Duncan Coutts wrote:
On Tue, 2007-01-09 at 10:35 +0000, Jeremy O'Donoghue wrote:
Oddly, I was about to ask almost exactly the same question.
The supplementary is:
I'm trying to convert wxHaskell to use a cabal based build system.
I have similar issues in trying to convert Gtk2Hs to use Cabal.
Basically Cabal doesn't yet have any coherent story for larger projects like Gtk2Hs, wxHaskell, GHC etc that are made up of many components and where some bits are needed to generate others.
This is the sort of problems that make has been written for. Why re-invent this special wheel? Make tracks /any/ sort of dependency, and it is very good at that, you just need to give it all the necessary information i.e. write the appropriate rules. I think a large part of the (generic) rules needed for Haskell projects (including the large ones) could be written once and for all and thus shared among projects. It is of course necessary that these rules are completely configurable. Cabal could automatically generate make-variable definitions from the .cabal file to be included together with the generic rules; you could do this even for multiple sub-projects (which nevertheless might share some sources and depend on one another), using gnu-make's so called 'static pattern rules' (which are formulated generically but apply only to a given list of targets). This would mean that cabal becomes a generator for makefiles (or rather: make include files). The project author will write the top-level makefile which includes generic rules and cabal-generated variable definitions; for simple projects it wouldn't be necessary to add anything; complex projects could define extra rules (e.g. for special pre- or post-processing, for compiling in code in foreign languages, or for tracking dependencies on things external to the project). Well, that's how I would do this, anyway. Cheers Ben