only added events show up on OSX about hfsnotify HOT 4 CLOSED

{-# LANGUAGE OverloadedStrings #-}

import Prelude hiding (FilePath)

import Control.Concurrent
import Control.Monad (forever)
import Data.Text
import Filesystem
import Filesystem.Path.CurrentOS
import System.Cmd (rawSystem)
import System.IO.FSNotify

main :: IO ()
main = do
  wd <- getWorkingDirectory
  withManager $ \man -> coffee man wd
  void

coffee :: WatchManager -> FilePath -> IO ()
coffee man dir = do
  -- guardExt method:
  guardExt man dir "coffee" "js" doAction
  _ <- getLine
  void

  -- guardExtChan method:
  -- tid <- guardExtChan man dir "coffee" "js" doAcdtion
  -- _ <- getLine
  -- killThread tid

void :: IO ()
void = return ()

-- | assumes you are running a compile function that produces a file in the same directory but with a different extension
guardExt :: WatchManager
         -> FilePath -- ^ Directory to watch
         -> Text -- ^ old extension
         -> Text -- ^ new extension
         -> (FilePath -> IO ()) -- ^ compile action to run on file
         -> IO ()
guardExt man dir oldExt newExt action = do
  print $ dir
  watchTreeAction man dir (predicate oldExt) (compile newExt action)
  where

readChanLoop :: Chan Event -> Text -> (FilePath -> IO ()) -> IO ()
readChanLoop chan newExt action = do
  event <- readChan chan
  case event of
    Added    f _ -> actionWrapper newExt action f
    Modified f _ -> actionWrapper newExt action f
    Removed  f _ -> void

-- | for debugging
guardExtChan :: WatchManager
         -> FilePath -- ^ Directory to watch
         -> Text -- ^ old extension
         -> Text -- ^ new extension
         -> (FilePath -> IO ()) -- ^ compile action to run on file
         -> IO ThreadId
guardExtChan man dir oldExt newExt action = do
  chan <- newChan
  watchTreeChan man dir (predicate oldExt) chan
  forkIO $ forever (readChanLoop chan newExt action)


doAction fp =
  -- Debug:
  putStrLn $ "Dispatching on: " ++ show fp

  -- Do stuff:
  -- rawSystem "coffee" ["-c", encodeString fp] >> void

actionWrapper newExt action f = do
  print f
  print $ convert newExt f
  action . (convert newExt) $ f

extFilter oldExt = flip hasExtension oldExt

convert newExt = flip replaceExtension newExt

compile newExt action event = do
  print event
  case event of
    Added    f _ -> actionWrapper newExt action f
    Modified f _ -> actionWrapper newExt action f
    Removed  f _ -> void

predicate oldExt event =
  case event of
    Added    f _ -> extFilter oldExt f
    Modified f _ -> extFilter oldExt f
    Removed  f _ -> extFilter oldExt f