let marshal o = Marshal.to_string o [] |> Format.sprintf "%S"

let unmarshal o =
  let s = Scanf.sscanf o "%S" (fun s -> s) in
  Marshal.from_string s 0

type server_message =
  | Full_state of State.t
  | Update_result of (State.action', string) result

type client_message = Action_msg of State.action