实施计划中的清单 [英] Implementing has-list in scheme

问题描述

如何递归实现Scheme函数has-list，该功能测试列表是否包含其他列表作为元素.例如((has-list'(1 2 3))应该返回false，而(has-list'(1 2(3 4)5))应该返回true.

how can you implement a Scheme function has-list recursively, which tests whether a list contains other list as an element. For example (has-list '(1 2 3)) should return false, and (has-list '(1 2 (3 4) 5)) should return true.

推荐答案

如果您需要递归且不使用map进行操作:

If you need to do it recursively and without using map:

 (define (has-list? lst)
    (cond
      ((null? lst) #f)
      ((list? (car lst)) #t)
      (else (has-list? (cdr lst)))))

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