Merge pull request #4153 from tarleb/unify-lua-init

Unify lua initalization

6 files changed, 184 insertions, 149 deletions

diff --git a/pandoc.cabal b/pandoc.cabal
index fa02ebfd9..0d05172d5 100644
--- a/pandoc.cabal
+++ b/pandoc.cabal
@@ -523,9 +523,10 @@ library
                    Text.Pandoc.Readers.Org.ParserState,
                    Text.Pandoc.Readers.Org.Parsing,
                    Text.Pandoc.Readers.Org.Shared,
+                   Text.Pandoc.Lua.Filter,
+                   Text.Pandoc.Lua.Init,
                    Text.Pandoc.Lua.Packages,
                    Text.Pandoc.Lua.PandocModule,
-                   Text.Pandoc.Lua.Filter,
                    Text.Pandoc.Lua.StackInstances,
                    Text.Pandoc.Lua.Util,
                    Text.Pandoc.CSS,
diff --git a/src/Text/Pandoc/App.hs b/src/Text/Pandoc/App.hs
index f7d6450cc..e70b606a9 100644
--- a/src/Text/Pandoc/App.hs
+++ b/src/Text/Pandoc/App.hs
@@ -223,7 +223,7 @@ convertWithOpts opts = do
             if ".lua" `isSuffixOf` format
                -- note:  use non-lowercased version writerName
                then return (TextWriter
-                       (\o d -> liftIO $ writeCustom writerName o d)
+                       (\o d -> writeCustom writerName o d)
                                :: Writer PandocIO, mempty)
                else case getWriter writerName of
                          Left e  -> E.throwIO $ PandocAppError $
@@ -846,7 +846,7 @@ applyLuaFilters :: Maybe FilePath -> [FilePath] -> String -> Pandoc
 applyLuaFilters mbDatadir filters format d = do
   expandedFilters <- mapM (expandFilterPath mbDatadir) filters
   let go f d' = do
-        res <- runLuaFilter mbDatadir f format d'
+        res <- runLuaFilter f format d'
         case res of
           Right x               -> return x
           Left (LuaException s) -> E.throw (PandocFilterError f s)
diff --git a/src/Text/Pandoc/Lua.hs b/src/Text/Pandoc/Lua.hs
index 7132ad718..a56e89511 100644
--- a/src/Text/Pandoc/Lua.hs
+++ b/src/Text/Pandoc/Lua.hs
@@ -1,9 +1,3 @@
-{-# LANGUAGE CPP                   #-}
-{-# LANGUAGE FlexibleContexts      #-}
-{-# LANGUAGE FlexibleInstances     #-}
-{-# LANGUAGE MultiParamTypeClasses #-}
-{-# LANGUAGE ScopedTypeVariables   #-}
-{-# OPTIONS_GHC -fno-warn-orphans #-}
 {-
 Copyright © 2017 Albert Krewinkel <tarleb+pandoc@moltkeplatz.de>
 
@@ -29,48 +23,36 @@ Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
    Maintainer  : Albert Krewinkel <tarleb+pandoc@moltkeplatz.de>
    Stability   : alpha
 
-Pandoc lua utils.
+Running pandoc Lua filters.
 -}
 module Text.Pandoc.Lua
   ( LuaException (..)
-  , LuaPackageParams (..)
-  , pushPandocModule
   , runLuaFilter
-  , initLuaState
-  , luaPackageParams
+  , runPandocLua
+  , pushPandocModule
   ) where
 
 import Control.Monad (when, (>=>))
-import Control.Monad.Identity (Identity)
-import Control.Monad.Trans (MonadIO (..))
-import Data.IORef (newIORef, readIORef)
 import Foreign.Lua (FromLuaStack (peek), Lua, LuaException (..),
                     Status (OK), ToLuaStack (push))
-import Text.Pandoc.Class (PandocIO, getCommonState, getMediaBag, setMediaBag)
-import Text.Pandoc.Definition
+import Text.Pandoc.Class (PandocIO)
+import Text.Pandoc.Definition (Pandoc)
 import Text.Pandoc.Lua.Filter (LuaFilter, walkMWithLuaFilter)
-import Text.Pandoc.Lua.Packages (LuaPackageParams (..),
-                                 installPandocPackageSearcher)
+import Text.Pandoc.Lua.Init (runPandocLua)
 import Text.Pandoc.Lua.PandocModule (pushPandocModule) -- TODO: remove
-import Text.Pandoc.Lua.Util (loadScriptFromDataDir)
 import qualified Foreign.Lua as Lua
-import qualified Foreign.Lua.Module.Text as Lua
 
