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

Neil Mitchell ndmitchell at gmail.com
Tue Feb 27 19:39:37 EST 2007


> 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!



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