more applicative.

error msg fix.

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