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{-# LANGUAGE BangPatterns, ScopedTypeVariables #-}
import Control.Monad
import qualified Data.ByteString as B
import Data.Csv.Incremental
import System.Exit
import System.IO
main :: IO ()
main = withFile "salaries.csv" ReadMode $ \ csvFile -> do
let loop !_ (Fail _ errMsg) = putStrLn errMsg >> exitFailure
loop acc (Many rs k) = loop (acc + sumSalaries rs) =<< feed k
loop acc (Done rs) = putStrLn $ "Total salaries: " ++
show (sumSalaries rs + acc)
feed k = do
isEof <- hIsEOF csvFile
if isEof
then return $ k B.empty
else k `fmap` B.hGetSome csvFile 4096
loop 0 (decode NoHeader)
where
sumSalaries rs = sum [salary | Right (_ :: String, salary :: Int) <- rs]
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