14 lines
317 B
Haskell
14 lines
317 B
Haskell
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import Control.Monad
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import Control.Monad.ST
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import Data.STRef
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sum' ref_i lo hi term =
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return sum `ap`
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mapM (\i -> writeSTRef ref_i i >> term) [lo..hi]
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foo = runST $ do
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i <- newSTRef undefined -- initial value doesn't matter
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sum' i 1 100 $ return recip `ap` readSTRef i
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main = print foo
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