Looks like it's from the same guy as CHICKEN Scheme. Looks pretty neat; coming from Erlang, it's cool to see another concurrency-focused Prolog descendant.

Yeah, when I read "concurrent logic programming language", I immediately thought of Prolog -> Erlang.

> All goals of a clause are executed in parallel, in an arbitrary order.

That's way cool, but how would backtracking work then, especially if multiple goals in a clause end up failing?

You don't back track, you just try everything from scratch

I like the underlying design ideas. At first blush however the language itself seems like a more limited subset of Prolog?

Prolog was the first kind of logic programming that existed. It opened the door to a world but as a language and depending on the domain, it can be considered to have numerous deficiencies.

Constraints liberate. A datalog program for example can be considered a very restricted prolog program, but it is guaranteed to terminate and there are alternative evaluation strategies that can be very efficient.