file 'appending' in haskell

gistfile1.hs

main = do
      handle <- openFile "todo.txt" ReadMode
      (tempName, tempHandle) <- openTempFile "." "temp"
      contents <- hGetContents handle
      let todoTasks = lines contents
          numberedTasks = zipWith (\n line -> show n ++ " - " ++
          line) [0..] todoTasks
      putStrLn "These are your TO-DO items:"
      putStr $ unlines numberedTasks
      putStrLn "Which one do you want to delete?"
      numberString <- getLine
      let number = read numberString
          newTodoItems = delete (todoTasks !! number) todoTasks
      hPutStr tempHandle $ unlines newTodoItems
      hClose handle
      hClose tempHandle
      removeFile "todo.txt"
      renameFile tempName "todo.txt"

-- some IO / String fiddle
 import System.IO
   
     main :: IO ()
     main = do
       inh <- openFile "sampleEvents" ReadMode
       inContents <- getContentsHereInstead inh
       putStrLn inContents
       hClose inh
   
     getContentsHereInstead :: Handle -> IO String
     getContentsHereInstead handle = do
       inContents <- hGetContents handle
       return inContents