Switch to hslua-2.0

The new HsLua version takes a somewhat different approach to marshalling
and unmarshalling, relying less on typeclasses and more on specialized
types. This allows for better performance and improved error messages.

Furthermore, new abstractions allow to document the code and exposed
functions.

1 files changed, 26 insertions, 40 deletions

diff --git a/src/Text/Pandoc/Lua/Module/Types.hs b/src/Text/Pandoc/Lua/Module/Types.hs
index bb4f02c3c..a9ce14ce7 100644
--- a/src/Text/Pandoc/Lua/Module/Types.hs
+++ b/src/Text/Pandoc/Lua/Module/Types.hs
@@ -1,3 +1,4 @@
+{-# LANGUAGE OverloadedStrings #-}
 {- |
    Module      : Text.Pandoc.Lua.Module.Types
    Copyright   : © 2019-2021 Albert Krewinkel
@@ -13,56 +14,41 @@ module Text.Pandoc.Lua.Module.Types
   ) where
 
 import Data.Version (Version)
-import Foreign.Lua (Lua, NumResults)
-import Text.Pandoc.Definition
-import Text.Pandoc.Lua.Marshaling.AST (LuaAttr, LuaListAttributes)
+import HsLua (LuaE, NumResults, Peeker, Pusher)
+import Text.Pandoc.Error (PandocError)
+import Text.Pandoc.Lua.ErrorConversion ()
+import Text.Pandoc.Lua.Marshaling.AST
 import Text.Pandoc.Lua.Marshaling.Version ()
 import Text.Pandoc.Lua.Util (addFunction)
 
-import qualified Foreign.Lua as Lua
+import qualified HsLua as Lua
 
--- | Push the pandoc.system module on the Lua stack.
-pushModule :: Lua NumResults
+-- | Push the pandoc.types module on the Lua stack.
+pushModule :: LuaE PandocError NumResults
 pushModule = do
   Lua.newtable
-  addFunction "Version" (return :: Version -> Lua Version)
+  addFunction "Version" (return :: Version -> LuaE PandocError Version)
   pushCloneTable
-  Lua.setfield (Lua.nthFromTop 2) "clone"
+  Lua.setfield (Lua.nth 2) "clone"
   return 1
 
-pushCloneTable :: Lua NumResults
+pushCloneTable :: LuaE PandocError NumResults
 pushCloneTable = do
   Lua.newtable
-  addFunction "Attr" cloneAttr
-  addFunction "Block" cloneBlock
-  addFunction "Citation" cloneCitation
-  addFunction "Inline" cloneInline
-  addFunction "Meta" cloneMeta
-  addFunction "MetaValue" cloneMetaValue
-  addFunction "ListAttributes" cloneListAttributes
-  addFunction "Pandoc" clonePandoc
+  addFunction "Attr"      $ cloneWith peekAttr pushAttr
+  addFunction "Block"     $ cloneWith peekBlock pushBlock
+  addFunction "Citation"  $ cloneWith peekCitation Lua.push
+  addFunction "Inline"    $ cloneWith peekInline pushInline
+  addFunction "Meta"      $ cloneWith peekMeta Lua.push
+  addFunction "MetaValue" $ cloneWith peekMetaValue pushMetaValue
+  addFunction "ListAttributes" $ cloneWith peekListAttributes pushListAttributes
+  addFunction "Pandoc"    $ cloneWith peekPandoc pushPandoc
   return 1
 
-cloneAttr :: LuaAttr -> Lua LuaAttr
-cloneAttr = return
-
-cloneBlock :: Block -> Lua Block
-cloneBlock = return
-
-cloneCitation :: Citation -> Lua Citation
-cloneCitation = return
-
-cloneInline :: Inline -> Lua Inline
-cloneInline = return
-
-cloneListAttributes :: LuaListAttributes -> Lua LuaListAttributes
-cloneListAttributes = return
-
-cloneMeta :: Meta -> Lua Meta
-cloneMeta = return
-
-cloneMetaValue :: MetaValue -> Lua MetaValue
-cloneMetaValue = return
-
-clonePandoc :: Pandoc -> Lua Pandoc
-clonePandoc = return
+cloneWith :: Peeker PandocError a
+          -> Pusher PandocError a
+          -> LuaE PandocError NumResults
+cloneWith peeker pusher = do
+  x <- Lua.forcePeek $ peeker (Lua.nthBottom 1)
+  pusher x
+  return (Lua.NumResults 1)