I've been keeping an eye on this to use for the rules engine in a card game I'm writing[0]. Very excited to get back into using Prolog; I think it's fallen by the wayside a bit in the last decade or two but there's some sectors that still have strong arguments for using it if not as the main language then at least an extension language.
[0] Inspired by a HN comment a while back about Gleemin, the MTG expert engine in Prolog: https://github.com/stassa/Gleemin
Have you had a look at Expr? https://github.com/antonmedv/expr
We are using it for ETL processing and are very happy with it. The performance is excellent and it is easily extendable.