Common Prolog includes a graphic environment, consisting of a specialized listener and graphic debugging tools. With the debugging tools it is possible to step through a program at the source level and control the 4-port debugger using the mouse. Call trees for predicates may also be displayed and manipulated.
The specialized listener provides mouse control over:
The Logic Listener interaction is similar to a normal Lisp Listener and will accept normal Lisp expressions except that:
KnowledgeWorks and Prolog User Guide (Unix version) - 26 Feb 2015