08 Aug 2019

Racket v7.4

posted by John Clements

Racket version 7.4 is now available from https://racket-lang.org/

With this 7.4 release, we are making Racket CS available, a beta version of the Racket on Chez Scheme implementation. Racket CS is “beta” quality for the v7.4 release. It works well enough to be worth trying, but there are likely too many lingering problems for a project to switch to Racket CS for production use at this time. We encourage you to kick the tires of the new CS releases, and to help push this project forward by reporting any problems that you find.

  • Racket CS is available as a download option. To download Racket CS, select “CS” instead of “Regular” from the “Variant” popup menu.

  • Single-precision floating-point literals, a.k.a. single-flonums, are no longer supported by default.

This is a backward-incompatible change, but the use of single-flonums appears to be rare. Since Racket CS does not support single-flonums, disabling single-flonums by default smooths the transition from regular Racket and Racket CS.

The read-single-flonum parameter can be set to #t to enable reading single-flonum literals, but a better strategy in most cases is to use real->single-flonum when single-flonum-available? reports #t or when single-flonum? reports #t for a value (which implies that single-flonums must be supported). Where single-flonums are supported, Racket’s compiler will fold a call of real->single-flonum on a literal number to a constant single-flonum value.

  • New compilation flags including --disable-generations and --enable-ubsan provide better support for alternative architectures.

  • The 2htdp/universe teachpack supports an event log window for big-bang. With this option, students can inspect the events that big-bang handled, plus their payload. The event log includes messages from external sources.

The following people contributed to this release: Alex Knauth, Alexander B. McLin, Alexis King, Andreas Düring, Asumu Takikawa, Atharva Raykar, Ben Greenman, Benjamin Yeung, Dmitry Moskowski, Fred Fu, Gustavo Massaccesi, Ilnar Salimzianov, Jason Hemann, Jay McCarthy, Jesse A. Tov, Jesse Alama, John Clements, Leif Andersen, Lukas Lazarek, Matthew Flatt, Matthias Felleisen, Mike Sperber, Morgan Lemmer-Webber, Noah W M, Paulo Matos, Philip McGrath, Robby Findler, Rodrigo, Roman Klochkov, Ryan Culpepper, Sam Tobin-Hochstadt, Simon ‘Sze’ L. Schlee, Sorawee Porncharoenwase, Spencer Florence, Stephan Renatus, Stephen Chang, Stephen De Gabrielle, Thomas Dickerson, Vincent St-Amour, yjqww6

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