Traversable package:optics-core

class (FunctorWithIndex i t, FoldableWithIndex i t, Traversable t) => TraversableWithIndex i (t :: Type -> Type) | t -> i
optics-core Optics.Indexed.Core Optics.IxTraversal
A Traversable with an additional index. An instance must satisfy a (modified) form of the Traversable laws: 
itraverse (const Identity) ≡ Identity
fmap (itraverse f) . itraverse g ≡ getCompose . itraverse (\i -> Compose . fmap (f i) . g i)