JLog is a Prolog interpreter written in Java that is well suited for educational purposes. It runs as either an Applet or as an Application. It includes built-in source editor, query panels, online help, animation primitives, and a GUI debugger.
Version 1.2.1 fixes a critical issue with an overly-aggressive tail-recursive optimization introduced in version 1.2.0.
This version improves the animation quality by double-buffering to remove flicker. Some additional graphical examples are included, including a game of Sokoban.
There is now an API for the jlogic Prolog Engine making it easy to perform Prolog queries from within other programs.
Lists can now be arbitrary lengths (previously they were limited by the Java stack size).
Several small fixes and improvements were also introduced.
More information, including screenshots, an online demo applet, and release notes are available from: