case pos
α : Type u_1
a : Array α
i : Nat
h✝¹ h✝ : i < size a
⊢ List.get a.data { val := i, isLt := (_ : i < size a) } = a[i]
α : Type u_1
a : Array α
i : Nat
⊢ a[i]? = List.get? a.data i
by_cases i < a.size <;> simp_all [getElem?_pos, getElem?_neg, List.get?_eq_get, eq_comm]
no goals
case pos
α : Type u_1
a : Array α
i : Nat
h✝¹ h✝ : i < size a
⊢ List.get a.data { val := i, isLt := (_ : i < size a) } = a[i]
rfl