mapAccumR -text -bytestring

mapAccumR :: (acc -> x -> (acc, y)) -> acc -> [x] -> (acc, [y])
base Data.List
The mapAccumR function behaves like a combination of map and foldr; it applies a function to each element of a list, passing an accumulating parameter from right to left, and returning a final value of this accumulator together with the new list.
mapAccumR :: Traversable t => (a -> b -> (a, c)) -> a -> t b -> (a, t c)
base Data.Traversable
The mapAccumR function behaves like a combination of fmap and foldr; it applies a function to each element of a structure, passing an accumulating parameter from right to left, and returning a final value of this accumulator together with the new structure.
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.