Debugging functional programs

In this paper, we use a logic-based system description for a simple (non-logic) functional language to examine the ways in which a diagnosis system can use its system description to improve debugging performance. The key concept is that the notion of expression replacement, which is the basis for repairing a program, can also serve as a fundamental heuristic for searching the source of an error. We formally define replacements in terms of fault modes, explicitly define a replacement order, and use the replacement heuristic for finding diagnoses. Finally, we incorporate the use of multiple test cases and discuss their use in discriminating between diagnoses.