Quicksort in Haskell & Python

qa.coffee

qs = (arr) ->
  [].concat qs(i for i in arr when i < arr[0]), [arr[0]], qs(i for i in arr when i > arr[0]) if arr.length <= 1 else arr

qa2.hs

qsort (p:xs) = qsort [x | x<-xs, x<p] ++ [p] ++ qsort [x | x<-xs, x>=p]

qs.py

def qs(array):
    if len(array) == 0 or len(array) == 1:
        return array

    p = array[0]

    lesser = [i for i in array if i < p]
    greater = [i for i in array if i > p]

    return qs(lesser) + [p] + qs(greater)

# Or even


def qs(ar):
    if len(ar) == 0 or len(ar) == 1:
        return ar

    p = ar[0]
    return qs([i for i in ar if i < p]) + [p] + qs([i for i in ar if i > p])

quicksort.hs

quicksort :: Ord a => [a] -> [a]
quicksort []     = []
quicksort (p:xs) = (quicksort lesser) ++ [p] ++ (quicksort greater)
    where
        lesser  = filter (< p) xs
        greater = filter (>= p) xs