# Demonstration of tail recursion in recursive parallel calls
#
# Paul Griffioen 2012

module message_loop

include channel

public procedure main(args) = 
  let
      channel_A := open_channel("channel A") |
      channel_B := open_channel("channel B")
  in
    sender(channel_A) | buffer(channel_A, channel_B) | receiver_rec(channel_B)	
  end
  
procedure sender(channel) =
  while true do
      send(channel, "Hello World!");
      sleep(0.001)
  end

procedure buffer(input, output) =
  let m := receive([input]) in
      send(output, m.message) | buffer(input, output)
  end

procedure receiver(channel) =
  while true do
      let m := receive([channel]) in
          print_message(m)
      end
  end

procedure receiver_rec(channel) =
  let m := receive([channel]) in
      print_message(m);
      receiver_rec(channel)
  end

procedure print_message(m) = 
  print_line(format("$message from $channel",
                    message := m.message;
                    channel := channel_name(m.channel)))