Types passed to callback

[waldemarhorwat]

What is the type of the second parameter passed to the callback? Is it a String or a Number? The current implementation is passing neither — it's passing a mathematical value k there.

[ljharb]

Array methods seem to mostly pass numbers, so it seems like the spec could wrap it in 𝔽().

[jridgewell]

It's supposed to be a number like Array.p.map. It seems I missed the F() call, will fix.