Suggestion: Don't shy away from concurrent structures early on

[QuineDot]

I found it sort of odd that Arc and friends weren't mentioned until the last day, while for example you have a slide on Rc (also mentioning RefCell and Cell in passing) Why not mention Arc as well? If you use Rc, you're opting out of being able to be multi-threaded... and one of the great things about Rust is how it assumes you're going to want to be concurrent eventually. If Rc<T> meets your shared-ownership needs, usually Arc<T> does too.

Other places they come up:

• Arc<str> (or Rc) as a string type
• Arc<Self> (or Rc) as a method receiver
• Global state

[mgeisler]

Good point. Let me start by mentioning Arc on the Rc page (#83).