Vega-Lite author here. The reason why we integrated the two is that we wanted to provide support for interactions with a fully reactive runtime system (https://

Vega-Lite author here. The reason why we integrated the two is that we wanted to provide support for interactions with a fully reactive runtime system (https://idl.cs.washington.edu/papers/reactive-vega-architecture/ https://idl.cs.washington.edu/papers/reactive-vega-architect...). It's difficult to do that while being agnostic to different implementations of these transformations.