Add ifolded (purescript-contrib#146)

CHANGELOG.md

@@ -7,7 +7,7 @@ Notable changes to this project are documented in this file. The format is based
 Breaking changes:
 
 New features:
-- Add `imapped` (#146 by @twhitehead)
+- Add `ifolded` and `imapped` (#146 by @twhitehead)
 
 Bugfixes:
 

src/Data/Lens/Indexed.purs

@@ -6,11 +6,12 @@ import Control.Monad.State (evalState, get, modify)
 import Data.Functor.Compose (Compose(..))
 import Data.Lens.Iso.Newtype (_Newtype)
 import Data.Lens.Setter ((%~))
-import Data.Lens.Types (Indexed(..), IndexedOptic, IndexedSetter, IndexedTraversal, Optic, Traversal, wander)
-import Data.Newtype (unwrap)
+import Data.Lens.Types (Indexed(..), IndexedOptic, IndexedFold, IndexedSetter, IndexedTraversal, Optic, Traversal, wander)
+import Data.Newtype (wrap, unwrap)
 import Data.Profunctor (class Profunctor, dimap, lcmap)
 import Data.Profunctor.Star (Star(..))
 import Data.Profunctor.Strong (first)
+import Data.FoldableWithIndex (class FoldableWithIndex, foldMapWithIndex)
 import Data.FunctorWithIndex (class FunctorWithIndex, mapWithIndex)
 import Data.TraversableWithIndex (class TraversableWithIndex, traverseWithIndex)
 import Data.Tuple (curry, fst, snd)
@@ -47,6 +48,10 @@ iwander
   -> IndexedTraversal i s t a b
 iwander itr = wander (\f s -> itr (curry f) s) <<< unwrap
 
+-- | Folds over a `FoldableWithIndex` container.
+ifolded :: forall r i f t a b. Monoid r => FoldableWithIndex i f => IndexedFold r i (f a) t a b
+ifolded = wrap <<< foldMapWithIndex <<< curry <<< unwrap <<< unwrap
+
 -- | Sets over a `FunctorWithIndex` container.
 imapped
   :: forall i f a b