ref: a4229eb282ca32bc14103a33092e94382c3c7ca0
dir: /lib/Data/IORef.hs/
module Data.IORef(
IORef,
newIORef,
readIORef,
writeIORef,
modifyIORef,
) where
import Prelude() -- do not import Prelude
import Primitives
import Data.Eq
import {-# SOURCE #-} Data.Typeable
-- An IORef is represented as an IOArray with a single element.
newtype IORef a = R (IOArray a)
deriving (Typeable)
instance forall a . Eq (IORef a) where
R x == R y = primArrEQ x y
newIORef :: forall a . a -> IO (IORef a)
newIORef a = primArrAlloc 1 a `primBind` \ p -> primReturn (R p)
readIORef :: forall a . IORef a -> IO a
readIORef (R p) = primArrRead p 0
writeIORef :: forall a . IORef a -> a -> IO ()
writeIORef (R p) a = primArrWrite p 0 a
modifyIORef :: forall a . IORef a -> (a -> a) -> IO ()
modifyIORef (R p) f = primArrRead p 0 `primBind` \ a -> primArrWrite p 0 (f a)