replace redundant liftM7 function with applicatives

Language/Haskell/GhcMod/CabalHelper.hs

@@ -38,7 +38,7 @@ import Paths_ghc_mod as GhcMod
 
 -- | Only package related GHC options, sufficient for things that don't need to
 -- access home modules
-getGhcPkgOptions :: (MonadIO m, GmEnv m, GmLog m)
+getGhcPkgOptions :: (Applicative m, MonadIO m, GmEnv m, GmLog m)
                  => m [(ChComponentName, [GHCOption])]
 getGhcPkgOptions = map (\c -> (gmcName c, gmcGhcPkgOpts c)) `liftM` getComponents
 
@@ -54,7 +54,7 @@ helperProgs opts = Programs {
 --
 -- The Component\'s 'gmcHomeModuleGraph' will be empty and has to be resolved by
 -- 'resolveGmComponents'.
-getComponents :: (MonadIO m, GmEnv m, GmLog m)
+getComponents :: (Applicative m, MonadIO m, GmEnv m, GmLog m)
               => m [GmComponent GMCRaw ChEntrypoint]
 getComponents = do
   opt <- options
@@ -67,35 +67,31 @@ getComponents = do
           )
   withCabal $ cached cradleRootDir cabalHelperCache d
 
-cabalHelperCache :: MonadIO m => Cached m
-                      (Programs, FilePath, (Version, String))
-                      [GmComponent GMCRaw ChEntrypoint]
+cabalHelperCache
+  :: (Functor m, Applicative m, MonadIO m)
+  => Cached m (Programs, FilePath, (Version, String)) [GmComponent GMCRaw ChEntrypoint]
 cabalHelperCache = Cached {
     cacheFile = cabalHelperCacheFile,
     cachedAction = \ _ (progs, root, _) _ ->
       runQuery' progs root $ do
-        q <- liftM7 join7
-               ghcOptions
-               ghcPkgOptions
-               ghcSrcOptions
-               ghcLangOptions
-               entrypoints
-               entrypoints
-               sourceDirs
+        q <- join7
+               <$> ghcOptions
+               <*> ghcPkgOptions
+               <*> ghcSrcOptions
+               <*> ghcLangOptions
+               <*> entrypoints
+               <*> entrypoints
+               <*> sourceDirs
         let cs = flip map q $ curry8 (GmComponent mempty)
         return ([setupConfigPath], cs)
   }
  where
    curry8 fn (a, (b, (c, (d, (e, (f, (g, h))))))) = fn a b c d e f g h
 
-   liftM7 fn ma mb mc md me mf mg = do
-     a <- ma; b <- mb; c <- mc; d <- md; e <- me; f <- mf; g <- mg
-     return (fn a b c d e f g)
-
    join7 a b c d e f = join' a . join' b . join' c . join' d . join' e . join' f
    join' :: Eq a => [(a,b)] -> [(a,c)] -> [(a,(b,c))]
    join' lb lc = [ (a, (b, c))
-                 | (a, b) <- lb
+                 | (a, b)  <- lb
                  , (a', c) <- lc
                  , a == a'
                  ]

Language/Haskell/GhcMod/Target.hs

@@ -18,7 +18,7 @@
 module Language.Haskell.GhcMod.Target where
 
 import Control.Arrow
-import Control.Applicative ((<$>))
+import Control.Applicative (Applicative, (<$>))
 import Control.Monad.Reader (runReaderT)
 import GHC
 import GHC.Paths (libdir)
@@ -257,11 +257,11 @@ findCandidates scns = foldl1 Set.intersection scns
 pickComponent :: Set ChComponentName -> ChComponentName
 pickComponent scn = Set.findMin scn
 
-packageGhcOptions :: (MonadIO m, GmEnv m, GmLog m) => m [GHCOption]
+packageGhcOptions :: (Applicative m, MonadIO m, GmEnv m, GmLog m) => m [GHCOption]
 packageGhcOptions = do
     crdl <- cradle
     case cradleCabalFile crdl of
-      Just _ -> do
+      Just _ ->
         (Set.toList . Set.fromList . concat . map snd) `liftM` getGhcPkgOptions
       Nothing -> sandboxOpts crdl