syntax :=
-  alt[0][0]
+  (getAltLhses alt)[0]
 /-- Return `inductionAlt` name. It assumes `alt` does not have multiple `inductionAltLHS` -/
 private def getAltName (alt : Syntax) : Name :=
   let lhs := getFirstAltLhs alt
@@ -70,7 +72,9 @@ def evalAlt (mvarId : MVarId) (alt : Syntax) (addInfo : TermElabM Unit) : Tactic
       let goals ← getGoals
       try
         setGoals [mvarId]
-        closeUsingOrAdmit (withTacticInfoContext alt (addInfo *> evalTactic rhs))
+        closeUsingOrAdmit <|
+          withTacticInfoContext (mkNullNode #[getAltLhses alt, getAltDArrow alt]) <|
+            (addInfo *> evalTactic rhs)
       finally
         setGoals goals
 

src/Lean/Elab/Term.lean

@@ -914,7 +914,9 @@ private def applyAttributesCore
   Remark: if the declaration has syntax errors, `declName` may be `.anonymous` see issue #4309
   In this case, we skip attribute application.
   -/
-  unless declName == .anonymous do
+  if declName == .anonymous then
+    return
+  withDeclName declName do
     for attr in attrs do
       withRef attr.stx do withLogging do
       let env ← getEnv

src/Lean/Expr.lean

@@ -1038,6 +1038,14 @@ def getForallBinderNames : Expr → List Name
   | forallE n _ b _ => n :: getForallBinderNames b
   | _ => []
 
+/--
+Returns the number of leading `∀` binders of an expression. Ignores metadata.
+-/
+def getNumHeadForalls : Expr → Nat
+  | mdata _ b => getNumHeadForalls b
+  | forallE _ _ body _ => getNumHeadForalls body + 1
+  | _ => 0
+
 /--
 If the given expression is a sequence of
 function applications `f a₁ .. aₙ`, return `f`.
@@ -1085,6 +1093,16 @@ private def getAppNumArgsAux : Expr → Nat → Nat
 def getAppNumArgs (e : Expr) : Nat :=
   getAppNumArgsAux e 0
 
+/-- Like `getAppNumArgs` but ignores metadata. -/
+def getAppNumArgs' (e : Expr) : Nat :=
+  go e 0
+where
+  /-- Auxiliary definition for `getAppNumArgs'`. -/
+  go : Expr → Nat → Nat
+    | mdata _ b, n => go b n
+    | app f _  , n => go f (n + 1)
+    | _        , n => n
+
 /--
 Like `Lean.Expr.getAppFn` but assumes the application has up to `maxArgs` arguments.
 If there are any more arguments than this, then they are returned by `getAppFn` as part of the function.

src/Lean/Language/Basic.lean

@@ -243,11 +243,16 @@ instance : ToSnapshotTree SnapshotLeaf where
 structure DynamicSnapshot where
   /-- Concrete snapshot value as `Dynamic`. -/
   val  : Dynamic
-  /-- Snapshot tree retrieved from `val` before erasure. -/
-  tree : SnapshotTree
+  /--
+  Snapshot tree retrieved from `val` before erasure. We do thunk even the first level as accessing
+  it too early can create some unnecessary tasks from `toSnapshotTree` that are otherwise avoided by
+  `(sync := true)` when accessing only after elaboration has finished. Early access can even lead to
+  deadlocks when later forcing these unnecessary tasks on a starved thread pool.
+  -/
+  tree : Thunk SnapshotTree
 
 instance : ToSnapshotTree DynamicSnapshot where
-  toSnapshotTree s := s.tree
+  toSnapshotTree s := s.tree.get
 
 /-- Creates a `DynamicSnapshot` from a typed snapshot value. -/
 def DynamicSnapshot.ofTyped [TypeName α] [ToSnapshotTree α] (val : α) : DynamicSnapshot where

