Implementation techniques for prolog databases

All clauses comprising a Prolog program are stored in a database from which they can be removed later. Other long‐term data structures are represented as clauses and are also stored and removed from the same database. Implementation techniques for the manipulation of clauses are not well known, and a lack of information has led to incorrect and incomplete implementations. Further previously unresolved issues are apparent when considering the storage of compiled clauses. We describe the way database manipulations are performed in Prolog‐X, a new compiler‐based Prolog system. We also introduce a new technique for storing the source form of compiled clauses.