Specifying Hyperdocuments with Algebraic Methods

Algebraic specification methods, well-known in the area of programming languages, are adapted to present a tailored framework for hyperdocuments and hyperdocument systems. In this framework, a hyperdocument is defined via its abstract syntax, which is a variable-free term of a suitable constructor-based signature. Both the representation in a markup language and the graphical presentation on the screen as well as further representations are elements of particular algebraic interpretations of the same signature. This technique allows the application of well-known methods from the field of compiler construction to the development of hyperdocument systems. Ideas for its implementation in the functional language Haskell are roughly drafted. It is shown how XML-based markup languages with schemas and stylesheets can be defined in terms of this framework and how this framework can be extended so that it can deal with partially specified documents, called semi documents. These semi documents can be automatically adapted to the users' needs, which e.g. is helpful to ensure accessibility.