Run in backwards, so they say, but not really. Most things you'll write can't run backwards. You have to write them in a special way for that to be possible, and even then what it means is that you can do a depth first search to find the value.

There are some useful extensions like clpfd and asp but really if what you're doing is solving a constraint programming problem, you're much better of with OR-tools or MiniZinc.

Prolog is beautiful. I have practically no use for it. I've struggled to find something I can do better with Prolog than other tools, but I just love it aesthetically and that's enough for me sometimes.