constructor
α : Type
x' : α
xs : List α
IH : ∀ (i : ℕ) (INBOUND : i < length xs), Mem (getF xs i INBOUND) xs
i' : ℕ
INBOUND : Nat.succ i' < length (x' :: xs)
⊢ Mem (getF xs i' (_ : i' < length xs)) (x' :: xs)
case a
α : Type
x' : α
xs : List α
IH : ∀ (i : ℕ) (INBOUND : i < length xs), Mem (getF xs i INBOUND) xs
i' : ℕ
INBOUND : Nat.succ i' < length (x' :: xs)
⊢ Mem (getF xs i' (_ : i' < length xs)) xs