test2.erl

-module(tr).
-compile([export_all]).


-define(PRIORITIES, [high, med, low]).

next_priority(high) ->
  med;
next_priority(med) ->
  low;
next_priority(low) ->
  any.

proc1(any) ->
  receive
    {_, M} ->
      io:format("~p~n", [M]),
      timer:sleep(1000),
      proc1(high)
  end;
proc1(P) ->
  receive
    {P, M} ->
      io:format("~p~n", [M]),
      timer:sleep(1000),  
      proc1(high)
  after
    0 ->
      proc1(next_priority(P))
  end.



proc2() ->
  Pid = spawn(tr, proc1, [high]),
  Pid ! {low, low},
  Pid ! {med, med},
  Pid ! {high, high}.