ping_pong.erl

-module(process_exc).
-export([start/1, proc/1]).

start(M) ->
  N1 = spawn(process_exc, proc, [M]),
  N2 = spawn(process_exc, proc, [M]),
  N1 ! {N2, ping}.

proc(M) ->
  proc(M, 0).

proc(M, M) ->
  io:format("~p Process exiting...~n", [self()]);
proc(M, C) ->
  receive
    {From, ping} ->
      print(ping, C),
      From ! {self(), pong},
      proc(M, C+1);
    {From, pong} ->
      print(pong, C),
      From ! {self(), ping},
      proc(M, C+1);
    _ ->
      io:format("Unrecognized message...~n"),
      proc(M, C)
  end.

print(M, C) ->
  io:format("~p received ~p: ~p~n", [self(), M, C]).