Build system idea

[Simon Marlow]

Roman Leshchinskiy wrote:

> But that is precisely my (other) point. A lot of that work is really 
> unnecessary and could be done by Cabal since it only or mostly depends 
> on the package information. Instead, it is implemented somewhere in 
> Distribution.Simple and not really usable from the outside. For 
> instance, a lot of the functionality of setup sdist, setup register and 
> so on could be implemented generically and used by a make-based build 
> system as well.

That's exactly what I'm proposing we do in GHC: re-use Cabal's setup 
register and some of the other parts of the simple build system in a 
make-based build system for packages.  It might require a bit of 
refactoring of Cabal, but I don't expect it to be a major upheaval at all.

I think what you're proposing is mostly a matter of abstracting parts of 
Cabal with cleaner and more modular APIs, which is absolutely a good thing, 
but doesn't require a fundamental redesign.  The tight coupling and lack of 
separation between Cabal's generic parts and the simple build system is 
somewhat accidental (lazy implementors :-), and is actually a lot better 
than it used to be thanks to the work Duncan has put in.  I'm sure it'll 
improve further over time.

The other part of your complaint is that the BuildInfo is in the .cabal 
file along with the PackageDescription (the types are pretty well separated 
internally).  Again I don't think there's anything fundamental here, and in 
fact some packages have separate .buildinfo files.

Cheers,
	Simon