Swap the order of the operands to splitDiffByLines.

src/Alignment.hs

@@ -37,8 +37,8 @@ hasChanges :: Line (SplitDiff leaf Info) -> Bool
 hasChanges = or . fmap (or . (True <$))
 
 -- | Split a diff, which may span multiple lines, into rows of split diffs.
-splitDiffByLines :: Diff leaf Info -> Both (Source Char) -> [Row (SplitDiff leaf Info, Range)]
-splitDiffByLines diff sources = case diff of
+splitDiffByLines :: Both (Source Char) -> Diff leaf Info -> [Row (SplitDiff leaf Info, Range)]
+splitDiffByLines sources diff = case diff of
   Free (Annotated annotation syntax) -> splitAnnotatedByLines sources (ranges annotation) (Diff.categories <$> annotation) syntax
   Pure patch -> splitPatchByLines sources patch
   where ranges annotations = characterRange <$> annotations
@@ -81,7 +81,7 @@ splitAnnotatedByLines sources ranges categories syntax = case syntax of
           fmap (wrapRowContents (makeBranchTerm (\ info -> Free . Annotated info . constructor) <$> categories <*> previous)) . adjoin $ rows ++ (zipWithDefaults makeRow (pure mempty) (fmap (pure . (,) Nothing) <$> (actualLineRanges <$> (Range <$> previous <*> (end <$> ranges)) <*> sources)))
 
         childRows :: (Copointed f, Functor f) => ([Row (Maybe (f (SplitDiff leaf Info)), Range)], Both Int) -> f (Diff leaf Info) -> ([Row (Maybe (f (SplitDiff leaf Info)), Range)], Both Int)
-        childRows (rows, previous) child = let childRows = splitDiffByLines (copoint child) sources in
+        childRows (rows, previous) child = let childRows = splitDiffByLines sources (copoint child) in
           -- We depend on source ranges increasing monotonically. If a child invalidates that, e.g. if it’s a move in a Keyed node, we don’t output rows for it in this iteration. (It will still show up in the diff as context rows.) This works around https://github.com/github/semantic-diff/issues/488.
           if or $ (<) . start <$> (unionLineRangesFrom <$> (rangeAt <$> previous) <*> sequenceA (unRow <$> childRows)) <*> previous
             then (rows, previous)

src/Renderer/JSON.hs

@@ -28,7 +28,7 @@ import Term
 -- | Render a diff to a string representing its JSON.
 json :: Renderer a ByteString
 json diff sources = toLazyByteString . fromEncoding . pairs $
-     "rows" .= annotateRows (splitDiffByLines diff (source <$> sources))
+     "rows" .= annotateRows (splitDiffByLines (source <$> sources) diff)
   <> "oids" .= (oid <$> sources)
   <> "paths" .= (path <$> sources)
   where annotateRows = fmap (fmap NumberedLine) . Prelude.reverse . numberedRows

src/Renderer/Patch.hs

@@ -90,7 +90,7 @@ header blobs hunk = filepathHeader ++ blobOidHeader ++ maybeOffsetHeader
 -- | Render a diff as a series of hunks.
 hunks :: Renderer a [Hunk (SplitDiff a Info)]
 hunks _ blobs | Both (True, True) <- Source.null . source <$> blobs = [Hunk { offset = mempty, changes = [], trailingContext = [] }]
-hunks diff blobs = hunksInRows (Both (1, 1)) $ fmap Prelude.fst <$> splitDiffByLines diff (source <$> blobs)
+hunks diff blobs = hunksInRows (Both (1, 1)) $ fmap Prelude.fst <$> splitDiffByLines (source <$> blobs) diff
 
 -- | Given beginning line numbers, turn rows in a split diff into hunks in a
 -- | patch.

src/Renderer/Split.hs

@@ -61,7 +61,7 @@ split diff blobs = renderHtml
         . mconcat $ numberedLinesToMarkup <$> reverse numbered
   where
     sources = Source.source <$> blobs
-    numbered = numberedRows (fmap Prelude.fst <$> splitDiffByLines diff sources)
+    numbered = numberedRows (fmap Prelude.fst <$> splitDiffByLines sources diff)
     maxNumber = case numbered of
       [] -> 0
       (row : _) -> runBothWith max $ Prelude.fst <$> row