[sizzla]

This looks like yet another Haskell "variant." From what I can tell this sort does not occur in place and thus would not make a particularly good quicksort. Memory use, number of accesses per element, etc. This style of programming is more suitable for heapsort or maybe mergesort.

[zbanks]

You can't exactly sort "in place" in functional languages like F#/Haskell... at least trivially.

[fleitz]

Given the level of abstraction in most modern programing languages/ operating systems it's really hard to say that any modern language could implement quicksort in the most strict definitions.

For example, is a quicksort 'in-place' if your memory gets swapped to disk?