2021/11/2 paradigm 笔记_paradigm epos教程

1 嵌套列表结构的遍历

if … else … 的注意事项：

1.1 cond

cond是if…else… 的扩展，能够级联实现if… else if… else…

1.2 递归实现flatten函数

(define (flatten sequence)
      (cond ((null? sequence) '())
            ((list? (car sequence))
                    (append (flatten (car sequence))
                            (flatten (cdr sequence))))
            (else (cons (car sequence)
                        (flatten (cdr sequence))))))
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