(* An Interface Intervenes *)

let ap : (int -> int) -> int -> int =
  fun f: (int -> int) ->
    fun x: int ->
      f x

let iap = (ap :> (int -o int) -> int -o int)

let inc : int -> int =
  fun y: int ->
    (fun g: (int -o int) ->
       iap g y)
    (fun z: int -> z + 1)

in print[int] (inc 5)