Safe Haskell	None
Language	Haskell2010

Bluefin.State

Contents

Description

This is an old interface and will be deprecated in the future. You are encouraged to use Bluefin.Capability.Modify instead.

Synopsis

data State s (e :: Effects)
evalState :: forall s (es :: Effects) a. s -> (forall (e :: Effects). State s e -> Eff (e :& es) a) -> Eff es a
runState :: forall s (es :: Effects) a. s -> (forall (e :: Effects). State s e -> Eff (e :& es) a) -> Eff es (a, s)
withState :: forall s (es :: Effects) a. s -> (forall (e :: Effects). State s e -> Eff (e :& es) (s -> a)) -> Eff es a
get :: forall (e :: Effects) (es :: Effects) s. e <: es => State s e -> Eff es s
put :: forall (e :: Effects) (es :: Effects) s. e <: es => State s e -> s -> Eff es ()
modify :: forall (e :: Effects) (es :: Effects) s. e <: es => State s e -> (s -> s) -> Eff es ()

Handle

data State s (e :: Effects) #

Capability to modify a reference to an s

Instances details

e <: es => OneWayCoercible (State s e :: Type) (State s es :: Type)
Instance details Defined in Bluefin.Internal Methods oneWayCoercibleImpl :: OneWayCoercibleD (State s e) (State s es) #
Handle (State s)
Instance details Defined in Bluefin.Internal Methods handleImpl :: HandleD (State s) #
CloneableHandle (State s)	Cloning a `State` copies its contents to a new `State`. Changes to one will not effect the other.
Instance details Defined in Bluefin.Internal.CloneableHandle Methods cloneableHandleImpl :: CloneableHandleD (State s) #

Handlers

Arguments

:: forall s (es :: Effects) a. s	Initial state
-> (forall (e :: Effects). State s e -> Eff (e :& es) a)	Stateful computation
-> Eff es a	Result

>>> runPureEff $ evalState 10 $ \st -> do
      n <- get st
      pure (2 * n)
20

Arguments

:: forall s (es :: Effects) a. s	Initial state
-> (forall (e :: Effects). State s e -> Eff (e :& es) a)	Stateful computation
-> Eff es (a, s)	Result and final state

>>> runPureEff $ runState 10 $ \st -> do
      n <- get st
      pure (2 * n)
(20,10)

Arguments

:: forall s (es :: Effects) a. s	Initial state
-> (forall (e :: Effects). State s e -> Eff (e :& es) (s -> a))	Stateful computation
-> Eff es a	Result

>>> runPureEff $ withState 10 $ \st -> do
      n <- get st
      pure (s -> (2 * n, s))
(20,10)

Arguments

:: forall (e :: Effects) (es :: Effects) s. e <: es
=> State s e
-> Eff es s	The current value of the state

>>> runPureEff $ runState 10 $ \st -> do
      n <- get st
      pure (2 * n)
(20,10)

Arguments

:: forall (e :: Effects) (es :: Effects) s. e <: es
=> State s e
-> s	The new value of the state. The new value is forced before writing it to the state.
-> Eff es ()

Set the value of the state

>>> runPureEff $ runState 10 $ \st -> do
      put st 30
((), 30)

Arguments

:: forall (e :: Effects) (es :: Effects) s. e <: es
=> State s e
-> (s -> s)	Apply this function to the state. The new value of the state is forced before writing it to the state.
-> Eff es ()

>>> runPureEff $ runState 10 $ \st -> do
      modify st (* 2)
((), 20)