src/Lean/LazyInitExtension.lean

@@ -1,42 +0,0 @@
-/-
-Copyright (c) 2021 Microsoft Corporation. All rights reserved.
-Released under Apache 2.0 license as described in the file LICENSE.
-Authors: Leonardo de Moura
--/
-prelude
-import Lean.MonadEnv
-
-namespace Lean
-
-structure LazyInitExtension (m : Type → Type) (α : Type) where
-  ext : EnvExtension (Option α)
-  fn  : m α
-
-instance [Monad m] [Inhabited α] : Inhabited (LazyInitExtension m α) where
-  default := {
-    ext := default
-    fn  := pure default
-  }
-
-/--
-  Register an environment extension for storing the result of `fn`.
-  We initialize the extension with `none`, and `fn` is executed the
-  first time `LazyInit.get` is executed.
-
-  This kind of extension is useful for avoiding work duplication in
-  scenarios where a thunk cannot be used because the computation depends
-  on state from the `m` monad. For example, we may want to "cache" a collection
-  of theorems as a `SimpLemmas` object.  -/
-def registerLazyInitExtension (fn : m α) : IO (LazyInitExtension m α) := do
-  let ext ← registerEnvExtension (pure none)
-  return { ext, fn }
-
-def LazyInitExtension.get [MonadEnv m] [Monad m] (init : LazyInitExtension m α) : m α := do
-  match init.ext.getState (← getEnv) with
-  | some a => return a
-  | none   =>
-    let a ← init.fn
-    modifyEnv fun env => init.ext.setState env (some a)
-    return a
-
-end Lean

src/Lean/Linter/ConstructorAsVariable.lean

@@ -37,7 +37,7 @@ def constructorNameAsVariable : Linter where
     let warnings : IO.Ref (Std.HashMap String.Range (Syntax × Name × Name)) ← IO.mkRef {}
 
     for tree in infoTrees do
-      tree.visitM' (preNode := fun ci info _ => do
+      tree.visitM' (postNode := fun ci info _ => do
         match info with
         | .ofTermInfo ti =>
           match ti.expr with

src/Lean/Linter/UnusedVariables.lean

@@ -10,41 +10,55 @@ set_option linter.missingDocs true -- keep it documented
 
 /-! # Unused variable Linter
 
-This file implements the unused variable linter, which runs automatically on all commands
-and reports any local variables that are never referred to, using information from the info tree.
+This file implements the unused variable linter, which runs automatically on all
+commands and reports any local variables that are never referred to, using
+information from the info tree.
 
-It is not immediately obvious but this is a surprisingly expensive check without some optimizations.
-The main complication is that it can be difficult to determine what constitutes a "use".
-For example, we would like this to be considered a use of `x`:
+It is not immediately obvious but this is a surprisingly expensive check without
+some optimizations.  The main complication is that it can be difficult to
+determine what constitutes a "use" apart from direct references to a variable
+that we can easily find in the info tree.  For example, we would like this to be
+considered a use of `x`: 
 ```
 def foo (x : Nat) : Nat := by assumption
 ```
 
-The final proof term is `fun x => x` so clearly `x` was used, but we can't make use of this because
-the final proof term is after we have abstracted over the original `fvar` for `x`. If we look
-further into the tactic state we can see the `fvar` show up in the instantiation to the original
-goal metavariable `?m : Nat := x`, but it is not always the case that we can follow metavariable
-instantiations to determine what happened after the fact, because tactics might skip the goal
-metavariable and instantiate some other metavariable created prior to it instead.
+The final proof term is `fun x => x` so clearly `x` was used, but we can't make
+use of this because the final proof term is after we have abstracted over the
+original `fvar` for `x`. Instead, we make sure to store the proof term before
+abstraction but after instantiation of mvars in the info tree and retrieve it in
+the linter. Using the instantiated term is very important as redoing that step
+in the linter can be prohibitively expensive. The downside of special-casing the
+definition body in this way is that while it works for parameters, it does not
+work for local variables in the body, so we ignore them by default if any tactic
+infos are present (`linter.unusedVariables.analyzeTactics`).
 
-Instead, we use a (much more expensive) overapproximation, which is just to look through the entire
-metavariable context looking for occurrences of `x`. We use caching to ensure that this is still
-linear in the size of the info tree, even though there are many metavariable contexts in all the
-intermediate stages of elaboration; these are highly similar and make use of `PersistentHashMap`
-so there is a lot of subterm sharing we can take advantage of.
+If we do turn on this option and look further into the tactic state, we can see
+the `fvar` show up in the instantiation to the original goal metavariable
+`?m : Nat := x`, but it is not always the case that we can follow metavariable
+instantiations to determine what happened after the fact, because tactics might
+skip the goal metavariable and instantiate some other metavariable created prior
+to it instead.  Instead, we use a (much more expensive) overapproximation, which
+is just to look through the entire metavariable context looking for occurrences
+of `x`. We use caching to ensure that this is still linear in the size of the
+info tree, even though there are many metavariable contexts in all the
+intermediate stages of elaboration; these are highly similar and make use of
+`PersistentHashMap` so there is a lot of subterm sharing we can take advantage
+of.
 
