datafusion-spark: Spark-compatible Expressions

This crate provides Apache Spark-compatible expressions for use with DataFusion.

Testing Guide

When testing functions by directly invoking them (e.g., test_scalar_function!()), input coercion (from the signature or coerce_types) is not applied.

Therefore, direct invocation tests should only be used to verify that the function is correctly implemented.

Please be sure to add additional tests beyond direct invocation. For more detailed testing guidelines, refer to the Spark SQLLogicTest README.

Implementation References

When implementing Spark-compatible functions, you can check if there are existing implementations in the Sail or Comet projects first. If you do port functionality from these sources, make sure to port over the corresponding tests too, to ensure correctness and compatibility.