Hugs version: Dec 2001. Platform: Windows. Both WinHugs and command line hugs have the same bug.

start hugs with -98 option and try the following program:

class Monad m => ExMonad where
raise :: String-> m a

instead of reporting an error, an internal error is raised:

INTERNAL ERROR: inheritFundeps - predicate failed to match it's own head!

Regards.

Deling