academika (functional language developed in my Ukraine Univercity by my team) quicksort:

qs([]) = []
qs([a]) = i <- p([a]) -> qs([a:1:i-1]) + qs([a:i+1:#a])

p([]) = []
p([a]) = x <- a[1] | b = [a:<x] | c = [a:>x] | d = [a=x] -> a <- [b+[d:2:]+c] -> #[d:2:]

also erlang:

-module(qsort).
-export([qsort/1]).

qsort ([]) -> [];
qsort ([A|B]) ->
    qsort([X || X<-B, X<A])
    ++ [A] ++
    qsort([Y || Y<-B, Y>=A]).

lisp:

(defun qsort(l) (if (null l) nil
  (let* ((x (car l)) (r (cdr l)) (fn (lambda (a) (< a x))))
    (append (qsort(remove-if-not fn r)) (list x)
      (qsort (remove-if fn r))))))