gistfile1.txt

{-# LANGUAGE StaticPointers #-}
{-# LANGUAGE NoMonomorphismRestriction #-}
{-# LANGUAGE TypeApplications #-}
module SPT where

import GHC.StaticPtr
import Data.Typeable

-- Polymorphic static pointer
foo3 :: Typeable a => StaticPtr (a -> a)
foo3 = static id

-- But now we look it up as `Int -> Int`
foo4 :: IO (Maybe (StaticPtr (Int -> Int)))
foo4 = unsafeLookupStaticPtr (staticKey (foo3 @Bool))

-- And it works fine..
foo5 :: IO Int
foo5 = do
  Just sp <- foo4
  return $ (deRefStaticPtr sp) 5