Are there any tools for beginning programmers that give traces of Haskell programs? I want something like the following. Given the defintion sum [] = 0 sum (x:xs) = x + sum xs typing sum [1,2,3] should yield this trace sum [1,2,3] 1 + sum [2,3] 1 + 2 + sum [3] 1 + 2 + 3 + sum [] 1 + 2 + 3 + 0 1 + 2 + 3 1 + 5 6 I know there are advanced tools like Hat, but (unless I'm missing something) they don't yield anything as naive as the above, and it's naive users I'm trying to help here. -- P PS. Google search on "Haskell trace" yields lots on Hat, plus the following. The Mystery of Brigadier General Harry L. Haskell ... we have developed a short biography of General Haskell and been able to trace the locations where he lived, and, possibly, how the medal came into my family. ... family.phelpsinc.com/branches/haskell/ - 28k - Cached - Similar pages Philip Wadler, Professor of Theoretical Computer Science School of Informatics, University of Edinburgh JCMB, Mayfield Road, Edinburgh EH9 3JZ SCOTLAND +44 131 650 5174 http://homepages.inf.ed.ac.uk/wadler/