simp only [getElem_eq_get, get_pmap]
case h
α : Type u
β : Type v
p : α → Prop
l : List α
nodup : Nodup l
f : (a : α) → p a → β
h : ∀ (a : α), a ∈ l → p a
f_inj : ∀ (a₁ a₂ : α) (h₁ : p a₁) (h₂ : p a₂), f a₁ h₁ = f a₂ h₂ → a₁ = a₂
i j : Nat
hi : i < length (List.pmap f l h)
hj : j < length (List.pmap f l h)
⊢ (List.pmap f l h)[i] = (List.pmap f l h)[j] → i = j
case h
α : Type u
β : Type v
p : α → Prop
l : List α
nodup : Nodup l
f : (a : α) → p a → β
h : ∀ (a : α), a ∈ l → p a
f_inj : ∀ (a₁ a₂ : α) (h₁ : p a₁) (h₂ : p a₂), f a₁ h₁ = f a₂ h₂ → a₁ = a₂
i j : Nat
hi : i < length (List.pmap f l h)
hj : j < length (List.pmap f l h)
⊢ f (get l (Fin.cast (_ : length (List.pmap f l h) = length l) { val := i, isLt := hi }))
        (_ : p (get l (Fin.cast (_ : length (List.pmap f l h) = length l) { val := i, isLt := hi }))) =
      f (get l (Fin.cast (_ : length (List.pmap f l h) = length l) { val := j, isLt := hj }))
        (_ : p (get l (Fin.cast (_ : length (List.pmap f l h) = length l) { val := j, isLt := hj }))) →
    i = j