-runLuaFilter :: Maybe FilePath -> FilePath -> String
+-- | Run the Lua filter in @filterPath@ for a transformation to target
+-- format @format@. Pandoc uses Lua init files to setup the Lua
+-- interpreter.
+runLuaFilter :: FilePath -> String
              -> Pandoc -> PandocIO (Either LuaException Pandoc)
-runLuaFilter datadir filterPath format pd = do
-  luaPkgParams <- luaPackageParams datadir
-  res <- liftIO . Lua.runLuaEither $
-         runLuaFilter' luaPkgParams filterPath format pd
-  newMediaBag <- liftIO (readIORef (luaPkgMediaBag luaPkgParams))
-  setMediaBag newMediaBag
-  return res
+runLuaFilter filterPath format doc =
+  runPandocLua (runLuaFilter' filterPath format doc)
 
-runLuaFilter' :: LuaPackageParams
-              -> FilePath -> String
+runLuaFilter' :: FilePath -> String
               -> Pandoc -> Lua Pandoc
-runLuaFilter' luaPkgOpts filterPath format pd = do
-  initLuaState luaPkgOpts
+runLuaFilter' filterPath format pd = do
   -- store module in global "pandoc"
   registerFormat
   top <- Lua.gettop
@@ -90,24 +72,6 @@ runLuaFilter' luaPkgOpts filterPath format pd = do
     push format
     Lua.setglobal "FORMAT"
 
-luaPackageParams :: Maybe FilePath -> PandocIO LuaPackageParams
-luaPackageParams datadir = do
-  commonState <- getCommonState
-  mbRef <- liftIO . newIORef =<< getMediaBag
-  return LuaPackageParams
-    { luaPkgCommonState = commonState
-    , luaPkgDataDir = datadir
-    , luaPkgMediaBag = mbRef
-    }
-
--- Initialize the lua state with all required values
-initLuaState :: LuaPackageParams -> Lua ()
-initLuaState luaPkgParams = do
-  Lua.openlibs
-  Lua.preloadTextModule "text"
-  installPandocPackageSearcher luaPkgParams
-  loadScriptFromDataDir (luaPkgDataDir luaPkgParams) "init.lua"
-
 pushGlobalFilter :: Lua ()
 pushGlobalFilter = do
   Lua.newtable
@@ -117,6 +81,3 @@ pushGlobalFilter = do
 
