A key part of the Reader monad is the ask (https://hackage.haskell.org/package/mtl-2.2.1/docs/Control-Monad-Reader.html#v:ask) function, which is defined for illustrative purposes:
import Control.Monad.Trans.Reader hiding (ask)
import Control.Monad.Trans
ask :: Monad m => ReaderT r m r
ask ...
