open Event

let ch = (new_channel() : string channel)

let rec f tag msg =
  select [
    send ch msg;
    wrap (receive ch) (fun x -> print_string(tag ^ ": " ^ x); print_newline())
  ];
  f tag msg

let _ =
  Thread.new (f "A") "hello";
  f "B" "world";
  exit 0