JVM是否会阻止尾调用优化？ [英] Does the JVM prevent tail call optimizations?

问题描述

我在这个问题上看到了这句话：构建网络服务的优秀功能语言是什么？

I saw this quote on the question: What is a good functional language on which to build a web service?

除了自递归函数外，Scala特别不​​支持尾调用消除，这限制了你可以做的组合种类（这是一个JVM的基本限制。

Scala in particular doesn't support tail-call elimination except in self-recursive functions, which limits the kinds of composition you can do (this is a fundamental limitation of the JVM).

这是真的吗？如果是这样，那么创建这个基本限制的JVM是什么呢？

Is this true? If so, what is it about the JVM that creates this fundamental limitation?

推荐答案

这篇文章：递归或迭代？可能有所帮助。

This post: Recursion or Iteration? might help.

简而言之，尾调用由于安全模型以及始终需要堆栈跟踪的需要，在JVM中很难进行优化。理论上可以支持这些要求，但可能需要一个新的字节码（参见 John Rose的非正式提案） ）。

In short, tail call optimization is hard to do in the JVM because of the security model and the need to always have a stack trace available. These requirements could in theory be supported, but it would probably require a new bytecode (see John Rose's informal proposal).

Sun bug＃4726340 ，其中评估（从2002年开始）结束：

There is also more discussion in Sun bug #4726340, where the evaluation (from 2002) ends:

I相信这可以做到，但这不是一个小任务。

I believe this could be done nonetheless, but it is not a small task.

目前，在中有一些工作正在进行href =http://openjdk.java.net/projects/mlvm/subprojects.html =nofollow noreferrer>达芬奇机器项目。尾调用子项目的状态列为proto 80％;它不太可能进入Java 7，但我认为它在Java 8上有很好的机会。

Currently, there is some work going on in the Da Vinci Machine project. The tail call subproject's status is listed as "proto 80%"; it is unlikely to make it into Java 7, but I think it has a very good chance at Java 8.

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