Sequential debugging at a high level of abstraction

Efforts to build a better mousetrap for bugs in sequential programs are described. The resulting debugger, called Dalek, is intended to remedy limitations in conventional execution harnesses. Beyond the simple ´stop and look´ features offered by typical breakpoint debuggers, Dalek offers a rich control and query language. Dalek´s linguistic capabilities for treating sequences of program events offer an improvement over scratch paper as a compensatory technology for human memory limitations. Example applications are given. The very interactive, dynamic style of debugging encouraged by Dalek is discussed.<>