Add first-class support for polars

[maximlt]

I know @hoxbro has that in mind but couldn't find an issue about it. I'm updating hvPlot's docs for the 0.9.0 release and want to mention the support of Polars isn't as deep as it is with other data types like Dask. Opening this issue to link it from hvPlot's docs.

[MarcoGorelli]

Would the task here be to implement PolarsInterface in holoviews/core/data/polars.py, just like there's PandasInterface in holoviews/core/data/pandas.py?

[maximlt]

Yes I think that's the minimum required. Looking through the code base for dask or cudf for example reveals some other places where different data types are handled.

[douglas-raillard-arm]

Is there any plan to add support for the dataframe protocol ?
https://data-apis.org/dataframe-protocol/latest/index.html
polars seems to implement it, although my understanding is that it would be less efficient than handling polars directly since that API only allows converting between formats rather than accessing the content directly.

[hoxbro]

Maybe in the future. Currently, my plan is:

1. Update pandas DataFrame with MultiIndex support (Implement support for retaining Pandas index #6061).
2. Implement a PolarsInterface.
3. Maybe take a look at the dataframe protocol.

[MarcoGorelli]

Implement a PolarsInterface

If you ever wanted to pair on this, feel free to book some time https://calendly.com/marcogorelli