[Haskell-cafe] Again, version conflicting problem with cabal-install

[Andres Löh]

Hi.

>>  --force-allow=foo-1.3
>>
>> with the semantics that all dependencies on foo will be changed to
>> allow foo-1.3 to be chosen. Would that be ok? Other suggestions?
>
> Can't this be integrated with the current --constraint flag?

It could be, but ...

> If the
> constraint is able to be satisfied without unrestricting any bounds,
> fine.  Otherwise, unrestrict any bounds on that constraint.  What
> would be the drawbacks?

... it shouldn't happen automatically. There are perfectly valid and
safe reasons to use --constraint, whereas this new feature is
inherently unsafe. But allowing general constraint syntax and calling
the flag something with "constraint" in it is perhaps a good idea.

> An advantage is being able to specify --constraint='foo >= 1.3' to get
> foo-1.3.7.2 instead of having to find out exactly which version you
> want.  And if you already know what you want, you may always say
> --constraint='foo == 1.3.7.2'.

Yes.

> Looking forward to the new solver! =)

I need testers and feedback. You can already use it. It's in the
cabal-install development version, and can be enabled by saying
--solver=modular on the command line.

Cheers,
  Andres