Give Invisible a definition for fail. The default definition of fail calls error.  This is very bad, as we rely on a non-bottom result.  We should consider moving to MonadZero, to be on the safe side.
Give Invisible a definition for fail.
The default definition of fail calls error.  This is very bad, as we rely on a
non-bottom result.  We should consider moving to MonadZero, to be on the safe
side.


MP2E/XMonadContrib,MP2E/XMonadContrib,reenberg/XMonadContrib,reenberg/XMonadContrib