An overview of the Object-Oriented Functional Data Language

The Object-Oriented Functional Data Language (O/sup 2/FDL), an interactive, strongly typed database programming language, is discussed. It features inheritance and encapsulation of object-oriented languages and a functional notation for message expressions. The main contributions of the O/sup 2/FDL are: (1) functions of indefinite nesting levels that simplify nested list processing and form the basis of an efficient computation model; (2) path expressions that allow a flexible, graphical correspondence for database queries; (3) a type system featuring parametric and inclusion polymorphism, function restrictions, and type inferencing; and (4) system-defined functions that provide a concise and convenient notation for filtering aggregating, and combining objects. The versatility of the O/sup 2/FDL is demonstrated here for both relationally-complete expressions and more general computations.<
>