Execute LISP Online

;; 11) Escriba una función Filtra-vocales que reciba como argumento una lista (con elementos de
;; cualquier tipo y anidada a cualquier nivel de profundidad) y, como respuesta entregue una copia
;; de la lista argumento en la cual se han removido las letras vocales (tanto mayúsculas como
;; minúsculas).
;; Answer: A simbol is not a vowel
(defun vocal? (elem)
    (or (equal current #\a)
		 (equal current #\e)
		 (equal current #\i)
		 (equal current #\o)
		 (equal current #\u)
		 (equal current #\A)
		 (equal current #\E)
		 (equal current #\I)
		 (equal current #\O)
		 (equal current #\U)
		 (equal current "a")
		 (equal current "e")
		 (equal current "i")
		 (equal current "o")
		 (equal current "u")
		 (equal current "A")
		 (equal current "E")
		 (equal current "I")
		 (equal current "O")
		 (equal current "U")))

(defun vowelsFilter (list)
    (let ((current (first list))
         (left (rest list)))
        (cond ((null list) NIL)
            ((listp current) (append (flatten current) (flatten left)))
            ((not (vocal? current)) (append (list current) (flatten left))))))
;; Tests:
(print (vowelsFilter '(1 "a" c (a (#\a) #\c))))      ;; => (1 C A #\c)
(print (vowelsFilter '((4) (#\c) T ("b") (a (b) c))));; => (4 #\c T "b" A B C)
(print (vowelsFilter '(0 #\a (b) 1.2 (4 ("u") 3/2))));; => (0 B 1.2 4 3/2)
(print (vowelsFilter '(2 T "e" ((("o")) ("i") bc)))) ;; => (2 T BC)
(print "================================================")