LDL++ Experience

The logical data language LDL is a rule based language for databases [NT89,Zan88] developed at Microelectronics and Computer Technology Corporation. LDL++ supports lists, sets, complex objects, recursion and extensible aggregates. In LDL++ every aggregate function f on a set is inductively defined by:

1. BASE: f({x}) on a singleton set {x}
2. INDUCTION: for any other set S = S {x} derive the value of f(S) from those of S and f({x})

In this extension of LDL++ the first function is called single, and the second one is called multi. We can rewrite count and sum as

• UCLA Extension