 runAll :: [LuaFilter] -> Pandoc -> Lua Pandoc
 runAll = foldr ((>=>) . walkMWithLuaFilter) return
-
-instance (FromLuaStack a) => FromLuaStack (Identity a) where
-  peek = fmap return . peek
diff --git a/src/Text/Pandoc/Lua/Init.hs b/src/Text/Pandoc/Lua/Init.hs
new file mode 100644
index 000000000..a2bfa3801
--- /dev/null
+++ b/src/Text/Pandoc/Lua/Init.hs
@@ -0,0 +1,79 @@
+{-
+Copyright © 2017 Albert Krewinkel <tarleb+pandoc@moltkeplatz.de>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program; if not, write to the Free Software
+Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+-}
+{- |
+   Module      : Text.Pandoc.Lua
+   Copyright   : Copyright © 2017 Albert Krewinkel
+   License     : GNU GPL, version 2 or above
+
+   Maintainer  : Albert Krewinkel <tarleb+pandoc@moltkeplatz.de>
+   Stability   : alpha
+
+Functions to initialize the Lua interpreter.
+-}
+module Text.Pandoc.Lua.Init
+  ( LuaException (..)
+  , LuaPackageParams (..)
+  , runPandocLua
+  , initLuaState
+  , luaPackageParams
+  ) where
+
+import Control.Monad.Trans (MonadIO (..))
+import Data.IORef (newIORef, readIORef)
+import Foreign.Lua (Lua, LuaException (..))
+import GHC.IO.Encoding (getForeignEncoding, setForeignEncoding, utf8)
+import Text.Pandoc.Class (PandocIO, getCommonState, getUserDataDir, getMediaBag,
+                          setMediaBag)
+import Text.Pandoc.Lua.Packages (LuaPackageParams (..),
+                                 installPandocPackageSearcher)
+import Text.Pandoc.Lua.Util (loadScriptFromDataDir)
+
+import qualified Foreign.Lua as Lua
+import qualified Foreign.Lua.Module.Text as Lua
+
+-- | Run the lua interpreter, using pandoc's default way of environment
+-- initalization.
+runPandocLua :: Lua a -> PandocIO (Either LuaException a)
+runPandocLua luaOp = do
+  datadir <- getUserDataDir
+  luaPkgParams <- luaPackageParams datadir
+  enc <- liftIO $ getForeignEncoding <* setForeignEncoding utf8
+  res <- liftIO $ Lua.runLuaEither (initLuaState luaPkgParams *> luaOp)
+  liftIO $ setForeignEncoding enc
+  newMediaBag <- liftIO (readIORef (luaPkgMediaBag luaPkgParams))
+  setMediaBag newMediaBag
+  return res
+
+-- | Generate parameters required to setup pandoc's lua environment.
+luaPackageParams :: Maybe FilePath -> PandocIO LuaPackageParams
+luaPackageParams datadir = do
+  commonState <- getCommonState
+  mbRef <- liftIO . newIORef =<< getMediaBag
+  return LuaPackageParams
+    { luaPkgCommonState = commonState
+    , luaPkgDataDir = datadir
+    , luaPkgMediaBag = mbRef
+    }
+
+-- Initialize the lua state with all required values
+initLuaState :: LuaPackageParams -> Lua ()
+initLuaState luaPkgParams = do
+  Lua.openlibs
+  Lua.preloadTextModule "text"
+  installPandocPackageSearcher luaPkgParams
+  loadScriptFromDataDir (luaPkgDataDir luaPkgParams) "init.lua"
diff --git a/src/Text/Pandoc/Writers/Custom.hs b/src/Text/Pandoc/Writers/Custom.hs
index 87b97dcee..72f443ed0 100644
--- a/src/Text/Pandoc/Writers/Custom.hs
+++ b/src/Text/Pandoc/Writers/Custom.hs
@@ -1,11 +1,5 @@
-{-# OPTIONS_GHC -fno-warn-orphans #-}
-{-# LANGUAGE CPP                  #-}
 {-# LANGUAGE DeriveDataTypeable   #-}
 {-# LANGUAGE FlexibleInstances    #-}
-#if MIN_VERSION_base(4,8,0)
-#else
-{-# LANGUAGE OverlappingInstances #-}
-#endif
 {- Copyright (C) 2012-2017 John MacFarlane <jgm@berkeley.edu>
 
 This program is free software; you can redistribute it and/or modify
@@ -36,19 +30,23 @@ Conversion of 'Pandoc' documents to custom markup using
 a lua writer.
 -}
 module Text.Pandoc.Writers.Custom ( writeCustom ) where
+import Control.Arrow ((***))
 import Control.Exception
 import Control.Monad (when)
+import Control.Monad.Trans (MonadIO (liftIO))
 import Data.Char (toLower)
 import Data.List (intersperse)
 import qualified Data.Map as M
 import Data.Text (Text, pack)
 import Data.Typeable
-import Foreign.Lua (Lua, ToLuaStack (..), callFunc, runLua)
+import Foreign.Lua (Lua, ToLuaStack (..), callFunc)
 import Foreign.Lua.Api
-import GHC.IO.Encoding (getForeignEncoding, setForeignEncoding, utf8)
+import Text.Pandoc.Class (PandocIO)
 import Text.Pandoc.Definition
 import Text.Pandoc.Error
-import Text.Pandoc.Lua.Util (addValue)
+import Text.Pandoc.Lua.Init (runPandocLua)
+import Text.Pandoc.Lua.StackInstances ()
+import Text.Pandoc.Lua.Util (addValue, dostring')
 import Text.Pandoc.Options
 import Text.Pandoc.Templates
 import qualified Text.Pandoc.UTF8 as UTF8
@@ -60,43 +58,31 @@ attrToMap (id',classes,keyvals) = M.fromList
     : ("class", unwords classes)
     : keyvals
 
