Safe Haskell	None
Language	Haskell2010

Control.Monad.Trans.Ether.Reader

Contents

Description

Synopsis

The Reader monad

The parameterizable reader monad.

Computations are functions of a shared environment.

The return function ignores the environment, while >>= passes the inherited environment to both subcomputations.

reader :: Monad m => proxy tag -> (r -> a) -> ReaderT tag r m a Source

Constructor for computations in the reader monad (the inverse of runReader).

runReader :: proxy tag -> Reader tag r a -> r -> a Source

Runs a ReaderT with the given environment and returns the vinal value.

The ReaderT monad transformer

data ReaderT tag r m a Source

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.

Instances

MonadReader tag r m => MonadReader tag r (ReaderT tag' r' m) Source
Monad m => MonadReader tag r (ReaderT tag r m) Source
MonadState tag s m => MonadState tag s (ReaderT tag' r m) Source
MonadExcept tag e m => MonadExcept tag e (ReaderT tag' r m) Source
MonadWriter tag w m => MonadWriter tag w (ReaderT tag' r m) Source
MonadError e m => MonadError e (ReaderT tag r m) Source
MonadReader r' m => MonadReader r' (ReaderT tag r m) Source
MonadState s m => MonadState s (ReaderT tag r m) Source
MonadWriter w m => MonadWriter w (ReaderT tag r m) Source
MonadTrans (ReaderT tag r) Source
Monad m => Monad (ReaderT tag r m) Source
Functor m => Functor (ReaderT tag r m) Source
MonadFix m => MonadFix (ReaderT tag r m) Source
Applicative m => Applicative (ReaderT tag r m) Source
Alternative m => Alternative (ReaderT tag r m) Source
MonadPlus m => MonadPlus (ReaderT tag r m) Source
MonadIO m => MonadIO (ReaderT tag r m) Source
MonadCont m => MonadCont (ReaderT tag r m) Source
Taggable (ReaderT tag r m) Source
Tagged (ReaderT tag r m) tag Source
Generic (ReaderT tag r m a) Source
Newtype (ReaderT tag r m a) Source
type Untagged (ReaderT tag r m) = ReaderT r m Source
type Tag (ReaderT tag r m) = Just * tag Source
type Inner (ReaderT tag r m) = Just (* -> *) m Source
type Rep (ReaderT tag r m a) Source
type O (ReaderT tag r m a) = GO (Rep (ReaderT tag r m a))

readerT :: proxy tag -> (r -> m a) -> ReaderT tag r m a Source

Constructor for computations in the reader monad transformer.

runReaderT :: proxy tag -> ReaderT tag r m a -> r -> m a Source

Runs a ReaderT with the given environment and returns the vinal value.

mapReaderT :: proxy tag -> (m a -> n b) -> ReaderT tag r m a -> ReaderT tag r n b Source

Transform the computation inside a ReaderT.

runReaderT tag (mapReaderT tag f m) = f . runReaderT tag m

Arguments

:: proxy tag
-> (r' -> r)	The function to modify the environment.
-> ReaderT tag r m a	Computation to run in the modified environment.
-> ReaderT tag r' m a

Execute a computation in a modified environment (a more general version of local).

runReaderT tag (withReaderT tag f m) = runReaderT tag m . f

ask :: Monad m => proxy tag -> ReaderT tag r m r Source

Fetch the value of the environment.

Arguments

:: proxy tag
-> (r -> r)	The function to modify the environment.
-> ReaderT tag r m a	Computation to run in the modified environment.
-> ReaderT tag r m a

Execute a computation in a modified environment (a specialization of withReaderT).

runReaderT tag (local tag f m) = runReaderT tag m . f

liftCatch :: proxy tag -> Catch e m a -> Catch e (ReaderT tag r m) a Source

Lift a catchE operation to the new monad.

liftCallCC :: proxy tag -> CallCC m a b -> CallCC (ReaderT tag r m) a b Source

Lift a callCC operation to the new monad.