Little Schemer第4版:rember函数讨论 [英] The Little Schemer 4th Edition: rember function discussion

问题描述

在简化了rember函数后的第41页上，有一个问题回答我不太了解.

On page 41 after simplification of the rember function, there is a question-respond that I don't understand very well.

Q: So why don't we simplify right away?
R: Because then a function's structure does not coincide with its argument's structure. 

我已经尝试了几天，但我不明白回答这个问题的确切含义.

I have tried to figure it out for a couple of days, but I don't understand what exactly means that question-respond.

有人能解释我弗里德曼想回答的问题吗?

Could anyone explain me what Friedman want to show with that question-respond?

预先感谢

推荐答案

直到本章这一点为止，列表的递归都是使用带有两个条件的cond编写的，其中第二个条件又是另一个.这就是作者对参数结构"(列表)与函数结构"(两个条件cond)不一致的意思-因为现在函数被构造为具有三个条件的单个cond，更简单而且更容易理解.

Up until this point in the chapter, recursions on lists had been written using a cond with two conditions, where the second condition was in turn another cond. That's what the author meant with "the argument structure" (a list) not coinciding with "the function structure" (a two-condition cond) - because now the function is structured as a single cond with three conditions, simpler and easier to understand.

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