Debugging by asking questions about program output

One reason debugging is the most time-consuming part of software development is because developers struggle to map their questions about a program's behavior onto debugging tools' limited support for analyzing code. Interrogative debugging is a new debugging paradigm that allows developers to ask questions directly about their programs' output, helping them to more efficiently and accurately determine what parts of the system to understand. An interrogative debugging prototype called the Whyline is described, which has been shown to reduce debugging time by a factor of eight. Several extensions and generalizations to it are proposed, including plans for evaluating their effectiveness.