[Haskell-cafe] What inhabits this type: (forall a. a -> b) -> (forall a. m a -> m b)

[Neil Mitchell]

Hi

> I have looked on Hoogle.  I would have asked Djinn, but I don't have it
> around.  So, can someone find a term that inhabits
> (forall a. a -> b) -> (forall a. m a -> m b)

Asking hoogle about rank-2 types won't get you very far, the
development version of Hoogle gives a warning that it ignores rank-2
types, but that is as close as it will probably get for quite a while!

Thanks

Neil