Control.Monad.Readers

MonadState without the function dependency m -> s.

Documentation

module Control.Monad.Trans.Reader

class Monad m => MonadReaders r m where

Minimal complete definition

askPoly, localPoly

Methods

askPoly :: m r

localPoly :: (r -> r) -> m a -> m a

readerPoly :: (r -> a) -> m a

Retrieves a function of the current environment.

Instances

MonadReaders r m => MonadReaders r (MaybeT m)

Methods

askPoly :: MaybeT m r

localPoly :: (r -> r) -> MaybeT m a -> MaybeT m a

readerPoly :: (r -> a) -> MaybeT m a

MonadReaders r m => MonadReaders r (ListT m)

Methods

askPoly :: ListT m r

localPoly :: (r -> r) -> ListT m a -> ListT m a

readerPoly :: (r -> a) -> ListT m a

MonadReaders r ((->) r)

Methods

askPoly :: r -> r

localPoly :: (r -> r) -> (r -> a) -> r -> a

readerPoly :: (r -> a) -> r -> a

(Monoid w, MonadReaders r m) => MonadReaders r (WriterT w m)

Methods

askPoly :: WriterT w m r

localPoly :: (r -> r) -> WriterT w m a -> WriterT w m a

readerPoly :: (r -> a) -> WriterT w m a

(Monoid w, MonadReaders r m) => MonadReaders r (WriterT w m)

Methods

askPoly :: WriterT w m r

localPoly :: (r -> r) -> WriterT w m a -> WriterT w m a

readerPoly :: (r -> a) -> WriterT w m a

MonadReaders r m => MonadReaders r (StateT s m)

Methods

askPoly :: StateT s m r

localPoly :: (r -> r) -> StateT s m a -> StateT s m a

readerPoly :: (r -> a) -> StateT s m a

MonadReaders r m => MonadReaders r (StateT s m)

Methods

askPoly :: StateT s m r

localPoly :: (r -> r) -> StateT s m a -> StateT s m a

readerPoly :: (r -> a) -> StateT s m a

MonadReaders r m => MonadReaders r (IdentityT * m)

Methods

askPoly :: IdentityT * m r

localPoly :: (r -> r) -> IdentityT * m a -> IdentityT * m a

readerPoly :: (r -> a) -> IdentityT * m a

MonadReaders r m => MonadReaders r (ExceptT e m)

Methods

askPoly :: ExceptT e m r

localPoly :: (r -> r) -> ExceptT e m a -> ExceptT e m a

readerPoly :: (r -> a) -> ExceptT e m a

(Error e, MonadReaders r m) => MonadReaders r (ErrorT e m)

Methods

askPoly :: ErrorT e m r

localPoly :: (r -> r) -> ErrorT e m a -> ErrorT e m a

readerPoly :: (r -> a) -> ErrorT e m a

MonadReaders r' m => MonadReaders r' (ContT * r m)

Modiifed copies of instances from mtl.

Methods

askPoly :: ContT * r m r'

localPoly :: (r' -> r') -> ContT * r m a -> ContT * r m a

readerPoly :: (r' -> a) -> ContT * r m a

Monad m => MonadReaders r (ReaderT * r m)

Methods

askPoly :: ReaderT * r m r

localPoly :: (r -> r) -> ReaderT * r m a -> ReaderT * r m a

readerPoly :: (r -> a) -> ReaderT * r m a

(Monad m, Monoid w) => MonadReaders r (RWST r w s m)

Methods

askPoly :: RWST r w s m r

localPoly :: (r -> r) -> RWST r w s m a -> RWST r w s m a

readerPoly :: (r -> a) -> RWST r w s m a

(Monad m, Monoid w) => MonadReaders r (RWST r w s m)

Methods

askPoly :: RWST r w s m r

localPoly :: (r -> r) -> RWST r w s m a -> RWST r w s m a

readerPoly :: (r -> a) -> RWST r w s m a

viewPoly :: forall r m a. MonadReaders r m => Getting a r a -> m a

Modified view function that works if there is a MonadReaders r instance