Re: [e4-dev] Introduction + Clojure in e4 / Introduction

[Neil Bartlett <njbartlett@xxxxxxxxx>]

Hi Gaetan,

I'm also very interested in the work you have done. Clojure does look
like a really innovative approach to concurrency, meaning it could be
a powerful alternative to Java in general.

However, I tried to use Clojure with OSGi about 6 months ago and ran
into some quite significant problems. At the time I wasn't able to
devote enough time to resolving them, so I'd be interested to hear if
you have hit them yet and if so whether you have any solutions.

1) Clojure is not really an interpreted language like JavaScript. It
is compiled, with compilation to .class files occurring on the fly
during VM initialisation. The compilation runtime and the Clojure
standard library are bound tightly together so they cannot be
separated, and the compilation runtime is started by a static
initialiser block. As soon as any class from the standard library is
loaded, the compilation runtime will be kicked off. This is expensive:
on my 2.33Ghz Macbook Pro it takes over 2 seconds to start. Therefore
it is imperative to use just one "copy" of the Clojure runtime by
placing it in its own bundle.
2) Compilation and execution of Clojure sources happens in the
classloader of the compilation runtime. Under OSGi this would be the
classloader of our Clojure bundle. There appears to be no way to
request Clojure to use a different classloader, and in my discussions
with Rich Hickey he felt it would be "unsound" to add such a facility.
Therefore there can be no proper separation of Clojure classes across
bundles, and the Clojure code in your bundle will not be able to see
the Java classes in your bundle unless you use DynamicImport-Package
or buddy loading.
3) The Java implementation of Clojure itself is difficult to work
with. Hickey does not believe in OO, so all of his Java code is
contained in static methods, fields and initialisers.

Now, this was 6 months ago and perhaps some of these issues have been
resolved now. I hope so because I would like to use Clojure, but it
was just not practical the last time I looked.

Regards
Neil


2009/1/23 Simon Kaegi <Simon_Kaegi@xxxxxxxxxx>:
> Hi Gaetan,
>
> I'm definitely interested in the work you're doing here. You're right in
> that I'm doing work to better support JavaScript bundles however I don't
> believe it's a stretch to support other JVM based languages in a similar
> fashion.
> The current status of e4 "multi-languge" is that we're just ramping up and
> now is an ideal time to join in. (In addition to this list I'd suggest
> speaking up at the bi-weekly meeting -- see calendar on
> http://wiki.eclipse.org/E4)
>
> The JavaScript/Rhino support code I've been working on is still fairly
> prototype-y however it probably would make sense to more formally do and
> share the work in the e4 incubator especially if other are interested.
> --
> For those not on the call...
>
> Hi, I'm Simon. I'm a committer on the Equinox project where I work on
> various aspects including p2, server-side, OSGi compendium services, and
> bits and pieces of the framework.
> I'm interested in contributing to e4 in the areas of multi-language support
> (with an initial focus on JavaScript) as well as anything to do with
> server-side interaction and runtimes.
>
> -Simon
>
>
> gaetan morice ---01/23/2009 12:30:24 PM---Hi all,
>
>
> From:
> gaetan morice <gaetan.morice@xxxxxxxxxxxxxxxx>
> To:
> e4-dev@xxxxxxxxxxx
> Date:
> 01/23/2009 12:30 PM
> Subject:
> [e4-dev] Introduction + Clojure in e4
> ________________________________
>
>
> Hi all,
>
>
> I am head of the Eclipse Products Team at Anyware Technologies. I lead
> Eclipse based IDE projects for embedded software tooling that involve lots
> of Eclipse technologies such as EMF, CDT, TM and DLTK. I also lead research
> efforts on alternative JVM languages use in Eclipse plugins development.
>
> I am currently working on a proof of concept on the programming language
> clojure (a functional dynamic jvm based language, which has a very
> interesting way to deal with multi-threading : www.clojure.org and my
> EclipseCon talk at http://www.eclipsecon.org/2009/sessions?id=630). >From my
> point of view, writing plug-ins using clojure could be very interesting due
> to its features (multithreading, dynamism, native Java interop) and its
> performances which are very close to Java (vs. JRuby, Groovy, ...).
> I made some hacks in the core of clojure runtime in order to use Bundles'
> class loaders. And after some efforts I managed to use clojure code in
> Eclipse plug-ins (I made a little builder in order to compile clojure files
> into class files ). This code interacts in both directions with java and
> share the dependency and visibility of the plugin in which it is hosted.
> But the most interesting feature is that it is fully dynamic, enabling, for
> example, live code modification in a running instance of Eclipse or
> interaction with Eclipse components.
> I've seen in yesterday's meeting notes that Simon Kaegi has managed to write
> OSGi bundles in Javascript (but the code is not yet in e4 CVS, right?), and
> I'd like to know the current status of e4 wrt dynamic languages integration,
> and how I could join the effort.
>
> Cheers,
> Gaetan
> --
> Gaetan MORICE
> Eclipse Expert
> gaetan.morice@xxxxxxxxxxxxxxxx
> Tel : +33(0)5 61 00 06 47
> Fax : +33(0)5 61 00 51 46
> New address
> ________________________________
> Anyware Technologies
> Lake Park
> ZAC de l'Hers - Allée du Lac
> BP 87216
> 31672 Labège Cedex
> France
> www.anyware-tech.com
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