(* A bad example with threads.  (type error!) *)

let printer : unit -> unit =
  let rec loop (_ : unit) : unit =
    Thread.delay 100000;
    putStr "x";
    flush ();
    loop ()
  in loop

let startStop : unit -> unit -o unit =
  fun _: unit ->
    let id = Thread.fork printer in
    let id = Thread.print id in
      fun _: unit ->
        Thread.kill id

let after : int -> (unit -o unit) -> unit =
  fun delay: int ->
    fun stop: (unit -o unit) ->
      Thread.fork (fun _:unit  -> Thread.delay delay; stop ());
      ()

let main : unit -> unit =
  fun _: unit ->
    let stop = startStop () in
      after 2000000 stop;
      getLine ();
      stop ()    (* stop used twice! *)

in main ()