[timgilbert]

The immutable database Datomic (from Rich Hickey, inventor of Clojure) is all based on datalog, and is fairly popular in the nichey world of Clojure development; there are several other similar datalog-based systems outside of Clojure as well.

Various marketing case study blurbs are here if that's your thing: https://www.datomic.com/nubanks-story.html