Safe Haskell	None
Language	Haskell2010

Foundation.Monad.Reader

Contents

MonadReader
ReaderT

Description

The Reader monad transformer.

This is useful to keep a non-modifiable value in a context

Synopsis

MonadReader

class Monad m => MonadReader m where Source #

Minimal complete definition

ask

Associated Types

type ReaderContext m Source #

Methods

ask :: m (ReaderContext m) Source #

Instances

Monad m => MonadReader (ReaderT r m) Source #
Associated Types type ReaderContext (ReaderT r m :: * -> ) :: Source # Methods ask :: ReaderT r m (ReaderContext (ReaderT r m)) Source #

ReaderT

data ReaderT r m a Source #

Reader Transformer

Instances

MonadTrans (ReaderT r) Source #
Methods lift :: Monad m => m a -> ReaderT r m a Source #
Monad m => Monad (ReaderT r m) Source #
Methods (>>=) :: ReaderT r m a -> (a -> ReaderT r m b) -> ReaderT r m b # (>>) :: ReaderT r m a -> ReaderT r m b -> ReaderT r m b # return :: a -> ReaderT r m a # fail :: String -> ReaderT r m a #
Functor m => Functor (ReaderT r m) Source #
Methods fmap :: (a -> b) -> ReaderT r m a -> ReaderT r m b # (<$) :: a -> ReaderT r m b -> ReaderT r m a #
Applicative m => Applicative (ReaderT r m) Source #
Methods pure :: a -> ReaderT r m a # (<>) :: ReaderT r m (a -> b) -> ReaderT r m a -> ReaderT r m b # (>) :: ReaderT r m a -> ReaderT r m b -> ReaderT r m b # (<*) :: ReaderT r m a -> ReaderT r m b -> ReaderT r m a #
MonadIO m => MonadIO (ReaderT r m) Source #
Methods liftIO :: IO a -> ReaderT r m a #
MonadCatch m => MonadCatch (ReaderT r m) Source #
Methods catch :: Exception e => ReaderT r m a -> (e -> ReaderT r m a) -> ReaderT r m a Source #
MonadThrow m => MonadThrow (ReaderT r m) Source #
Methods throw :: Exception e => e -> ReaderT r m a Source #
MonadFailure m => MonadFailure (ReaderT r m) Source #
Associated Types type Failure (ReaderT r m :: * -> ) :: Source # Methods mFail :: Failure (ReaderT r m) -> ReaderT r m () Source #
Monad m => MonadReader (ReaderT r m) Source #
Associated Types type ReaderContext (ReaderT r m :: * -> ) :: Source # Methods ask :: ReaderT r m (ReaderContext (ReaderT r m)) Source #
type Failure (ReaderT r m) Source #
type Failure (ReaderT r m) = Failure m
type ReaderContext (ReaderT r m) Source #
type ReaderContext (ReaderT r m) = r

runReaderT :: ReaderT r m a -> r -> m a Source #