Prolog hits a sweet spot where you can start with built-in resolution and then use Prolog as implementation language for specific searches.

Prolog should also be very popular with developers who like pattern matching and destructuring; it's pattern-matching by unification is, er, unmatched.

Prolog is also excellent for DSLs, either usings it's built-in facility for defining new functors (unary or binary operators/keywords), or standard DCG recursive-descent parsers or more complex grammars. Prolog was designed for NLP, used for prototyping Erlang, and a major inspiration for Haskell after all.