clpz VS ciao

As pointed out in the comments in the article, these kinds of logic puzzles are easier to solve using constraint programming than "regular" logic programming.

For example, see the solution to the Zebra Puzzle here: https://www.metalevel.at/prolog/puzzles which uses CLPZ[^1].

[^1]: https://github.com/triska/clpz

Scryer has the strings-as-lists-but-implemented-efficiently thing, possibly more strict ISO Prolog compatible syntax, and it may ship with a more advanced constraint library (I'm not clear on the relationship between SWI's clpfd and Scryer clpz).

None of these are full-fledged programming languages, however. They're limited to problems that lie in the polynomial hierarchy (A class which contains P and NP). Logic programming is generally only used to solve hard problems for which no good algorithm is known. Prolog also sort of fits this niche and it has a bunch of solvers integrated into it. Notably CLPFD which uses https://github.com/triska/clpz for constraint logic programming. Rosette (https://docs.racket-lang.org/rosette-guide/index.html) is another solver-based language. Except it uses lisp syntax (it's embedded in the Racket language). It uses Z3 as a solver (linked above for SMT theories)

Constraint programming I guess is when one uses a prolog library such as: https://github.com/triska/clpz

Some Prolog systems (like Ciao Prolog https://github.com/ciao-lang/ciao/blob/master/core/lib/forei...) implement bidirectional foreign interfaces. Once you have C bindings it is easy to write bindings from Rust, C++, or any other language (that can interoperate with C). I give here some details about Ciao because this is the system I know better but it should be similar for other popular Prolog implementations.

The tradeoffs depend on the complexity of the Prolog code and your needs for performance and features: pure LP, Prolog (search+unification+cut), garbage collection, dynamic database updates, constraint domains, etc. The Ciao Prolog engine is around 300-400KB. Adding a few libraries, compiler, etc. it goes to 2MB. Naive Prolog systems can be one order of magnitude smaller at the cost of sacrificing ISO compatibility, performance, etc. Note that "performance" can be very misleading. Some Prolog programs may run particularly fast in some Prolog system and very badly in others.