Move utility error functions to Text.Pandoc.Shared

1 files changed, 10 insertions, 0 deletions

diff --git a/src/Text/Pandoc/Shared.hs b/src/Text/Pandoc/Shared.hs
index 90d0941c1..e0460c66e 100644
--- a/src/Text/Pandoc/Shared.hs
+++ b/src/Text/Pandoc/Shared.hs
@@ -85,6 +85,8 @@ module Text.Pandoc.Shared (
                      -- * Error handling
                      err,
                      warn,
+                     mapLeft,
+                     hush,
                      -- * Safe read
                      safeRead,
                      -- * Temp directory
@@ -855,6 +857,14 @@ warn msg = do
   name <- getProgName
   UTF8.hPutStrLn stderr $ name ++ ": " ++ msg
 
+mapLeft :: (a -> b) -> Either a c -> Either b c
+mapLeft f (Left x) = Left (f x)
+mapLeft _ (Right x) = Right x
+
+hush :: Either a b -> Maybe b
+hush (Left _) = Nothing
+hush (Right x) = Just x
+
 -- | Remove intermediate "." and ".." directories from a path.
 --
 -- > collapseFilePath "./foo" == "foo"