Add watch mode

app/Main.hs

 module Main where
 
+import           Control.Concurrent (threadDelay)
 import           Control.Monad
 import           Data.Aeson
 import qualified Data.Map                      as M
 import           System.Console.ArgParser
 import           System.Directory
 import           System.FilePath
+import           System.FSNotify
 import           Text.Pandoc
 
 import           Build                          ( buildRawPost
             _ -> putStrLn $ unlines $ map show renderErrors
     _ -> putStrLn $ unlines $ map show parseErrors
 
+handleEvent :: FilePath -> Bool -> Event -> IO ()
+handleEvent dir drafts _event = do
+  putStrLn "Rebuilding"
+  build dir drafts
+
+watch :: FilePath -> Bool -> IO ()
+watch dir drafts = do
+  withManager $ \mgr -> do
+    putStrLn "Watching..."
+    watchTree
+      mgr
+      dir
+      (const True)
+      (handleEvent dir drafts)
+    forever $ threadDelay 1000000
+
 new :: String -> IO ()
 new name = do
   path            <- makeAbsolute name
 run :: Config -> IO ()
 run config = case config of
   (Build dir drafts) -> build dir drafts
+  (Watch dir drafts) -> watch dir drafts
   (New name        ) -> new name
 
 main :: IO ()

package.yaml

   - directory
   - doctemplates
   - filepath
+  - fsnotify
   - pandoc
   - path
   - path-io

src/CLI.hs

 
 data Config =
   Build FilePath Bool
+  | Watch FilePath Bool
   | New String
   deriving (Show)
 
       (Build `parsedBy` optPos "." "directory" `andBy` boolFlag "drafts")
       "build"
     )
+  , ( "watch"
+    , mkDefaultApp
+      (Watch `parsedBy` optPos "." "directory" `andBy` boolFlag "drafts")
+      "watch"
+    )
   , ("new", mkDefaultApp (New `parsedBy` reqPos "name") "new")
   ]