Narwhals is actually already a requirement of great-expectations, because great-expectations requires Altair which in turn requires Narwhals, so it could be used without introducing any extra dependencies 😉

Happy to help if the maintainers are open to this, feel free to reach out on Discord if you're interested

@MarcoGorelli

This is super interesting.
The first step might be to copy the PandasExecutionEngine and create a NarwhalsExecutionEngine. At that point, it should be trivial to create a new PolarsDatasource type that simply uses the NarwhalsExecutionEngine instead of the pandas one.

A specific PolarsExecutionEngine could also be created directly, but I suspect that might be a bit more work.

There seems to be a fair amount of interest in this.

• See Use Narwhals instead of Pandas #10702