perm1tations.ss

;;; permutations with repetitions.  Base to get all possible
;;; mastermind solutions.
;;; 
;;; Example usage:
;;; (perm '(1 2 3) 2) => ((1 1) (2 1) (3 1) (1 2) (2 2) (3 2) (1 3) (2 3) (3 3))
(define (perm lst len)
  (cond ((= 0 len) '(()))
	(else (append-map (lambda (x)
			    (map (lambda (y) (cons y x )) lst))
			  (perm lst (- len 1))))))