git-annex/Annex/Exception.hs
2013-06-02 15:01:58 -04:00

39 lines
1.1 KiB
Haskell

{- exception handling in the git-annex monad
-
- Note that when an Annex action fails and the exception is handled
- by these functions, any changes the action has made to the
- AnnexState are retained. This works because the Annex monad
- internally stores the AnnexState in a MVar.
-
- Copyright 2011-2013 Joey Hess <joey@kitenet.net>
-
- Licensed under the GNU GPL version 3 or higher.
-}
module Annex.Exception (
bracketIO,
tryAnnex,
throwAnnex,
catchAnnex,
) where
import qualified "MonadCatchIO-transformers" Control.Monad.CatchIO as M
import Control.Exception
import Common.Annex
{- Runs an Annex action, with setup and cleanup both in the IO monad. -}
bracketIO :: IO v -> (v -> IO b) -> (v -> Annex a) -> Annex a
bracketIO setup cleanup go = M.bracket (liftIO setup) (liftIO . cleanup) go
{- try in the Annex monad -}
tryAnnex :: Annex a -> Annex (Either SomeException a)
tryAnnex = M.try
{- throw in the Annex monad -}
throwAnnex :: Exception e => e -> Annex a
throwAnnex = M.throw
{- catch in the Annex monad -}
catchAnnex :: Exception e => Annex a -> (e -> Annex a) -> Annex a
catchAnnex = M.catch