follow-file-0.0.2: app/Main.hs

import Path
import qualified Data.ByteString.Lazy as BS
import qualified Data.Text as T
import Data.Attoparsec.Text (parseOnly, endOfInput, eitherP)
import Data.Attoparsec.Path (absFilePath, relFilePath, absDirPath)
import Data.Conduit ((=$=), runConduit)
import Data.Conduit.Combinators (stdout)
import System.INotify (initINotify, removeWatch, killINotify)
import System.File.Follow (follow)
import System.Directory (getCurrentDirectory)
import System.Environment (getArgs)
import Control.Monad (forever)
import Control.Exception (bracket)
import Control.Concurrent (threadDelay)


main = do
  [f] <- getArgs
  f <- case parseOnly (eitherP absFilePath relFilePath <* endOfInput) (T.pack f) of
          Left e -> error e
          Right eAR -> case eAR of
            Left a -> pure a
            Right r -> do
              d <- getCurrentDirectory
              case parseOnly (absDirPath <* endOfInput) (T.pack (d ++ "/")) of
                Left e -> error e
                Right d' ->
                  pure (d' </> r)
  i <- initINotify
  bracket (follow i f (\source -> runConduit $ source =$= stdout)) (\watch -> removeWatch watch >> killINotify i) $ \_ -> forever $ threadDelay 50000