Enhancing Usefulness of Declarative Programming Frameworks through   Complete Integration
  The Gisela framework for declarative programming was developed with the specific aim of providing a tool that would be useful for knowledge representation and reasoning within real-world applications. To achieve this, a complete integration into an object-oriented application development environment was used. The framework and methodology developed provide two alternative application programming interfaces (APIs): Programming using objects or programming using a traditional equational declarative style. In addition to providing complete integration, Gisela also allows extensions and modifications due to the general computation model and well-defined APIs. We give a brief overview of the declarative model underlying Gisela and we present the methodology proposed for building applications together with some real examples. 
Goran Falkman, Olof Torgersson