Comment by deathanatos

Can you? Yes, and TFA demonstrates this quite clearly.

Should you?

This is where I'd be more careful. Maybe it makes sense to some of the langs in TFA. But it reminds me of [named]tuples in Python, which are iterable, but when used as tuples, in particular, as heterogeneous arrays¹ to support returning multiple values or a quick and dirty product type (/struct), the ability to iterate is just a problem. Doing so is almost always a bug, because iteration through a such tuple is nigh always nonsensical.

So, can an array also be f(index) -> T? Sure. But does that make sense in enough context, or does it promote more bugs and less clear code is what I'd be thinking hard about before I implemented such a thing.

¹sometimes tuples are used as an immutable homogeneous array, and that case is different; iteration is clearly sane, then