Re: [Haskell-cafe] converting IOException to Either in ErrorT

On Sun, May 3, 2009 at 6:36 PM, wrote:

I wrote this to make it a little nicer to catch IO exceptions and convert them to ErrorT failure:

onExceptionThrowError  :: (Error ce) =>     IO a  -> (String -> ce)  -> ErrorT ce IO a onExceptionThrowError a ce =    liftIO (try a) >>=      either        (\(e :: IOException) -> throwError (ce (show e)))        return

So now I can do, e.g., writeFile fp s `onExceptionThrowError` SpecificErrorConstructor ...

It works, but seems bad. Please let me know if you see ways to improve it. Thanks.

What about this? liftCatch :: (IOException -> e) -> IO a -> ErrorT e IO a liftCatch f m = ErrorT $ liftM (either (Left . f) Right) (try m) -- Dave Menendez http://www.eyrie.org/~zednenem/