Roles of Program Extension

A formal and effective approach to the extension of the computational behaviour of logic programs is presented. The approach builds upon the following concepts. The extension of computational behaviour is modelled by semantics-preserving program transformations. Several basic roles involved in such transformations are identified. Every transformation defined solely in terms of the basic roles will be semanticspreserving by definition. Functional meta-programs on logic object programs are used to specify the basic roles and to derive programming techniques in the style of stepwise enhancement. Thus, the process of extending the computational behaviour of logic programs is regarded as disciplined meta-programming.