Re: heads-up: Haskell updates

[Ricardo Wurmus <rekado@elephly.net>]

Ludovic Courtès <ludo@gnu.org> writes:

>> * updating Haskell packages automatically is dangerous as not all
>>   packages work well together.  When updating I often had to take a few
>>   steps back to reduce the version number.  On Hackage I picked the LTS
>>   version where available.
>
> Does that mean that Hackage provides a package set that doesn’t work
> well together?  Or is it a defect in our updater?

Packages on Hackage are not guaranteed to work well together.  Having
impossible version constraints in any larger set of packages has a long
tradition in the Haskell world.  That’s what led to Stackage and
LTSHaskell, which both work on ensuring package compatibility.

> I think it would be great if running “guix refresh -t hackage” would
> give us a package set that works together, provided Hackage does the
> necessary QA.  (I thought it did because Nixpkgs imports all of it
> wholesale AIUI.)

Unfortunately, that’s not the case.  Nixpkgs provides the latest
versions (if the “Distributions” row on Hackage pages is to be
believed), but we really want to provide the version that LTSHaskell or
Stackage use.  The latest version is only of interest to developers.

We have a Stackage importer but I haven’t been able to make it work for
this round of updates.

--
Ricardo

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