(DEFUN numar(L)
    (COND
        ((NULL L) NIL)

        ((NUMBERP (CAR L))
            (PRINT (CAR L))
            (numar (CDR L))
        )

        (T (numar (CDR L)))
    )
)

;; (SETQ L `(a 5 b c 7))
;; (numar L) ; 5 7

(DEFUN rev (L)
    (COND
        ((NULL L) NIL)

        (T (APPEND
            (rev (CDR L))
            (CONS (CAR L) NIL)
        ))
    )
)

;; (SETQ L `(a 5 b c 7))
;; (setq LREV (rev L))
;; (write LREV) ; (7 C B 5 A)

(DEFUN egal (L1 L2)
    (COND
        ((AND (ATOM L1) (ATOM L2))  (EQ L1 L2))
        ((OR (ATOM L1) (ATOM L2))   NIL)
        ((egal (CAR L1) (CAR L2))  (egal (CDR L1) (CDR L2)))
    )
)

;; (SETQ L1 `(a 5 b c 7))
;; (SETQ L2 `(a 5 b c 7))
;; (SETQ L3 `(b 3 8 1 3))

;; (print (egal L1 L2)) ; T
;; (print (egal L1 L3)) ; NIL

(DEFUN revc (L1 &OPTIONAL REZ)
    (COND
        ((NULL L1) REZ)

        (T (revc
            (CDR L1)
            (CONS (CAR L1) REZ)
        ))
    )
)

;; (SETQ L `(a 5 b c 7))
;; (setq LREV (revc L))
;; (write LREV) ; (7 C B 5 A)