DataLog is used to verify smart contracts. I don’t know any specific examples of prolog used in the industry, though I am sure there are a few. Probably, there are expert systems implemented with prolog that are still used.

Logic programming in general has a few usages, the unification algorithm is used for pretty much every type system. Also, it is quite good for verification systems. For example, I know some symbolic execution systems implemented in OCaml.

Wondering if it’s possible to put this observation into number…