data Ref :: !

data RefVal :: * -> *

modifyRef :: forall s r. RefVal s -> (s -> s) -> Eff (ref :: Ref | r) Unit

newRef :: forall s r. s -> Eff (ref :: Ref | r) (RefVal s)

readRef :: forall s r. RefVal s -> Eff (ref :: Ref | r) s

writeRef :: forall s r. RefVal s -> s -> Eff (ref :: Ref | r) Unit

unsafeRunRef :: forall eff a. Eff (ref :: Ref | eff) a -> Eff eff a