(defun modify-file (in function &optional (out in))
  (let ((content (with-open-file (stream in :direction :input)
                   (with-output-to-string (string)
                     (let ((buffer (make-array 4096 :element-type 'character)))
                       (loop for bytes = (read-sequence buffer stream)
                             do (write-sequence buffer string :start 0 :end bytes)
                             while (= bytes 4096)))))))
    (with-open-file (stream out :direction :output :if-exists :supersede)
      (write-sequence (funcall function content) stream))))

(modify-file #p"wordlist.txt" #'(lambda (a) (cl-ppcre:regex-replace-all "([^×]*)×(.*)\\n" a "\\2 \\1
")))