set-of-set-p：符号的变量值无效：false

Question

我从Sicp最小化了intersction-set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-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

报告错误：

 element-of-set-p: Symbol’s value as variable is void: false

有什么问题？

Answer 1

您的代码中有几次错别字：