1 files changed, 9 insertions, 9 deletions
diff --git a/src/Text/Pandoc/Lua/Module/Utils.hs b/src/Text/Pandoc/Lua/Module/Utils.hs
index 057e6580b..7d6dd0fab 100644
--- a/src/Text/Pandoc/Lua/Module/Utils.hs
+++ b/src/Text/Pandoc/Lua/Module/Utils.hs
@@ -15,7 +15,6 @@ module Text.Pandoc.Lua.Module.Utils
 
 import Prelude
 import Control.Applicative ((<|>))
-import Data.Char (toLower)
 import Data.Default (def)
 import Data.Version (Version)
 import Foreign.Lua (Peekable, Lua, NumResults)
@@ -27,6 +26,7 @@ import Text.Pandoc.Lua.Util (addFunction)
 
 import qualified Data.Digest.Pure.SHA as SHA
 import qualified Data.ByteString.Lazy as BSL
+import qualified Data.Text as T
 import qualified Foreign.Lua as Lua
 import qualified Text.Pandoc.Builder as B
 import qualified Text.Pandoc.Filter.JSON as JSONFilter
@@ -64,7 +64,7 @@ makeSections number baselevel =
 -- 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 (Lua.Optional String)
+normalizeDate :: T.Text -> Lua (Lua.Optional T.Text)
 normalizeDate = return . Lua.Optional . Shared.normalizeDate
 
 -- | Run a JSON filter on the given document.
@@ -88,13 +88,13 @@ runJSONFilter mbDatadir doc filterFile optArgs = do
 
 -- | Calculate the hash of the given contents.
 sha1 :: BSL.ByteString
-     -> Lua String
-sha1 = return . SHA.showDigest . SHA.sha1
+     -> Lua T.Text
+sha1 = return . T.pack . SHA.showDigest . SHA.sha1
 
 -- | Convert pandoc structure to a string with formatting removed.
 -- Footnotes are skipped (since we don't want their contents in link
 -- labels).
-stringify :: AstElement -> Lua String
+stringify :: AstElement -> Lua T.Text
 stringify el = return $ case el of
   PandocElement pd -> Shared.stringify pd
   InlineElement i  -> Shared.stringify i
@@ -102,11 +102,11 @@ stringify el = return $ case el of
   MetaElement m    -> Shared.stringify m
   CitationElement c  -> Shared.stringify c
   MetaValueElement m -> stringifyMetaValue m
-  _                  -> ""
+  _                  -> mempty
 
-stringifyMetaValue :: MetaValue -> String
+stringifyMetaValue :: MetaValue -> T.Text
 stringifyMetaValue mv = case mv of
-  MetaBool b   -> map toLower (show b)
+  MetaBool b   -> T.toLower $ T.pack (show b)
   MetaString s -> s
   _            -> Shared.stringify mv
 
@@ -139,5 +139,5 @@ instance Peekable AstElement where
         "Expected an AST element, but could not parse value as such."
 
 -- | Convert a number < 4000 to uppercase roman numeral.
-toRomanNumeral :: Lua.Integer -> Lua String
+toRomanNumeral :: Lua.Integer -> Lua T.Text
 toRomanNumeral = return . Shared.toRomanNumeral . fromIntegral