-module(counter).
-export([start/0,loop/1,increment/1,value/1,stop/1]).

%% First the interface functions.
start() ->
    spawn(counter, loop, [0]).

increment(Counter) ->
    Counter ! increment.

value(Counter) ->
    Counter ! {self(),value}
    receive
        {Counter,Value} ->
            Value
    end.

stop(Counter) ->
    Counter ! stop.

%% The counter loop.
loop(Val) ->
    receive
        increment ->
            loop(Val + 1);
        {From,value} ->
            From ! {self(),Val},
            loop(Val);
        stop ->                  % No recursive call here
            true;
        Other ->                 % All other messages
            loop(Val)
    end.