Of course, I'd like to see a core based on pure type systems and the lambda cube rather than system F :) but I can make do. pretty much all of jhc's constructs that come from haskell code can directly map to ghc core, however my implementation of type classes would require creating a datatype that exactly mirrors the type hierarchy and turn each typelike lambda in jhc into a type "lambda" and a data lambda in ghc core (and typelike applications similarly modified). I found the main difficulty in trying to use ghc's core from other systems was not the core itself, but rather a 'primitive operation impeadance mismatch', ghc defines a whole lot of primitives, jhc has almost none. everything but the most basic numerical operations is imported via the FFI (and I am coming up with a foreign syntax to get rid of those too, the goal being every in scope name is declared in haskell source, one way or another) and it is up to the compiler to make FFI calls fast. my current plan is to create a 'foreign ghc primitive' decl for jhc which will let me import and use ghc primitives when using the ghc backend. some low level stuff in the built-in libraries will have to change, but it is no worse than porting to a new OS interface. John -- John Meacham - ⑆repetae.net⑆john⑈