comment from James Gosling on multi-language VM

[John Rose]

James made some relevant comments on the JVM as a multi-language engine.

It was just a little while ago, as I noticed going through some old files.

Folks are still working on specialized allocation (aka. value types) and continuations (aka. coroutines & tailcall).

Also, C is no longer "right out"; see Project Panama.

— John

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hotjava-interest-digest        Sunday, 2 April 1995        Volume 01 : Number 024


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From: richard at cogsci.ed.ac.uk
Date: Fri, 31 Mar 95 13:30:04 BST
Subject: How general is the Java bytecode language?

Has anyone looked at the possibility of compiling languages other than
Java to the Java bytecodes?  In particular, there seem to be many people
interested in using Scheme as a scripting language, and the ability
to download Scheme programs into HotJava would be nice.

- -- Richard

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From: jag at scndprsn.Eng.Sun.COM (James Gosling)
Date: Fri, 31 Mar 1995 20:34:24 +0800
Subject: Re: How general is the Java bytecode language?

> Has anyone looked at the possibility of compiling languages other than
> Java to the Java bytecodes?  In particular, there seem to be many people
> interested in using Scheme as a scripting language, and the ability
> to download Scheme programs into HotJava would be nice.

It's reasonably general, although the security restrictions make some
languages hard.  C and C++ with general pointer arithmetic are right
out.  Fortran's pass-by-reference call semantics and "common" are
tough.  Pascal is pretty straightforward.  Scheme is easy or hard,
depending on how good you want the performance to be: the invocation
model in Java is very C like with no provision for continuations.
Continuations can be handled as classes & the key trick in a compiler
would be to decide when a full-blown continuation can be optimized
away.  The story is similar with datatypes like numbers: in general,
every number would be an instance of some class & the trick is to
optimize that into direct machine instructions.  Using the Java
bytecodes is likely to be somewhat less than optimal because things
like continuations and general numbers need to be done as classes, the
underlying engine doesn't have things like specialized allocators for
boxed integers.


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