∀ {m : Type u_1 → Type u_2} {β₁ : Type u_3} {β₂ : Type u_4} {α : Type u_1} [inst : Monad m] [LawfulMonad m]
  {f : β₁ → β₂} {g : β₂ → α → m α} {l : List β₁} {init : α},
  List.foldrM g init (List.map f l) = List.foldrM (fun x y => g (f x) y) init l