A state-based visual language for a demonstrational visual shell

We present a new visual programming language and environment that serves as a form of feedback and representation in a Programming by Demonstration (PBD) system. The language differs from existing visual languages because it explicitly represents data objects and implicitly represents operations by changes in data objects. To improve feedback and provide a closer union between the PBD system and the program representation, the visual language is integrated into other parts of the system, such as the editor. Finally, in order to enable new operations to be added easily to the system, we introduce a declarative language for specifying how an operation´s visual representation is generated