This crate contains the definitions of the DataFusion UDFs that are used to implement select Vega expression functions and transforms. These UDFs are used in two places.
- The DataFusionConnection provided by vegafusion-sql adds these UDFs to its SessionContext so that they are available for use in SQL querires.
- The vegafusion-runtime crate uses these UDFs for the evaluation of signal expressions and for simplifying expressions passed to the filter and formula transforms. Note: Even when a non-DataFusion Connection is used, DataFusion is still used for signal evaluation and expression simplification.