Support pint (unit of measure library)

[kszlim]

Problem description

It would be great to have support for pint in polars.

Ideally this would avoid a direct dependency on pint but would involve opening the appropriate hooks needed to enable a package similar to pint-pandas.

Relates to:
hgrecco/pint#1811

If you have a good idea for polars extension points and provide the necessary extension points, I perhaps could try to write pint-polars.

[stinodego]

We do not plan to implement this functionality directly in Polars.

You can implement an integration as a plugin. See the docs:
https://pola-rs.github.io/polars/user-guide/expressions/plugins/

More simple integrations could be done as a custom namespace. See the docs on extending the API:
https://pola-rs.github.io/polars/py-polars/html/reference/api.html

[kszlim]

I realize this issue is closed, but I think this might require extension datatypes support in polars, do you know if anything like that will be supported similar to https://pandas.pydata.org/docs/reference/api/pandas.api.extensions.register_extension_dtype.html

and/or a subset of this functionality https://pandas.pydata.org/docs/reference/extensions.html

I guess related to #9112

Ideally it could go through a combination of the above and https://pint.readthedocs.io/en/stable/user/numpy.html + taking an approach similar to https://github.com/hgrecco/pint-pandas/blob/master/pint_pandas/pint_array.py