module Main where

import Control.Monad.MultiLift
import Control.Monad.MultiWrap
import Control.Monad.Reader
import Control.Monad.State
import Control.Monad.Trans
import Control.Monad.Wrap

newtype Type1 = Type1 { unType1 :: String }
type Reader1 = ReaderT Type1 IO

newtype Type2 = Type2 { unType2 :: String }
type Reader2 = ReaderT Type2 Reader1

type Outer = StateT () Reader2

r3 :: Outer ()
r3 = do
  -- Note that you have to specify the inner type
  s1 <- mlift (asks unType1 :: Reader1 String)
  liftIO $ putStrLn $ "s1: " ++ s1
  s2 <- mlift (asks unType2 :: Reader2 String)
  liftIO $ putStrLn $ "s2: " ++ s2

r2 :: Outer ()
r2 = do
  mwrap (local augment :: Reader1 a -> Reader1 a) r3
  where
    augment (Type1 s) = Type1 $ s ++ " (augmented)"

r1 :: Reader2 ()
r1 = do
  liftM fst $ runStateT r3 ()
  liftM fst $ runStateT r2 ()
  -- runContWrapT r2 return
  

main :: IO ()
main = do
  runReaderT (runReaderT r1 $ Type2 "this is the Reader2 contents")
       $ Type1 "this is the Reader1 contents"