example of using GHC 9.4 or other version

[peterbecich]

Thank you for this project and haskell-flake!

Would you provide an example of overriding the default GHC version in nixpkgs-unstable from 9.2 to 9.4, etc.?

I am not sure how to use these:

• haskellPackages.ghc_9_4_4
• haskell.compiler.ghc943

[srid]

You want to set basePackages to the appropriate package set:

https://flake.parts/options/haskell-flake.html#opt-perSystem.haskellProjects._name_.basePackages

For eg.,

basePackages = pkgs.haskell.packages.ghc943;

[peterbecich]

great, it works, thanks

[wolverian]

Hmm, this doesn't actually work for me anymore. For some reason upstream Nixpkgs asserts graphql like this:

error: assertion '((lib).versionOlder (self).hspec.version "2.10")' failed
       at /nix/store/88fpp9lrbs0vk8yf94bz045y3bfz7m2r-source/pkgs/development/haskell-modules/configuration-common.nix:290:5:
          289|   graphql =
          290|     assert lib.versionOlder self.hspec.version "2.10";
             |     ^
          291|     doJailbreak super.graphql;

[wolverian]

(I don't use graphql so this is annoying.)

[wolverian]

I found a possible related PR, but I don't understand it: NixOS/nixpkgs#166425

[billksun]

I just hit the same issue (with the graphql assertion).