constructor
case refl
α : Type u_1
f : α → Bool
h : ∀ (a1 a2 : α), f a1 = true → f a2 = true → a1 = a2
x : α
L : List α
⊢ List.find? f L = some x ↔ x ∈ L ∧ f x = true
case refl.mp
α : Type u_1
f : α → Bool
h : ∀ (a1 a2 : α), f a1 = true → f a2 = true → a1 = a2
x : α
L : List α
⊢ List.find? f L = some x → x ∈ L ∧ f x = true

case refl.mpr
α : Type u_1
f : α → Bool
h : ∀ (a1 a2 : α), f a1 = true → f a2 = true → a1 = a2
x : α
L : List α
⊢ x ∈ L ∧ f x = true → List.find? f L = some x