{-# language ImpredicativeTypes #-}

import Control.Monad.Reader.Class (MonadReader)
import Control.Monad.IO.Class (MonadIO)

f :: f (forall m a. MonadReader () m => m a -> m a)
f = undefined

g :: f (forall m a. MonadIO m => m a -> m a)
g = undefined

h1, h2, h3 :: Applicative f => f (forall m a. (MonadReader () m, MonadIO m) => m a -> m a)
h1 = (\f g -> f . g) <$> f <*> g

h2 = specialisedCompose <$> f <*> g where

specialisedCompose ::
    (forall m a. MonadReader () m => m a -> m a)
    -> (forall m a. MonadIO m => m a -> m a)
    -> forall m a. (MonadReader () m, MonadIO m) => m a -> m a
specialisedCompose f g = f . g

h3 = generalisedCompose <$> f <*> g where

generalisedCompose f g = f . g

main = putStrLn "hello"