(* Polymorphic version: An Ill-Typed Module (type error) *)

let ap =
  fun `a ->
    fun `b ->
      fun f: (`a -o `b) ->
        fun x: `a ->
          f x

let inc2 =
  fun y: int ->
    let g = ap (fun z: int -> z + 1) in
      g (g y)   (* g: (int -o int) is used twice here *)

in print (inc2 5)