Safe Haskell	Safe-Inferred
Language	Haskell2010

Effectful.Reader.Static

Contents

Description

Support for access to a read only value of a particular type.

Synopsis

data Reader (r :: Type) :: Effect
runReader :: HasCallStack => r -> Eff (Reader r : es) a -> Eff es a
withReader :: HasCallStack => (r1 -> r2) -> Eff (Reader r2 : es) a -> Eff (Reader r1 : es) a
ask :: (HasCallStack, Reader r :> es) => Eff es r
asks :: (HasCallStack, Reader r :> es) => (r -> a) -> Eff es a
local :: (HasCallStack, Reader r :> es) => (r -> r) -> Eff es a -> Eff es a

Effect

Provide access to a strict (WHNF), thread local, read only value of type r.

Instances details

type DispatchOf (Reader r) Source #
Instance details Defined in Effectful.Reader.Static type DispatchOf (Reader r) = 'Static 'NoSideEffects
newtype StaticRep (Reader r) Source #
Instance details Defined in Effectful.Reader.Static newtype StaticRep (Reader r) = Reader r

Handlers

Arguments

Run a Reader effect with the given initial environment.

Arguments

:: HasCallStack
=> (r1 -> r2)	The function to modify the environment.
-> Eff (Reader r2 : es) a	Computation to run in the modified environment.
-> Eff (Reader r1 : es) a

Execute a computation in a modified environment.

Since: 1.1.0.0

Fetch the value of the environment.

Arguments

:: (HasCallStack, Reader r :> es)
=> (r -> a)	The function to apply to the environment.
-> Eff es a

Retrieve a function of the current environment.

asks f ≡ f <$> ask

Arguments

:: (HasCallStack, Reader r :> es)
=> (r -> r)	The function to modify the environment.
-> Eff es a
-> Eff es a

Execute a computation in a modified environment.

runReader r (local f m) ≡ runReader (f r) m