(defun palindrome-p (str)
  (let ((str (remove-if-not #'alpha-char-p str)))
    (string-equal str (reverse str))))

(defun check-palindrome (str)
  (format t "~s is ~:[NOT ~;~]a palindrome.~%"
		  str (palindrome-p str)))

(check-palindrome "boo")
(check-palindrome "A man, a plan, a cat, a ham, a yak, a yam, a hat, a canal-Panama!")
(check-palindrome "A tin mug for a jar of gum, Nita.")
(check-palindrome "A Toyota! Race fast, safe car! A Toyota!")