lean4-htt/tests/lean/run/grind_pattern2.lean
Leonardo de Moura af4c693030
feat: improve E-matching pattern inference in grind (#8196)
This PR improves the E-matching pattern inference procedure in `grind`.
Consider the following theorem:
```lean
@[grind →]
theorem eq_empty_of_append_eq_empty {xs ys : Array α} (h : xs ++ ys = #[]) : xs = #[] ∧ ys = #[] :=
  append_eq_empty_iff.mp h
```
Before this PR, `grind` inferred the following pattern:
```lean
@HAppend.hAppend _ _ _ _ #2 #1
```
Note that this pattern would match any `++` application, even if it had
nothing to do with arrays. With this PR, the inferred pattern becomes:
```lean
@HAppend.hAppend (Array #3) (Array _) (Array _) _ #2 #1
```
With the new pattern, the theorem will not be considered by `grind` for
goals that do not involve `Array`s.
2025-05-01 23:48:32 +00:00

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def Set (α : Type) := α → Bool
def insertElem [DecidableEq α] (s : Set α) (a : α) : Set α :=
fun x => a = x || s x
def contains (s : Set α) (a : α) : Bool :=
s a
theorem contains_insert [DecidableEq α] (s : Set α) (a : α) : contains (insertElem s a) a := by
simp [contains, insertElem]
grind_pattern contains_insert => contains (insertElem s a) a
-- TheoremPattern activation test
set_option trace.grind.ematch true
set_option trace.grind.ematch.pattern true
/-- info: [grind.ematch] activated `contains_insert`, [@contains #3 (@insertElem _ #2 #1 #0) #0] -/
#guard_msgs (info) in
example [DecidableEq α] (s₁ s₂ : Set α) (a₁ a₂ : α) :
s₂ = insertElem s₁ a₁ → a₁ = a₂ → contains s₂ a₂ := by
grind
/-- info: [grind.ematch] activated `contains_insert`, [@contains #3 (@insertElem _ #2 #1 #0) #0] -/
#guard_msgs (info) in
example [DecidableEq α] (s₁ s₂ : Set α) (a₁ a₂ : α) :
¬ contains s₂ a₂ → s₂ = insertElem s₁ a₁ → a₁ = a₂ → False := by
grind
def a := 10
def b := 20
def foo (x : List Nat) (y : List Nat) := x ++ y ++ x
theorem fooThm : foo x [a, b] = x ++ [a, b] ++ x := rfl
/-- info: [grind.ematch.pattern] fooThm: [foo #0 `[[a, b]]] -/
#guard_msgs in
grind_pattern fooThm => foo x [a, b]
/--
info: [grind.internalize] foo x y
[grind.internalize] [a, b]
[grind.internalize] Nat
[grind.internalize] a
[grind.internalize] [b]
[grind.internalize] b
[grind.internalize] []
[grind.ematch] activated `fooThm`, [foo #0 `[[a, b]]]
[grind.internalize] x
[grind.internalize] y
[grind.internalize] z
-/
#guard_msgs (info) in
set_option trace.grind.internalize true in
example : foo x y = z → False := by
fail_if_success grind
sorry
theorem arrEx [Add α] (as : Array α) (h₁ : i < as.size) (h₂ : i = j) : as[i]+as[j] = as[i] + as[i] := by sorry
/--
info: [grind.ematch.pattern] arrEx: [@HAdd.hAdd #6 _ _ _ (@getElem (Array _) `[Nat] _ _ _ #2 #5 _) (@getElem (Array _) `[Nat] _ _ _ #2 #4 _)]
-/
#guard_msgs in
grind_pattern arrEx => as[i]+as[j]'(h₂▸h₁)