quicksort :: (Ord a) => [a] -> [a]  
    quicksort [] = []  
    quicksort (x:xs) =   
        let smallerSorted = quicksort [a | a <- xs, a <= x]  
            biggerSorted = quicksort [a | a <- xs, a > x]  
        in  smallerSorted ++ [x] ++ biggerSorted