Foundation.Monad.Reader

The Reader monad transformer.

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

MonadReader

class Monad m => MonadReader m where

Minimal complete definition

ask

Associated Types

type ReaderContext m

Methods

ask :: m (ReaderContext m)

Instances

Monad m => MonadReader (ReaderT r m)

Associated Types

type ReaderContext (ReaderT r m :: * -> *) :: *

Methods

ask :: ReaderT r m (ReaderContext (ReaderT r m))

ReaderT

data ReaderT r m a

Reader Transformer

Instances

MonadTrans (ReaderT r)

Methods

lift :: Monad m => m a -> ReaderT r m a

Monad m => Monad (ReaderT r m)

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)

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)

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)

Methods

liftIO :: IO a -> ReaderT r m a

MonadCatch m => MonadCatch (ReaderT r m)

Methods

catch :: Exception e => ReaderT r m a -> (e -> ReaderT r m a) -> ReaderT r m a

MonadThrow m => MonadThrow (ReaderT r m)

Methods

throw :: Exception e => e -> ReaderT r m a

MonadFailure m => MonadFailure (ReaderT r m)

Associated Types

type Failure (ReaderT r m :: * -> *) :: *

Methods

mFail :: Failure (ReaderT r m) -> ReaderT r m ()

Monad m => MonadReader (ReaderT r m)

Associated Types

type ReaderContext (ReaderT r m :: * -> *) :: *

Methods

ask :: ReaderT r m (ReaderContext (ReaderT r m))

type Failure (ReaderT r m)

type Failure (ReaderT r m) = Failure m

type ReaderContext (ReaderT r m)

type ReaderContext (ReaderT r m) = r

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