What changed in Racket from 8 to 9

---

• The raco setup command can generate markdown documentation, using the --doc-markdown option.
• The "#lang" teaching languages (BSL, ..., ISL+; plus DeinProgram) have reached parity with the ones chosen using the Language dialog, and are the recommended choice.
• DrRacket's background expansion disables errortrace annotations, for faster syntax checking.
• The raco pkg install command includes new options that provide more install-time configuration flexibility: --adjacent-deps, --destdir, and --attach, and a refined --skip-installed.
• The ffi/unsafe/runtime-lib library provides a define-runtime-lib mechanism similar to define-runtime-path, allowing location of libraries located relative to a source file.
• The prompt-tag/c contract generator no longer performs checking on call/cc when the #:call/cc option is not present.
• The impersonate-prompt-tag function takes an additional argument that allows checking and update of results for composable continuations.
• The error-syntax->srcloc-handler parameter provides control over the mapping from syntactic forms to source locations for error handling.
• Uses of (tcp-listen 0) will retry when it fails with "address in use".
• The racket/base module requires fewer internal modules and instantiations.
• The file/zip package provides a new mechanism for greatly increased control over zip file generation, allowing in-memory file sources and per-file compression control.

The following people contributed to this release:

Alex Knauth, Alexander Shopov, Aris Spathis, Bert De Ketelaere, Bob Burger, Caleb Mazalevskis, Cameron Moy, Geoffrey J. Teale, Gustavo Massaccesi, Hannes Braun, Jade Sailor, Jason Hemann, Jens Axel Søgaard, John Clements, Jordan Johnson, Matthew Flatt, Matthias Felleisen, Mike Sperber, Nathan Dykman, Noah Ma, Philip McGrath, Robby Findler, Romeo Ahmed, Sam Tobin-Hochstadt, Shu-Hung You, Stefan Schwarzer, Stephen De Gabrielle, and Wing Hei Chan.

---

---

• The match form 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. This repair could cause existing code to fail.
• Typed Racket's types for the asin and acos procedures correctly handle situations where the function produces a complex number, avoiding unsound results that were previously possible. This repair could cause existing code to fail at compile time.
• The #%foreign-inline core syntactic form provides unsafe access to facilities provided at the linklet layer by a Racket implementation. This means that any code that handles all core forms by enumeration will need to be updated.
• Unicode 17.0 is used for character and string operations.
• This release includes internal support for a more static "ffi2" foreign interface (to be used in a future package).
• The terminal-file-position function counts bytes written to ports connected to a terminal, such as stdin and stderr.
• Cross-phase persistent modules allow more types of quoted data.
• The implementations of member, memw, when, unless, let/ec, and cond are rewritten to use only racket/kernel syntax
• The impersonator-property-predicate-procedure? function identifies procedures created by make-impersonator-property.
• In Typed Racket, polymorphic struct types are printed using type arguments (e.g., (Array Byte)) rather than exposing an internal representation.
• The stepper's display of numbers better matches the language settings.
• Scribble documents that do not use the Racket-manual style get an initial-scale of 1.0, instead of the manual style's 0.8, but this can be configured using the initial-scale property.
• By default, margin notes appear inline for narrow displays in all styles, not just in the Racket-manual style.
• Big-bang programs distributed as .dmg files correctly handle the close-on-stop feature.
• There are many other repairs and documentation improvements!

The following people contributed to this release:

Alexander Shopov, Alexis King, Asilo, Bert De Ketelaere, Bob Burger, Bogdan Popa, Chung-chieh Shan, François-René Rideau, Gustavo Massaccesi, Ilya Klyuchnikov, Jade Sailor, Jamie Taylor, John Clements, Jonathan Simpson, LS_Hower, Matthew Flatt, Matthias Felleisen, Mike Sperber, Pavel Panchekha, Philippe Meunier, RMOlive, Robby Findler, Roman Klochkov, Sam Tobin-Hochstadt, Shu-Hung You, Stephen de Gabrielle, Tejas Sanap, Vincent Lee, and Wing Hei Chan.

---

---

• Documentation organization and navigation can be specialized by language family, to allow users to interact with documentation in a way that is tailored to that language family. This is currently used by Rhombus.
• The for form and its variants accept an #:on-length-mismatch specifier. 3.18 Iterations and Comprehensions: for, for/list, ...
• DrRacket improves the GUI for choosing color schemes.
• DrRacket has curved syntax arrows. The degree of curvature indicates the relative left- or right-displacement of the arrow's target.
• DrRacket's "Insert Large Letters" uses characters that match the comment syntax of the buffer's language, making it useful (and fun!) in Rhombus.
• The exn-classify-errno maps network and filesystem error numbers on various platforms to posix-standard symbols, to enable more portable code. 10.2 Exceptions
• The behavior of Racket BC on certain character operations (most notably eq?) is changed to match that of Racket CS, with a small performance penalty for these operations for BC programs. 19 Performance 1.5 Implementations
• The make-struct-type procedure can inherit the current inspector using a 'current flag. This is the default behavior, but there are situations in which it's not possible to refer to the current inspector. 5.2 Creating Structure Types
• Bundle configurations can better control the conventions for locating shared object files with the --enable-sofind=<conv> flags.
• The system-type function can report on platform and shared-object-library conventions with new flags. 15.8 Environment and Runtime Information
• The openssl/legacy library makes it possible to access OpenSSL's built-in "legacy" provider, to get access to insecure and outdated algorithms. OpenSSL: Secure Communication
• Typed Racket improves expected type propagation for keyword argument functions.
• There are many other repairs and documentation improvements!

The following people contributed to this release:

Alexander Shopov, beast-hacker, Bob Burger, Brad Lucier, Cadence Ember, David Van Horn, evan, François-René Rideau, Gustavo Massaccesi, Jacqueline Firth, Jade Sailor, Jason Hemann, Jens Axel Søgaard, John Clements, Jonas Rinke, Matthew Flatt, Matthias Felleisen, Mike Sperber, Noah Ma, Pavel Panchekha, Rob Durst, Robby Findler, Ryan Culpepper, Sam Tobin-Hochstadt, Stephen De Gabrielle, and Wing Hei Chan.

---

---

• 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!

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.

---