(use mailbox-threads)

(define (make-result-collector count)
  (thread-start!
   (lambda ()
     (let loop ((res '()) (remaining (- count 1)))
       (if (zero? remaining)
           '()
           (cons (thread-receive) 
                 (loop res (- remaining 1))))))))

(define (make-sleeper n rc)
  (lambda ()
    (thread-sleep! n)
    (thread-send rc n)))

(define (sleep-sort lst)
  (let ((rc (make-result-collector (length lst))))
    (for-each (lambda (n)
                (thread-start! (make-sleeper n rc)))
              lst)
    (thread-join! rc)))

(write (sleep-sort '(5 4 6 3 1 2)))
(newline)
(exit 0)