Sleep sort in Erlang

sleepsort.erl

-module(sleepsort).
-export([sort/1]).

sort(List) ->
    sort(List, [], []).

sort([], NewList, []) ->
    lists:reverse(NewList);
sort(List, [], []) ->
    Pids = lists:map(fun(Element) -> spawn(sleepsort, sleep, [self(), Element]) end, List),
    sort([], [], Pids);
sort([], NewList, Pids) ->
    receive
	{Pid, Element} -> sort([], [Element|NewList], Pids--[Pid])
    end.  
    
sleep(Pid, Element) ->
    timer:sleep(Element),
    Pid ! {self(), Element}.