Yes, but you have to wrap it up:

{-# LANGUAGE RankNTypes #-}

-- obviously not to useful for this example :)

newtype Id = Id (forall a. a -> a)

f :: IO Id

f = return (Id id)

main = do

  Id g <- f

  print $ g 1

  print $ g "ciao"

Can I ask what you're trying to do with this?

Patrick

On Mon, Jun 15, 2015 at 3:11 PM, Paolino <paolo.veronelli@gmail.com> wrote:

Hello list, I'm trying to accomplish something along this line

{-# LANGUAGE ScopedTypeVariables #-}

f :: IO (a -> a)
f = return id

main = do
  (g :: a -> a) <- f
  print $ g 1
  print $ g "ciao"

Is it possible or I have to call f more than once to get different g's

Thanks

paolino

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