Can I add mapMaybeM to vector? The type signature would be:

mapMaybeM :: (a -> m (Maybe b)) -> Vector a -> m (Vector b)

Although the list-equivalent of mapMaybeM is not in base, it's a pretty common thing for people to write. I can see from some googling that it exists in monad-extras, extra, and in stack. I bring this up because I think it highlights the utility of such a function and the common expected semantics people seem to have for it.