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nix develop of haskell packages (programming.dev)

submitted 1 year ago by jakalx@programming.dev to c/nix@programming.dev

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I've got a small haskell project and I am building it using a flake using cabal2nix based on a package.yaml file.

nix build works fine, but I have trouble with my nix develop shell. The shell is built using shellFor from haskellPackages.

Is it possible to construct a shell that contains all dependencies to build the package, but not the package itself? I tried returning the buildInputs from the packages function, but that didn't seem to have any effect. When I return my package from that function, all dependencies are available, however the package is also built - is that how it is supposed to be?

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[–] expr@programming.dev 3 points 1 year ago (1 children)

The packages you specify via the packages attribute are the ones it will build dependencies for, but not build. You want to return a list of packages selected from the argument attribute set, like

packages = hsPkgs: [hsPkgs.pkgA, hsPkgs.pkgB];

[–] jakalx@programming.dev 1 points 1 year ago

Thanks for clearing that up for me!

I have this snippet in my flake now:

packages = _: [ self.packages.${system}.default ];

And it seems to do exactly what I wanted.