[callmekit]

Loops, optional destructive assignment, tabling (although some Prolog implementations also have tabling), better constraint programming support than many Prolog implementations.

With version 3.0 Picat is also mostly backward-compatible with Prolog.

[felixyz]

One of the main differences is that Picat allows both deterministic functions (like in functional languages) and non-deterministic predicates (like in logic languages), which often simplifies code and makes for more efficient execution (although functions are translated into predicates).

In my opinion, Picat's biggest attraction is its facilities for constraint solving and optimization, which are in some respects state of the art.

[callmekit]

Picat was born out for BProlog, and it used to be like a pre-processor for BProlog, but I don't think this is true anymore.