case cons ys_hd ys_tl =>
  simp only [Function.updateListITE]
  simp only [Function.updateITE]
  split_ifs
  case pos c1 =>
    subst c1
    simp at h1
  case neg c1 =>
    simp at h1
    push_neg at h1
    cases h1
    case intro h1_left h1_right =>
      apply xs_ih ys_tl h1_right
α β : Type
inst✝ : DecidableEq α
f : α → β
v xs_hd : α
xs_tl : List α
xs_ih : ∀ (ys : List β), v ∉ xs_tl → updateListITE f xs_tl ys v = f v
h1 : v ∉ xs_hd :: xs_tl
ys_hd : β
ys_tl : List β
⊢ updateListITE f (xs_hd :: xs_tl) (ys_hd :: ys_tl) v = f v
no goals