-instance ToLuaStack Double where
-  push = push . (realToFrac :: Double -> LuaNumber)
-
-instance ToLuaStack Int where
-  push = push . (fromIntegral :: Int -> LuaInteger)
-
-instance ToLuaStack Format where
-  push (Format f) = push (map toLower f)
-
-#if MIN_VERSION_base(4,8,0)
-instance {-# OVERLAPS #-} ToLuaStack [Inline] where
-#else
-instance ToLuaStack [Inline] where
-#endif
-  push ils = push =<< inlineListToCustom ils
-
-#if MIN_VERSION_base(4,8,0)
-instance {-# OVERLAPS #-} ToLuaStack [Block] where
-#else
-instance ToLuaStack [Block] where
-#endif
-  push ils = push =<< blockListToCustom ils
-
-instance ToLuaStack MetaValue where
-  push (MetaMap m)       = push m
-  push (MetaList xs)     = push xs
-  push (MetaBool x)      = push x
-  push (MetaString s)    = push s
-  push (MetaInlines ils) = push ils
-  push (MetaBlocks bs)   = push bs
-
-instance ToLuaStack Citation where
-  push cit = do
+newtype Stringify a = Stringify a
+
+instance ToLuaStack (Stringify Format) where
+  push (Stringify (Format f)) = push (map toLower f)
+
+instance ToLuaStack (Stringify [Inline]) where
+  push (Stringify ils) = push =<< inlineListToCustom ils
+
+instance ToLuaStack (Stringify [Block]) where
+  push (Stringify blks) = push =<< blockListToCustom blks
+
+instance ToLuaStack (Stringify MetaValue) where
+  push (Stringify (MetaMap m))       = push (fmap Stringify m)
+  push (Stringify (MetaList xs))     = push (map Stringify xs)
+  push (Stringify (MetaBool x))      = push x
+  push (Stringify (MetaString s))    = push s
+  push (Stringify (MetaInlines ils)) = push (Stringify ils)
+  push (Stringify (MetaBlocks bs))   = push (Stringify bs)
+
+instance ToLuaStack (Stringify Citation) where
+  push (Stringify cit) = do
     createtable 6 0
     addValue "citationId" $ citationId cit
-    addValue "citationPrefix" $ citationPrefix cit
-    addValue "citationSuffix" $ citationSuffix cit
+    addValue "citationPrefix" . Stringify $ citationPrefix cit
+    addValue "citationSuffix" . Stringify $ citationSuffix cit
     addValue "citationMode" $ show (citationMode cit)
     addValue "citationNoteNum" $ citationNoteNum cit
     addValue "citationHash" $ citationHash cit
@@ -107,14 +93,11 @@ data PandocLuaException = PandocLuaException String
 instance Exception PandocLuaException
 
 -- | Convert Pandoc to custom markup.
-writeCustom :: FilePath -> WriterOptions -> Pandoc -> IO Text
+writeCustom :: FilePath -> WriterOptions -> Pandoc -> PandocIO Text
 writeCustom luaFile opts doc@(Pandoc meta _) = do
-  luaScript <- UTF8.readFile luaFile
-  enc <- getForeignEncoding
-  setForeignEncoding utf8
-  (body, context) <- runLua $ do
-    openlibs
-    stat <- loadstring luaScript
+  luaScript <- liftIO $ UTF8.readFile luaFile
+  res <- runPandocLua $ do
+    stat <- dostring' luaScript
     -- check for error in lua script (later we'll change the return type
     -- to handle this more gracefully):
     when (stat /= OK) $
@@ -127,7 +110,9 @@ writeCustom luaFile opts doc@(Pandoc meta _) = do
                inlineListToCustom
                meta
     return (rendered, context)
-  setForeignEncoding enc
+  let (body, context) = case res of
+        Left e -> throw (PandocLuaException (show e))
+        Right x -> x
   case writerTemplate opts of
        Nothing  -> return $ pack body
        Just tpl ->
@@ -138,7 +123,7 @@ writeCustom luaFile opts doc@(Pandoc meta _) = do
 docToCustom :: WriterOptions -> Pandoc -> Lua String
 docToCustom opts (Pandoc (Meta metamap) blocks) = do
   body <- blockListToCustom blocks
-  callFunc "Doc" body metamap (writerVariables opts)
+  callFunc "Doc" body (fmap Stringify metamap) (writerVariables opts)
 
 -- | Convert Pandoc block element to Custom.
 blockToCustom :: Block         -- ^ Block element
@@ -146,41 +131,45 @@ blockToCustom :: Block         -- ^ Block element
 
 blockToCustom Null = return ""
 
