@@ -268,7 +268,9 @@ patchThatChangesMap oldByIndex newByIndex = patch
268 putRemainingKeys $ Set.delete k fromKs
268 putRemainingKeys $ Set.delete k fromKs
269 return $ NodeInfo (From_Move k mempty) $ Just undefined -- There's an existing value, and it's here, so no patch necessary
269 return $ NodeInfo (From_Move k mempty) $ Just undefined -- There's an existing value, and it's here, so no patch necessary
271+ (fromK, remainingKeys) <- return $
272+ fromMaybe (error "PatchMapWithPatchingMove.patchThatChangesMap: impossible: fromKs was empty") $
271− (fromK, remainingKeys) <- return . fromMaybe (error "patchThatChangesMap: impossible: fromKs was empty") $ Set.minView fromKs -- There's an existing value, but it's not here; move it here
273+ Set.minView fromKs -- There's an existing value, but it's not here; move it here
272 putRemainingKeys remainingKeys
274 putRemainingKeys remainingKeys
273 return $ NodeInfo (From_Move fromK mempty) $ Just undefined
275 return $ NodeInfo (From_Move fromK mempty) $ Just undefined
274 Map.traverseWithKey f newByIndex
276 Map.traverseWithKey f newByIndex