From 7115d1ec162b4059b3e8e8f84bd8d5898c1db025 Mon Sep 17 00:00:00 2001 From: Joey Hess Date: Wed, 14 May 2014 19:41:05 -0400 Subject: moved source code to src This is to work around OSX's brain-damange regarding filename case insensitivity. Avoided moving config.hs, because it's a config file. Put in a symlink to make build work. --- src/Utility/Exception.hs | 59 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 59 insertions(+) create mode 100644 src/Utility/Exception.hs (limited to 'src/Utility/Exception.hs') diff --git a/src/Utility/Exception.hs b/src/Utility/Exception.hs new file mode 100644 index 00000000..1fecf65d --- /dev/null +++ b/src/Utility/Exception.hs @@ -0,0 +1,59 @@ +{- Simple IO exception handling (and some more) + - + - Copyright 2011-2012 Joey Hess + - + - License: BSD-2-clause + -} + +{-# LANGUAGE ScopedTypeVariables #-} + +module Utility.Exception where + +import Control.Exception +import qualified Control.Exception as E +import Control.Applicative +import Control.Monad +import System.IO.Error (isDoesNotExistError) +import Utility.Data + +{- Catches IO errors and returns a Bool -} +catchBoolIO :: IO Bool -> IO Bool +catchBoolIO = catchDefaultIO False + +{- Catches IO errors and returns a Maybe -} +catchMaybeIO :: IO a -> IO (Maybe a) +catchMaybeIO a = catchDefaultIO Nothing $ Just <$> a + +{- Catches IO errors and returns a default value. -} +catchDefaultIO :: a -> IO a -> IO a +catchDefaultIO def a = catchIO a (const $ return def) + +{- Catches IO errors and returns the error message. -} +catchMsgIO :: IO a -> IO (Either String a) +catchMsgIO a = either (Left . show) Right <$> tryIO a + +{- catch specialized for IO errors only -} +catchIO :: IO a -> (IOException -> IO a) -> IO a +catchIO = E.catch + +{- try specialized for IO errors only -} +tryIO :: IO a -> IO (Either IOException a) +tryIO = try + +{- Catches all exceptions except for async exceptions. + - This is often better to use than catching them all, so that + - ThreadKilled and UserInterrupt get through. + -} +catchNonAsync :: IO a -> (SomeException -> IO a) -> IO a +catchNonAsync a onerr = a `catches` + [ Handler (\ (e :: AsyncException) -> throw e) + , Handler (\ (e :: SomeException) -> onerr e) + ] + +tryNonAsync :: IO a -> IO (Either SomeException a) +tryNonAsync a = (Right <$> a) `catchNonAsync` (return . Left) + +{- Catches only DoesNotExist exceptions, and lets all others through. -} +tryWhenExists :: IO a -> IO (Maybe a) +tryWhenExists a = eitherToMaybe <$> + tryJust (guard . isDoesNotExistError) a -- cgit v1.2.3