Hi Bulat, Firstly, as someone who has an interest in at least 5 different projects which either do use the base libraries, or would like to, I think this is a great idea! Having the GHC stuff in the base, and having a massive load of #ifdef's just means that its hard to figure out whats going on, hard to add additional tools etc.
what is a 'base' library now? it is the library that implements common set of operations for latest versions of ghc, hugs and nhc. it contains low-level implementation for ghc, but relies on separate hugsbase package for hugs (the same for nhc, afaiu). so, first step is obvious - separate ghc-base library from the rest. hugsbase, ghc-base and nhc-base packages should provide common set of low-level operations, hiding from other libraries implementation details, differences between compilers, and differences between compiler versions. they should provide _incremental_ interfaces so that old code will continue to work with newer compilers. eventually compiler-specific code for stm and th should also go into these libraries but that is not the immediate goal
then, a base library may be written against "virtual Haskell compiler", which provides uniform set of low-level features while 'base' decorates these features with user-friendly interfaces
Nice idea. There are a few practical issues - for example does this virtual Haskell copmiler support higher rank types? Multi-parameter type classes? Bang patterns? It quickly gets a lot more complicated.
- ghc-base/hugsbase/.. libs to implement _subset_ of common low-level API Sounds like a very good idea.
- base lib to "equalize" several compilers and compiler versions, Yes, some operations might be implemented in the base library, but have more efficient versions in the ghc-base library. For example, map for base should be defined the obvious way, for ghc it should be defined with foldr. How can you accomodate this?
last line: i have some experience of writing compiler-independent code with Haskell and C++ and believe that this plan is realistic The differences between Haskell compilers may well be bigger than those between C++ compilers!
I wish you the best of luck, and think this would be really nice to hvae - unfortunately I think its unobtainable - but if we could just get some of this goodness that would be fantastic! Thanks Neil