If your main use case is browser form validation, have a look at Tau Prolog. It doesn't have constraint library but standard Prolog should be enough for somethi

If your main use case is browser form validation, have a look at Tau Prolog. It doesn't have constraint library but standard Prolog should be enough for something like this. http://tau-prolog.org/ http://tau-prolog.org/ The newly released Yarn 2 uses Tay Prolog to implement constraints on package versions and usage: https://github.com/yarnpkg/berry/tree/master/packages/plugin-constraints/sources https://github.com/yarnpkg/berry/tree/master/packages/plugin...