conv at hi => rewrite [Array.toList_eq]
case mk
α : Type u
β : Type v
n : Nat
f : Fin n → α
i : Nat
hi : i < length (Array.toList (Array.ofFn f))
⊢ (Array.ofFn f)[i] = f (Fin.cast (_ : length (ofFn f) = n) { val := i, isLt := hi })
case mk
α : Type u
β : Type v
n : Nat
f : Fin n → α
i : Nat
hi✝ : i < length (Array.toList (Array.ofFn f))
hi : i < length (Array.ofFn f).data
⊢ (Array.ofFn f)[i] = f (Fin.cast (_ : length (ofFn f) = n) { val := i, isLt := hi✝ })