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{-# LANGUAGE NoImplicitPrelude #-}
module Data.Exception where
import Data.Typeable -- for Typeable
import Text.Show -- for Show
import Data.Maybe -- for Maybe
import Compiler.Base -- for String
import Data.List -- for ++
import Compiler.IO -- for IO
data SomeException = forall e. Exception e => SomeException e
class ({-Typeable e,-} Show e) => Exception e where
-- toException :: e -> SomeException
-- fromException :: SomeException -> Maybe e
displayException :: e -> String
displayException e = show e
data IOException = IOException String
instance Show IOException where
show (IOException s) = "IOException " ++ show s
instance Exception IOException
-- toException e = SomeException e
-- fromException e = Just e
data ArithException
data ArrayExeption
--throw :: forall a e. Exception e => e -> a
foreign import bpcall "Prelude:" throw :: IOException -> b
{-
throwIO :: Exception e => e -> IO a
-}
--catch :: Exception e => IO a -> (e -> IO a) -> IO a
foreign import bpcall "Prelude:" catchRaw :: a -> (IOException -> a) -> a
catch :: IO a -> (IOException -> IO a) -> IO a
catch action handler = IO (\s -> catchRaw (runIO action s) (\e -> runIO (handler e) s))
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