Control.Monad.Ether.Reader

See Control.Monad.Reader.

MonadReader class

class Monad m => MonadReader tag r m | m tag -> r where

See MonadReader.

Minimal complete definition

(ask | reader), local

Methods

ask :: proxy tag -> m r

Retrieves the monad environment.

local

Arguments

:: proxy tag

-> (r -> r)

The function to modify the environment.

-> m a

Reader to run in the modified environment.

-> m a

Executes a computation in a modified environment.

reader

Arguments

:: proxy tag

-> (r -> a)

The selector function to apply to the environment.

-> m a

Retrieves a function of the current environment.

Instances

(LiftLocal t, Monad (t m), MonadReader tag r m) => MonadReader tag r (t m)

MonadReader tag r m => MonadReader tag r (WrappedEther tag' m)

Monad m => MonadReader tag r (ReaderT tag r m)

asks

Arguments

:: MonadReader tag r m

=> proxy tag

-> (r -> a)

The selector function to apply to the environment.

-> m a

Retrieves a function of the current environment.

The Reader monad

type Reader tag r = ReaderT tag r Identity

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.

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

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

The ReaderT monad transformer

data ReaderT tag r m a

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

Monad m => MonadReader tag r (ReaderT tag r m)

MonadState tag s m => MonadState tag s (ReaderT tag' r m)

MonadBase b m => MonadBase b (ReaderT tag r m)

MonadBaseControl b m => MonadBaseControl b (ReaderT tag r m)

MonadError e m => MonadError e (ReaderT tag r m)

MonadReader r' m => MonadReader r' (ReaderT tag r m)

MonadState s m => MonadState s (ReaderT tag r m)

MonadWriter w m => MonadWriter w (ReaderT tag r m)

MFunctor (ReaderT tag r)

MMonad (ReaderT tag r)

MonadTrans (ReaderT tag r)

MonadTransControl (ReaderT tag r)

LiftLocal (ReaderT tag r)

LiftCallCC (ReaderT tag r)

LiftPass (ReaderT tag r)

LiftListen (ReaderT tag r)

LiftCatch (ReaderT tag r)

Alternative m => Alternative (ReaderT tag r m)

Monad m => Monad (ReaderT tag r m)

Functor m => Functor (ReaderT tag r m)

MonadFix m => MonadFix (ReaderT tag r m)

MonadPlus m => MonadPlus (ReaderT tag r m)

Applicative m => Applicative (ReaderT tag r m)

MonadIO m => MonadIO (ReaderT tag r m)

MonadCont m => MonadCont (ReaderT tag r m)

Taggable (ReaderT tag r m)

Tagged (ReaderT tag r m) tag

Generic (ReaderT tag r m a)

Newtype (ReaderT tag r m a)

type StT (ReaderT tag r) a = StT (ReaderT r) a

type StT (ReaderT tag r) a = StT (ReaderT tag r) a

type Untagged (ReaderT tag r m) = ReaderT r m

type Tag (ReaderT tag r m) = Just * tag

type Inner (ReaderT tag r m) = Just (* -> *) m

type StM (ReaderT tag r m) a = ComposeSt (ReaderT tag r) m a

type Rep (ReaderT tag r m a)

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

Constructor for computations in the reader monad transformer.

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

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