-blockToCustom (Plain inlines) = callFunc "Plain" inlines
+blockToCustom (Plain inlines) = callFunc "Plain" (Stringify inlines)
 
 blockToCustom (Para [Image attr txt (src,tit)]) =
-  callFunc "CaptionedImage" src tit txt (attrToMap attr)
+  callFunc "CaptionedImage" src tit (Stringify txt) (attrToMap attr)
 
-blockToCustom (Para inlines) = callFunc "Para" inlines
+blockToCustom (Para inlines) = callFunc "Para" (Stringify inlines)
 
-blockToCustom (LineBlock linesList) = callFunc "LineBlock" linesList
+blockToCustom (LineBlock linesList) = callFunc "LineBlock" (map Stringify linesList)
 
 blockToCustom (RawBlock format str) =
-  callFunc "RawBlock" format str
+  callFunc "RawBlock" (Stringify format) str
 
 blockToCustom HorizontalRule = callFunc "HorizontalRule"
 
 blockToCustom (Header level attr inlines) =
-  callFunc "Header" level inlines (attrToMap attr)
+  callFunc "Header" level (Stringify inlines) (attrToMap attr)
 
 blockToCustom (CodeBlock attr str) =
   callFunc "CodeBlock" str (attrToMap attr)
 
-blockToCustom (BlockQuote blocks) = callFunc "BlockQuote" blocks
+blockToCustom (BlockQuote blocks) = callFunc "BlockQuote" (Stringify blocks)
 
-blockToCustom (Table capt aligns widths headers rows') =
-  callFunc "Table" capt (map show aligns) widths headers rows'
+blockToCustom (Table capt aligns widths headers rows) =
+  let aligns' = map show aligns
+      capt' = Stringify capt
+      headers' = map Stringify headers
+      rows' = map (map Stringify) rows
+  in callFunc "Table" capt' aligns' widths headers' rows'
 
-blockToCustom (BulletList items) = callFunc "BulletList" items
+blockToCustom (BulletList items) = callFunc "BulletList" (map Stringify items)
 
 blockToCustom (OrderedList (num,sty,delim) items) =
-  callFunc "OrderedList" items num (show sty) (show delim)
+  callFunc "OrderedList" (map Stringify items) num (show sty) (show delim)
 
 blockToCustom (DefinitionList items) =
-  callFunc "DefinitionList" items
+  callFunc "DefinitionList" (map (Stringify *** map Stringify) items)
 
 blockToCustom (Div attr items) =
-  callFunc "Div" items (attrToMap attr)
+  callFunc "Div" (Stringify items) (attrToMap attr)
 
 -- | Convert list of Pandoc block elements to Custom.
 blockListToCustom :: [Block]       -- ^ List of block elements
@@ -205,23 +194,23 @@ inlineToCustom Space = callFunc "Space"
 
 inlineToCustom SoftBreak = callFunc "SoftBreak"
 
-inlineToCustom (Emph lst) = callFunc "Emph" lst
+inlineToCustom (Emph lst) = callFunc "Emph" (Stringify lst)
 
-inlineToCustom (Strong lst) = callFunc "Strong" lst
+inlineToCustom (Strong lst) = callFunc "Strong" (Stringify lst)
 
-inlineToCustom (Strikeout lst) = callFunc "Strikeout" lst
+inlineToCustom (Strikeout lst) = callFunc "Strikeout" (Stringify lst)
 
-inlineToCustom (Superscript lst) = callFunc "Superscript" lst
+inlineToCustom (Superscript lst) = callFunc "Superscript" (Stringify lst)
 
-inlineToCustom (Subscript lst) = callFunc "Subscript" lst
+inlineToCustom (Subscript lst) = callFunc "Subscript" (Stringify lst)
 
-inlineToCustom (SmallCaps lst) = callFunc "SmallCaps" lst
+inlineToCustom (SmallCaps lst) = callFunc "SmallCaps" (Stringify lst)
 
-inlineToCustom (Quoted SingleQuote lst) = callFunc "SingleQuoted" lst
+inlineToCustom (Quoted SingleQuote lst) = callFunc "SingleQuoted" (Stringify lst)
 
-inlineToCustom (Quoted DoubleQuote lst) = callFunc "DoubleQuoted" lst
+inlineToCustom (Quoted DoubleQuote lst) = callFunc "DoubleQuoted" (Stringify lst)
 
