clisp:变量x没有值

Question

我variable MAP has no value在Common Lisp代码中收到错误(我在Ubuntu终端中使用clisp shell).我的代码看起来像这样(*map*只是一个关联列表,所以你可以跳过它):

(setf *map* '((shore (stars cast reflections on the rippling sea.  
                            it fills you with a strong but unplaceable emotion.) 
                     (east forest))
              (forest (a roof of treetops blots out the sun.  something rustles 
                         behind you.) 
                      (west shore) 
                      (north cliff))
              (cliff (you nearly stumble into a long and fatal fall into the 
                          sea far below you.  you feel a strange urge to throw 
                          yourself off the ledge.  it would probably wisest to 
                          leave this place.) 
                     (south forest))))

(defun walk-direction (direction room map)
  (second (assoc direction (cddr (assoc room map)))))

(defmacro defspel (&rest rest) `(defmacro ,@rest))

(defspel walk-to (direction room map)
  `(walk-direction ',direction ',room map))

(walk-to east shore *map*)

(我正在关注liserpati教程,对那些想知道我可能犯下的任何奇怪的事情)

如果改变步行到

(defspel walk-to (direction room)
  `(walk-direction ',direction ',room *map*))

那一切都很顺利.然而,这打破了函数式编程的美妙习惯,我希望尽可能保持完整 - 更不用说我仍然不知道为什么我的代码不起作用的事实.

Answer 1

之前的定义walk-to是缺少逗号map.看一下输出:

(macroexpand-1 '(walk-to east shore *map*))