ch18/CountEntries.hs


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{-- snippet countEntriesTrad --}
module CountEntries (listDirectory, countEntriesTrad) where

import System.Directory (doesDirectoryExist, getDirectoryContents)
import System.FilePath ((</>))
import Control.Monad (forM, liftM)

listDirectory :: FilePath -> IO [String]
listDirectory = liftM (filter notDots) . getDirectoryContents
    where notDots p = p /= "." && p /= ".."

countEntriesTrad :: FilePath -> IO [(FilePath, Int)]
countEntriesTrad path = do
  contents <- listDirectory path
  rest <- forM contents $ \name -> do
            let newName = path </> name
            isDir <- doesDirectoryExist newName
            if isDir
              then countEntriesTrad newName
              else return []
  return $ (path, length contents) : concat rest
{-- /snippet countEntriesTrad --}