Racket v8.6

Racket version 8.6 is now available from

https://racket-lang.org/

As of this release:

• Racket has an "equal-always?" primitive that equates values that will stay
  the same even if mutated. See
  https://docs.racket-lang.org/reference/Equality.html#%28def._%28%28quote._~23~25kernel%29._equal-always~3f%29%29

• This release uses a new build system, Zuo, which is implemented as a
  little language, in accordance with the ideas of Language Oriented
  Programming (LOP). The implementation has a single C file (plus libraries
  implemented in Zuo), so it compiles easily. The zuo/build
  library is modeled on make and Shake for tracking dependencies and
  build steps. See https://docs.racket-lang.org/zuo/index.html and
  https://racket.discourse.group/t/new-build-system-pushed-to-git-repo/873

• Racket supports stencil vectors, which associate a virtual bitmask
  with a vector, enabling certain mask-equipped update operations. See
  https://docs.racket-lang.org/reference/stencil_vectors.html

• Racket supports Arm64 machines running Windows.

• Redex has support for simultaneous substitutions. See
  https://docs.racket-lang.org/redex/reference.html#%28form._%28%28lib._redex%2Freduction-semantics..rkt%29._substitute%29%29

• The Web Server provides control over the maximum number of
  concurrent connections via its "safety limits" construct. See
  https://docs.racket-lang.org/web-server-internal/dispatch-server-unit.html#%28part._safety-limits%29

• The Web Server has improved logging performance and improved
  request parsing performance, reducing tail latencies.

• The Web Server supports logging response status code via
  web-server/dispatchers/dispatch-logresp. See
  https://docs.racket-lang.org/web-server-internal/dispatch-logresp.html

• The db library supports custom types for PostgreSQL connections; see
  pg-custom-type for details. See
  https://docs.racket-lang.org/db/util.html#%28def._%28%28lib._db%2Futil%2Fpostgresql..rkt%29._pg-custom-type%29%29

• The release includes many other repairs and changes!

The following people contributed to this release:

Alex Knauth, Alexander Shopov, Alexis King, Amirouche Amazigh BOUBEKKI,
Andy Keep, Ashish SHUKLA, Bob Burger, Bogdan Popa, Cameron Moy,
Chung-chieh Shan, David K. Storrs, FrankHB, Fred Fu, Gustavo Massaccesi,
helado de brownie, J. Ryan Stinnett, Jack Firth, Jamie Taylor, Jason
Hemann, Jens Axel Søgaard, Jimmy McNutt, Joel Dueck, John Clements, José
Manuel Calderón Trilla, Kevin Tew, Laurent Orseau, Matt Audesse, Matthew
Flatt, Matthias Felleisen, Mike Sperber, naveen srinivasan, Niklas
Larsson, Noah Ma, Oscar Waddell, Pavel Panchekha, Phil Nguyen, Philip
McGrath, Philippe Meunier, rgkirch, Robby Findler, Robert Postill, Ryan
Culpepper, Sam Tobin-Hochstadt, Sergiu Ivanov, Sorawee Porncharoenwase,
Stephen De Gabrielle, Vincent Lee, wackbyte, and Zibing Zhang

Link to package regressions issue for the 8.6 release:
#4366