じゃんけん

janken.lisp

;;; * (read-hand)
;;; > rock
;;; ROCK
;;; > very-dangerous-words
;;; hands: rock, paper, scissor
;;; >
(defun read-hand ()
  (princ "> ")
  (finish-output) ;SBCLの最適化によるIO順序の入れ替わりを防ぐ
  (let ((p-hand (read)))
       (if (member p-hand '(rock paper scissor))
         p-hand
         (progn (princ "hands: rock, paper, scissor") (fresh-line) (finish-output) (read-hand)))))

(defun select-hand ()
  (case (random 3 (make-random-state t))
    (0 'rock)
    (1 'paper)
    (2 'scissor)))

(defun eval-hand (p-hand np-hand)
  (cond ((eq p-hand np-hand) "draw")
        ((member (cons p-hand np-hand) '((rock . scissor) (scissor . paper) (paper . rock)) :test #'equal) "you win")
        (t "you lose")))

;;; ROCK vs SCISSOR -> you win
(defun print-hand (p-hand np-hand game-result)
  (format t "~A vs ~A -> ~A~%" p-hand np-hand game-result))

(defun game-loop ()
  (let ((p-hand (read-hand)) (np-hand (select-hand)))
       (print-hand p-hand np-hand (eval-hand p-hand np-hand)))
  (game-loop))