My hobbyist coding updates and releases as the mysterious "Mr. Tines"

Thursday, 31 January 2008

Confusion of Babel

I really would like to put a functional layer in the cross-VM stack, but...

Ocamljava and F# might be code compatible, but the former has a cumbersome build and interop process (and doesn't seem to advertise call-from-Java); while Bigloo seems entirely silent on interop.

Cross-compiling Scala class bytecodes to CLR doesn't seem to be a goer -- IKVM balks at referencing CLR 2.0 assemblies. I might be able decompile the classes and rebuild them via J# -- the hiccup there is that I would have to translate the runtime .jar as well -- my simple "Hello World!" level class decompiles to invoke scala.runtime.BoxesRunTime, but that's not in any of the scalac-net assemblies. On the up-side that would remove any nagging issues about CLR 2.0 compatibility, though; on the down-side, it would mean that I need a decompiler able to handle the generated code... Jode -- which I happened to have to hand -- balked at half the classes in the runtime; Jad seemed to have dealt with them all, though with a lot of goto statements replacing things like jumps out of loops -- but leaves a lot of JVM INSTR monitorenter;...JVM INSTR monitorexit; where a synchronized{} block should be, and possibly other horrors.

Meanwhile I took another prod at scalac-net, using the magic -Ydebug flag:

>\scala-2.6.1-final\bin\scalac-net -d classes -Xassem-path JavaLayer.dll SClass.
scala  -Ydebug
[running phase parser on SClass.scala]
[running phase namer on SClass.scala]
java.lang.ClassCastException:$ClassSymbol cannot
be cast to scala.runtime.Nothing$

... type 'scala.Predef' is broken
($ClassSymbol cannot be cast to scala.runtime.Nothing$)

Kudos to the scala implementors -- the line numbers match up down the stack, and show the culprit to be

      unpickler.unpickle(symtab, 0, clazz.asInstanceOf, staticModule.asInstanceOf, typ.FullName);

which looks like it's doing the right sort of thing; and there's nothing particularly odd about the scala.Predef class in the assembly; and I get the same error trying to compile some of the examples in the distro...

Next diversion, rebuilding scalac with more instrumentation, piling the tower higher.

1 comment:

Anonymous said...

IKVM works fine with .NET 2.0 assemblies, but you have to run it on .NET 2.0.

The easiest way to do this is by putting an ikvmc.exe.config file next to ikvmc.exe that contains the following:

<?xml version="1.0"?>
<supportedRuntime version="v2.0.50727"/>
<requiredRuntime version="v2.0.50727"/>