Debugging 集合p元素:符号作为变量的值无效:false
I minic从sicp执行的区间集操作Debugging 集合p元素:符号作为变量的值无效:false,debugging,emacs,sicp,Debugging,Emacs,Sicp,I minic从sicp执行的区间集操作 #+name: case-2.3.3-element-of-set-p #+BEGIN_SRC elisp :session sicp :results value (defun element-of-set-p(x set) (cond ((null set) false) ((equal x (car set)) t) (t (element-of-setp x (cdr set))))) (element-of-
#+name: case-2.3.3-element-of-set-p
#+BEGIN_SRC elisp :session sicp :results value
(defun element-of-set-p(x set)
(cond ((null set) false)
((equal x (car set)) t)
(t (element-of-setp x (cdr set)))))
(element-of-set-p 1 (list 1 2 3))
#+END_SRC
#+RESULTS: case-2.3.3-element-of-set-p
: t
和交集
#+BEGIN_SRC elisp :session sicp :results value
(defun intersection-set (set1 set2)
(cond ((or (null set1) (null set2))
'())
((element-of-set-p (car set1) set2)
(cons (car set1)
(intersection-set (cdr set1)
set2)))
(t (intresection-set (cdr set1)
set2))))
(trace-function #'intersection-set)
(intersection-set (list 1 2) (list 2 3 4))
#+END_SRC
It报告错误:
element-of-set-p: Symbol’s value as variable is void: false
有什么问题吗 您的代码中有几个输入错误: 这不是setp的元素,而是setp的元素 这不是交集,这是交集 这不是假的,是零 这应该起作用:
(defun element-of-set-p (x set)
(cond ((null set) nil)
((equal x (car set)) t)
(t (element-of-set-p x (cdr set)))))
(defun intersection-set (set1 set2)
(cond ((or (null set1) (null set2))
'())
((element-of-set-p (car set1) set2)
(cons (car set1)
(intersection-set (cdr set1) set2)))
(t (intersection-set (cdr set1) set2))))