Racket v9.0

posted by Stephen De Gabrielle and John Clements

We are pleased to announce Racket v9.0 is now available from https://download.racket-lang.org/.

* Racket 9.0 is here!*

A major release is always exciting and Racket 9.0 is no exception in that it introduces Parallel Threads. While Racket has had green threads for some time, and supports parallelism via futures and places, we feel parallel threads is a major addition.

As of this release:

• Racket supports parallel threads. For more information see the new blog post on the topic.
  • Parallel threads can be created using the #:pool argument to thread creation.
  • Threads created with #:keep set to 'results will record their results for later retrieval with thread-wait.
• The black-box wrapper prevents the optimizing compiler from optimizing away certain computations entirely. This can be helpful in ensuring that benchmarks are accurate.
• The decompile-linklet function can map linklets back to s-expressions.
• When using BC Racket, the processor-count function is changed to always return the parallel count.
• We now distribute “natipkg” packages for AArch64, useful for package-build and package-testing infrastructure.
• Check Syntax tracks identifiers more deeply nested in the “origin” field of syntax objects.
• The math library includes Weibull distributions.
• There are many other repairs and documentation improvements!

Thank you

The following people contributed to this release:

Alexander Shopov, Anthony Carrico, Bert De Ketelaere, Bogdan Popa, Cadence Ember, David Van Horn, Gustavo Massaccesi, Jade Sailor, Jakub Zalewski, Jens Axel Søgaard, jestarray, John Clements, Jordan Johnson, Matthew Flatt, Matthias Felleisen, Mike Sperber, Philip McGrath, RMOlive, Robby Findler, Ruifeng Xie, Ryan Culpepper, Sam Phillips, Sam Tobin-Hochstadt, Sebastian Rakel, shenleban tongying, Shu-Hung You, Stephen De Gabrielle, Steve Byan, and Wing Hei Chan.

Racket is a community developed open source project and we welcome new contributors. See racket/README.md to learn how you can be a part of this amazing project.

Feedback Welcome

Questions and discussion welcome at the Racket community on Discourse or Discord.

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If you can - please help get the word out to users and platform specific repo packagers

Racket - the Language-Oriented Programming Language - version 9.0 is now available from https://download.racket-lang.org

See https://blog.racket-lang.org/2025/11/racket-v9-0.html for the release announcement and highlights.

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