lambda - 应该是lambda表达式-LISP

Question

我的代码只有一个功能:

(defun equalprev (x y)
  (cond ((or (atom x) (atom y))
         (if (not (null isLoop))
             t
           ((setq list1 (append list1 (list x)))
            (setq list2 (append list2 (list y)))
            (eql x y))))
        ((equalprev (car x) (car y))
         (equalprev (cdr x) (cdr y)))))

*** - SYSTEM::%EXPAND-FORM: (SETQ LIST1 (APPEND LIST1 (LIST X))) should be a `lambda`
expression
The following restarts are available:
ABORT          :R1      Abort main loop

感谢任何帮助

Answer 1

'if' 表达式的替代表达式是 ((set! ...) ...)。第一个位置需要是函数或句法形式。在这种情况下你需要 progn as:

(progn
  (setq list1 ...)
  (setq list2 ...)
  (eql x y))