Re: Calling Java From Haskell

[S. Alexander Jacobson]

My interpretation of the last set of mailings on the issue was that people
had given up.  Obviously that was incorrect.
I would love to alpha test your Hakell2Java code.
I browsed through the Opal docs and could not find the relevant
documentation on a Java interface.   Can you provide a more specific URL?

-Alex-


On Fri, 13 Nov 1998, Claus Reinke wrote:

> 
> >Now that Javasoft is on the verge of releasing the jdk1.2, I figure that
> >it is time to try to call Java from Haskell again.
> 
> fine. do it.
> 
> Alternatively, you might scan your mailbox for related messages and find
> one - addressed to you and to the Haskell list. Or you might check the
> home page of that particular author and find a recent paper (IFL'98,
> September, London) that discusses some of the issues and points to some
> related work and documentation. And since there is still no link to my
> Haskell/JNI pages from my home page, you might even ask me why I don't
> seem to make any progress..
> 
> In that earlier posting, I mentioned that I intended to use Green Card
> and JNI and that I wanted to have a basis for further experiments before
> this year is over. The background and my design decisions are explained
> in the IFL paper and I haven't announced any software because I don't
> think it is ready yet (even if it was, it depends on software that
> hasn't been released yet). 
> 
> And before others swamp me with personal email now;-), here are some
> comments on the state of the art:
> 
>   - While it is reasonably easy to use the invocation API in Java's
>     native interface (JNI) from C, I didn't have much luck in trying 
>     to get JDKs in the 1.x range to cooperate with Hugs on my SUN
>     SPARCstation. 
>     
>     My best bet are interactions with the user-level thread packages
>     used in those JDK implementations (or, as SUN's JNI FAQ used to put
>     it: ``The Solaris Java VM shipped with JDK 1.1 is not suitable for
>     embedding into certain native applications. Because it depends on a
>     user-level thread package to implement Java threads, the VM
>     overrides a number of system calls in order to support non-blocking
>     I/O. This may have undesirable affects on the hosting native
>     application.'').
> 
>   - JDK1.2 betas have been available for some time now, so there is
>     no need to wait for the official release to develop something.
>     Of course, betas have bugs - e.g., JDK1.2beta3 had serious problems
>     with its invocation API, betas change, so you have to track
>     the changes, and betas might not have complete documentation.
> 
>   - Nevertheless, I've been testing successfully with JDK1.2beta4 and
>     JDK1.2 RC1 (release candidate 1), using Hugs1.4June1998 and Green Card.
>     Example programs run both on a SPARCstation with Solaris 2.6 (with
>     the suitable linker patches) and on a PC with Windows/NT.
> 
>   - My tentative conclusion is that I'll probably be able to release 
>     a beta version of Haskell/JNI by the end of this month (which is
>     also the expected release date for JDK1.2 proper). I'll be looking
>     for alpha-testers before that, but there are still some things
>     I would like to check/change before I release anything..
> 
>   - As I said before: If anyone else is working on this, please let me
>     know. Also, if you desperately want to be an alpha-tester, please
>     contact me directly.
> 
> In other words: watch this space!-)
> Claus
> 
> PS. I've been planning to investigate the generation of Haskell modules
>     from Java classes to hide calls to Haskell/JNI even before I got
>     caught in ``implementation details'', although not along the lines
>     of your suggested mapping. The OPAL group in Berlin seems to have
>     such a thing already (http://uebb.cs.tu-berlin.de/~opal/, look for
>     the Subsystem Java in their library documentation).
> 
> --
> Claus Reinke                                Department of Computer Science
> email: [EMAIL PROTECTED]                    University of Nottingham
> http://www.cs.nott.ac.uk/~czr/              Nottingham NG7 2RD
> 

___________________________________________________________________
S. Alexander Jacobson                   i2x Media  
1-212-697-0184 voice                    1-212-697-1427 fax