Templates: change signature of getDefaultTemplate.

Now it runs in any instance of PandocMonad, and returns
a String rather than an Either value.

src/Text/Pandoc/App.hs

@@ -218,7 +218,8 @@ convertWithOpts opts = do
   templ <- case optTemplate opts of
                 _ | not standalone -> return Nothing
                 Nothing -> do
-                           deftemp <- getDefaultTemplate datadir format
+                           deftemp <- runIO $
+                                        getDefaultTemplate datadir format
                            case deftemp of
                                  Left e  -> E.throwIO e
                                  Right t -> return (Just t)
@@ -991,10 +992,10 @@ options =
     , Option "D" ["print-default-template"]
                  (ReqArg
                   (\arg _ -> do
-                     templ <- getDefaultTemplate Nothing arg
+                     templ <- runIO $ getDefaultTemplate Nothing arg
                      case templ of
                           Right t -> UTF8.hPutStr stdout t
-                          Left e  -> E.throwIO $ PandocAppError (show e)
+                          Left e  -> E.throwIO e
                      exitSuccess)
                   "FORMAT")
                  "" -- "Print default template for FORMAT"

src/Text/Pandoc/Templates.hs

@@ -38,28 +38,28 @@ module Text.Pandoc.Templates ( module Text.DocTemplates
                              , getDefaultTemplate
                              ) where
 
-import qualified Control.Exception as E (IOException, try)
 import Control.Monad.Except (throwError)
 import Data.Aeson (ToJSON (..))
 import qualified Data.Text as T
 import System.FilePath ((<.>), (</>))
 import Text.DocTemplates (Template, TemplateTarget, applyTemplate,
                           compileTemplate, renderTemplate, varListToJSON)
-import Text.Pandoc.Class (PandocMonad)
+import Text.Pandoc.Class (PandocMonad(readDataFile))
 import Text.Pandoc.Error
-import Text.Pandoc.Shared (readDataFileUTF8)
+import qualified Text.Pandoc.UTF8 as UTF8
 
 -- | Get default template for the specified writer.
-getDefaultTemplate :: (Maybe FilePath) -- ^ User data directory to search first
+getDefaultTemplate :: PandocMonad m
+                   => (Maybe FilePath) -- ^ User data directory to search 1st
                    -> String           -- ^ Name of writer
-                   -> IO (Either E.IOException String)
+                   -> m String
 getDefaultTemplate user writer = do
   let format = takeWhile (`notElem` ("+-" :: String)) writer  -- strip off extensions
   case format of
-       "native"  -> return $ Right ""
-       "json"    -> return $ Right ""
-       "docx"    -> return $ Right ""
-       "fb2"     -> return $ Right ""
+       "native"  -> return ""
+       "json"    -> return ""
+       "docx"    -> return ""
+       "fb2"     -> return ""
        "odt"     -> getDefaultTemplate user "opendocument"
        "html"    -> getDefaultTemplate user "html5"
        "docbook" -> getDefaultTemplate user "docbook5"
@@ -70,7 +70,7 @@ getDefaultTemplate user writer = do
        "markdown_mmd"      -> getDefaultTemplate user "markdown"
        "markdown_phpextra" -> getDefaultTemplate user "markdown"
        _        -> let fname = "templates" </> "default" <.> format
-                   in  E.try $ readDataFileUTF8 user fname
+                   in  UTF8.toString <$> readDataFile user fname
 
 -- | Like 'applyTemplate', but runs in PandocMonad and
 -- raises an error if compilation fails.