 ## The `@[unused_variables_ignore_fn]` attribute
 
-Some occurrences of variables are deliberately unused, or at least we don't want to lint on unused
-variables in these positions. For example:
+Some occurrences of variables are deliberately unused, or at least we don't want
+to lint on unused variables in these positions. For example:
 
 ```
 def foo (x : Nat) : (y : Nat) → Nat := fun _ => x
                   -- ^ don't lint this unused variable because it is public API
 ```
 
-They are generally a syntactic criterion, so we allow adding custom `IgnoreFunction`s so that
-external syntax can also opt in to lint suppression, like so:
+They are generally a syntactic criterion, so we allow adding custom
+`IgnoreFunction`s so that external syntax can also opt in to lint suppression,
+like so:
 
 ```
 macro (name := foobarKind) "foobar " name:ident : command => `(def foo ($name : Nat) := 0)
@@ -77,6 +91,17 @@ register_builtin_option linter.unusedVariables.patternVars : Bool := {
   defValue := true,
   descr := "enable the 'unused variables' linter to mark unused pattern variables"
 }
+/-- Enables linting variables defined in tactic blocks, may be expensive for complex proofs -/
+register_builtin_option linter.unusedVariables.analyzeTactics : Bool := {
+  defValue := false
+  descr := "enable analysis of local variables in presence of tactic proofs\
+          \n\
+          \nBy default, the linter will limit itself to linting a declaration's parameters \
+            whenever tactic proofs are present as these can be expensive to analyze. Enabling this \
+            option extends linting to local variables both inside and outside tactic proofs, \
+            though it can also lead to some false negatives as intermediate tactic states may \
+            reference some variables without the declaration ultimately depending on them."
+}
 
 /-- Gets the status of `linter.unusedVariables` -/
 def getLinterUnusedVariables (o : Options) : Bool :=
@@ -356,55 +381,82 @@ structure References where
 
 /-- Collect information from the `infoTrees` into `References`.
 See `References` for more information about the return value. -/
-def collectReferences (infoTrees : Array Elab.InfoTree) (cmdStxRange : String.Range) :
-    StateRefT References IO Unit := do
-  for tree in infoTrees do
-    tree.visitM' (preNode := fun ci info _ => do
-      match info with
-      | .ofTermInfo ti =>
-        match ti.expr with
-        | .const .. =>
-          if ti.isBinder then
-            let some range := info.range? | return
-            let .original .. := info.stx.getHeadInfo | return -- we are not interested in canonical syntax here
-            modify fun s => { s with constDecls := s.constDecls.insert range }
-        | .fvar id .. =>
-          let some range := info.range? | return
-          let .original .. := info.stx.getHeadInfo | return -- we are not interested in canonical syntax here
-          if ti.isBinder then
-            -- This is a local variable declaration.
-            let some ldecl := ti.lctx.find? id | return
-            -- Skip declarations which are outside the command syntax range, like `variable`s
-            -- (it would be confusing to lint these), or those which are macro-generated
-            if !cmdStxRange.contains range.start || ldecl.userName.hasMacroScopes then return
-            let opts := ci.options
-            -- we have to check for the option again here because it can be set locally
-            if !getLinterUnusedVariables opts then return
-            let stx := skipDeclIdIfPresent info.stx
-            if let .str _ s := stx.getId then
-              -- If the variable name is `_foo` then it is intentionally (possibly) unused, so skip.
-              -- This is the suggested way to silence the warning
-              if s.startsWith "_" then return
-            -- Record this either as a new `fvarDefs`, or an alias of an existing one
-            modify fun s =>
-              if let some ref := s.fvarDefs[range]? then
-                { s with fvarDefs := s.fvarDefs.insert range { ref with aliases := ref.aliases.push id } }
-              else
-                { s with fvarDefs := s.fvarDefs.insert range { userName := ldecl.userName, stx, opts, aliases := #[id] } }
-          else
-            -- Found a direct use, keep track of it
