Duncan Coutts
This is not high priority at any rate. The build-depends field would default on the value of depends.
How about tools that are needed only at build time? I know that a hypothetical Cabalised Gtk2Hs would like to express a versioned build-time dep on c2hs.
For built or run time deps on tools do you suggest only deps on cabal-installed binaries or general external tools? We do not yet have any particular support for specifying external/foreign deps eg on C libs. Another reason is that we do not have any standard way of detecting cabal-installed programs like we do with libs so detecting tools is more ad-hoc than libs.
This is my view as well.
There is a slight danger here of duplicating too much on the job of a distro package manager.
I tend to agree. I think other things are higher priority than supporting this, which will end up being much magic. The highest leverage stuff for Cabal right now is Haskell libraries and automatic installation. OTOH, there's a "Program" abstraction that does a pretty good job of locating programs in PATH and stuff. You could build on top of this in the Setup script to detect stuff; there's a hook for it too. Maybe we could even add more library helper functions, and maybe eventually something in the .cabal file. We don't even have all of the preprocessors and libraries properly using the Program abstraction, though. peace, isaac