[Haskell-cafe] A new cabal odissey: cabal-1.8 breaking its own neck by updating its dependencies

[Paolo Giarrusso]

Hi,
after Andrew Coppin's odissey [1], I also had a few problem with
cabal, which stopped installing new packages. Details will follow;
meanwhile, here are some questions prompted by what happened:

- when recompiling a package with ABI changes, does cabal always
update dependent packages? It seems "not always" - it didn't update
itself, nor refuse the breaking upgrade, and the ABI breakage caused
linker errors on Setup.hs. Luckily, cabal was already linked so I
could always use it for queries.
- can cabal extract and check dependencies as specified in the .hi
files? I had a broken dependency which I could see with "grep" but not
otherwise.
- is there a "specification" of which are the "core" packages?

Not sure if this is more useful as a bug report or as discussion, or
if I just misused cabal and it's the only perfect software in the
world; still I wanted to share my experience.

Also I am not sure if this is the best place - but I'm not subscribed
to other lists, and the previous "cabal odissey" was posted here, so I
hope it's fine.

A related idea is that Gentoo had a tool which not only extracted such
dependencies, but recompiled all affected packages. While package
removal is not supported through cabal, it is sometimes needed (and
well, it should be supported at some point). See for instance this
FAQ:
http://www.haskell.org/cabal/FAQ.html#dependencies-conflict
My problem seems a nastier variation of the one described there :-(.

Details follow.

Best regards

[1] http://groups.google.com/group/haskell-cafe/browse_thread/thread/787c67b31fa46507/29585601feeb7bf2
-- 
Paolo Giarrusso - Ph.D. Student
http://www.informatik.uni-marburg.de/~pgiarrusso/