功能和列表在计划/球拍 [英] functions and lists in scheme/racket

问题描述

你如何定义一个带有一个参数的函数，它应该是一个列表，并返回
列表中的元素，它们本身就是列表？

<$ （$）$ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $

解决方案

通过一个列表？

与原始相同的一个简单的问题是这样的：设计一个函数，它需要一个数字列表，并只保留偶数。你能做到这一点吗？

看看 http://www.ccs.neu.edu/home/matthias/HtDP2e/htdp2e-part2.html 并且通过其指导练习也可能有所帮助。

How would you define a function which takes one argument, which should be a list, and returns the elements in the list which are themselves lists?

(check-expect (find-sublists ’(1 2 () (3) (a b c) a b c)) 
              ’(() (3) (a b c)))

解决方案

Do you have experience designing functions that can filter through a list?

A simpler problem with the same flavor as the original is something like this: design a function that takes a list of numbers and keeps only the even numbers. Would you be able to do that function?

Looking at http://www.ccs.neu.edu/home/matthias/HtDP2e/htdp2e-part2.html and going through its guided exercises may also help.

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