Freja, Hat and Hood - A Comparative Evaluation of Three Systems for Tracing and Debugging Lazy Functional Programs

In this paper we compare three systems for tracing and debugging Haskell programs: Freja, Hat and Hood. We evaluate their usefulness in practice by applying them to a number of moderately complex programs in which errors had deliberately been introduced. We identify the strengths and weaknesses of each system and then form ideas on how the systems can be improved further.