∀ {α : Type u_1} {stop : ℕ} {p : α → Prop} {xs : Array { x // p x }} {f : { x // p x } → Bool} {g : α → Bool},
  (∀ (x : α) (h : p x), f ⟨x, h⟩ = g x) → stop = xs.size → xs.all f 0 stop = xs.unattach.all g