I share your interest in the Datalog engine implementation. The free version of Datomic does include Datomic Datalog and you can certainly play with it against

I share your interest in the Datalog engine implementation. The free version of Datomic does include Datomic Datalog and you can certainly play with it against the normal Clojure data structures without bothering with the backend. You might be interested in Cascalog, which is a similar, datalog-style query engine designed for use on Hadoop. But it can be run locally with a play data space. The implementation is open source and you can peruse it nicely. fogus is working some on bacwn: https://github.com/fogus/bacwn https://github.com/fogus/bacwn which may also hold interest for you. Sooner or later I'm going to get back on the prolog-y, datalog-y chapter of ANSI Common Lisp as well.