View source for Odd word problem

=={{header|Common Lisp}}==
Even words are straightforward.  For odd words, the final punctuation is printed by a closure passed back up the caller chain.
<syntaxhighlight lang="lisp">(defun odd-word (s)
  (let ((stream (make-string-input-stream s)))
    (loop for forwardp = t then (not forwardp)
          while (if forwardp
                    (forward stream)
                    (funcall (backward stream)))) ))

(defun forward (stream)
  (let ((ch (read-char stream)))
    (write-char ch)
    (if (alpha-char-p ch)
	(forward stream)
        (char/= ch #\.))))

(defun backward (stream)
  (let ((ch (read-char stream)))
    (if (alpha-char-p ch)
        (prog1 (backward stream) (write-char ch))
        #'(lambda () (write-char ch) (char/= ch #\.)))) )
</syntaxhighlight>

Examples:

<syntaxhighlight lang="lisp">? (odd-word "what,is,the;meaning,of:life.")
what,si,the;gninaem,of:efil.
NIL
? (odd-word "we,are;not,in,kansas;any,more.")
we,era;not,ni,kansas;yna,more.
NIL</syntaxhighlight>