Функции пересечения и разности списков

(defun intersectionlist (list1 list2) 
(cond ((null list1) nil)
         ((null list2) nil)
        ((member (car list1) list2) 
        (cons (car list1) (intersectionlist (cdr list1) list2)))
        (t (intersectionlist (cdr list1) list2))))
 
(defun differencelist (list1 list2)
        (cond
        ((null list1) nil)
        ((not (member (car list1) list2)) 
        (cons (car list1) (differencelist (remove (car list1) list1) list2)))
        (t (differencelist (cdr list1) list2))))

(defun inters (lst1 lst2)
  (let ((l-atom-1 (remove-if-not 'atom lst1))
        (l-atom-2 (remove-if-not 'atom lst2))
        (l-lst-1  (remove-if-not 'listp lst1))
        (l-lst-2  (remove-if-not 'listp lst2)))
       (append (intersection l-atom-1 l-atom-2)
               (mapcar #'inters l-lst-1 l-lst-2))))
 
==> inters
 
(inters '( a s d ( f g 1 2 ( h ))) '( d f ( f g 1 (h k) ) ))
 
==> (d (f g 1 (h)))

;; racket-lang.org
(define (intersect lst1 lst2)
  (for/list ([i lst1] #:when (member i lst2))
    i))
 
(intersect '(1 2 3 4) '(3 4 5 6))
;'(3 4)
 
(define (difference lst1 lst2)
  (for/list ([i lst1] #:unless (member i lst2))
    i))
 
(difference '(1 2 3 4) '(3 4 5 6))
;'(1 2)