31 lines
957 B
Haskell
31 lines
957 B
Haskell
{-# LANGUAGE ScopedTypeVariables #-}
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module Language.Haskell.GhcMod.GHCChoice where
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import Control.Exception (IOException)
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import CoreMonad (liftIO)
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import qualified Exception as GE
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import GHC (GhcMonad)
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----------------------------------------------------------------
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-- | Try the left 'Ghc' action. If 'IOException' occurs, try
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-- the right 'Ghc' action.
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(||>) :: GhcMonad m => m a -> m a -> m a
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x ||> y = x `GE.gcatch` (\(_ :: IOException) -> y)
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-- | Go to the next 'Ghc' monad by throwing 'AltGhcgoNext'.
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goNext :: GhcMonad m => m a
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goNext = liftIO . GE.throwIO $ userError "goNext"
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-- | Run any one 'Ghc' monad.
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runAnyOne :: GhcMonad m => [m a] -> m a
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runAnyOne = foldr (||>) goNext
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----------------------------------------------------------------
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-- | Try the left 'GhcMonad' action. If 'IOException' occurs, try
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-- the right 'GhcMonad' action.
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(|||>) :: GhcMonad m => m a -> m a -> m a
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x |||> y = x `GE.gcatch` (\(_ :: IOException) -> y)
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