36 lines
1,015 B
Haskell
36 lines
1,015 B
Haskell
{- Simple IO exception handling
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-
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- Copyright 2011-2012 Joey Hess <joey@kitenet.net>
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-
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- Licensed under the GNU GPL version 3 or higher.
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-}
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module Utility.Exception where
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import Prelude hiding (catch)
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import Control.Exception
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import Control.Applicative
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{- Catches IO errors and returns a Bool -}
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catchBoolIO :: IO Bool -> IO Bool
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catchBoolIO a = catchDefaultIO False a
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{- Catches IO errors and returns a Maybe -}
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catchMaybeIO :: IO a -> IO (Maybe a)
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catchMaybeIO a = catchDefaultIO Nothing $ Just <$> a
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{- Catches IO errors and returns a default value. -}
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catchDefaultIO :: a -> IO a -> IO a
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catchDefaultIO def a = catchIO a (const $ return def)
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{- Catches IO errors and returns the error message. -}
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catchMsgIO :: IO a -> IO (Either String a)
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catchMsgIO a = either (Left . show) Right <$> tryIO a
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{- catch specialized for IO errors only -}
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catchIO :: IO a -> (IOException -> IO a) -> IO a
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catchIO = catch
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{- try specialized for IO errors only -}
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tryIO :: IO a -> IO (Either IOException a)
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tryIO = try
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