(defun accumulate (xss)
  ;; Take a list of lists, and consolidate sublists with a common
  ;; first element.
  (if (<= (length xss) 1) xss
    (if (string-equal (caar xss) (caadr xss))
	(accumulate (cons (cons (caar xss) (append (cdar xss) (cdadr xss)))
			  (cddr xss)))
      (cons (car xss) (accumulate (cdr xss))))))

(defun anags (words)
  ;; Take a list of strings, and return a list of lists of strings
  ;; which are anagrams of each other.
  (let ((a (mapcar (lambda (x) (list (sort (copy-seq x) #'char-lessp) x))
		   words)))
    (mapcar #'rest
	    (remove-if (lambda (x) (<= (length x) 2))
		       (accumulate (sort a #'string-lessp :key #'first))))))

(defun anags-file (filename)
  ;; Read a list of strings from named file, print sets of anagrams
  ;; on stdout.
  (with-open-file (in-stream filename :direction :input)
    (mapcar (lambda (x) (format t "~{~A ~}~&" x))
	    (anags (loop for line = (read-line in-stream nil)
		     until (equal line nil) collect line))))
  nil)