First off, thank you for the well thought out response. I was far too vague with my question. I did not mean a general purpose rules engine as in the middlewar

First off, thank you for the well thought out response. I was far too vague with my question. I did not mean a general purpose rules engine as in the middleware piece. What I'm thinking about is better described as a rules based system, but far more complex than anything I've written in the past. Just to add complexity, a few domain experts will have the ability to modify and implement rules. My inclination is towards a language with a small syntactic footprint and not a lot of tribute towards system stuff like memory management. So I was leaning towards Clojure but JS is a great thought. Other languages I wondered about were Prolog and Scala. I'm doing it as a learning exercise, an attempt at keeping my skills from rusting, and because my day job is boring. If it can be monetized, that's a bonus.