Scalable interfaces to support program comprehension

Studies of how programmers understand code suggest that programmers approach the understanding task in both bottom-up and top-town ways, depending on the context. We present a tool, VIPR, that provides a unified visual representation of both high-level and low-level constructs and a smooth transition between the two levels through smoothly animated zooming and focus and context (`fisheyeing´) techniques. VlPR is currently being used to visualize Tcl programs, but the technique is generally applicable to programs written in any imperative programming language