Lua filters: perform minor code clean-up

Change: minor

src/Text/Pandoc/Lua/Init.hs

@@ -50,8 +50,7 @@ import qualified Foreign.Lua.Module.Text as Lua
 -- initalization.
 runPandocLua :: Lua a -> PandocIO (Either LuaException a)
 runPandocLua luaOp = do
-  datadir <- getUserDataDir
-  luaPkgParams <- luaPackageParams datadir
+  luaPkgParams <- luaPackageParams
   enc <- liftIO $ getForeignEncoding <* setForeignEncoding utf8
   res <- liftIO $ Lua.runLuaEither (initLuaState luaPkgParams *> luaOp)
   liftIO $ setForeignEncoding enc
@@ -60,9 +59,10 @@ runPandocLua luaOp = do
   return res
 
 -- | Generate parameters required to setup pandoc's lua environment.
-luaPackageParams :: Maybe FilePath -> PandocIO LuaPackageParams
-luaPackageParams datadir = do
+luaPackageParams :: PandocIO LuaPackageParams
+luaPackageParams = do
   commonState <- getCommonState
+  datadir <- getUserDataDir
   mbRef <- liftIO . newIORef =<< getMediaBag
   return LuaPackageParams
     { luaPkgCommonState = commonState

src/Text/Pandoc/Lua/PandocModule.hs

@@ -71,16 +71,13 @@ pushPandocModule datadir = do
   return 1
 
 walkElement :: (ToLuaStack a, Walkable [Inline] a, Walkable [Block] a)
-            => a -> LuaFilter -> Lua NumResults
-walkElement x f = do
-  x' <- walkInlines f x >>= walkBlocks f
-  Lua.push x'
-  return 1
+            => a -> LuaFilter -> Lua a
+walkElement x f = walkInlines f x >>= walkBlocks f
 
-walkInline :: Inline -> LuaFilter -> Lua NumResults
+walkInline :: Inline -> LuaFilter -> Lua Inline
 walkInline = walkElement
 
-walkBlock :: Block -> LuaFilter -> Lua NumResults
+walkBlock :: Block -> LuaFilter -> Lua Block
 walkBlock = walkElement
 
 readDoc :: String -> String -> Lua NumResults