Safe Haskell	None
Language	Haskell2010

Bluefin.State

Contents

Synopsis

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

Handle

A handle to a strict mutable state of type a

Handlers

Arguments

:: forall s (es :: Effects) a. s	Initial state
-> (forall (st :: Effects). State s st -> Eff (st :& 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 (st :: Effects). State s st -> Eff (st :& 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 (st :: Effects) (es :: Effects) s. st :> es
=> State s st
-> Eff es s	The current value of the state

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

Arguments

:: forall (st :: Effects) (es :: Effects) s. st :> es
=> State s st
-> 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 (st :: Effects) (es :: Effects) s. st :> es
=> State s st
-> (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)