quick-sort.scm

(use util.match)

(define (take p lst c)
  (filter (lambda (x) (c p x))
	  lst))
(define (take-less p lst)
  (take p lst >))
(define (take-greater p lst)
  (take p lst <))

(define (quick-sort lst)
  (match lst
	 [() '()]
	 [(first . rest)
	  (append (quick-sort (take-less first rest))
		  (list first)
		  (quick-sort (take-greater first rest)))]))

(quick-sort '(3 9 2 8 4 1 0))
(quick-sort '(0 0 0 0 0 1 2 2 2 2))
(quick-sort '(0 0 0 0))