为什么在Clojure中Maybe / Option的使用不那么普遍？ [英] Why is the use of Maybe/Option not so pervasive in Clojure?

问题描述

为什么Clojure尽管强调了功能范例，却不使用 Maybe / Option 可选值？在我使用的函数式编程语言Scala中， Option 的使用非常普遍。

Why does Clojure, despite such an emphasis on functional paradigm, not use the Maybe/ Option monad to represent optional values? The use of Option is quite pervasive in Scala, a functional programming language I use regularly.

推荐答案

Clojure不是静态类型，所以不需要严格的this / that /任何类型的声明在haskell （和，我收集，斯卡拉）。如果你想返回一个字符串，你返回一个字符串;如果你返回nil，那也没问题。

Clojure is not statically typed, so doesn't need the strict this/that/whatever type declarations that are necessary in haskell (and, I gather, Scala). If you want to return a string, you return a string; if you return nil instead, that's okay too.

Functional不完全对应于严格的编译时打字。它们是正交概念，Clojure选择动态类型。事实上，在一段时间之后，我无法想象如何实现许多高级函数，如 map ，仍然保留静态类型。现在我有一个（很少）Haskell的经验，我可以看到，这是可能的，而且的确经常相当优雅。我怀疑，如果你玩Clojure一段时间，你会有相反的经验：你会意识到类型声明不是必要的给你的那种力量，你习惯了在功能语言中。

"Functional" does not correspond exactly to "strict compile-time typing". They are orthogonal concepts, and Clojure chooses dynamic typing. In fact, for quite some time I couldn't imagine how you could implement many of the higher-order functions like map and still preserve static typing. Now that I have a little (very little) experience with Haskell, I can see that it's possible, and indeed often quite elegant. I suspect that if you play with Clojure for a while, you will have the opposite experience: you'll realize the type declarations aren't necessary to give you the kind of power you're used to having in a functional language.

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