Erlang 8.11.2.3 (not refactored)

gistfile1.erl

-module(ring2).
-export([start/2]).

start(Msg,Max) ->
    Pid1 = clasp(Max),
    Pid2 = ring(),
    Pid3 = ring(),
    Pid4 = ring(),
    shackle(Pid1, Pid2),
    shackle(Pid2, Pid3),
    shackle(Pid3, Pid4),
    shackle(Pid4, Pid1),
    send(Pid2, Msg).

shackle(LPid, RPid) ->
    LPid ! {connect, LPid, RPid}.

clasp(Max) ->
    spawn(fun() -> loop(0,0,1,Max) end).

ring() ->
    spawn(fun() -> loop(0,0,0,0) end).

send(StartPid, Msg) ->
    StartPid ! {send, Msg}.

loop(LPid, RPid, Beacon, Max) ->
    receive
        {connect, Left, Right} ->
            io:format("shackle connected~n"),
            loop(Left, Right, Beacon, Max);
        {send, Msg} when (Beacon > 0) and (Beacon < Max) ->
            io:format("Message passed clasp: ~p~n", [Msg]),
            RPid ! {send, Msg},
            loop(LPid, RPid, Beacon + 1, Max);
        {send, Msg} when Beacon =:= 0 ->
            io:format("Message sent: ~p~n", [Msg]),
            RPid ! {send, Msg},
            loop(LPid, RPid, Beacon, Max);
        {send, Msg} when Beacon =:= 5 ->
            io:format("Ring round done.~p~n", [Msg])
    end.