Minor correction, I don't think Datomic is used. I believe it uses a variation of DataScript and in turn DataLog for queries. Whereas Datomic is a DB which is also based on and uses DataLog queries.

Either way, super powerful.

Refs: https://en.m.wikipedia.org/wiki/Datalog https://github.com/tonsky/datascript https://www.datomic.com/