Engine cast extension helpers

Engine modules expose Arrow↔engine conversion helpers in their cast.py modules.

Polars examples

import pyarrow as pa
import polars as pl
from yggdrasil.polars.cast import polars_dataframe_to_arrow_table

arrow_table = pa.table({"id": [1, 2]})

# Arrow → Polars (use polars directly)
pl_df = pl.from_arrow(arrow_table)

# Polars → Arrow
roundtrip = polars_dataframe_to_arrow_table(pl_df)

pandas and Spark

Equivalent conversion helpers exist in: - yggdrasil.pandas.cast - yggdrasil.spark.cast