I am currently learning about Monad Transformers and noticed that the MonadTrans class that the library I am using (Mageparsec) implements, does not define any way to group and split apart the Transformer, where I would expect these functions to both exist and have this signature.
group:: (MonadTrans t, Monad m) => t Identity (m a) -> t m a
split:: (MonadTrans t, Monad m) => t m a -> t Identity (m a)
... And be defined as inverses of each other.
The reason I was expecting some functions like this to be defined, is because without them I have no clue how I would define group $ f <$> split tmx <*> split tmy. Not that they would be only useful for that!
To my current knowledge: (TransMonadT m) a is isomorphic to TransMonad (m a)
- Do these functions exist within
Control.Monad.Trans? - And if not how do I define them in general?
- And if I cannot define them in general, at the very least how do I define them for
ParsecT?