How can I setup a python kernel

[hashPhoeNiX]

I'm currently doing this through a devenv using this script:

enterShell = let
    pythonEnv = pkgs.python311;
  in ''
    export KERNEL_NAME="uv-python"
    export KERNEL_DIR="$HOME/.local/share/jupyter/kernels/$KERNEL_NAME"

    # Create kernel with version tracking
    
    if [ ! -d "$KERNEL_DIR" ]; then
      python -m ipykernel install \
        --user \
        --name "$KERNEL_NAME" \
        --display-name "Python (uv)"
      echo "${pythonEnv}" > "$KERNEL_DIR/.nix-python-version"
    fi

    # Add uv-installed packages to PYTHONPATH
    export PYTHONPATH="$DEVENV_ROOT/.devenv/uv-venv/lib/python3.11/site-packages:$PYTHONPATH"
  '';

Is there anyway to do this with nixCats instead?

[BirdeeHub]

Ive never done that myself but, a few ways to go about it:

1, bashBeforeWrapper section in categoryDefinitions

You can literally run that script on startup if you want https://nixcats.org/nixCats_format.html#nixCats.flake.outputs.categories

2. You should be able to just keep using devenv for it?

Stuff you add to the path with lspsAndRuntimeDeps is suffixed to the path by default, so it should be overridden by the one from the shell?

3,

You could add ipykernel from nixpkgs to python.libraries section in categoryDefinitions?

And add --set PYTHONPATH whatever in python3.wrapperArgs or python3.envVars sections?

and then enable hosts.python3.enable = true in settings?

That would create a packagename-python3 in your path with those settings, and set vim.g.python3_host_prog to the path of it, which stuff will look for, possibly whatever you need to see the python kernel will look at that too? And if not you could likely configure it to point to that variable in lua?

https://nixcats.org/nixCats_format.html#nixCats.flake.outputs.settings.hosts

3 would have least impact on startup time, tied with 2

[BirdeeHub]

By the way, if you wanted to make a "jupyter host" you could actually with the new updates to hosts

Instead of bashBeforeWrapper, it would utilize the --run wrapper argument directly (unless you can find a more declarative way to install a jupyter kernel via nix, which would be preferrable, then you could just install it)

Then you could jupyter.envVars, jupyter.wrapperArgs and optionally also jupyter.libraries as well. Might be kinda cool.

But this works for now it sounds like, and stuff already knows how to look for vim.g.python3_host_prog so I wouldnt worry about it necessarily? But it would be possible and kinda cool.

Personally, I would be running the bash command in a shell for the project most likely unless I was sure that it would be quick if it wasnt needed.

There really has to be a way to run that command on install from nix so that the command isnt needed but I dont know it, but if you could find it, you would be able to add it to your config.

[hashPhoeNiX]

Thanks. Everything works fine now.

I'm still taking baby steps with nix, so I'd revisit some of the suggestions here later. I'd give the --run wrapper a try too.

I've not found a way to set up the jupyter kernel with nix (yet), but I'm still looking too.

I just wanted to be able to open a notebook file from anywhere on my system through neovim. I'll still be using devenv for project specific setups (I actually find this convenient, especially with direnv).

[BirdeeHub]

nix-repl> pkgs.jupyter-kernel.
pkgs.jupyter-kernel.create              pkgs.jupyter-kernel.default             pkgs.jupyter-kernel.override            pkgs.jupyter-kernel.overrideDerivation

Hmmmmmm... It has override which would be a first start...

But... It has a create.

That looks interesting. Possibly useful.

I cant look into that today but... yeah poke around the docs (dont forget to look in the manual! Its really good!) and the repl a bit. I bet there is something

[BirdeeHub]

https://github.com/NixOS/nixpkgs/blob/master/pkgs/applications/editors/jupyter/kernel.nix

This might be it actually tbh. Thats create

No idea how to use it and I cant spend more time looking right now, and I barely know python or jupyter, but, maybe that helps

If you manage to create an already set up jupyter kernel via nix you could just add it to the path or the python host's environment via lspsAndRuntimeDeps or python3.libraries (not sure which is needed)

Id definitely say I personally would go for this route over using --run or bashBeforeWrapper as bash provided to --run happens at runtime, and thus has a performance cost, however small it may be. I would in general aim to minimize my usage of those.

Definitely update here with what you find for others.

[BirdeeHub]

I'd give the --run wrapper a try too

And also, --run wrapper arg is basically just what bashBeforeWrapper section does. The only difference is I do witchcraft to make sure bashBeforeWrapper can be infinite length if you want, which is also inadviseable, because it is bash code that runs every time nvim starts, before the main wrapper.

Doing it as a host would mean you would want it to be contained to that definition, and host definitions can specify wrapper args for themselves and also neovim, so such a trick with --run would work the same as it did in bashBeforeWrapper as long as it wasnt longer than say, 2000 lines. You could expose the options of the wrapper you use to create your jupyter env, straight to your category definitions to include categories of with a bit of thinking

However, to be clear, thats also completely overkill

If you get it to build declaratively, you should just be able to either add it to lspsAndRuntimeDeps, or python3.libraries. Dont know which but one of those