Quicksort via filters in Haskell

gistfile1.hs

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