-inlineToCustom (Cite cs lst) = callFunc "Cite" lst cs
+inlineToCustom (Cite cs lst) = callFunc "Cite" (Stringify lst) (map Stringify cs)
 
 inlineToCustom (Code attr str) =
   callFunc "Code" str (attrToMap attr)
@@ -233,17 +222,17 @@ inlineToCustom (Math InlineMath str) =
   callFunc "InlineMath" str
 
 inlineToCustom (RawInline format str) =
-  callFunc "RawInline" format str
+  callFunc "RawInline" (Stringify format) str
 
 inlineToCustom LineBreak = callFunc "LineBreak"
 
 inlineToCustom (Link attr txt (src,tit)) =
-  callFunc "Link" txt src tit (attrToMap attr)
+  callFunc "Link" (Stringify txt) src tit (attrToMap attr)
 
 inlineToCustom (Image attr alt (src,tit)) =
-  callFunc "Image" alt src tit (attrToMap attr)
+  callFunc "Image" (Stringify alt) src tit (attrToMap attr)
 
-inlineToCustom (Note contents) = callFunc "Note" contents
+inlineToCustom (Note contents) = callFunc "Note" (Stringify contents)
 
 inlineToCustom (Span attr items) =
-  callFunc "Span" items (attrToMap attr)
+  callFunc "Span" (Stringify items) (attrToMap attr)
diff --git a/test/Tests/Lua.hs b/test/Tests/Lua.hs
index eaa7eb405..4f14a834b 100644
--- a/test/Tests/Lua.hs
+++ b/test/Tests/Lua.hs
@@ -10,9 +10,9 @@ import Text.Pandoc.Arbitrary ()
 import Text.Pandoc.Builder (bulletList, divWith, doc, doubleQuoted, emph,
                             header, linebreak, para, plain, rawBlock,
                             singleQuoted, space, str, strong, (<>))
-import Text.Pandoc.Class (runIOorExplode)
+import Text.Pandoc.Class (runIOorExplode, setUserDataDir)
 import Text.Pandoc.Definition (Block, Inline, Meta, Pandoc)
-import Text.Pandoc.Lua (initLuaState, runLuaFilter, luaPackageParams)
+import Text.Pandoc.Lua (runLuaFilter, runPandocLua)
 
 import qualified Foreign.Lua as Lua
 
@@ -95,8 +95,9 @@ tests = map (localOption (QuickCheckTests 20))
 
 assertFilterConversion :: String -> FilePath -> Pandoc -> Pandoc -> Assertion
 assertFilterConversion msg filterPath docIn docExpected = do
-  docEither <- runIOorExplode $
-               runLuaFilter (Just "../data") ("lua" </> filterPath) [] docIn
+  docEither <- runIOorExplode $ do
+    setUserDataDir (Just "../data")
+    runLuaFilter ("lua" </> filterPath) [] docIn
   case docEither of
     Left _       -> fail "lua filter failed"
     Right docRes -> assertEqual msg docExpected docRes
@@ -105,14 +106,18 @@ roundtripEqual :: (Eq a, Lua.FromLuaStack a, Lua.ToLuaStack a) => a -> IO Bool
 roundtripEqual x = (x ==) <$> roundtripped
  where
   roundtripped :: (Lua.FromLuaStack a, Lua.ToLuaStack a) => IO a
-  roundtripped = Lua.runLua $ do
-    initLuaState =<< Lua.liftIO (runIOorExplode (luaPackageParams (Just "../data")))
-    oldSize <- Lua.gettop
-    Lua.push x
-    size <- Lua.gettop
-    when (size - oldSize /= 1) $
-      error ("not exactly one additional element on the stack: " ++ show size)
-    res <- Lua.peekEither (-1)
+  roundtripped = runIOorExplode $ do
+    setUserDataDir (Just "../data")
+    res <- runPandocLua $ do
+      oldSize <- Lua.gettop
+      Lua.push x
+      size <- Lua.gettop
+      when (size - oldSize /= 1) $
+        error ("not exactly one additional element on the stack: " ++ show size)
+      res <- Lua.peekEither (-1)
+      case res of
+        Left _  -> error "could not read from stack"
+        Right y -> return y
     case res of
-      Left _  -> error "could not read from stack"
+      Left e -> error (show e)
       Right y -> return y