{-# LANGUAGE ScopedTypeVariables #-}
import Control.Applicative
import Control.Exception
import System.Environment (getArgs)
import System.Exit (ExitCode)
import System.IO (hClose)
import System.IO.Unsafe (unsafeInterleaveIO)
import qualified System.Process as P
import Text.JSON.AttoJSON
import qualified Data.ByteString as S
err :: String -> a
err s = error $ "JSON decoding: " ++ s
decodeFile :: FilePath -> IO (Either String JSValue)
decodeFile fp = parseJSON <$> S.readFile fp
parseJSONFiles :: [FilePath] -> IO [JSValue]
parseJSONFiles [] = (:[]) . either err id . parseJSON <$> S.getContents
parseJSONFiles xs = mapM (unsafeInterleaveIO . fmap (either err id) . decodeFile) xs
systemWithStdin :: String -> S.ByteString -> IO ExitCode
systemWithStdin shellCmd input = do
(Just stdinHdl, _, _, pHdl) <-
P.createProcess (P.shell shellCmd){ P.std_in = P.CreatePipe }
handle (\(_ :: IOException) -> return ()) $ do
S.hPutStr stdinHdl input
hClose stdinHdl
P.waitForProcess pHdl
unSequence :: JSValue -> [JSValue]
unSequence (JSArray a) = a
unSequence _ = error "unSequence: a JSON sequence was expected"
iterJSON :: String -> [String] -> IO ()
iterJSON cmd jsonfiles =
mapM_ (mapM_ (systemWithStdin cmd . showJSON) . unSequence)
=<< parseJSONFiles jsonfiles
main :: IO ()
main = do
cmd:args <- getArgs
iterJSON cmd args