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

Jacques Carette carette at mcmaster.ca
Tue Feb 27 18:01:44 EST 2007

Since my last query was answered so quickly, let's try another.

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)
?  I think of this as the type of functions that, given a function from 
any boxed-up a to a b, will give me a function from a boxed-up ma to a m 
b -- m does not have to be a Monad!.


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