-            modify fun s => { s with fvarUses := s.fvarUses.insert id }
-        | _ => pure ()
-      | .ofTacticInfo ti =>
-        -- Keep track of the `MetavarContext` after a tactic for later
-        modify fun s => { s with assignments := s.assignments.push ti.mctxAfter.eAssignment }
-      | .ofFVarAliasInfo i =>
-        -- record any aliases we find
-        modify fun s =>
-          let id := followAliases s.fvarAliases i.baseId
-          { s with fvarAliases := s.fvarAliases.insert i.id id }
-      | _ => pure ())
+partial def collectReferences (infoTrees : Array Elab.InfoTree) (cmdStxRange : String.Range) :
+    StateRefT References IO Unit := ReaderT.run (r := false) <| go infoTrees none
 where
+  go infoTrees ctx? := do
+    for tree in infoTrees do
+      tree.visitM' (ctx? := ctx?) (preNode := fun ci info children => do
+        -- set if `analyzeTactics` is unset, tactic infos are present, and we're inside the body
+        let ignored ← read
+        match info with
+        | .ofTermInfo ti =>
+          -- NOTE: we have to do this check *before* `ignored` because nested bodies (e.g. from
+          -- nested `let rec`s) do need to be included to find all `Expr` uses of the top-level
+          -- parameters
+          if ti.elaborator == `MutualDef.body &&
+              !linter.unusedVariables.analyzeTactics.get ci.options then
+            -- the body is the only `Expr` we will analyze in this case
+            -- NOTE: we include it even if no tactics are present as at least for parameters we want
+            -- to lint only truly unused binders
+            let (e, _) := instantiateMVarsCore ci.mctx ti.expr
+            modify fun s => { s with
+              assignments := s.assignments.push (.insert {} ⟨.anonymous⟩ e) }
+            let tacticsPresent := children.any (·.findInfo? (· matches .ofTacticInfo ..) |>.isSome)
+            withReader (· || tacticsPresent) do
+              go children.toArray ci
+            return false
+          if ignored then return true
+          match ti.expr with
+          | .const .. =>
+            if ti.isBinder then
+              let some range := info.range? | return true
+              let .original .. := info.stx.getHeadInfo | return true -- we are not interested in canonical syntax here
+              modify fun s => { s with constDecls := s.constDecls.insert range }
+          | .fvar id .. =>
+            let some range := info.range? | return true
+            let .original .. := info.stx.getHeadInfo | return true -- we are not interested in canonical syntax here
+            if ti.isBinder then
+              -- This is a local variable declaration.
+              if ignored then return true
+              let some ldecl := ti.lctx.find? id | return true
+              -- Skip declarations which are outside the command syntax range, like `variable`s
+              -- (it would be confusing to lint these), or those which are macro-generated
+              if !cmdStxRange.contains range.start || ldecl.userName.hasMacroScopes then return true
+              let opts := ci.options
+              -- we have to check for the option again here because it can be set locally
+              if !getLinterUnusedVariables opts then return true
+              let stx := skipDeclIdIfPresent info.stx
+              if let .str _ s := stx.getId then
+                -- If the variable name is `_foo` then it is intentionally (possibly) unused, so skip.
+                -- This is the suggested way to silence the warning
+                if s.startsWith "_" then return true
+              -- Record this either as a new `fvarDefs`, or an alias of an existing one
+              modify fun s =>
+                if let some ref := s.fvarDefs[range]? then
+                  { s with fvarDefs := s.fvarDefs.insert range { ref with aliases := ref.aliases.push id } }
+                else
+                  { s with fvarDefs := s.fvarDefs.insert range { userName := ldecl.userName, stx, opts, aliases := #[id] } }
+            else
+              -- Found a direct use, keep track of it
+              modify fun s => { s with fvarUses := s.fvarUses.insert id }
+          | _ => pure ()
+          return true
+        | .ofTacticInfo ti =>
+          -- When ignoring new binders, no need to look at intermediate tactic states either as
