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{-# OPTIONS -cpp #-}
--
-- 'sums' benchmark from the great language shootout
--
import System.IO
import qualified Data.ByteString as B
import Data.ByteString (ByteString)
import Data.ByteString.Unsafe (unsafeTail,unsafeIndex)
import Data.Char -- seems to help!
#define STRICT2(f) f a b | a `seq` b `seq` False = undefined
main = print . go 0 =<< B.getContents
STRICT2(go)
go i ps
| B.null ps = i
| x == 45 = neg 0 xs
| otherwise = pos (parse x) xs
where
(x, xs) = (ps `unsafeIndex` 0, unsafeTail ps)
STRICT2(neg)
neg n qs | x == 10 = go (i-n) xs
| otherwise = neg (parse x + (10 * n)) xs
where (x, xs) = (qs `unsafeIndex` 0, unsafeTail qs)
STRICT2(pos)
pos n qs | x == 10 = go (i+n) xs
| otherwise = pos (parse x + (10 * n)) xs
where (x, xs) = (qs `unsafeIndex` 0, unsafeTail qs)
parse w = fromIntegral (w - 48) :: Int
{-# INLINE parse #-}
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