more applicative.

error msg fix.

Cabal.hs

@@ -25,11 +25,9 @@ importDirs :: [String]
 importDirs = [".","..","../..","../../..","../../../..","../../../../.."]
 
 initializeGHC :: Options -> FilePath -> [String] -> Bool -> Ghc (FilePath,LogReader)
-initializeGHC opt fileName ghcOptions logging =
-    withCabal `gcatch` withoutCabal
+initializeGHC opt fileName ghcOptions logging = withCabal <|> withoutCabal
   where
-    withoutCabal :: SomeException -> Ghc (FilePath,LogReader)
-    withoutCabal _ = do
+    withoutCabal = do
         logReader <- initSession opt ghcOptions importDirs logging
         return (fileName,logReader)
     withCabal = do

CabalDev.hs

@@ -5,21 +5,20 @@ module CabalDev (modifyOptions) where
   options ghc-mod uses to check the source.  Otherwise just pass it on.
 -}
 
-import Control.Applicative    ((<$>))
-import Control.Exception      (SomeException, throwIO)
-import Data.List              (find)
-import GHC                    (gcatch)
+import Control.Applicative ((<$>),(<|>))
+import Control.Exception (throwIO)
+import Data.List (find)
 import System.Directory
-import System.FilePath        (splitPath,joinPath,(</>))
-import Text.Regex.Posix       ((=~))
+import System.FilePath (splitPath,joinPath,(</>))
+import Text.Regex.Posix ((=~))
 import Types
+import Data.Alternative.IO ()
 
 modifyOptions :: Options -> IO Options
-modifyOptions opts = found `gcatch` notFound
+modifyOptions opts = found <|> notFound
   where
     found = addPath opts <$> findCabalDev
-    notFound :: SomeException -> IO Options
-    notFound _ = return opts
+    notFound = return opts
 
 findCabalDev :: IO String
 findCabalDev = getCurrentDirectory >>= searchIt . splitPath

GHCApi.hs

@@ -1,6 +1,7 @@
 module GHCApi where
 
-import Control.Monad
+import Control.Exception
+import Control.Applicative
 import CoreMonad
 import DynFlags
 import ErrMsg
@@ -11,13 +12,13 @@ import Types
 
 ----------------------------------------------------------------
 
-withGHC :: (MonadPlus m) => Ghc (m a) -> IO (m a)
+withGHC :: Alternative m => Ghc (m a) -> IO (m a)
 withGHC body = ghandle ignore $ runGhc (Just libdir) $ do
     dflags <- getSessionDynFlags
     defaultCleanupHandler dflags body
   where
-    ignore :: (MonadPlus m) => SomeException -> IO (m a)
-    ignore _ = return mzero
+    ignore :: Alternative m => SomeException -> IO (m a)
+    ignore _ = return empty
 
 ----------------------------------------------------------------
 

Gap.hs

@@ -15,8 +15,8 @@ module Gap (
 #endif
   ) where
 
+import AA ()
 import Control.Applicative hiding (empty)
-import Control.Exception
 import Control.Monad
 import DynFlags
 import FastString
@@ -115,10 +115,7 @@ setCtx ms = do
     return (not . null $ top)
 #endif
   where
-    isTop mos = lookupMod `gcatch` returnFalse
+    isTop mos = lookupMod <|> returnFalse
       where
         lookupMod = lookupModule (ms_mod_name mos) Nothing >> return True
-        returnFalse = constE $ return False
-
-constE :: a -> (SomeException -> a)
-constE func = \_ -> func
+        returnFalse = return False

Info.hs

@@ -2,6 +2,7 @@
 
 module Info (infoExpr, typeExpr) where
 
+import AA
 import Cabal
 import Control.Applicative
 import CoreUtils
@@ -34,7 +35,8 @@ infoExpr :: Options -> ModuleString -> Expression -> FilePath -> IO String
 infoExpr opt modstr expr file = (++ "\n") <$> info opt file modstr expr
 
 info :: Options -> FilePath -> ModuleString -> FilePath -> IO String
-info opt fileName modstr expr = inModuleContext opt fileName modstr exprToInfo
+info opt fileName modstr expr =
+    inModuleContext opt fileName modstr exprToInfo "Cannot show info"
   where
     exprToInfo = infoThing expr
 
