Support Polars objects for cache hashing

[BartSchuurmans]

Checklist

• [x] I have searched the existing issues for similar feature requests.
• [x] I added a descriptive title and summary to this issue.

Summary

When passing a Polars dataframe to a function that is decorated with @st.cache_data, you get the following error:

UnhashableParamError: Cannot hash argument 'my_df' (of type polars.dataframe.frame.DataFrame) in 'my_func'.

Follow-up of https://github.com/streamlit/streamlit/issues/5088#issuecomment-2338389918

Why?

I want to be able to cache functions that have a Polars dataframe as input.

How?

There is already support for Pandas dataframes:

https://github.com/streamlit/streamlit/blob/9914751b0d59f55cb03c3e871e90f65264895431/lib/streamlit/runtime/caching/hashing.py#L434-L453

Support for Polars dataframes could be implemented the same way. Alternative: Use https://github.com/narwhals-dev/narwhals for a dataframe-agnostic implementation.

Additional Context

No response

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[MarcoGorelli]

Hey

Alternative: Use https://github.com/narwhals-dev/narwhals for a dataframe-agnostic implementation.

I just wanted to note that Streamlit depends on Altair, which in turn already depends on Narwhals. So, Streamlit would be able to use Narwhals functionality with zero cost to its users as they all already have it installed because of Altair