[WIP] std.range, map, ndslice type normalization

[9il]

No description provided.

[andralex]

This is very interesting work, thanks. How about the following idea, which allows us extensibility without having to change map to recognize special type patterns:

• Look for a method __map inside the range
• If the range defines that method, map should use it
• Otherwise, just do the usual

For the beginning, we don't document this and we only implement __map in the std ranges in this PR. If things go well, we change __map to mapImpl or even map and publish the API for anyone.

I've been thinking of this a lot lately: we should allow ranges to define additional methods under a specific nomenclature, similar to what allocators do. It's a great way to go about implementing features modularly.

[andralex]

How about TakeExactly?

[9il]

Look for a method __map inside the range
If the range defines that method, map should use it
Otherwise, just do the usual

Yes, will do.

The PR changes also retro and stride. The diff is very large, you may want press to the file to see it. Do you want also add __stride and __retro?

[andralex]

Eh, thanks I didn't see those two. I'd say how about we do this for map and see how it goes? Thx!