HH\KeyedTraversable

The HH\KeyedTraversable<Tk, Tv> interface

The iteration variables will have a type of Tk for the key and Tv for the value.

In addition to Hack collections, PHP arrays and anything that implement KeyedIterator are KeyedTraversable.

In general, if you are implementing your own Hack class, you will want to implement KeyedIterable instead of KeyedTraversable since KeyedTraversable is more of a bridge for PHP arrays to work well with Hack collections.

Interface synopsis

interface KeyedTraversable implements Traversable {...}