Rustc-dev-guide: chapter explaining how `Kind` works

[nikomatsakis]

We don't explain Kind at all!

cc @varkor -- want to write it =)

[varkor]

I can try to get around to writing something up :+1:

[nikomatsakis]

@varkor you rock

[varkor]

I've started writing something, but it's a little minimal at the moment: what sort of things would you expect/want to see in such a chapter?

[mark-i-m]

Ping @nikomatsakis ^^^

[mark-i-m]

Ping @nikomatsakis ^^^ ?

[nikomatsakis]

Argh, sorry =)

@varkor I think I would like to see:

• What is the purpose of Kind?
• How do I make a Kind?
• An example of using kind.unpack() works

Actually, some of that might be better as rustc-guide docs, tbh. Always a hard line to figure out where to draw.

[mark-i-m]

Ping @varkor ?

[varkor]

This is still on my radar, sorry. I'll try to get to it soon.