[JVM-B] Java VM Bridge / HC&A Report

[Ashley Y. <as...@se...>]

For the Haskell Communities and Activities Report:

Java VM Bridge
Java VM Bridge is a GHC package intended to allow full access to the Java 
Virtual Machine from Haskell, as a simple way of providing a wide range 
of imperative functionality. Its big advantage over earlier attempts at 
this is that it includes a straightforward way of creating Java classes 
at run-time that have Haskell methods (using DefineClass and the Java 
Class File Format). It also features reconciliation of thread models 
without requiring GPH.

It is intended to make writing "Java in Haskell" as straightforward as 
possible. To this end, each Java class is a separate type, and the 
argument lists of methods of automatically-generated interfaces to Java 
classes make use of subtype class relations to minimise explicit upward 
casting. Java exceptions are represented as Haskell monadic exceptions, 
and may be caught or thrown accordingly. Also, the two garbage collectors 
are integrated in such a way that cross-collector reference loops won't 
happen.

As a point of cleanliness and principle, it makes no use of "unsafe" 
Haskell calls (or pure function FFI). The layered design allows access to 
either lifted monads that keep track of context data (specifically, the 
JNIEnv pointer) and do all the work of preloading for you, or "IO"-based 
functions if you want to do all that yourself.

Current Status:
A beta-quality 0.1 was released in December 2001, for x86 Unix only. 
Release 0.2 will also be available for Windows and MacOS X, just as soon 
as stable 5.04 GHC is available on those platforms (unless I get tired 
waiting).

Contact: Ashley Yakeley <as...@se...>

-- 
Ashley Yakeley, Seattle WA