mutable.erl

-module(mutable).
-export([var/0, get/1, set/2]).

loop(Val) ->
    receive
        {get, Pid} ->
            Pid ! Val,
            loop(Val);
        {set, V} ->
            loop(V)
    end.

get(M) ->
    M !	{get, self()},
    receive
        Val -> Val
    end.

set(M, V) ->
    M ! {set, V},
    ok.

var() ->
    spawn(fun () -> loop(0) end).



% Example
% c(mutable).
% X = mutable:var().
% mutable:set(X, 15).
% mutable:get(X). % returns 15
% mutable:set(X, "hi").
% mutable.get(X). % returns "hi"