Re: [Haskell-beginners] Getting into nested monad transformers

23 Feb 2009

      On Thu, Feb 19, 2009 at 09:51:06PM -0800, Arthur Chan wrote:
...
Hey all,
I've been trying to access the inner state "s" for this type:
newtype TestThingey s a = TestThingey {
      runTrans :: ReaderT Int (StateT String (StateT s IO)) a
} deriving (Monad, MonadIO, MonadState String, MonadReader Int)
In this situation I would combine the String and s into one state:

  ReaderT Int (StateT (String,s) IO) a

Otherwise, yes, you'll just have to use the appropriate number of
lifts.

-Brent

Re: [Haskell-beginners] Getting into nested monad transformers

Brent Yorgey