On Monday 29 November 2010 20:16:32, José Romildo Malaquias wrote:

Hello.

I need a function to create a directory given its path. The function should return a "Maybe FilePath": "Nothing" for a failure, and "Just path" otherwise.

Two functions come to mind, both from System.Directory. - doesDirectoryExist - createDirectoryIfMissing The IO-action without error handling would be import Control.Monad (unless) mkDir :: FilePath -> IO FilePath mkDir path = do ex <- doesDirectoryExist path unless ex (createDirectoryIfMissing True path) return path

As I am not yet good at exception handling, would someone help me with this function?

To handle exceptions, import Control.Exception as Ex safeMkDir :: FilePath -> IO (Maybe FilePath) safeMkDir path = (fmap Just $ mkDir path) `Ex.catch` (\(e :: SomeException) -> return Nothing) well, you should better think which exceptions to actually catch and which not, so you'd better use Control.Exception.catches and a list of handlers for the exceptions you want to catch or catchJust.

Romildo