Adjustments for new Format newtype.

1 files changed, 6 insertions, 0 deletions

diff --git a/src/Text/Pandoc/Writers/Custom.hs b/src/Text/Pandoc/Writers/Custom.hs
index c250a240e..0234e1e35 100644
--- a/src/Text/Pandoc/Writers/Custom.hs
+++ b/src/Text/Pandoc/Writers/Custom.hs
@@ -33,6 +33,7 @@ module Text.Pandoc.Writers.Custom ( writeCustom ) where
 import Text.Pandoc.Definition
 import Text.Pandoc.Options
 import Data.List ( intersperse )
+import Data.Char ( toLower )
 import Scripting.Lua (LuaState, StackValue, callfunc)
 import qualified Scripting.Lua as Lua
 import Text.Pandoc.UTF8 (fromString, toString)
@@ -78,6 +79,11 @@ instance StackValue a => StackValue [a] where
     return (Just lst)
   valuetype _ = Lua.TTABLE
 
+instance StackValue Format where
+  push lua (Format f) = Lua.push lua (map toLower f)
+  peek l n = fmap Format `fmap` Lua.peek l n
+  valuetype _ = Lua.TSTRING
+
 instance (StackValue a, StackValue b) => StackValue (M.Map a b) where
   push lua m = do
     let xs = M.toList m