Fellow Haskellers, I have a package that uses some light typeclass hackery to automaticly build parsing algorithms based on the type of a function. I was recently informed that my package doesn't compile on GHC 6.6 due to the new restrictions on FD resolution; in particular I have instance declarations which fail the coverage condition. I can use undecidable instances to make the package compile again, but I'd prefer not to if I can avoid it. Are there any easy tricks I can use to make this work? I only sort-of understand the new restrictions, so I'm at something of a loss as to how to work around them. The problem is fairly isolated in my code: the affected section begins at line 140 in http://www.eecs.tufts.edu/~rdocki01/shellac/src/System/Console/Shell/Command... I've reproduced the class and a few of the instance declarations here: class CommandFunction f st | f -> st where parseCommand :: String -> f -> CommandParser st commandSyntax :: f -> [Doc] instance CommandFunction (Sh st ()) st where parseCommand wbc m str = -- list monad do (x,[]) <- runRegex (maybeSpaceBefore (Epsilon (CompleteParse m))) str return x commandSyntax _ = [] instance CommandFunction r st => CommandFunction (Int -> r) st where parseCommand = doParseCommand Nothing intRegex id commandSyntax f = text (show intRegex) : commandSyntax (f undefined) instance CommandFunction r st => CommandFunction (Integer -> r) st where parseCommand = doParseCommand Nothing intRegex id commandSyntax f = text (show intRegex) : commandSyntax (f undefined) -- Robert robdockins@fastmail.fm -- http://www.fastmail.fm - IMAP accessible web-mail