lisp - 和运算符 Lisp

Question

为什么和运算符会返回一个值？返回值取决于什么？

当我尝试以下示例时 -

(write (and a b c d)) ; prints the greatest integer among a b c d

其中a、b、c和d为正整数，则和 code> 返回其中最大的一个。

但是当a、b、c和d其中之一为0或负数时，则取最小的返回整数。为什么会这样？

Answer 1

如 documentation 中所述:

The macro and evaluates each form one at a time from left to right. As soon as any form evaluates to nil, and returns nil without evaluating the remaining forms. If all forms but the last evaluate to true values, and returns the results produced by evaluating the last form. If no forms are supplied, (and) returns t.

因此返回值不取决于参数中“最大”或“最小”的值。