@@ -44,7 +46,8 @@ typeExpr :: Options -> ModuleString -> Int -> Int -> FilePath -> IO String
 typeExpr opt modstr lineNo colNo file = Info.typeOf opt file modstr lineNo colNo
 
 typeOf :: Options -> FilePath -> ModuleString -> Int -> Int -> IO String
-typeOf opt fileName modstr lineNo colNo = inModuleContext opt fileName modstr exprToType
+typeOf opt fileName modstr lineNo colNo =
+    inModuleContext opt fileName modstr exprToType errmsg
   where
     exprToType = do
       modSum <- getModSummary $ mkModuleName modstr
@@ -66,6 +69,8 @@ typeOf opt fileName modstr lineNo colNo = inModuleContext opt fileName modstr ex
       | b `isSubspanOf` a = O.GT
       | otherwise = O.EQ
 
+    errmsg = convert opt ([] :: [((Int,Int,Int,Int),String)])
+
 findExpr :: TypecheckedModule -> Int -> Int -> [LHsExpr Id]
 findExpr tcm line col =
   let src = tm_typechecked_source tcm
@@ -119,19 +124,20 @@ pprInfo pefas (thing, fixity, insts)
 
 ----------------------------------------------------------------
 
-inModuleContext :: Options -> FilePath -> ModuleString -> Ghc String -> IO String
-inModuleContext opt fileName modstr action = withGHC valid
+inModuleContext :: Options -> FilePath -> ModuleString -> Ghc String -> String -> IO String
+inModuleContext opt fileName modstr action errmsg =
+    withGHC (valid <|> invalid <|> return errmsg)
   where
     valid = do
         (file,_) <- initializeGHC opt fileName ["-w"] False
         setTargetFile file
         load LoadAllTargets
-        mif setContextFromTarget action invalid
+        doif setContextFromTarget action
     invalid = do
         initializeGHC opt fileName ["-w"] False
         setTargetBuffer
         load LoadAllTargets
-        mif setContextFromTarget action (return errorMessage)
+        doif setContextFromTarget action
     setTargetBuffer = do
         modgraph <- depanal [mkModuleName modstr] True
         let imports = concatMap (map (showSDoc . ppr . unLoc)) $
@@ -141,9 +147,8 @@ inModuleContext opt fileName modstr action = withGHC valid
         importsBuf <- Gap.toStringBuffer header
         clkTime <- Gap.liftIO getClockTime
         setTargets [Target (TargetModule $ mkModuleName modstr) True (Just (importsBuf, clkTime))]
-    mif m t e = m >>= \ok -> if ok then t else e
+    doif m t = m >>= \ok -> if ok then t else goNext
     sanitize = fromMaybe "SomeModule" . listToMaybe . words
-    errorMessage = "Couldn't determine type"
 
 setContextFromTarget :: Ghc Bool
 setContextFromTarget = depanal [] False >>= Gap.setCtx

ghc-mod.cabal

@@ -23,7 +23,8 @@ Data-Files:             Makefile ghc.el ghc-func.el ghc-doc.el ghc-comp.el
                         ghc-flymake.el ghc-command.el ghc-info.el ghc-ins-mod.el
 Executable ghc-mod
   Main-Is:              GHCMod.hs
-  Other-Modules:        Browse
+  Other-Modules:        AA
+                        Browse
                         Cabal
                         CabalDev
                         Check
@@ -43,6 +44,7 @@ Executable ghc-mod
     GHC-Options:        -Wall
   Build-Depends:        base >= 4.0 && < 5
                       , Cabal
+                      , alternative-io
                       , directory
                       , filepath
                       , ghc