[Nix] lux-lua and lua.withPackages

[ALameLlama]

Normally with languages I like using withPackages e.g

    (python313.withPackages (
      p: with p; [
        playwright
        pip
        uv
      ]
    ))

This wraps the interpreter and sets it's path which simplifies setting things up but when I try to do this with lua and the lux-lua module it doesn't seem to work. e.g

    lux-cli
    (luajit.withPackages (
      p: with p; [
        luarocks
        lux-lua
        busted
        inspect
      ]
    ))

I can access lx and lua, and it says it's running luajit 2.1 but running lx commands will return a warning

 🕒 10:05 PM ❯ lx run "Hello World\!"
⚠️ WARNING: lux-lua library not found.
Cannot use the `lux.loader`.
To suppress this warning, set the `--no-loader` option.


Your input has the word 'hello' in it!

If I create a file with this

local inspect = require("inspect")
print(inspect({ 1, 2, 3, { a = "hello", b = "world" } }))

and run lua file.lua, inspect works so other packages seem to work with withPackages but I'm getting this warning with lux.

Thanks

[ALameLlama]

This totally could be pebcak too, I just haven't had any luck getting this to work

[mrcjkb]

Hey 👋

How are you setting up your environment?
Using nix develop or nix shell?

Lux uses pkg-config to detect lux-lua.
So you need to add that to your buildInputs.
With Nix, pkg-config gets setup via the shell hook when you use nix develop to enter a devShell, but not when you use nix shell.
I'm don't know if a package is included if it's behind lua.withPackages.

lux-lua is a Lua package, but it's not a luarocks package, and iirc lua.withPackages currently assumes that packages are luarocks packages (this would be a nixpkgs issue though).

Transferring this issue to discussions, as this is not a Lux bug.

I've also opened a feature request that may eliminate the need for pkg-config when using lua.withPackages, depending on whether it adds it to the lua path or not:

• [Feature] don't warn if lux-lua is available #1132

[mrcjkb]

Hey 👋
Can you please try with lua 5.1 - 5.4?
I believe this is an issue with how the luajit version is packaged.

Where it is:
/nix/store/55r8m0l5k9cpixmninfy5q6jvmlh1ns4-lux-lua-0.18.5/share/lux-lua/jit/lux.so
where it's looking:
/nix/store/dhrqspv0ywvbf5xyi3gmc01y24xw50q1-luajit-2.1.1741730670-env/lib/lua/5.1/lux.so

The "where it is" location is correct and there should be a symlink to the "where it's looking" location, but I suspect the luajit package doesn't symlink to a 5.1 directory.

[ALameLlama]

I am still getting that warning but using lua 5.2 it looks like the path is working so it looks like it's a luajit issue

~/lux-test/my-lua-project via 🌙 v5.2.4
❯ lx run "Hello World\!"
⚠️ WARNING: lux-lua library not found.
Cannot use the `lux.loader`.
To suppress this warning, set the `--no-loader` option.


Your input has the word 'hello' in it!

~/lux-test/my-lua-project via 🌙 v5.2.4
❯ lua test.lua
{ 1, 2, 3, {
   a = "hello",
   b = "world"
 } }
{
 config = {
   builder = <function 1>,
   default = <function 2>
 },
 loader = <function 3>,
 operations = {
   search = <function 4>
 },
 project = {
   current = <function 5>,
   new = <function 6>,
   new_fuzzy = <function 7>
 }
}

[mrcjkb]

Yep, lx run cannot infer from the nix Lua wrapper that it adds lux-lua to the lua path. So it prints the warning.
You can suppress it with the --no-loader flag.
I'll look into the luajit package in the next few days.

[ALameLlama]

Sorry for being a pain ahaha, I really do appricate it

[mrcjkb]

No problem, it's always good to have users reporting issues.
Btw, thanks for the sponsorship 😄