scala.collection.breakOut 与视图 [英] scala.collection.breakOut vs views

问题描述

这个 SO 答案 描述了如何使用 scala.collection.breakOut 来防止创建浪费的中间集合.比如这里我们创建一个中间的Seq[(String,String)]:

This SO answer describes how scala.collection.breakOut can be used to prevent creating wasteful intermediate collections. For example, here we create an intermediate Seq[(String,String)]:

val m = List("A", "B", "C").map(x => x -> x).toMap

通过使用breakOut，我们可以防止创建这个中间Seq:

By using breakOut we can prevent the creation of this intermediate Seq:

val m: Map[String,String] = List("A", "B", "C").map(x => x -> x)(breakOut)

视图解决了同样的问题，此外惰性访问元素:

val m = (List("A", "B", "C").view map (x => x -> x)).toMap

我假设 View 包装器的创建相当便宜，所以我的问题是:是否有任何真正的理由使用 breakOut 而不是 Views?

I am assuming the creation of the View wrappers is fairly cheap, so my question is: Is there any real reason to use breakOut over Views?

推荐答案

从 Scala 2.13 开始，这不再是一个问题.Breakout 已被移除，建议替换为视图.

As of Scala 2.13, this is no longer a concern. Breakout has been removed and views are the recommended replacement.

Scala 2.13 集合返工

视图也是 collection.breakOut 的推荐替代品.例如，

val s: Seq[Int] = ... 
val set: Set[String] = s.map(_.toString)(collection.breakOut)

可以用与以下相同的性能特征表示:

val s: Seq[Int] = ... 
val set = s.view.map(_.toString).to(Set)

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