unRow returns Both.

src/Row.hs

@@ -1,6 +1,7 @@
 module Row where
 
 import Control.Arrow
+import Data.Functor.Both
 import Line
 
 -- | A row in a split diff, composed of a before line and an after line.
@@ -8,8 +9,8 @@ data Row a = Row { unLeft :: !(Line a), unRight :: !(Line a) }
   deriving (Eq, Functor)
 
 -- | Return a tuple of lines from the row.
-unRow :: Row a -> (Line a, Line a)
-unRow (Row a b) = (a, b)
+unRow :: Row a -> Both (Line a)
+unRow (Row a b) = Both (a, b)
 
 -- | Map over both sides of a row with the given functions.
 wrapRowContents :: ([a] -> b) -> ([a] -> b) -> Row a -> Row b
@@ -21,19 +22,19 @@ adjoinRowsBy :: MaybeOpen a -> MaybeOpen a -> [Row a] -> Row a -> [Row a]
 adjoinRowsBy _ _ [] row = [row]
 
 adjoinRowsBy f g rows (Row left' right') | Just _ <- openLineBy f $ unLeft <$> rows, Just _ <- openLineBy g $ unRight <$> rows = zipWith Row (lefts left') (rights right')
-  where (lefts, rights) = adjoinLinesBy f *** adjoinLinesBy g $ unzip $ unRow <$> rows
+  where (lefts, rights) = adjoinLinesBy f *** adjoinLinesBy g $ unzip $ runBoth . unRow <$> rows
 
 adjoinRowsBy f _ rows (Row left' right') | Just _ <- openLineBy f $ unLeft <$> rows = case right' of
   EmptyLine -> rest
   _ -> Row EmptyLine right' : rest
   where rest = zipWith Row (lefts left') rights
-        (lefts, rights) = first (adjoinLinesBy f) $ unzip $ unRow <$> rows
+        (lefts, rights) = first (adjoinLinesBy f) $ unzip $ runBoth . unRow <$> rows
 
 adjoinRowsBy _ g rows (Row left' right') | Just _ <- openLineBy g $ unRight <$> rows = case left' of
   EmptyLine -> rest
   _ -> Row left' EmptyLine : rest
   where rest = zipWith Row lefts (rights right')
-        (lefts, rights) = second (adjoinLinesBy g) $ unzip $ unRow <$> rows
+        (lefts, rights) = second (adjoinLinesBy g) $ unzip $ runBoth . unRow <$> rows
 
 adjoinRowsBy _ _ rows row = row : rows