;; equal-as-sets? : set * set -> bool

;; set = a list of distinct scheme values

;; usage: (equal-as-sets? ans correct-ans)

;; compares ans and correct-ans to see if one is a permutation of 
;; the other.  Elements are compared using equal?.

;; ans and correct-ans are permutations iff they are the same length
;; and each element of correct-ans is a member of ans.

(define equal-as-sets?
  (lambda (ans correct-ans)
    (and
     (= (length ans) (length correct-ans))
     (let loop ((correct-ans correct-ans))
       (if (null? correct-ans) #t
           (and
            (not (member (car correct-ans) (cdr correct-ans)))
            (member (car correct-ans) ans)
            (loop (cdr correct-ans))))))))