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-rw-r--r--src/Propellor/Exception.hs12
1 files changed, 10 insertions, 2 deletions
diff --git a/src/Propellor/Exception.hs b/src/Propellor/Exception.hs
index 3ab783bf..c02fa61a 100644
--- a/src/Propellor/Exception.hs
+++ b/src/Propellor/Exception.hs
@@ -10,10 +10,15 @@ import Utility.Exception
import Control.Exception (AsyncException)
import Control.Monad.Catch
import Control.Monad.IO.Class (MonadIO)
+import Control.Applicative
+import Prelude
-- | Catches all exceptions (except for `StopPropellorException` and
-- `AsyncException`) and returns FailedChange.
-catchPropellor :: (MonadIO m, MonadCatch m) => m Result -> m Result
+catchPropellor
+ :: (Applicative m, MonadIO m, MonadCatch m)
+ => m Result
+ -> m Result
catchPropellor a = either err return =<< tryPropellor a
where
err e = warningMessage (show e) >> return FailedChange
@@ -27,5 +32,8 @@ catchPropellor' a onerr = a `catches`
-- | Catches all exceptions (except for `StopPropellorException` and
-- `AsyncException`).
-tryPropellor :: MonadCatch m => m a -> m (Either SomeException a)
+tryPropellor
+ :: (Functor m, Applicative m, MonadCatch m)
+ => m a
+ -> m (Either SomeException a)
tryPropellor a = (Right <$> a) `catchPropellor'` (pure . Left)