gistfile1.lisp

(ql:quickload "flexi-streams")

(defvar *words*
  (with-open-file (stream "dict" :element-type '(unsigned-byte 8))
    (let ((stream (flexi-streams:make-flexi-stream
                   stream :external-format :utf-8)))
      (loop for line = (read-line stream nil 'eof)
         until (eq line 'eof) collect
           (list (sort (coerce (string-downcase line) 'list) #'char<) line)))))

(defun string-minus (anagram word)
  (labels ((iter (anagram word)
             (cond ((or (null word) (null anagram)) anagram)
                   ((equal (car anagram) (car word))
                    (iter (cdr anagram) (cdr word)))
                   (t (iter anagram (cdr word))))))
    (iter anagram word)))

(defun find-anagrams (word &key reuse)
  (let ((diff (if reuse #'set-difference #'string-minus))
        (word (sort (coerce (string-downcase word) 'list) #'char<)))
    (loop for (sorted str) in *words*
       unless (funcall diff sorted word) collect str)))