http://erlangexamples.com/2009/08/28/recursion-in-erlang/

tailrecursion.erl

%% To demonstrate tail recursion in Erlang

-module (tailrecursion).
-export ([fact/1, qsort/1, loop/0]).

%% Factorial
fact(N) -> fact(N, 1).
fact(0, A) -> 1*A;
fact(N, A) -> fact(N-1, N*A).

%% Quick Sort
%% Think thru, you'll see it very easy to understand :p
qsort([]) -> [];
qsort([Single]) -> [Single];
qsort([Pivot|Rest]) ->
	{Smallers, Greaters} = qsort(Pivot, Rest),
	SortedSmallers = qsort(Smallers),
	SortedGreaters = qsort(Greaters),
	SortedSmallers ++ [Pivot] ++ SortedGreaters.

qsort(Pivot, List) -> qsort(Pivot, [], [], List).

qsort(_Pivot, Smallers, Greaters, []) -> {Smallers, Greaters};
qsort(Pivot, Smallers, Greaters, [First|Rest]) when First < Pivot ->
	qsort(Pivot, [First|Smallers], Greaters, Rest);
qsort(Pivot, Smallers, Greaters, [First|Rest]) when First >= Pivot ->
	qsort(Pivot, Smallers, [First|Greaters], Rest).

%% Loop
%% Just a sample, don't run!!!
loop() ->
	receive
		{status, ok} ->
			loop()
	end.