OnChange.hs

module Main where

import           System.Environment                      ( getArgs )
import           System.FSNotify
import           System.FilePath.Posix                   ( takeFileName )
import           System.Process                          ( spawnProcess )
import           Control.Monad                           ( forever, void )
import           Control.Concurrent                      ( threadDelay )

main :: IO ()
main = withManager $ \mgr -> do
  args <- getArgs
  let exe   = head args
      files = tail args
  watchDir mgr "." (modified files) (action exe files)
  forever $ threadDelay 1000000
    where
      modified :: [FilePath] -> Event -> Bool
      modified files (Modified path _ False) = (takeFileName path) `elem` files
      modified _ _ = False

      action :: FilePath -> [FilePath] -> Event -> IO ()
      action proc files ev = do
        print ev
        putStrLn $ "calling " <> show proc <> " with " <> show files
        void $ spawnProcess proc files

      watchConf :: WatchConfig
      watchConf = defaultConfig { confDebounce = Debounce 50 }