我正在尝试在 Lisp 中编写一个数字猜谜游戏，作为一个消磨时间的项目。但是，当我尝试使用 SBCL 加载程序时，出现以下错误：
debugger invoked on a SB-C::INPUT-ERROR-IN-COMPILE-FILE in thread #<THREAD
"initial thread" RUNNING
{AA14959}>:
READ failure in COMPILE-FILE at character 477:
end of file on #<SB-SYS:FD-STREAM
for "file /home/andy/Dropbox/Programming/Common Lisp/number-game.lisp"
{B4F45F9}>
Type HELP for debugger help, or (SB-EXT:QUIT) to exit from SBCL.
restarts (invokable by number or by possibly-abbreviated name):
0: [CONTINUE] Ignore runtime option --load "number-game.lisp".
1: [ABORT ] Skip rest of --eval and --load options.
2: Skip to toplevel READ/EVAL/PRINT loop.
3: [QUIT ] Quit SBCL (calling #'QUIT, killing the process).
(SB-C::READ-FOR-COMPILE-FILE
#<SB-SYS:FD-STREAM
for "file /home/andy/Dropbox/Programming/Common Lisp/number-game.lisp"
{B4F45F9}>
477)
这个错误是什么意思？代码如下，加载文件(play)从REPL调用时出现错误：
;;;; number-game.lisp
;;;;
;;;; Andrew Levenson
;;;; 10/25/2010
;;;;
;;;; Simple number guessing game. User has
;;;; five guesses to determine a number between
;;;; one and one hundred, inclusive (1-100).
;;; Set global variable for the target number:
(defparameter *target* nil)
;;; Set the iterator so we may check the number of guesses
(defparameter *number-of-guesses* 0)
;;; Welcome the user
(defun welcome-user ()
(format t "Welcome to the number guessing game!~%"))
;;; Prompt for a guess
(defun prompt-for-guess ()
(format t "Please enter your guess (1-100): ")
(finish-output nil) ; nil directs finish-output to standard IO
(check-guess((read-guess)))
;;; Read in a guess
(defun read-guess ()
(let ((guess (read)))
(if (numberp guess) ; If true, return guess. Else, call prompt-for-guess
(progn
(setq *number-of-guesses* (+ *number-of-guesses* 1))
guess)
(prompt-for-guess))))
;;; Check if the guess is higher than, lower than, or equal to, the target
(defun check-guess (guess)
(if (equal guess *target*)
(equal-to)
(if (> guess *target*)
(greater-than (guess))
(if (< guess *target*)
(less-than (guess))))))
;;; If the guess is equal to the target, the game is over
(defun equal-to ()
(format t "Congratulations! You have guessed the target number, ~a!~%" *target*)
(y-or-n-p "Play again? [y/n] "))
;;; If the guess is greater than the target, inform the player.
(defun greater-than (guess)
(format t "Sorry, ~a is greater than the target.~%" guess)
(if (< *number-of-guesses* 6)
(prompt-for-guess)
(game-over)))
;;; If the guess is less than the target, inform the player.
(defun less-than (guess)
(format t "Sorry, ~a is less than the target.~%" guess)
(if (< *number-of-guesses* 6)
(prompt-for-guess)
(game-over)))
;;; If the player has run out of guesses, give them the option
;;; of playing the game again.
(defun game-over ()
(y-or-n-p "You have run out of guesses. Play again? [y/n] "))
;;; Play the game
(defun play ()
;; If it's their first time playing this session,
;; make sure to greet the user.
(unless (> *number-of-guesses* 0)
(welcome-user))
;; Reset their remaining guesses
(setq *number-of-guesses* 0)
;; Set the target value
(setq *target*
;; Random can return float values,
;; so we must round the result to get
;; an integer value.
(round
;; Add one to the result, because
;; (random 100) yields a number between
;; 0 and 99, whereas we want a number
;; from 1 to 100 inclusive.
(+ (random 100) 1)))
(if (equal (prompt-for-guess) "y")
(play)
(quit)))
（我相当肯定该程序在减去那个错误后无法工作，当谈到 Lisp 时，我仍然是一个完整的新手。这只是我遇到的第一个错误，我无法弄清楚我的自己的。）
哦，问题很可能与prompt-for-guess,read-guess和check-guess函数有关，因为当出现此错误时，我正在处理这些函数。