ReaderT

ReaderT :: (r -> m a) -> ReaderT r a
mtl Control.Monad.Reader
ReaderT :: (r -> m a) -> ReaderT r m a
transformers Control.Monad.Trans.Reader
newtype ReaderT r m a
transformers Control.Monad.Trans.Reader
The reader monad transformer, which adds a read-only environment to the given monad. The return function ignores the environment, while >>= passes the inherited environment to both subcomputations.
mapReaderT :: (m a -> n b) -> ReaderT r m a -> ReaderT r n b
transformers Control.Monad.Trans.Reader, mtl Control.Monad.Reader
Transform the computation inside a ReaderT. *  (mapReaderT f m) = f . > runReaderT
runReaderT :: ReaderT r a -> r -> m a
mtl Control.Monad.Reader
The underlying computation, as a function of the environment.
runReaderT :: ReaderT r m a -> r -> m a
transformers Control.Monad.Trans.Reader
The underlying computation, as a function of the environment.
withReaderT :: (r' -> r) -> ReaderT r m a -> ReaderT r' m a
transformers Control.Monad.Trans.Reader, mtl Control.Monad.Reader
Execute a computation in a modified environment (a more general version of local). *  (withReaderT f m) = > runReaderT m .