(* An example with threads. *)

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

let timer : unit -> unit =
  fun _: unit ->
    let id = Thread.fork printer in
      Thread.delay 2000000;
      Thread.kill id

in timer ()