In case the execution of the program fails, you may want to recompile the Typol program in debug mode, by clicking on the item of the pulldown, followed once more by . Any time you recompile a Typol program, you may reload it into the prolog environment using the button. You may clear the entire prolog environment by clicking on the button.
When you run a program that has been compiled in debug mode, the debugger interface opens automatically. The Typol users manual provides a complete debugging example.