Safe Haskell	None
Language	Haskell2010

Control.Effect.Reader

Synopsis

data Reader r m k
- = Ask (r -> k)
- | Local (r -> r) (m b) (b -> k)
ask :: (Member (Reader r) sig, Carrier sig m) => m r
asks :: (Member (Reader r) sig, Carrier sig m) => (r -> a) -> m a
local :: (Member (Reader r) sig, Carrier sig m) => (r -> r) -> m a -> m a
runReader :: r -> ReaderC r m a -> m a
newtype ReaderC r m a = ReaderC {
- runReaderC :: r -> m a
}

Documentation

data Reader r m k Source #

Constructors

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

Instances

Effect (Reader r) Source #
Instance details 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)) Source #
HFunctor (Reader r) Source #
Instance details Defined in Control.Effect.Reader Methods fmap' :: (a -> b) -> Reader r m a -> Reader r m b Source # hmap :: (forall x. m x -> n x) -> Reader r m a -> Reader r n a Source #
Functor (Reader r m) Source #
Instance details 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 => Carrier (Reader r :+: sig) (ReaderC r m) Source #
Instance details Defined in Control.Effect.Reader Methods eff :: (Reader r :+: sig) (ReaderC r m) (ReaderC r m a) -> ReaderC r m a Source # ret :: a -> ReaderC r m a Source #

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

Retrieve the environment value.

run (runReader a ask) == a

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

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 Source #

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 :: r -> ReaderC r m a -> m a Source #

Run a Reader effect with the passed environment value.

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

newtype ReaderC r m a Source #

Constructors

ReaderC
Fields runReaderC :: r -> m a

Instances

MonadTrans (ReaderC r) Source #
Instance details Defined in Control.Effect.Reader Methods lift :: Monad m => m a -> ReaderC r m a #
Monad m => Monad (ReaderC r m) Source #
Instance details Defined in Control.Effect.Reader Methods (>>=) :: ReaderC r m a -> (a -> ReaderC r m b) -> ReaderC r m b # (>>) :: ReaderC r m a -> ReaderC r m b -> ReaderC r m b # return :: a -> ReaderC r m a # fail :: String -> ReaderC r m a #
Functor m => Functor (ReaderC r m) Source #
Instance details Defined in Control.Effect.Reader Methods fmap :: (a -> b) -> ReaderC r m a -> ReaderC r m b # (<$) :: a -> ReaderC r m b -> ReaderC r m a #
MonadFail m => MonadFail (ReaderC r m) Source #
Instance details Defined in Control.Effect.Reader Methods fail :: String -> ReaderC r m a #
Applicative m => Applicative (ReaderC r m) Source #
Instance details Defined in Control.Effect.Reader Methods pure :: a -> ReaderC r m a # (<>) :: ReaderC r m (a -> b) -> ReaderC r m a -> ReaderC r m b # liftA2 :: (a -> b -> c) -> ReaderC r m a -> ReaderC r m b -> ReaderC r m c # (>) :: ReaderC r m a -> ReaderC r m b -> ReaderC r m b # (<*) :: ReaderC r m a -> ReaderC r m b -> ReaderC r m a #
MonadIO m => MonadIO (ReaderC r m) Source #
Instance details Defined in Control.Effect.Reader Methods liftIO :: IO a -> ReaderC r m a #
Alternative m => Alternative (ReaderC r m) Source #
Instance details Defined in Control.Effect.Reader Methods empty :: ReaderC r m a # (<\|>) :: ReaderC r m a -> ReaderC r m a -> ReaderC r m a # some :: ReaderC r m a -> ReaderC r m [a] # many :: ReaderC r m a -> ReaderC r m [a] #
(Alternative m, Monad m) => MonadPlus (ReaderC r m) Source #
Instance details Defined in Control.Effect.Reader Methods mzero :: ReaderC r m a # mplus :: ReaderC r m a -> ReaderC r m a -> ReaderC r m a #
Carrier sig m => Carrier (Reader r :+: sig) (ReaderC r m) Source #
Instance details Defined in Control.Effect.Reader Methods eff :: (Reader r :+: sig) (ReaderC r m) (ReaderC r m a) -> ReaderC r m a Source # ret :: a -> ReaderC r m a Source #