Addressing the scalability problem in visual programming through containment, zooming and fisheyeing

Visual programming languages have often been criticized for their lack of scalability, particularly in the way in which they become unusable when used to describe large programs. This lack of scalability manifests itself in three ways: complex and unreadable diagrams, viscosity of representation, and excessive use of screen real estate. We describe a way in which language design and interface design may be integrated to address this problem. The VIPR [Visual Imperative PRogramming] language and its associated environment address this problem through the use of potentially unlimited nesting, fixed bounds on the screen real estate occupied by procedures regardless of their complexity, and the use of zooming, fisheyeing, and animation in the programming environment