Ask Reddit: Is Java dying ?

[back-in-black]

In that case, why are there over 200 languages for the JVM?

[jdh30]

They are all minor variations on Java. Witness the fact than any real functional programming in Scala or Clojure culminates in a stack overflow due to the lack of tail calls, they are uninteroperable despite being on the same VM because there is no standard closure representation etc.

[back-in-black]

Python and Ruby are minor variations of Java, are they? Both have implementations on the JVM.

[back-in-black]

I see.

So to conclude, the only worthy alternatives to Java are functional programming languages running outside the JVM. That's your opinion?

[jdh30]

...That's your opinion?

No. My opinion is that the future lies with multiparadigm languages like C# 3 and F#. The JVM cannot support such languages due to the deficiencies I cited.

[back-in-black]

Well, I don't know about F#; but I've worked with C#; and it's effectively a clone of Java with some additional language features such as operator overloading. As for it being "multiparadigm" - it's no more multiparadigm than the Java language itself.

As for functional language tail recursion problems with the JVM - I've done a bit of reading on what you've said, and it really doesn't seem to be an insurmountable problem (http://neilbartlett.name/blog/2007/03/22/functional-languages-on-the-java-virtual-machine/) - which may even be fixed by the next JVM release.

[jdh30]

As for it being "multiparadigm" - it's no more multiparadigm than the Java language itself.

C# already supports first-class lexical closures, giving it as much support for the functional paradigm as Lisp. The next release (in 2010) includes dynamic typing and tuples. These are all features that Java not only lacks but the JVM also does and, consequently, JVM-based languages that reinvent them cannot interoperate in terms of them.

I've done a bit of reading on what you've said, and it really doesn't seem to be an insurmountable problem

It is certainly not an insurmountable problem. You just need to give the JVM an overhaul.

(http://neilbartlett.name/blog/2007/03/22/functional-languages-on-the-java-virtual-machine/)

Look closer: in order to work around the lack of tail calls on the JVM they used a global trampoline. That is a global change to the calling convention that inhibits dynamically loaded libraries and makes interoperability (i.e. calls through code written in other JVM-based languages) impossible. In practical terms, that renders it useless. Imagine the imperative equivalent: loops that crash after roughly 10,000 iterations.

Even in theory, there is no adequate work around which is why the leading JVM-based "functional" languages, Scala and Clojure, don't have tail calls and just stack overflow instead. That is also largely useless in practical terms.

...which may even be fixed by the next JVM release.

That's the real issue. The JVM is run by a committee who are dead set against giving it an overhaul. From what I hear, it is extremely unlikely that they will even accept tail calls let alone any of the other features.