open Cupto;;

type 'a toplevel = 'a prompt;;
type ('a,'b) fcont = 'a -> 'b;;

let shift toplevel a = cupto toplevel (fun k -> set toplevel (fun () -> a k));;

let callcc toplevel a =
  shift toplevel
    (fun k -> k (fun () -> (a (fun r -> k (fun () -> r)))))
  ();;

let throw toplevel v1 v2 = shift toplevel (fun k -> v1 v2);;

let eval a =
  let toplevel = new_prompt () in
    set toplevel (fun () -> a toplevel)
;;

let reset = set;;