Change setVariable to use Text instead of String.

This avoids some unnecessary unpacking.
(This is only an internal module so it's not an API change.)

src/Text/Pandoc/App/CommandLineOptions.hs

@@ -202,7 +202,8 @@ options =
                   (\arg opt -> do
                      let (key, val) = splitField arg
                      return opt{ optVariables =
-                                  setVariable key val $ optVariables opt })
+                                  setVariable (T.pack key) (T.pack val) $
+                                    optVariables opt })
                   "KEY[:VALUE]")
                  ""
 
@@ -586,7 +587,8 @@ options =
                   (\arg opt ->
                     return opt {
                        optVariables =
-                         setVariable "title-prefix" arg $ optVariables opt,
+                         setVariable "title-prefix" (T.pack arg) $
+                           optVariables opt,
                        optStandalone = True })
                   "STRING")
                  "" -- "String to prefix to HTML window title"
@@ -609,7 +611,7 @@ options =
                  (ReqArg
                   (\arg opt ->
                      return opt { optVariables =
-                       setVariable "epub-cover-image" arg $
+                       setVariable "epub-cover-image" (T.pack arg) $
                          optVariables opt })
                   "FILE")
                  "" -- "Path of epub cover image"
@@ -1029,13 +1031,11 @@ deprecatedOption o msg =
        Left e   -> E.throwIO e
 
 -- | Set text value in text context.
-setVariable :: String -> String -> Context Text -> Context Text
-setVariable key val (Context ctx) = Context $ M.alter go (T.pack key) ctx
-  where go Nothing  = Just $ toVal (T.pack val)
-        go (Just (ListVal xs))
-                    = Just $ ListVal $ xs ++
-                             [toVal (T.pack val)]
-        go (Just x) = Just $ ListVal [x, toVal (T.pack val)]
+setVariable :: Text -> Text -> Context Text -> Context Text
+setVariable key val (Context ctx) = Context $ M.alter go key ctx
+  where go Nothing             = Just $ toVal val
+        go (Just (ListVal xs)) = Just $ ListVal $ xs ++ [toVal val]
+        go (Just x)            = Just $ ListVal [x, toVal val]
 
 addMeta :: String -> String -> Meta -> Meta
 addMeta k v meta =

src/Text/Pandoc/App/OutputSettings.hs

@@ -28,7 +28,7 @@ import Control.Monad
 import Control.Monad.Except (throwError)
 import Control.Monad.Trans
 import Data.Char (toLower)
-import Data.List (find, isPrefixOf)
+import Data.List (find)
 import Data.Maybe (fromMaybe)
 import Skylighting (defaultSyntaxMap)
 import Skylighting.Parser (addSyntaxDefinition, parseSyntaxDefinition)
@@ -36,7 +36,6 @@ import System.Directory (getCurrentDirectory)
 import System.Exit (exitSuccess)
 import System.FilePath
 import System.IO (stdout)
-import Data.String
 import Text.Pandoc
 import Text.Pandoc.App.FormatHeuristics (formatFromFilePaths)
 import Text.Pandoc.App.Opt (Opt (..))
@@ -116,7 +115,7 @@ optToOutputSettings opts = do
   hlStyle <- maybe (return Nothing) (fmap Just . lookupHighlightStyle . T.unpack)
                 (optHighlightStyle opts)
 
-  let setVariableM k v = return . setVariable k (fromString v)
+  let setVariableM k v = return . setVariable k v
 
   let setListVariableM _ [] ctx = return ctx
       setListVariableM k vs ctx = do
@@ -143,7 +142,7 @@ optToOutputSettings opts = do
     setListVariableM "sourcefile"
       (maybe ["-"] (fmap T.pack) (optInputFiles opts))
     >>=
-    setVariableM "outputfile" outputFile
+    setVariableM "outputfile" (T.pack outputFile)
     >>=
     setFilesVariableM "include-before" (optIncludeBeforeBody opts)
     >>=
@@ -153,21 +152,21 @@ optToOutputSettings opts = do
     >>=
     setListVariableM "css" (map T.pack $ optCss opts)
     >>=
-    maybe return (setVariableM "title-prefix" . T.unpack) (optTitlePrefix opts)
+    maybe return (setVariableM "title-prefix") (optTitlePrefix opts)
     >>=
     maybe return (setVariableM "epub-cover-image")
-                 (optEpubCoverImage opts)
+                 (T.pack <$> optEpubCoverImage opts)
     >>=
-    setVariableM "curdir" curdir
+    setVariableM "curdir" (T.pack curdir)
     >>=
     (\vars ->  if format == "dzslides"
                   then do
-                      dztempl <- UTF8.toString <$> readDataFile
+                      dztempl <- UTF8.toText <$> readDataFile
                                    ("dzslides" </> "template.html")
                       let dzline = "<!-- {{{{ dzslides core"
-                      let dzcore = unlines
-                                 $ dropWhile (not . (dzline `isPrefixOf`))
-                                 $ lines dztempl
+                      let dzcore = T.unlines
+                                 $ dropWhile (not . (dzline `T.isPrefixOf`))
+                                 $ T.lines dztempl
                       setVariableM "dzslides-core" dzcore vars
                   else return vars)