Design meeting: Let chains, guard patterns, and `is`; oh my!

[tmandry]

Summary

We have a lot of pending proposals out there to make binding patterns more powerful, some as accepted RFCs and some as new RFCs sponsored by members of the lang team:

• Tracking issue for RFC 2294, "if let guard" rust#51114
• Tracking issue for eRFC 2497, "if- and while-let-chains, take 2" rust#53667
• is operator for pattern-matching and binding rfcs#3573
• Guard Patterns rfcs#3637

These all seem useful on their own merits. Maybe it makes sense to consider them together as part of a broader picture. If not, we can at least spend time getting up to speed on some of the individual proposals and hashing them out.

Background reading

Include any links to material that folks ought to try to read before-hand.

The above RFCs are good background reading, but we may want to summarize them in a doc before the meeting.

About this issue

This issue corresponds to a lang-team design meeting proposal. It corresponds to a possible topic of discussion that may be scheduled for deeper discussion during one of our design meetings.