+          -- references to binders outside the body will be covered by the body `Expr`
+          if ignored then return true
+          -- Keep track of the `MetavarContext` after a tactic for later
+          modify fun s => { s with assignments := s.assignments.push ti.mctxAfter.eAssignment }
+          return true
+        | .ofFVarAliasInfo i =>
+          if ignored then return true
+          -- record any aliases we find
+          modify fun s =>
+            let id := followAliases s.fvarAliases i.baseId
+            { s with fvarAliases := s.fvarAliases.insert i.id id }
+          return true
+        | _ => return true)
   /-- Since declarations attach the declaration info to the `declId`,
   we skip that to get to the `.ident` if possible. -/
   skipDeclIdIfPresent (stx : Syntax) : Syntax :=
@@ -493,7 +545,7 @@ def unusedVariables : Linter where
         -- collect additional `fvarUses` from tactic assignments
         visitAssignments (← IO.mkRef {}) fvarUsesRef s.assignments
         -- Resolve potential aliases again to preserve `fvarUsesRef` invariant
-        fvarUsesRef.modify fun fvarUses => fvarUses.fold (·.insert <| getCanonVar ·) {}
+        fvarUsesRef.modify fun fvarUses => fvarUses.toArray.map getCanonVar |> .insertMany {}
         initializedMVars := true
         let fvarUses ← fvarUsesRef.get
         -- Redo the initial check because `fvarUses` could be bigger now

src/Lean/Meta/DiscrTree.lean

@@ -76,7 +76,7 @@ def Key.format : Key → Format
   | .const k _       => Std.format k
   | .proj s i _      => Std.format s ++ "." ++ Std.format i
   | .fvar k _        => Std.format k.name
-  | .arrow           => "→"
+  | .arrow           => "∀"
 
 instance : ToFormat Key := ⟨Key.format⟩
 
@@ -113,7 +113,8 @@ where
       mkApp m!"{mkFVar fvarId}" (← goN nargs) parenIfNonAtomic
     | .proj _ i nargs =>
       mkApp m!"{← go}.{i+1}" (← goN nargs) parenIfNonAtomic
-    | .arrow => return "<arrow>"
+    | .arrow =>
+      mkApp m!"∀ " (← goN 1) parenIfNonAtomic
     | .star => return "_"
     | .other => return "<other>"
     | .lit (.natVal v) => return m!"{v}"
@@ -129,21 +130,15 @@ def Key.arity : Key → Nat
   | .const _ a  => a
   | .fvar _ a   => a
   /-
-  Remark: `.arrow` used to have arity 2, and was used to encode non-dependent arrows.
-  However, this feature was a recurrent source of bugs. For example, a theorem about
-  a dependent arrow can be applied to a non-dependent one. The reverse direction may
-  also happen. See issue #2835.
-  ```
-  -- A theorem about the non-dependent arrow `a → a`
-  theorem imp_self' {a : Prop} : (a → a) ↔ True := ⟨fun _ => trivial, fun _ => id⟩
-
-  -- can be applied to the dependent one `(h : P a) → P (f h)`.
-  example {α : Prop} {P : α → Prop} {f : ∀ {a}, P a → α} {a : α} : (h : P a) → P (f h) := by
-    simp only [imp_self']
-  ```
-  Thus, we now index dependent and non-dependent arrows using the key `.arrow` with arity 0.
+  Remark: `.arrow` used to have arity 2, and was used to encode only **non**-dependent
+  arrows. However, this feature was a recurrent source of bugs. For example, a
+  theorem about a dependent arrow can be applied to a non-dependent one. The
+  reverse direction may also happen. See issue #2835. Therefore, `.arrow` was made
+  to have arity 0. But this throws away easy to use information, and makes it so
+  that ∀ and ∃ behave quite differently. So now `.arrow` at least indexes the
+  domain of the forall (whether dependent or non-dependent).
   -/
-  | .arrow      => 0
+  | .arrow      => 1
   | .proj _ _ a => 1 + a
   | _           => 0
 
@@ -422,7 +417,8 @@ private def pushArgs (root : Bool) (todo : Array Expr) (e : Expr) (config : Whnf
         return (.other, todo)
       else
         return (.star, todo)
-    | .forallE .. => return (.arrow, todo)
+    | .forallE _n d _ _ =>
+      return (.arrow, todo.push d)
     | _ => return (.other, todo)
 
 @[inherit_doc pushArgs]
@@ -581,7 +577,7 @@ private def getKeyArgs (e : Expr) (isMatch root : Bool) (config : WhnfCoreConfig
   | .proj s i a .. =>
     let nargs := e.getAppNumArgs
     return (.proj s i nargs, #[a] ++ e.getAppRevArgs)
-  | .forallE .. => return (.arrow, #[])
+  | .forallE _ d _ _ => return (.arrow, #[d])
   | _ => return (.other, #[])
 
 private abbrev getMatchKeyArgs (e : Expr) (root : Bool) (config : WhnfCoreConfig) : MetaM (Key × Array Expr) :=