[Haskell-cafe] version conflict on Hackage

[Duncan Coutts]

On Mon, 2009-01-12 at 13:21 +0100, Henning Thielemann wrote:
> I repeatedly encounter the following versioning problem on Hackage:
> There is a package A with version 1.0.
> I upload a package B which imports A.
> Thus B is bound to A-1.0
> Now a new version of A is uploaded, say 1.0.1.
> then I upload package C which depends both on A and B.
> However C is bound to the new A-1.0.1, which gives conflicts with the interface of B.
> All packages are sane. Both B and C work with either A-1.0 or A-1.0.1,
> but they must use the same version.

The package builder on hackage is broken for this reason, amongst
others.

> Currently I'm forced to upload many packages with different versions, 
> although nothing really changed.
> Maybe the most easiest fix to this problem is to let maintainers of a 
> package allow to trigger re-configuration and re-compilation of a package.

The plan with the new hackage server is that we have a smarter build
client (cabal-install) that does install plans and so always installs
consistent versions of packages.

> I would also like to flag package versions that people can safely ignore, 
> because there was a flaw in package dependencies.

There is a mechanism for doing this but no UI yet.

> On the other hand there are packages that are useful, but can no
> longer be compiled on Hackage, e.g. compatibility packages for older
> versions of GHC.

Right, we should leave those alone.

Duncan