[Nix-dev] Help with ghc errors after nix-channel --update

[Benno Fünfstück]

Or maybe I just have another version of hashable installed system wide via
configuration.nix

Benno Fünfstück <benno.fuenfstueck at gmail.com> schrieb am Sa., 6. Dez. 2014
18:57:

> Hi Peter,
>
> Oh, I just assumed that since I had two versions of hashable with
> different cabal hashes installed, that one of them was a GHC core package.
> But now that I think of it you're probably correct, and this just happened
> because I did something similar to the following:
>
> 1. Install a package depending on hashable.
> 2. Update nixpkgs. The new nixpkgs contains a hashable with a different
> cabal hash because hydra rebuilt hashable.
> 3. Now install another package depending on hashable. I now have two
> incompatible hashable versions.
>
> Is this possible? Maybe something similar happened to Carlo?
>
> Sorry for the confusion,
> Benno
>
> Carlo Nucera <meditans at gmail.com> schrieb am Sa., 6. Dez. 2014 18:29:
>
> Hi Peter
>>
>> I added this snippet to my ~/.nix-packages/config.nix
>>
>>   ghcTestEnv = self.haskellPackages_ghc783.ghcWithPackages (p: with p; [
>>     mtl
>>   ]);
>>
>> and ran:
>>
>>   $ nix-env -p /tmp/haskell -iA ghcTestEnv
>>   $ /tmp/haskell/bin/ghci
>>   Prelude> import Control.Monad.State.Lazy
>>
>> These commands worked well. However, when adding abcnotation, it
>> complains rightfully that it doesn't know what we are talking about:
>>
>> error: undefined variable `abcnotation' at
>> /home/carlo/settings/nix-local/config.nix:34:5
>>
>> this happens probably because I wrote the nix expression for
>> abcnotation, and it's not yet present in the channel. What would be
>> the right way to add an expression made by me in this setup?
>>
>> > Generally speaking, ghc-wrapper is fundamentally broken and many
>> > discerning Nix hackers gave up using it entirely a long time ago
>> > (precisely because of the kind of trouble that you seem to be having).
>>
>> More generally, I'd like a configuration in which I'm able to:
>> 1) install packages from nixos-unstable,
>> 2) from a nixpkgs local repo,
>> 3) from expressions mantained by me
>> 4) using ghc-mod and similar in emacs
>>
>> Regrettably, I really don't know how to set up such a thing.  Before I
>> copied the configuration I'm using (from Fuuzetsu), I was using a
>> function like ghcWithPackages similar to the one you proposed, but I
>> was unable to integrate that with things packaged by me (and so I
>> switched).
>>
>> Can you point me towards some dotFiles that obtaining what I'm
>> searching for with the ghcWithPackages function?
>>
>> Best regards,
>> Carlo
>>
>> 2014-12-06 18:04 GMT+01:00 Peter Simons <simons at cryp.to>:
>> > Hi Carlo,
>> >
>> >  > ghc-pkg check is full of errors
>> >
>> > I don't think that "ghc-pkg check" ever succeeded in any ghc-wrapper
>> > based installation.
>> >
>> >  > packages I installed no longer load in ghci
>> >
>> > There is no obvious explanation for the errors you've described. As
>> > random suggestion how you might obtain some additional insight, you
>> > could add
>> >
>> >   ghcTestEnv = self.haskellPackages_ghc783.ghcWithPackages (p: with p;
>> [
>> >     mtl
>> >   ]);
>> >
>> > to your ~/.nix-pkgs/config.nix and then run:
>> >
>> >   $ nix-env -p /tmp/haskell -iA ghcTestEnv
>> >   $ /tmp/haskell/ghci
>> >   Prelude> import Control.Monad.State.Lazy
>> >
>> > Does that succeed? If it does, you try adding 'abcnotation', too, to see
>> > whether that makes a difference.
>> >
>> > Generally speaking, ghc-wrapper is fundamentally broken and many
>> > discerning Nix hackers gave up using it entirely a long time ago
>> > (precisely because of the kind of trouble that you seem to be having).
>> >
>> > Best regards,
>> > Peter
>> >
>> > _______________________________________________
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>> > nix-dev at lists.science.uu.nl
>> > http://lists.science.uu.nl/mailman/listinfo/nix-dev
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