An integration of logic and object-oriented programming

The Alltalk project ([MELLENDER88], [RIEGEL88]) provides permanence to Smalltalk object s without adding any new language syntax, classes, or methods to the 'standard' image . ALF, the Alltalk Logic Facility, provides the programmer with a Prolog-like model for logic programming . Since ALF is implemented in the Alltalk system, ALF also provides permanence for its objects, i .e ., rules, facts and queries .