Release Announcement for v9.2

Internals
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8
  1. Better to link to the Pull Request, here: Reject non-linear `match` patterns with mismatched ellipsis depth by samth · Pull Request #5467 · racket/racket · GitHub
  2. For the changes to asin/acos, the PR is here: Fix types of `asin` and `acos`. by samth · Pull Request #1428 · racket/typed-racket · GitHub
  3. The changes to asin and acos are indeed soundness issues; you can read about the problem here: Acos behaves differently on #s > 1.0 in TR?
  4. Here are some suggested bullet points:
  • match actually checks that when non-linear patterns (patterns where the same variable is used multiple times) are used with ..., the two parts of the matched value actually are equal. Additionally, match rejects non-linear patterns where one use of the variable is used with ... and another is not.
  • Typed Racket's types for the asin and acos procedures correctly handle situations where the function produces a complex number, avoid unsound result that were previously possible.