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bananu7/hoistState.hs

Created November 11, 2014 10:58
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hoistState.hs
--hoistState :: Monad m => S.State s a -> S.StateT s m a
--hoistState = S.StateT . (return .) . S.runState
hoistState :: (Monad m, S.MonadState s m) => S.State s a -> m a
hoistState op = do
x <- S.get
let (r, x') = S.runState op x
S.put x'
return r
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