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aljce/Region.hs

Created January 16, 2019 21:04
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Region.hs
newtype Region s a = Region (IO a) deriving (Functor, Applicative, Monad)
liftIO :: IO a -> Region s a
liftIO = Region
runRegion :: (forall s. Region s a) -> IO a
runRegion (Region x) = x
newtype Ref s a = Ref (IORef a)
newRef :: a -> Region s (Ref s a)
newRef x = coerce (newIORef x)
-- Type error so invariant maintained
-- leak :: Region s (Ref s a) -> IO (Ref s a)
-- leak = runRegion
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