Picat is a simple, and yet powerful, logic-based multi-paradigm programming language aimed for general-purpose applications. Picat is a rule-based language, in which predicates, functions, and actors are defined with pattern-matching rules.

[ … ]

This Picat system is distributed under the Mozilla Public License (http://mozilla.org/MPL/2.0/). The Picat system is provided free of charge for any fair application, including commercial applications.

Picat is a logic programming language with built in constraint and GOAP solving, plus an imperative programming escape hatch. I like it a lot! Wrote about it here: https://buttondown.email/hillelwayne/archive/picat-is-my-favorite-new-toolbox-language/