module Simulation.Aivika.Dynamics.Ref
(Ref,
refQueue,
newRef,
readRef,
writeRef,
modifyRef) where
import Data.IORef
import Control.Monad
import Control.Monad.Trans
import Simulation.Aivika.Dynamics.Internal.Simulation
import Simulation.Aivika.Dynamics.Internal.Dynamics
import Simulation.Aivika.Dynamics.EventQueue
data Ref a =
Ref { refQueue :: EventQueue,
refRun :: Dynamics (),
refValue :: IORef a }
newRef :: EventQueue -> a -> Simulation (Ref a)
newRef q a =
do x <- liftIO $ newIORef a
return Ref { refQueue = q,
refRun = queueRun q,
refValue = x }
readRef :: Ref a -> Dynamics a
readRef r = Dynamics $ \p ->
do let Dynamics m = refRun r
m p
readIORef (refValue r)
writeRef :: Ref a -> a -> Dynamics ()
writeRef r a = Dynamics $ \p ->
a `seq` writeIORef (refValue r) a
modifyRef :: Ref a -> (a -> a) -> Dynamics ()
modifyRef r f = Dynamics $ \p ->
do let Dynamics m = refRun r
m p
a <- readIORef (refValue r)
let b = f a
b `seq` writeIORef (refValue r) b