L1_soca, Common Lisp

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;gnu clisp 2.49

;8
;a) Write a function to return the difference of two sets

;function which verifies the membership of an element into a list
(defun memberList(list E)
    (cond
        ((= 0 (length list)) nil)
        ((and (numberP (car list)) (numberP E) (= E (car list)) ) t)
        ((and (numberP E) (listP (car list)) (memberList (car list) E)) t)
        ((and (listP E) (listP (car list)) (equal E (car list))) t)
        (t (memberList (cdr list) E))
    )
)

;main function
(defun difference(set1 set2)
    (cond
       ((null set1) nil)
       ((memberList set2 (car set1)) (append (difference (cdr set1) set2)))
       (t (cons (car set1) (difference (cdr set1) set2)))
    )
)

;wrapper
(defun wrapper(set1 set2)
    (append (difference set1 set2) (difference set2 set1))
)

(print (wrapper '(1 2 3 4 5 6) '(1 4 7 5 3)))

;b) Write a function to reverse a list with its all sublists, on all levels.

;c) Write a function to return the list of the first elements of all list elements of a given list with an odd
;number of elements at superficial level. Example:
; (1 2 (3 (4 5) (6 7)) 8 (9 10 11)) => (1 3 9).

(defun func(lis)
    (cond
        ((listp lis) (if (oddp (length lis)) (cons (car lis) (mapcar #' func lis)) (mapcar #' func lis)) )
        (t '())
    )
)

(print (func '(1 2 (3 (4 5) (6 7)) 8 (9 10 11)) ))

;d) Write a function to return the sum of all numerical atoms in a list at superficial level.

(defun fund(lis)
     (cond
         ((null lis) 0)
         ((numberp lis) lis)
         ((atom lis) 0)
         (t (apply #' +(mapcar #' fund lis)))
     )
)

(print (fund '(1 2 (4 (d 2 0) 7) 5) ))

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