Source code in the common programming language

(defun rosetta-y-or-n ()
  (clear-input *query-io*)
  (y-or-n-p))


(defun y-or-n ()
  (clear-input *standard-input*)
  (loop as dum = (format t "Y or N for yes or no: ")
        as c = (read-char)
        as q = (and (not (equal c #\n)) (not (equal c #\y)))
        when q do (format t "~%Need Y or N~%")
        unless q return (if (equal c #\y) 'yes 'no)))


(defun y-or-no ()
  (with-screen (scr :input-buffering nil :input-blocking t)
    (clear scr)
    (princ "Do you want to continue? [Y/N]" scr)
    (refresh scr)
    (event-case (scr event)
      ((#\Y #\y) (return-from event-case t))
      ((#\N #\n) (return-from event-case nil)))))