{-# Language RankNTypes #-}
import Control.Lens.Type
import Control.Lens.Zoom (zoom)
import Control.Monad.RWS.Strict (RWS)

{-- semantically, bad=good but it does not compile with GHC >= 9
bad :: Monoid w => Lens' s a ->
  RWS r w a x -> 
  RWS r w s x
bad = zoom
--}

good :: Monoid w => Lens' s a ->
  RWS r w a x -> 
  RWS r w s x
good x = zoom x

main = return ()