As people have suggested on this list, in order to write a haskell program you need to develop a mathematical model which requires some serious up front thinking. Writing java code on the other hand is more about "coding" and then "re-factoring". 'Thinking" is discouraged (agile), as the design is more about how you organize your objects for the illusive "reuse" and "future requirements" than anything else. The approach make sense if you consider design as an excersize in object organization as you would have better idea on the object organization (aka design) as you plow through the code. On the other hand if you have a mathematical idea, then a language like java doesn't give you the abstraction tools necessary to implement it as well as a language like Haskell. But if you don't have a model, then java's approach may be more natural (as is evenident by its popularity) It seems to me that the two can work side by side if you model your application in Service Oriented Architecture. I think the boundries of the services should be thought of as langauges rather than api (function calls). Two different examples that comes to mind are the SQL and Google Chart. A Java programmer doesn't care about the SQL Server implementation, but it depends on its query langauge to create the tables, populate them, and issue rather complicated queries on them. Google Chart is interesting in that it porvideds a language in a URL to implement a service that has been traditionally considered as library. I would think if you can defines such services in your application then you can define a langaugage and mathematical model around it to implement the service in Haskell. Daryoush On Wed, Sep 10, 2008 at 5:01 AM, Mauricio wrote:

At this time It's not really a question of better implementation, but cooperation. I know Haskell, they know Java, and it would be nice if we could share code and work. The idea of the api, or maybe dbus, seems OK. It just would be easier if we could join everything in a single piece, but it is no big deal.

Maurício

Daryoush Mehrtash a écrit :

...

Why do you want to mix haskall and Java in one VM? If there are functionality within your code that is better implemented in haskell, then why not make that into a service (run it as haskell) with some api that Java code can use.

Daryoush

On Tue, Sep 9, 2008 at 2:36 AM, Maurí­cio > wrote:

Hi,

I use Haskell, and my friends at work use Java. Do you think it could be a good idea to use Haskell with Java, so I could understand and cooperate with them? Is there a a Haskell to Java compiler that's already ready to use?

Thanks, Maurício

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Weblog: http://perlustration.blogspot.com/

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On Wed, Sep 10, 2008 at 02:12:00PM +0200, Marc Weber wrote:

There used to be. http://www.cs.rit.edu/~bja8464/lambdavm/ (Last darcs change log entry: Sun Oct 21 03:05:20 CEST 2007 Brian Alliet * fix build for hsjava change )

Sorry about this. I hit a critical mass of darcs conflicts (I look forward to giving git a try) around the same time I got really busy at work. I've been meaning to get back into it (and update it to GHC HEAD) but I haven't received sufficient nagging yet. Please yell if you're interested in LambdaVM. At the very least I should be able to help get whatever is in darcs compiling. -Brian

Mauricio wrote:

...

Sorry about this. I hit a critical mass of darcs conflicts (I look forward to giving git a try) around the same time I got really busy at work. I've been meaning to get back into it (and update it to GHC HEAD) but I haven't received sufficient nagging yet. Please yell if you're interested in LambdaVM. At the very least I should be able to help get whatever is in darcs compiling.

Would it allow allow Haskell to also call Java code, besides running in JVM?

I think I'm not enough to nag you alone.

If you're looking for more people to nag you... I'm working on a compiler for a new declarative language. Right now we're using Haskell for a proof-of-concept interpreter, though one of the near-term goals for the compiler itself is a Java FFI/backend. Since much of the language is in the runtime engine, it'd be a shame to have to rewrite it all in Java or deal with the horror of JNI. -- Live well, ~wren

On Wed, Sep 10, 2008 at 09:50:36PM -0300, Mauricio wrote:

Would it allow allow Haskell to also call Java code, besides running in JVM?

Yep. LambdaVM can fully access existing Java code. The base library heavily uses FFI to access java.io.* to implement Handle, etc. 'foreign export' even works so you can call back into Haskell from Java. For more information see: http://wiki.brianweb.net/LambdaVM/FFI -Brian

+1 Due to the commercial environment I work in, there's really no chance of me using Haskell at work unless it runs under JVM or CLR. Brian, consider yourself nagged! And if there's anywhere you need some help, please yell. Neil On Fri, Sep 12, 2008 at 8:44 AM, John Goerzen wrote:

On Wed, Sep 10, 2008 at 05:35:20PM -0400, Brian Alliet wrote:

...

On Wed, Sep 10, 2008 at 02:12:00PM +0200, Marc Weber wrote:

...

There used to be. http://www.cs.rit.edu/~bja8464/lambdavm/ (Last darcs change log entry: Sun Oct 21 03:05:20 CEST 2007 Brian Alliet * fix build for hsjava change )

Sorry about this. I hit a critical mass of darcs conflicts (I look forward to giving git a try) around the same time I got really busy at work. I've been meaning to get back into it (and update it to GHC HEAD) but I haven't received sufficient nagging yet. Please yell if you're interested in LambdaVM. At the very least I should be able to help get whatever is in darcs compiling.

I for one would welcome the ability to compile Haskell programs into Java bytecode. One issue I have right now is the ability to get my code into the hands of a wide audience, since the Haskell toolchain is not widely installed by default. That and I tend to use a ton of Haskell modules, and there isn't a "just install all the deps" in ghc yet ;-)

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