module Util.UniqueMonad(UniqT,Uniq, runUniq, runUniqT, execUniq1, execUniq, execUniqT) where import GenUtil import Data.Unique import Control.Monad.State import Control.Monad.Reader import Control.Monad.Writer import Control.Monad.Identity instance UniqueProducer IO where newUniq = do u <- newUnique return $ hashUnique u instance Monad m => UniqueProducer (UniqT m) where newUniq = UniqT $ do modify (+1) get -- | Run the transformer version of the unique int generator. runUniqT :: Monad m => UniqT m a -> Int -> m (a,Int) runUniqT (UniqT sm) s = runStateT sm s -- | Run the bare version of the unique int generator. runUniq :: Int -> Uniq a -> (a,Int) runUniq x y = runIdentity $ runUniqT y x -- | Execute the bare unique int generator starting with 1. execUniq1 :: Uniq a -> a execUniq1 x = fst $ runUniq 1 x -- | Execute the bare unique int generator starting with the suplied number. execUniq :: Int -> Uniq a -> a execUniq st x = fst $ runUniq st x -- | Execute the transformer version of the unique int generator starting with the suplied number. execUniqT :: Monad m => Int -> UniqT m a -> m a execUniqT s (UniqT sm) = liftM fst $ runStateT sm s instance (Monad m, Monad (t m), MonadTrans t, UniqueProducer m) => UniqueProducer (t m) where newUniq = lift newUniq -- | Unique integer generator monad transformer. newtype UniqT m a = UniqT (StateT Int m a) deriving(Monad, MonadTrans, Functor, MonadFix, MonadPlus) instance MonadReader s m => MonadReader s (UniqT m) where ask = UniqT $ ask local f (UniqT x) = UniqT $ local f x -- | Unique integer generator monad. type Uniq = UniqT Identity