On Wed, Sep 10, 2014 at 2:20 PM, Mike Meyer <mwm@mired.org> wrote:

I've got a library that needed some simple matrix computation, so I added the bedandbreakfast package. While my library builds fine on both 7.6 and 7.8, the last released version of that package won't build on 7.8. However, the current HUB was update a couple of weeks ago, and now builds on 7.8.

Is there some way to capture that information in a cabal file? That if you're using GHC 7.8, you need bedandbreakfast >= 5.*, but for GHC7.6 you can use bedandbreakfast >= 4.*?

While you can do this, there's really no reason to. All your package depends on is any version of bedandbreakfast that the user can install. cabal will prefer to install newer versions of packages over older ones, so I don't think there's any situation in which adding this information to your cabal file would allow your package to install when it otherwise wouldn't.

Your real problem, as you note, is just that bedandbreakfast 5 is not available on hackage.

Regards,
Reid Barton