foldMap package:rio

foldMap :: (Foldable t, Monoid m) => (a -> m) -> t a -> m

Map each element of the structure to a monoid, and combine the results.

foldMapWithKey :: Monoid m => (k -> a -> m) -> Map k a -> m

O(n). Fold the keys and values in the map using the given monoid, such that

foldMapWithKey f = fold . mapWithKey f

This can be an asymptotically faster than foldrWithKey or foldlWithKey for some monoids.

foldMapM :: (Monad m, Monoid w, Foldable t) => (a -> m w) -> t a -> m w

rio RIO.Prelude

Extend foldMap to allow side effects. Internally, this is implemented using a strict left fold. This is used for performance reasons. It also necessitates that this function has a Monad constraint and not just an Applicative constraint. For more information, see https://github.com/commercialhaskell/rio/pull/99#issuecomment-394179757.

foldMapWithIndex :: Monoid m => (Int -> a -> m) -> Seq a -> m

rio RIO.Seq

bifoldMap :: (Bifoldable p, Monoid m) => (a -> m) -> (b -> m) -> p a b -> m

rio RIO.Prelude

Combines the elements of a structure, given ways of mapping them to a common monoid.

bifoldMap f g
≡ bifoldr (mappend . f) (mappend . g) mempty