Hello! Daft developer here - we don’t directly use Polars as an execution engine, but parts of the codebase (e.g. the expressions API) are heavily influenced by Polars code and hence you may see references to Polars in those sections.
We do have a dependency on the Arrow2 crate like Polars does, but that has been deprecated recently so both projects are having to deal with that right now.
I don't see any direct dependencies to polars. But in the comment, they wrote that some part are "taken from", "influenced by", "adapted from" and "based on" polars.