Hello café, I want to replace the -fglasgow-exts in the snippet below by LANGUAGE pragmas. Rank2Types alone doesn't suffice. Which do I need to get the snippet to compile?

{-# OPTIONS -fglasgow-exts #-}

module RunMud where

import Control.Monad.State

type Mud = StateT MudState IO data MudState = MudState { mRunMud :: RunMud } type RunMud = forall a. Mud a -> IO a

getRunMud :: Mud RunMud getRunMud = do s <- get return (mRunMud s)

Thanks in advance, Martijn.