I've been using GHC for years and my honest opinion is that the warnings very rarely flag an actual maintainability problem in the code I write, and very frequently annoying highlight something I knew I was doing, and did quite deliberately - most often inexhaustive patterns or shadowing. I would agree to a certain extent about the warnings. Name shadowing is not really a problem, and it's often hard to avoid shadowing names that already exist in an imported module (why shouldn't I have a variable named lines?). It's also usually the case that when I write inexhaustive pattern matches, it's because I know that the function (in a where clause) cannot be called with the missing pattern. Type defaulting and monomorphism bits may be useful to some, but I only usually fix them to get rid of the warning, not because they cause a
Jules Bean wrote: problem. The ones I find useful are unused imports (handy for tidying up the import list), overlapping patterns, missing fields, warnings about tabs and a few others. Of course, you can easily customise which warnings are on and which are off, so we can all have different preferences. It would be nice to be able to set some warnings to be errors though, while leaving others as warnings, or turned off (don't think GHC can do this?). Neil.