Thank you a lot Mark for participating in this discussion, and for all your work on Scryer Prolog during the last few years!

In the hope to attract further contributors to Scryer Prolog, especially with interest in Rust, I have now created a GitHub issue that collects a few self-contained features that could be interesting to look into for Rust programmers:

https://github.com/mthom/scryer-prolog/issues/319

I hope that's OK, and I invite everyone who is interested in these topics to contribute to this very innovative new Prolog system! Already in this early stage, it provides several important features that no other system currently has. Thank you again!