obj GenericDB =  GenericRecord*;

obj GenericRecord =  key:GenericKey
    ops:
	FindRecord(GenericDB,GenericKey)->(GenericRecord);
    description: (*
	Specifying FindRecord explicitly here avoids the typical inheritance
	problem of type mismatch in the coarity of selectors.  This is the case
	due to the copy-and-substitute semantics of inheritance for operations.
    *);
end;

obj GenericKey
    ops:
	DelRecord(GenericDB,GenericKey)->(GenericDB);
	DelRecord(GenericDB,GenericKey)->(GenericDB);
	FindRecord(GenericDB,GenericKey)->(GenericRecord);
end;

op AddRecord(gdb:GenericDB, gr:GenericRecord)->(gdb':GenericDB);