test-pipes-recursive.hs

-- | http://stackoverflow.com/questions/14259229/streaming-recursive-descent-of-a-directory-in-haskell/14261710#14261710
--
-- Updated to latest Pipes 4.

module Main where

import Pipes
import qualified Pipes.Prelude as P
import Control.Monad (forM_)
import System.Directory (doesDirectoryExist, getDirectoryContents)
import System.Environment (getArgs)
import System.FilePath ((</>))

getRecursiveContents :: FilePath -> Producer FilePath IO ()
getRecursiveContents topPath = do
  names <- lift $ getDirectoryContents topPath
  let properNames = filter (`notElem` [".", ".."]) names
  forM_ properNames $ \name -> do
    let path = topPath </> name
    isDirectory <- lift $ doesDirectoryExist path
    if isDirectory
      then getRecursiveContents path
      else yield path

main :: IO ()
main = do
  [path] <- getArgs
  runEffect $
    getRecursiveContents path
    >-> P.map ("Found file " ++)
    >-> P.stdoutLn