&rest [discussion] replacement/addition

[Barry Margolin <barmar@Think.COM>]

I noticed you didn't try the following version.  This is identical to
the version you included in your message, except that it takes the
previous words as a single argument rather than as an &REST argument.
One definite advantage of this version is that it won't exceed
CALL-ARGUMENTS-LIMIT if it recurses deeply.

(defun anagrams (string &optional previous-words)
   (let ((chars (unused-characters string previous-words)))
      (if chars
	  ;; there are unused characters left
	  (let ((new-word (find-word chars)))
	     (when new-word
		 ;; found a new word
		 (anagrams string (cons new-word previous-words))
		 ;; if no new word could be found, just return  
		 ))
	  ;; all characters are used by previous-words, we have a weiner
	  (save-and/or-print-anagram string previous-words)
	  )))