Re: [Caml-list] A js_of_ocaml equivalent for the JVM?

[Philippe Veber <philippe.veber@gmail.com>]

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Thank you Xavier and Johan for the replies.

2012/3/9 forum@x9c.fr <forum@x9c.fr>

>
> Le 9 mars 2012 à 18:45, Johan Grande a écrit :
>
> > Le 09/03/2012 18:12, Philippe Veber a écrit :
> >> Dear camlers,
> >> I used js_of_ocaml several times and was really stunned of how clever
> >> (notably because writing interfaces boils down to writing types) and
> >> efficient this approach is. Would a similar thing work for the JVM, that
> >> is a compiler from ocaml bytecode to java bytecode?
>
> It is not easy to envision such a tool on the JVM, because of the current
> restrictions imposed on Java bytecode. As an example, the size of a method
> is currently limited to 64Ko, which is clearly way too small for non
> trivial
> programs.

I see the point. It sure is a problem to reuse the same compilation scheme
than in js_of_ocaml.



>
>
> >> I guess it wouldn't
> >> provide a full interoperability with java, in the sense that creating or
> >> extending classes may not be possible (well, why not after all?).
> >> However, being able to run an ocaml program on the JVM reusing existing
> >> java libraries would be so useful already!
>
> I am currently working on this for OCaml-Java (see below).
>
I must admit one of the most exciting feature of js_of_ocaml (beside
efficiency) is the way ocaml interfaces with javascript. I remember the
procedure was much heavier with nickel. In another thread (
http://www.mail-archive.com/caml-list@inria.fr/msg02094.html) you said that
this has changed in the version you're currently developing. I look forward
to see how it works (I'm in if you need alpha testers).


>
>
> >> Are there known obstacles to this? Has anyone tried something in this
> >> direction?
>
> Well, no real obstacle as OCaml-Java showed.
> However, OCaml-Java 1.x is still a bare proof of concept due to both
> poor design choices and JVM limitations. But then came Java 1.7 and
> some limitations were removed (e. g. a garbage collector better suited
> to functional languages, and an implementation of method handles).
> OCaml-Java has been largely rewritten and now exhibit acceptable
> performances.
>
This is really great.


>
>
> >> Would there be a chance to support multicore programming that
> >> way?
>
> Yes, it is actually working. But not released yet.
> Starting from vanilla OCaml, you "only" need two things:
>  1/ have a reentrant runtime;
>  2/ have a parallel garbage collector.
> OCaml-Java implements the former, while all modern JVMs provide the latter.
> So, basically, it just works.

itou


> The great difficulty is then to provide the good
> abstractions to make the life of the programmer as easy as possible.
> I mean: who would like to program with locks?
>
Well I'm not much into multicore programming myself, but at least for
advertisement purposes, it cannot hurt ;o).



>
>
> >> I hope these are not silly questions (sorry if they are!)
> >
> > http://ocamljava.x9c.fr
>
> Thanks for the plug. However, OCaml-Java is quite different and provides
> two tools:
>  - an equivalent of ocamlrun written in Java (meaning you can interpret
>    OCaml bytecode inside a JVM);
>  - an equivalent of ocamlc/ocamlopt for Java (meaning you can compile
>    OCaml sources to Java jar files to be executed by a JVM).
>

Thanks for the news and clarifications!


>
>
> Kind regards,
>
> Xavier Clerc
>
>
>
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