Re: [Haskell-cafe] Info on dependencies among libs distributed with ghc?

On 21 April 2014 15:40, Magnus Therning wrote:

On Mon, Apr 21, 2014 at 08:18:20AM +1000, Ivan Lazar Miljenovic wrote:

...

On 21 April 2014 02:11, Magnus Therning wrote:

...

I'm working on the packaging of Ghc for Arch Linux and the packaging of Ghc 7.8 was in place about a week ago. It was delivered with `Cabal` 1.18, and already now there's a 1.20 available, which is required by the latest version of `cabal-install` :(

Ghc 7.8 comes with quite a few other basic libraries. Are there any dependencies between these libraries besides the obvious one on `base`?

In other words, can I update Cabal without running into the diamond-dependency problem?

The only time I've had a problem with Exherbo packages is that some of them (e.g. haskell-docs) require using the version of Cabal shipped with GHC (I think it was to have consistency with the version of Cabal that Haddock was built with); as long as the Arch packages can specify "use GHC's Cabal" for the few cases which it's necessary then you shouldn't have a problem.

That is exactly the kind of situation I want to avoid :)

I have no problem re-compiling everything that depends on Cabal, but I want that recompile to result in a situation where neither the user (nor me) need to ever ask "Which of the installed Cabal versions should I use to compile this program?".

I think cabal-install can get away with this because it ensures the same version of Cabal is used throughout, as the .cabal file for haskell-docs doesn't explicitly state that it requires the same version of Cabal as used by Haddock. So if Arch's dependency resolver is smart enough, this might work. -- Ivan Lazar Miljenovic Ivan.Miljenovic@gmail.com http://IvanMiljenovic.wordpress.com