quicksort [] = []

quicksort (x:xs) = 
      (quicksort less)  ++ [x] ++ (quicksort greater)
          where
             (less,greater) = (partition xs x)

    

partition [] piv = ([],[])

partition (x:xs) piv | x < piv     = ((x:lessxs),greaterxs)
                     | otherwise   = (lessxs,(x:greaterxs))
                    where
                     (lessxs,greaterxs) = (partition xs piv)







qs([]) -> [];

qs([X| Xs]) ->
    {Less , Greater } = partition (Xs,X),
    qs( Less ) ++ [X] ++ qs( Greater ).



partition ([],Piv ) -> {[],[]}
;
partition ([X| Xs],Piv) ->
                      {Less,Greater} = partition (Xs, X),
                      if
                            X < Piv -> {[X|Less],Greater}
                            ;
                            true ->  {Less,[X|Greater]}
                      end .