On Wed, Jun 10, 2015 at 12:42 AM, David Luposchainsky <dluposchainsky@googlemail.com> wrote:

I think there are two important consequences of MonadFail. First of all, we can
all safely write failable patterns if we so desire. Second, the compiler can
ensure other people's codebases do not lie to us (knowingly or unknowingly).

The second is a bit overstated I think. Any function you call can still have partial pattern matches in all the other places Haskell allows them and you wouldn't know from the type.