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module Main
where
import System.Directory.Tree
import qualified Data.Foldable as F
import System.IO
import Control.Monad
main = du "/etc"
-- Here are a few examples of using the directory-tree package to recreate
-- the basic functionality of some linux command-line tools. This module
-- uses the lazy directory building IO provided by `readDirectoryWithL`:
-- the command `ls <dir>`. Try:
-- ghci> ls "/"
-- ...IO is done lazily.
ls :: FileName -> IO ()
ls d = do (_ :/ Dir _ c) <- readDirectoryWithL readFile d
mapM_ (putStrLn . name) c
-- the command `du -bs <dir> 2> /dev/null` gets the total size of all files
-- under the supplied directory. We use a more compositional style here, where
-- (<=<) is equivalent to (.) but for monadic functions (a -> m b):
du :: FileName -> IO ()
du = print . F.foldl' (+) 0 . free <=< readDirectoryWithL (hFileSize <=< readHs)
where readHs = flip openFile ReadMode
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