qsort in Erlang

gistfile1.txt

-module(qsort).
-export([qsort/1]).

% qsort/1
qsort([]) -> [];
qsort([Head|Rest]) ->
	{Less,Geq} = partition(Rest,Head),
	concat(qsort(Less), Head, qsort(Geq)).

% partition/2
partition(List,Pivot) ->
	partition(List,Pivot,[],[]).
partition([],_,Less,Geq) -> {Less, Geq};
partition([Head|Rest],Pivot,Less,Geq) when Head < Pivot ->
	partition(Rest,Pivot,[Head|Less],Geq);
partition([Head|Rest],Pivot,Less,Geq) ->
	partition(Rest,Pivot,Less,[Head|Geq]).

% concat/3
concat(Less,Pivot,Geq) ->
	concat(reverse(Less), [Pivot|Geq]).
concat([],Acc) -> Acc;
concat([Head|Rest],Acc) -> concat(Rest, [Head|Acc]).

% reverse/1
reverse(List) -> reverse(List,[]).
reverse([],Acc) -> Acc;
reverse([Head|Rest],Acc) -> reverse(Rest,[Head|Acc]).