case pos c1 =>
  subst c1
  simp at h1
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
c1 : v = xs_hd
⊢ ys_hd = f v
no goals