scala中的递归是非常必要的吗？ [英] Is recursion in scala very necessary?

问题描述

在coursera scala教程中，大多数示例都使用自上而下的迭代。部分地，正如我所看到的，迭代用于避免for / while循环。我来自C ++，对此感到有些困惑。

迭代选择了/ while循环吗？它在生产中是否实用？任何风险的stackoverflow？效率如何？如何自下而上的动态规划（特别是当他们不是尾巴回收）？

另外，我应该使用更少的if条件，而是使用更多的case和子类？

解决方案

真正高质量的Scala将使用非常少的迭代并且只有更多的递归。循环使用较低级的命令式语言通常最好使用高阶combinator，特别是map和flatmap，而且还要过滤，zip，fold，foreach，reduce，collect，partition，scan，groupBy和a好几个人。迭代最好只在性能关键部分完成，而递归只在高阶组合器不太适合的情况下（通常不是尾递归，fwiw）进行。在生产系统的三年编码Scala中，我使用迭代一次，递归两次，每天映射五次。

In the coursera scala tutorial, most examples are using top-down iterations. Partially, as I can see, iterations are used to avoid for/while loops. I'm from C++ and feel a little confused about this.

Is iteration chosen over for/while loops? Is it practical in production? Any risk of stackoverflow? How about efficiency? How about bottom up Dynamic Programming (especially when they are not tail-recusions)?

Also, should I use less "if" conditions, instead use more "case" and subclasses?

解决方案

Truly high-quality Scala will use very little iteration and only slightly more recursion. What would be done with looping in lower-level imperative languages is usually best done with higher-order combinators, map and flatmap most especially, but also filter, zip, fold, foreach, reduce, collect, partition, scan, groupBy, and a good few others. Iteration is best done only in performance critical sections, and recursion done only in a some deep edge cases where the higher-order combinators don't quite fit (which usually aren't tail recursive, fwiw). In three years of coding Scala in production systems, I used iteration once, recursion twice, and map about five times per day.

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