Use black --preview for formatting.

[mcrumiller]

Description

Edit: looks like we don't use black anyway, but ruff's formatter which is a close equivalent, but doesn't yet support black's style. Not sure if this is feasible at the moment.

---

The black preview style can be enabled with the preview = true flag in our pyproject.toml file. Enabling this would (in my opinion) make a lot of the code more readable. Primarily, the improved multiline dictionary and list indentation makes this:

pl.DataFrame(
    {
        "a": [1, 2, 3],
        "b": [4, 5, 6],
    }
)

into this:

pl.DataFrame({
    "a": [1, 2, 3],
    "b": [4, 5, 6],
})

Which is much more concise and removes an entire level of indentation.

The drawback is of course that the preview style is subject to change, but I think the pros outweigh the cons.

[cmdlineluser]

I think ruff just added this: astral-sh/ruff#8293

[stinodego]

That would match what rustfmt does so I would be in favor. When ruff releases this along with their docstring formatter, we can have a nice big diff :)

[cmdlineluser]

The previously mentioned pull request was in the ruff 0.1.7 release.

ruff 0.1.8 is out now and contains the docstring formatter.

https://astral.sh/blog/ruff-v0.1.8

[stinodego]

We cannot use the docstring formatter yet because there is a bug in it. It was fixed and I hope to be able to use it when 0.1.9 comes out.

Regarding the preview style: we will just patiently wait for it to become stable, which should happen in ruff 0.2.0. There is no rush with this and we don't want to mess with the formatting more than needed. So I'll close this issue, but we will pick this up automatically when upgrading ruff.