Non-deterministic Updates in Daplex

We have developed a new loop construct for the Daplex Functional Data Language which allows users to specify the creation of sets of objects in terms of a constraint speciication that they must meet, rather than a direct assignment of attribute values. Programs written in the extended language are compiled into Prolog routines that use a backtrack search strategy to locate a sequence of updates that will cause the constraints to be satissed in the new database. The constraints are described in terms of relationships with existing objects in a database, and use the full power of the Daplex language. Objects, once constructed, are committed into the persistent object database. The idea is to take advantage of uniication and non-determinism, which are beneets of the underlying logic programming implementation, whilst preserving the clarity of expression of the higher-level functional language. The construct has been implemented and tested on a sizeable object database, and suggests interesting new directions.