Control.Effect.Reader

Documentation

data Reader r m k

Constructors

Ask (r -> k)

Local (r -> r) (m b) (b -> k)

Instances

Effect (Reader r)

Defined in Control.Effect.Reader

Methods

handle :: Functor f => f () -> (forall x. f (m x) -> n (f x)) -> Reader r m (m a) -> Reader r n (n (f a))

HFunctor (Reader r)

Defined in Control.Effect.Reader

Methods

fmap' :: (a -> b) -> Reader r m a -> Reader r m b

hmap :: (forall x. m x -> n x) -> Reader r m a -> Reader r n a

Functor (Reader r m)

Defined in Control.Effect.Reader

Methods

fmap :: (a -> b) -> Reader r m a -> Reader r m b

(<$) :: a -> Reader r m b -> Reader r m a

(Carrier sig m, Monad m) => Carrier (Reader r :+: sig) (ReaderC r m)

Defined in Control.Effect.Reader

Methods

ret :: a -> ReaderC r m a

eff :: (Reader r :+: sig) (ReaderC r m) (ReaderC r m a) -> ReaderC r m a

ask :: (Member (Reader r) sig, Carrier sig m) => m r

Retrieve the environment value.

run (runReader a ask) == a

asks :: (Member (Reader r) sig, Carrier sig m, Functor m) => (r -> a) -> m a

Project a function out of the current environment value.

snd (run (runReader a (asks (applyFun f)))) == applyFun f a

local :: (Member (Reader r) sig, Carrier sig m) => (r -> r) -> m a -> m a

Run a computation with an environment value locally modified by the passed function.

run (runReader a (local (applyFun f) ask)) == applyFun f a

run (runReader a ((,,) <$> ask <*> local (applyFun f) ask <*> ask)) == (a, applyFun f a, a)

runReader :: (Carrier sig m, Monad m) => r -> Eff (ReaderC r m) a -> m a

Run a Reader effect with the passed environment value.

run (runReader a (pure b)) == b

newtype ReaderC r m a

Constructors

ReaderC

Fields

• runReaderC :: r -> m a

Instances

(Carrier sig m, Monad m) => Carrier (Reader r :+: sig) (ReaderC r m)

Defined in Control.Effect.Reader

Methods

ret :: a -> ReaderC r m a

eff :: (Reader r :+: sig) (ReaderC r m) (ReaderC r m a) -> ReaderC r m a