languages.python.package = pkgs.python310.withPackages (…) does not work

[dpaetzel]

Thank you for developing and maintaining this awesome project! 🙂

Describe the bug

I'm trying to specify Python packages by

languages.python = {
  enable = true;
  package =
    pkgs.python310.withPackages (ps: [
      ps.xlrd
    ]);
};

but this does not work, i.e.

nix develop --impure --command python -c 'import xlrd; print("yeah!")'

yields

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ModuleNotFoundError: No module named 'xlrd'

Interestingly, as also described in this comment, instead specifying

packages = with pkgs.python310Packages; [ xlrd ];
languages.python.enable = true;

does work but does not seem to be preferable due to the uncoupling of Python packages and interpreter. Or maybe I misunderstood something? Of course I could use let and friends to extract python310 somehow but that seems clunky.

To reproduce

https://gist.github.com/dpaetzel/303644fc1aa7863a4d0194c9f205b4b1

Version

I'm using Flakes.

[domenkozar]

For that to work you'll need to use https://github.com/cachix/devenv-nixpkgs for nixpkgs

[therealpxc]

For that to work you'll need to use https://github.com/cachix/devenv-nixpkgs for nixpkgs

Is this just because of the way the devenv's Python language module invokes Nixpkgs' Python wrapper via callPackage, in that if the wrapper's interface or behavior changes, that callPackage invocation might no longer have the desired effect?

[srounce]

I'm trying to do the same thing and set the nixpkgs input to

nixpkgs:
  url: github:cachix/devenv-nixpkgs

and I now get the following error when trying to enter the shell

Updating devenv.lock ...
error:
       … while updating the lock file of flake 'git+file:///Users/s/repos/myproject'

       … while updating the flake input 'nixpkgs'

       error:
       error: flake '«github:cachix/devenv-nixpkgs/aaadd7348d76c258d788dcc6712276abb78393ab»/.devenv.flake.nix' does not exist

✖ Command produced the following output:



✔ Updating devenv.lock in 0.3s.
Error:   × Command `/nix/store/y2w7cpc5b7l43hrpkzc47dgyshjcc7c0-nix-2.21-devenv/bin/nix --show-trace --extra-experimental-features nix-
  │ command --extra-experimental-features flakes --option warn-dirty false --option eval-cache false --keep-going --max-jobs 4
  │ flake update` failed with with exit code 1

[YPares]

@srounce I had the same problem, it should actually be:

inputs:
    nixpkgs:
        url: github:cachix/devenv-nixpkgs/rolling

But @domenkozar even using it, the original error (import error) remains.
I'm using devenv directly, not in a flake.