mapAccumR -bytestring -base

mapAccumR :: (a -> Char -> (a, Char)) -> a -> Text -> (a, Text)
text Data.Text, text Data.Text.Lazy
The mapAccumR function behaves like a combination of map and a strict foldr; it applies a function to each element of a Text, passing an accumulating parameter from right to left, and returning a final value of this accumulator together with the new Text. Performs replacement on invalid scalar values.
mapAccumRWithKey :: (a -> Key -> b -> (a, c)) -> a -> IntMap b -> (a, IntMap c)
containers Data.IntMap.Strict, containers Data.IntMap.Lazy
O(n). The function mapAccumR threads an accumulating argument through the map in descending order of keys.
mapAccumRWithKey :: (a -> k -> b -> (a, c)) -> a -> Map k b -> (a, Map k c)
containers Data.Map.Lazy, containers Data.Map.Strict
O(n). The function mapAccumR threads an accumulating argument through the map in descending order of keys.