-- QuickSort in descending order
qsort :: Ord a => [a] -> [a]
qsort [] = []
qsort (x : xs) = qsort large_list ++ [x] ++ qsort small_list
                 where
                    large_list = [a | a <- xs, a >= x]
                    small_list = [b | b <- xs, b < x]