Exception secrecy

MyException.hs

-- In response to http://existentialtype.wordpress.com/2012/12/03/exceptions-are-shared-secrets/

{-# LANGUAGE DeriveDataTypeable #-}

module MyException
  ( Secret
  , MyException
  , throwMyException
  , handleMyException
  ) where

import Data.Typeable
import Control.Exception

type Secret = Int

newtype MyException = MyException { unMyException :: Secret }
  deriving Typeable

instance Show MyException where
  show _ = "<secret>"

instance Exception MyException

throwMyException :: Secret -> a
throwMyException = throw . MyException

handleMyException :: (Secret -> IO a) -> IO a -> IO a
handleMyException h = handle $ h . unMyException