Data instance for Data.Version

Duncan Coutts duncan.coutts at
Mon Mar 18 15:34:45 CET 2013

On Fri, 2013-03-15 at 19:29 -0300, Administrator wrote:
> > Hi,
> >
> > Can we derive Data for Data.Version.Version? It would benefit Cabal.
> >
> > Thanks,
> > David
> On a related note, what about also moving some (maybe all) of the nice
> Distribution.Version related functions from the Cabal package to
> Data.Version? I am sure other libraries would also be interested in
> using this functionality without having to include Cabal as a whole.
> One example is the Ghc runtime itself: this could be one small step in
> removing dependencies from Ghc to Cabal.

If someone wants to do this, then at the same time we really must remove
the versionTags part of the Version type. It's wrong (makes the Eq and
Ord instances inconsistent) and I don't think it can be rescued.
Fortunately it's also unused (because it's so broken).


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