Quicksort in Python. Functional-programming style, zero data mutation.

quicksort.py

#   Recursive quicksort algorithm implemented in Python
#   FP-style, with no data mutation whatsoever

#   One major advantage of not mutating the data is that if you throw an immutable 
#   data structure at it - such as a tuple or a string - it won't blow up in your face.

#   Jack Hooper 2014

def quicksort(array):
    if len(array) <= 1: 
        return array
    higher = [i for i in array[1:] if i > array[0]]
    lower = [i for i in array[1:] if i <= array[0]]
    return quicksort(lower) + [array[0]] + quicksort(higher)