Merge pull request #330 from DanielG/dev-error

Remove dedicated exception handling in `check` completely

Language/Haskell/GhcMod/Check.hs

@@ -12,7 +12,6 @@ import qualified GHC as G
 import Language.Haskell.GhcMod.Logger
 import Language.Haskell.GhcMod.Monad (IOish, GhcModT, overrideGhcUserOptions)
 import Language.Haskell.GhcMod.Target (setTargetFiles)
-import Language.Haskell.GhcMod.Utils (liftExceptions)
 
 ----------------------------------------------------------------
 
@@ -22,7 +21,7 @@ checkSyntax :: IOish m
             => [FilePath]  -- ^ The target files.
             -> GhcModT m String
 checkSyntax []    = return ""
-checkSyntax files = liftExceptions $ either id id <$> check files
+checkSyntax files = either id id <$> check files
 
 ----------------------------------------------------------------
 
@@ -43,7 +42,7 @@ expandTemplate :: IOish m
                => [FilePath]  -- ^ The target files.
                -> GhcModT m String
 expandTemplate []    = return ""
-expandTemplate files = liftExceptions $ either id id <$> expand files
+expandTemplate files = either id id <$> expand files
 
 ----------------------------------------------------------------
 

Language/Haskell/GhcMod/Types.hs

@@ -2,15 +2,12 @@ module Language.Haskell.GhcMod.Types where
 
 import Data.List (intercalate)
 import qualified Data.Map as M
-import Control.Exception (SomeException)
 import Control.Monad.Error (Error(..))
 
 import PackageConfig (PackageConfig)
 
 data GhcModError = GMENoMsg
                  -- ^ Unknown error
-                 | GMEException SomeException
-                 -- ^ Regular exception lifted by 'liftExceptions'
                  | GMEString { gmeMsg :: String }
                  -- ^ Some Error with a message. These are produced mostly by
                  -- 'fail' calls on GhcModT.

Language/Haskell/GhcMod/Utils.hs

@@ -2,7 +2,6 @@ module Language.Haskell.GhcMod.Utils where
 
 
 import MonadUtils (MonadIO, liftIO)
-import Exception (ExceptionMonad, gtry)
 import Control.Exception
 import Control.Monad.Error (MonadError(..), Error(..))
 import System.Directory (getCurrentDirectory, setCurrentDirectory)
@@ -10,7 +9,6 @@ import System.Process (readProcessWithExitCode)
 import System.Exit (ExitCode(..))
 import System.IO (hPutStrLn, stderr)
 import System.IO.Error (tryIOError)
-import Language.Haskell.GhcMod.Types
 
 -- dropWhileEnd is not provided prior to base 4.5.0.0.
 dropWhileEnd :: (a -> Bool) -> [a] -> [a]
@@ -64,14 +62,3 @@ liftIOExceptions action = do
     Left e -> case show e of
                 ""  -> throwError $ noMsg
                 msg -> throwError $ strMsg msg
-
--- | Exceptions thrown in the computation passed to this function will be
--- converted to 'MonadError' failures using 'throwError'.
-liftExceptions :: (MonadIO m, ExceptionMonad m, MonadError GhcModError m)
-               => m a
-               -> m a
-liftExceptions action = do
-  res <- gtry action
-  case res of
-    Right a -> return a
-    Left e -> throwError $ GMEException e

src/GHCMod.hs

@@ -141,8 +141,6 @@ main = flip E.catches handlers $ do
       cmd       -> E.throw (NoSuchCommand cmd)
     case res of
       Right s -> putStr s
-      Left (GMEException e) ->
-          hPutStrLn stderr $ "Exception: " ++ show e
       Left (GMENoMsg) ->
           hPutStrLn stderr "Unknown error"
       Left (GMEString msg) ->