Harry R. Schwartz

Datalog is a declarative programming language. It’s a strict subset of Prolog, with a couple slick properties:

• Its queries are guaranteed to terminate (so it’s not Turing-complete).
• Query evaluation is sound and complete.

That’s (usually) exactly what you want out of a simple query language. As such, it’s been getting some not-just-academic interest in the last few of years, most notably as the query language for Datomic.

I got kinda interested in Datalog a year or so ago. I started out by reading the Datalog User Manual, which is a nice introduction to the language. However, the manual’s only available as a website, so I went on a brief yak-shaving expedition and converted it to epub, mobi, and pdf.

If you’re interested in learning Datalog and also don’t like doing your long-form reading in a web browser, give it a read!