Hello Andrew, Sunday, June 21, 2009, 1:52:22 PM, you wrote:
> d1x <- doesDirectoryExist d1 > if d1x > then do > f1x <- doesFileExist (d1 </> f1) > if f1x > then do > d2x <- doesDirectoryExist d2 > if d2x > then do > f2x <- doesFileExist (d2 </> f2) > if f2x > then do_stuff d1 d2 f1 f2 > else hPutStrLn stderr $ "File " ++ f2 ++ " not found." > else hPutStrLn stderr $ "Directory " ++ d2 ++ " not found." > else hPutStrLn stderr $ "File " ++ f1 ++ " not found." > else hPutStrLn stderr $ "Directory " ++ d1 ++ " not found." d1x <- doesDirectoryExist d1 if not d1x then hPutStrLn stderr $ "Directory " ++ d1 ++ " not found." else do f1x <- doesFileExist (d1 </> f1) if not f1x then hPutStrLn stderr $ "File " ++ f1 ++ " not found." else do d2x <- doesDirectoryExist d2 if not d2x then hPutStrLn stderr $ "Directory " ++ d2 ++ " not found." else do f2x <- doesFileExist (d2 </> f2) if not f2x then hPutStrLn stderr $ "File " ++ f2 ++ " not found." else do do_stuff d1 d2 f1 f2 or, with a little additional combinators: ifM (not ==<< doesDirectoryExist d1) (hPutStrLn stderr $ "Directory " ++ d1 ++ " not found.") $ do ifM (not ==<< doesFileExist (d1 </> f1)) (hPutStrLn stderr $ "File " ++ f1 ++ " not found.") $ do ifM (not ==<< doesDirectoryExist d2) (hPutStrLn stderr $ "Directory " ++ d2 ++ " not found.") $ do ifM (not ==<< doesFileExist (d2 </> f2)) (hPutStrLn stderr $ "File " ++ f2 ++ " not found.") $ do do_stuff d1 d2 f1 f2 -- Best regards, Bulat mailto:bulat.zigans...@gmail.com _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
