QuickSort in Racket

gistfile1.txt

#lang racket
(define (qsort a)
  (cond 
    [(empty? a) a]
    [else (let* 
              ([hd (first a)]
               [tl (rest a)]
               [smaller (filter (lambda (x) (< x hd)) tl)]
               [bigger (filter (lambda (x) (>= x hd)) tl)])
            (append (qsort smaller) (list hd) (qsort bigger)))]))

(require math/distributions)
(define ary (sample (normal-dist 0 1) 1000000))
(time (let ([x (qsort ary)]) 3))