Question

我感到困惑。我正在玩常见LISP的第10章中发现的井字游戏：一个温和的符号计算简介 https://www.cs.cmu.edu/~dst/LispBook/book.pdf。我在IDE中完成了所有工作，保存了它然后编译+加载它。我跑了几场比赛都没有问题。所以，我复制了已知工作文件并开始调整。再一次，没有问题 - 一切都运转良好。然而，现在，当我跑（玩一场比赛）时，我收到以下错误：

错误：尝试获取未绑定变量的值＆＃39; * OPPONENT **＆＃39;

我在原件和副本中都收到错误。我关闭了AllegroCL并重新启动了我的计算机，但重启后问题仍然存在。然后我更新了程序并在它的app目录中运行了./update.sh。

最后，我决定将PDF中的示例直接复制到另一个目录中的全新文件中，我遇到了同样的问题。我不知道发生了什么变化，但至少可以说我这么做了。

(defun make-board ()
  (list 'board 0 0 0 0 0 0 0 0 0))

(defun convert-to-letter (v)
  (cond ((equal v 1) "O")
        ((equal v 10) "X")
        (t " ")))

(defun print-row (x y z)
  (format t "~& ~A | ~A | ~A"
    (convert-to-letter x)
    (convert-to-letter y)
    (convert-to-letter z)))

(defun print-board (board)
  (format t "~%")
  (print-row
   (nth 1 board) (nth 2 board) (nth 3 board))
  (format t "~& -----------")
  (print-row
   (nth 4 board) (nth 5 board) (nth 6 board))
  (format t "~& -----------")
  (print-row
   (nth 7 board) (nth 8 board) (nth 9 board))
  (format t "~%~%"))

(defun make-move (player pos board)
  (setf (nth pos board) player)
  board)

(setf *triplets*
  '((1 2 3) (4 5 6) (7 8 9) ;Horizontal triplets.
    (1 4 7) (2 5 8) (3 6 9) ;Vertical triplets.
    (1 5 9) (3 5 7))) ;Diagonal triplets.

(defun sum-triplet (board triplet)
  (+ (nth (first triplet) board)
     (nth (second triplet) board)
     (nth (third triplet) board)))

(defun compute-sums (board)
  (mapcar #'(lambda (triplet)
              (sum-triplet board triplet))
    *triplets*))

(defun winner-p (board)
  (let ((sums (compute-sums board)))
    (or (member (* 3 *computer*) sums)
        (member (* 3 *opponent*) sums))))

(defun play-one-game ()
  (if (y-or-n-p "Would you like to go first? ")
      (opponent-move (make-board))
    (computer-move (make-board))))

(defun opponent-move (board)
  (let* ((pos (read-a-legal-move board))
         (new-board (make-move
                     *opponent*
                     pos
                     board)))
    (print-board new-board)
    (cond ((winner-p new-board)
           (format t "~&You win!"))
          ((board-full-p new-board)
           (format t "~&Tie game."))
          (t (computer-move new-board)))))

(defun read-a-legal-move (board)
  (format t "~&Your move: ")
  (let ((pos (read)))
    (cond ((not (and (integerp pos)
                     (<= 1 pos 9)))
           (format t "~&Invalid input.")
           (read-a-legal-move board))
          ((not (zerop (nth pos board)))
           (format t
               "~&That space is already occupied.")
           (read-a-legal-move board))
          (t pos))))

(defun board-full-p (board)
  (not (member 0 board)))

(defun computer-move (board)
  (let* ((best-move (choose-best-move board))
         (pos (first best-move))
         (strategy (second best-move))
         (new-board (make-move
                     *computer* pos board)))
    (format t "~&My move: ~S" pos)
    (format t "~&My strategy: ~A~%" strategy)
    (print-board new-board)
    (cond ((winner-p new-board)
           (format t "~&I win!"))
          ((board-full-p new-board)
           (format t "~&Tie game."))
          (t (opponent-move new-board)))))

(defun random-move-strategy (board)
  (list (pick-random-empty-position board)
        "random move"))


(defun pick-random-empty-position (board)
  (let ((pos (+ 1 (random 9))))
    (if (zerop (nth pos board))
        pos
      (pick-random-empty-position board))))

(defun make-three-in-a-row (board)
  (let ((pos (win-or-block board
                           (* 2 *computer*))))
    (and pos (list pos "make three in a row"))))


(defun block-opponent-win (board)
  (let ((pos (win-or-block board
                           (* 2 *opponent*))))
    (and pos (list pos "block opponent"))))


(defun win-or-block (board target-sum)
  (let ((triplet (find-if
                  #'(lambda (trip)
                      (equal (sum-triplet board
                                          trip)
                             target-sum))
                  *triplets*)))
    (when triplet
      (find-empty-position board triplet))))


(defun find-empty-position (board squares)
  (find-if #'(lambda (pos)
               (zerop (nth pos board)))
           squares))

(defun choose-best-move (board) ;Second version.
  (or (make-three-in-a-row board)
      (block-opponent-win board)
      (random-move-strategy board)))

Answer 1

如果您按照本书的说明操作，它会告诉您调用

(setf *computer* 10)
(setf *opponent* 1)

显然你没有在你的代码清单中包含它。

一般情况下 - 如果您收到某些内容未绑定的错误，那么显而易见的事情就是查找应该将其绑定到值的代码。

Common-Lisp Code工作正常，现在“错误：尝试获取未绑定变量`* OPPONENT *'的值。”

1 个答案: