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aarroyoc/sumst.hs

Created April 9, 2018 15:17
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Suma con mónada ST
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sumst.hs
import Data.STRef
import Control.Monad
import Control.Monad.ST
sumST :: Num a => [a] -> a
sumST xs = runST $ do
n <- newSTRef 0
forM_ xs $ \x -> do
modifySTRef n (+x)
readSTRef n
main :: IO ()
main = do
putStrLn "Suma imperativa"
let x = sumST [1,2,3,4,5,6,7,8,9]
putStrLn ("Suma: "++(show x))
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