Control.Monad.Representable.Reader

Representable functors on Hask are all monads, because they are isomorphic to a Reader monad.

Representable functor monad

type Reader f = ReaderT f Identity

runReader :: Representable f => Reader f b -> Rep f -> b

Monad Transformer

newtype ReaderT f m b

Constructors

ReaderT

Fields

getReaderT :: f (m b)

Instances

(Representable f, MonadWriter w m) => MonadWriter w (ReaderT f m)

Representable f => MonadTrans (ReaderT f)

(Representable f, Monad m) => Monad (ReaderT f m)

(Functor f, Functor m) => Functor (ReaderT f m)

(Representable f, Applicative m) => Applicative (ReaderT f m)

(Foldable f, Foldable m) => Foldable (ReaderT f m)

(Traversable f, Traversable m) => Traversable (ReaderT f m)

(Representable f, Representable m, Monoid (Rep f), Monoid (Rep m)) => Comonad (ReaderT f m)

(Representable f, Distributive m) => Distributive (ReaderT f m)

(Representable f, MonadIO m) => MonadIO (ReaderT f m)

(Traversable1 f, Traversable1 m) => Traversable1 (ReaderT f m)

(Representable f, Apply m) => Apply (ReaderT f m)

(Representable f, Bind m) => Bind (ReaderT f m)

(Representable f, Representable m, Semigroup (Rep f), Semigroup (Rep m)) => Extend (ReaderT f m)

(Foldable1 f, Foldable1 m) => Foldable1 (ReaderT f m)

(Representable f, Representable m) => Representable (ReaderT f m)

type Rep (ReaderT f m) = (Rep f, Rep m)

readerT :: Representable f => (Rep f -> m b) -> ReaderT f m b

runReaderT :: Representable f => ReaderT f m b -> Rep f -> m b

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

See examples in Control.Monad.Reader. Note, the partially applied function type (->) r is a simple reader monad. See the instance declaration below.

Minimal complete definition

ask, local

Methods

ask :: m r

Retrieves the monad environment.

local

Arguments

:: (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

:: (r -> a)

The selector function to apply to the environment.

-> m a

Retrieves a function of the current environment.

Instances

(Representable f, (~) * (Rep f) a) => MonadReader a (Co f)

MonadReader r m => MonadReader r (MaybeT m)

MonadReader r m => MonadReader r (ListT m)

MonadReader r m => MonadReader r (IdentityT m)

MonadReader r ((->) r)

(Functor m, MonadReader e m) => MonadReader e (Free m)

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

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

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

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

Monad m => MonadReader r (ReaderT r m)

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

MonadReader r' m => MonadReader r' (ContT r m)

(Representable g, MonadReader e m) => MonadReader e (StateT g m)

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

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

module Data.Functor.Rep