I regard miniKanren, Racklog, core.logic, and many other Prolog-style implementations and embeddings of logic programming as extremely valuable and useful contr

I regard miniKanren, Racklog, core.logic, and many other Prolog-style implementations and embeddings of logic programming as extremely valuable and useful contributions that are both of academic and practical importance. They also serve the important strategic purpose of drawing more attention to logic programming languages in general. However, these implementations, although elegant and admirable in their own right also due to their innovative approaches, cannot yet compare in terms of features or performance with what a full-fledged modern Prolog system offers. In my experience, the main attraction of a professional Prolog system is often found precisely in its _constraint solvers_, and it is in these areas where professional Prolog implementors compete extremely vigorously, and more simplistic implementations currently fall short either in terms of features or performance. Still, even a very simplistic Prolog implementation can definitely be very useful, and if you do not need sophisticated constraints, then you may not need a commercial Prolog system. This situation arises for example in parsing, web applications, rule-based systems and other tasks where Prolog can help a lot, and constraints are not primarily needed. For a use case like sports scheduling and combinatorial tasks in general, I definitely recommend a Prolog system with very strong support of constraints, since what you can do with constraints in this application area by far exceeds the possibilities of "plain" Prolog, both in terms of performance and convenience.