Merge pull request #200 from NicolasDP/master

add instance of MonadFailure to CryptoFailable

Crypto/Error/Types.hs

@@ -8,6 +8,7 @@
 -- Cryptographic Error enumeration and handling
 --
 {-# LANGUAGE DeriveDataTypeable #-}
+{-# LANGUAGE TypeFamilies       #-}
 module Crypto.Error.Types
     ( CryptoError(..)
     , CryptoFailable(..)
@@ -21,6 +22,7 @@ module Crypto.Error.Types
 import qualified Control.Exception as E
 import           Data.Data
 
+import           Foundation.Monad (MonadFailure(..))
 import           Crypto.Internal.Imports
 
 -- | Enumeration of all possible errors that can be found in this library
@@ -87,6 +89,10 @@ instance Monad CryptoFailable where
             CryptoPassed a -> m2 a
             CryptoFailed e -> CryptoFailed e
 
+instance MonadFailure CryptoFailable where
+    type Failure CryptoFailable = CryptoError
+    mFail = CryptoFailed
+
 -- | Throw an CryptoError as exception on CryptoFailed result,
 -- otherwise return the computed value
 throwCryptoErrorIO :: CryptoFailable a -> IO a