Use hslua utils where possible

Some helper functions and types have been moved to hslua.

Change: minor

src/Text/Pandoc/Lua/Module/MediaBag.hs

@@ -32,11 +32,11 @@ module Text.Pandoc.Lua.Module.MediaBag
 import Control.Monad (zipWithM_)
 import Data.IORef (IORef, modifyIORef', readIORef)
 import Data.Maybe (fromMaybe)
-import Foreign.Lua (Lua, NumResults, liftIO)
+import Foreign.Lua (Lua, NumResults, Optional, liftIO)
 import Text.Pandoc.Class (CommonState (..), fetchItem, putCommonState,
                           runIOorExplode, setMediaBag)
 import Text.Pandoc.Lua.StackInstances ()
-import Text.Pandoc.Lua.Util (OrNil (toMaybe), addFunction)
+import Text.Pandoc.Lua.Util (addFunction)
 import Text.Pandoc.MIME (MimeType)
 
 import qualified Data.ByteString.Lazy as BL
@@ -57,12 +57,12 @@ pushModule commonState mediaBagRef = do
 
 insertMediaFn :: IORef MB.MediaBag
               -> FilePath
-              -> OrNil MimeType
+              -> Optional MimeType
               -> BL.ByteString
               -> Lua NumResults
-insertMediaFn mbRef fp nilOrMime contents = do
+insertMediaFn mbRef fp optionalMime contents = do
   liftIO . modifyIORef' mbRef $
-    MB.insertMedia fp (toMaybe nilOrMime) contents
+    MB.insertMedia fp (Lua.fromOptional optionalMime) contents
   return 0
 
 lookupMediaFn :: IORef MB.MediaBag

src/Text/Pandoc/Lua/Module/Pandoc.hs

@@ -34,14 +34,13 @@ import Control.Monad (when)
 import Data.Default (Default (..))
 import Data.Maybe (fromMaybe)
 import Data.Text (pack)
-import Foreign.Lua (ToLuaStack, FromLuaStack, Lua, NumResults, liftIO)
+import Foreign.Lua (ToLuaStack, FromLuaStack, Lua, NumResults, Optional, liftIO)
 import System.Exit (ExitCode (..))
 import Text.Pandoc.Class (runIO)
 import Text.Pandoc.Definition (Block, Inline)
 import Text.Pandoc.Lua.Filter (walkInlines, walkBlocks, LuaFilter)
 import Text.Pandoc.Lua.StackInstances ()
-import Text.Pandoc.Lua.Util (OrNil (toMaybe), addFunction, addValue,
-                             loadScriptFromDataDir, raiseError)
+import Text.Pandoc.Lua.Util (addFunction, addValue, loadScriptFromDataDir)
 import Text.Pandoc.Walk (Walkable)
 import Text.Pandoc.Options (ReaderOptions (readerExtensions))
 import Text.Pandoc.Process (pipeProcess)
@@ -72,19 +71,19 @@ walkInline = walkElement
 walkBlock :: Block -> LuaFilter -> Lua Block
 walkBlock = walkElement
 
-readDoc :: String -> OrNil String -> Lua NumResults
+readDoc :: String -> Optional String -> Lua NumResults
 readDoc content formatSpecOrNil = do
-  let formatSpec = fromMaybe "markdown" (toMaybe formatSpecOrNil)
+  let formatSpec = fromMaybe "markdown" (Lua.fromOptional formatSpecOrNil)
   case getReader formatSpec of
-    Left  s      -> raiseError s -- Unknown reader
+    Left  s      -> Lua.raiseError s -- Unknown reader
     Right (reader, es) ->
       case reader of
         TextReader r -> do
           res <- liftIO $ runIO $ r def{ readerExtensions = es } (pack content)
           case res of
             Right pd -> (1 :: NumResults) <$ Lua.push pd -- success, push Pandoc
-            Left s   -> raiseError (show s)              -- error while reading
-        _  -> raiseError "Only string formats are supported at the moment."
+            Left s   -> Lua.raiseError (show s)              -- error while reading
+        _  -> Lua.raiseError "Only string formats are supported at the moment."
 
 -- | Pipes input through a command.
 pipeFn :: String
@@ -95,7 +94,7 @@ pipeFn command args input = do
   (ec, output) <- liftIO $ pipeProcess Nothing command args input
   case ec of
     ExitSuccess -> 1 <$ Lua.push output
-    ExitFailure n -> raiseError (PipeError command n output)
+    ExitFailure n -> Lua.raiseError (PipeError command n output)
 
 data PipeError = PipeError
   { pipeErrorCommand :: String

src/Text/Pandoc/Lua/Module/Utils.hs

@@ -33,7 +33,7 @@ import Control.Applicative ((<|>))
 import Foreign.Lua (FromLuaStack, Lua, LuaInteger, NumResults)
 import Text.Pandoc.Definition (Pandoc, Meta, MetaValue, Block, Inline)
 import Text.Pandoc.Lua.StackInstances ()
-import Text.Pandoc.Lua.Util (OrNil (OrNil), addFunction)
+import Text.Pandoc.Lua.Util (addFunction)
 
 import qualified Data.Digest.Pure.SHA as SHA
 import qualified Data.ByteString.Lazy as BSL
@@ -59,8 +59,8 @@ hierarchicalize = return . Shared.hierarchicalize
 -- limit years to the range 1601-9999 (ISO 8601 accepts greater than
 -- or equal to 1583, but MS Word only accepts dates starting 1601).
 -- Returns nil instead of a string if the conversion failed.
-normalizeDate :: String -> Lua (OrNil String)
-normalizeDate = return . OrNil . Shared.normalizeDate
+normalizeDate :: String -> Lua (Lua.Optional String)
+normalizeDate = return . Lua.Optional . Shared.normalizeDate
 
 -- | Calculate the hash of the given contents.
 sha1 :: BSL.ByteString

src/Text/Pandoc/Lua/Util.hs

@@ -38,7 +38,6 @@ module Text.Pandoc.Lua.Util
   , addRawInt
   , raiseError
   , popValue
-  , OrNil (..)
   , PushViaCall
   , pushViaCall
   , pushViaConstructor
@@ -115,21 +114,6 @@ popValue = do
     Left err -> Lua.throwLuaError err
     Right x -> return x
 
--- | Newtype wrapper intended to be used for optional Lua values. Nesting this
--- type is strongly discouraged and will likely lead to a wrong result.
-newtype OrNil a = OrNil { toMaybe :: Maybe a }
-
-instance FromLuaStack a => FromLuaStack (OrNil a) where
-  peek idx = do
-    noValue <- Lua.isnoneornil idx
-    if noValue
-      then return (OrNil Nothing)
-      else OrNil . Just <$> Lua.peek idx
-
-instance ToLuaStack a => ToLuaStack (OrNil a) where
-  push (OrNil Nothing)  = Lua.pushnil
-  push (OrNil (Just x)) = Lua.push x
-
 -- | Helper class for pushing a single value to the stack via a lua function.
 -- See @pushViaCall@.
 class PushViaCall a where