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authorJesse Rosenthal <jrosenthal@jhu.edu>2014-07-12 08:56:59 +0100
committerJesse Rosenthal <jrosenthal@jhu.edu>2014-07-12 18:04:06 +0100
commitfe2eda9d54e64ffa0c6c5c5295c19941040a5f3d (patch)
tree637d6bb84df637b1287bf83e7a26e6a3b566ea45 /src
parentd65fd581713f181032ac29afe9843f1de99c70e0 (diff)
downloadpandoc-fe2eda9d54e64ffa0c6c5c5295c19941040a5f3d.tar.gz
Docx Reader: Add a compatibility layer for Except.
mtl switched from ErrorT to ExceptT, but we're not sure which mtl we'll be dealing with. This should make errors work with both. The main difference (beside the name of the module and the monad transformer) is that Except doesn't require an instance of an Error Typeclass. So we define that for compatability. When we switch to a later mtl, using Control.Monad.Exception, we can just erase the instance declaration, and all should work fine.
Diffstat (limited to 'src')
-rw-r--r--src/Text/Pandoc/Compat/Except.hs27
-rw-r--r--src/Text/Pandoc/Readers/Docx/Parse.hs6
2 files changed, 30 insertions, 3 deletions
diff --git a/src/Text/Pandoc/Compat/Except.hs b/src/Text/Pandoc/Compat/Except.hs
new file mode 100644
index 000000000..7f5648e7a
--- /dev/null
+++ b/src/Text/Pandoc/Compat/Except.hs
@@ -0,0 +1,27 @@
+{-# LANGUAGE CPP #-}
+module Text.Pandoc.Compat.Except ( ExceptT
+ , Error(..)
+ , runExceptT
+ , throwError
+ , catchError )
+ where
+
+#if MIN_VERSION_mtl(2,2,1)
+import Control.Monad.Except
+
+class Error a where
+ noMsg :: a
+ strMsg :: String -> a
+
+ noMsg = strMsg ""
+ strMsg _ = noMsg
+
+#else
+import Control.Monad.Error
+type ExceptT = ErrorT
+
+runExceptT :: ExceptT e m a -> m (Either e a)
+runExceptT = runErrorT
+#endif
+
+
diff --git a/src/Text/Pandoc/Readers/Docx/Parse.hs b/src/Text/Pandoc/Readers/Docx/Parse.hs
index bb65236a3..4b5a11fa8 100644
--- a/src/Text/Pandoc/Readers/Docx/Parse.hs
+++ b/src/Text/Pandoc/Readers/Docx/Parse.hs
@@ -69,7 +69,7 @@ import qualified Data.ByteString.Lazy as B
import qualified Text.Pandoc.UTF8 as UTF8
import Control.Monad.Reader
import qualified Data.Map as M
-import Control.Monad.Error
+import Text.Pandoc.Compat.Except
data ReaderEnv = ReaderEnv { envNotes :: Notes
, envNumbering :: Numbering
@@ -84,10 +84,10 @@ data DocxError = DocxError | WrongElem
instance Error DocxError where
noMsg = WrongElem
-type D = ErrorT DocxError (Reader ReaderEnv)
+type D = ExceptT DocxError (Reader ReaderEnv)
runD :: D a -> ReaderEnv -> Either DocxError a
-runD dx re = runReader (runErrorT dx ) re
+runD dx re = runReader (runExceptT dx ) re
maybeToD :: Maybe a -> D a
maybeToD (Just a) = return a