Scala 集合不一致 [英] Scala Collections inconsistencies

问题描述

为什么 Scala Collections API 中的 Sets 和 Lists 之间缺乏一致性?

Why is there a lack of consistency between Sets and Lists in Scala Collections API?

比如有不可变的Set，也有可变的.如果我想使用后者，我可以简单地这样做:

For example, there is immutable Set, but also a mutable one. If I want to use the latter, I can simply do this:

val set = Set[A]()
set += new A

然而，本质上没有可变列表.如果我想使用 Lists 编写类似的代码片段，该使用哪种数据结构?LinkedList 听起来是一个不错的候选者，因为它是可变的，但没有定义 += 方法.ListBuffer 似乎满足要求，但它不是一个列表.

However, there is no mutable List, per se. If I want to write a similar code snippet using Lists, which data structure to use? LinkedList sounds as a good candidate, because it is mutable, but has no += method defined. ListBuffer seems to satisfy the requirements, but it is not a list.

阅读 2.8 Collections 文档后，我得出结论 MutableList 可能是最合适的.

After reading 2.8 Collections docs I come to the conclusion MutableList is probably the best fit.

我仍然希望有 scala.collection.mutable.List.

I still somehow wish there was scala.collection.mutable.List.

推荐答案

这样做的原因是 Java 选择了 functional List 类型来表示某些东西它不是(即 java.util.List 不是 list).

The reason for this is that Java has co-opted the functional List type to mean something that it is not (i.e. java.util.List is not a list).

对于函数式编程语言来说，拥有 mutable List 可能没有意义，因为这样的类型是矛盾的.因此ListBuffer 或ArrayBuffer.或者直接使用IndexedSeq，其中有可变和不可变的实现

It probably makes no sense for a functional programming language to have a mutable List as such a type is an oxymoron. Hence ListBuffer or ArrayBuffer. Or just use IndexedSeq, of which there are mutable and immutable implementations

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