[Haskell-cafe] GSoC: Improving Cabal's Test Support

[Jason Dagit]

On Thu, Apr 1, 2010 at 6:13 PM, Rogan Creswick <creswick at gmail.com> wrote:

> On Thu, Apr 1, 2010 at 3:52 PM, Thomas Tuegel <ttuegel at gmail.com> wrote:
> >
> > At this point, the package author need only run:
> >
> > $ ./Setup configure
> > $ ./Setup build
> > $ ./Setup test
>
> My general feeling has been that Setup is being discouraged in favor
> of using 'cabal <foo>', but I don't have any solid evidence for that
> (and I could very well be wrong!).  They do do slightly different
> things, so I think it's wise to figure out which idiom is most likely
> to be used and work with that.
>

I haven't figured out how it's possible, but I'm convinced that ./Setup
configure vs. cabal configure can lead to a different set of dependencies
being selected.  This can lead to diamond dependency problems.  (I'm
convinced this happen on at least one machine I know of.)

What I don't understand is how it's possible for the discrepancy to happen.
 It's as if ./Setup and cabal-install use different algorithms for
dependency resolution, but as I understand it, both should be using the
Cabal library for that.  My only other thought is that perhaps ./Setup uses
a different version of the Cabal library than what cabal-install uses.

Perhaps Duncan can comment on this.

Jason
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