Hi Bernie,
I would also argue strongly against that approach.
It is important that debugging tools preserve the semantics of the underlying program as closely as possible.
Yes, but if the alternative is to make debugging so annoying that no one uses the debugging tool, then its probably a worthwhile trade off. Currently I don't use Hat, as when I am ready to debug a Haskell program (i.e. its broken) I can be pretty much 100% certain that it won't work with Hat without several changes. At the point I am trying to solve a complex bug, I don't want to go and do something else.
Probably the best solution is to lobby various compiler writers to generalise the defaulting mechanism, but that may be easier said than done :)
If you came up with a concrete proposal, that was a generalisation of the existing defaulting method, and provided an implementation for GHC, you might have a lot more success at your attempts. (Certainly if you implement in for Yhc, we'd accept it) Thanks Neil