type buyer =
    { id: string;
      accept: unit Join.chan;
      refuse: int Join.chan;
      win: unit Join.chan }

def seller(Some buyer, _) & bid_timeout() = buyer.win()
or  seller(win, curr_bid) & bid(buyer, amount) =
  print_endline (buyer.id ^ " bet " ^ (string_of_int amount));
  if curr_bid < amount then
    match win with
    Some a -> seller(Some buyer, amount) & buyer.accept() & a.refuse(amount)
      | _ -> seller(Some buyer, amount) & buyer.accept()
  else seller(win, curr_bid) & buyer.refuse(curr_bid)

let mk_buyer id init_amount =
  def buyer(money) & refuse(curr_bid) =
    print_endline (id ^ " was refused; money: " ^ (string_of_int money) ^ "; current bid: " ^ (string_of_int curr_bid));
    if money > 0 && money > curr_bid then begin
      print_endline (id ^ " will bid " ^ (string_of_int (curr_bid + 1)));
      bid(self(), curr_bid + 1) & buyer(money - curr_bid - 1)
    end
  or  buyer(money) & accept() =
    print_endline (id ^ " was accepted");
    buyer(money)
  or  buyer(_) & win() =
    print_endline (id ^ " won!"); 0
  and self() = reply { id = id;
               accept = accept;
               refuse = refuse;
               win = win } to self in
  spawn buyer(init_amount) & bid(self(), 1)

def timer(t) =
  Unix.sleep t;
  spawn bid_timeout(); 0

let start () =
  spawn timer(10) & seller(None, 0);
  mk_buyer "a" 10;
  mk_buyer "b" 2;
  mk_buyer "c" 3