Opium - An Advanced Debugging System

views of executions are the basis for a trace browser. 2.1 A trace query language based on Prolog We model an execution into a trace which is a stream of events. Execution events have a uniform representation, and can be analysed by programs. At a conceptual level, only two tracing primitives are necessary to retrieve trace information on the fly: one to retrieve the information related to the current event, another one to retrieve ? in, G. Comyn and N. Fuchs editors, Proceedings of the Second Logic Programming Summer School, September 1992, Zurich. Springer-Verlag, Lecture Notes in Artificial Intelligence 636. ??? Author's current address: IRISA/INSA, Campus Universitaire de Beaulieu, F-35042 Rennes, email: [email protected] information related to the next event. A trace can be considered as a history of execution events, and the two primitives can be matched on the notions of today (current event) and tomorrow (next event). These two primitives, plus Prolog, make a powerful tra..