Software Update: Racket 7.4

Racket is a development language with which other development languages ​​can be developed. In addition, you can simply develop in Racket itself. It was previously known as the PLT Scheme and comes from the Lisp-Scheme family. For the background we refer to the manifesto, written under the direction of Matthias Felleisen. The developers have released version 7.4 of Racket, with the following announcement:

Release Announcement for Version 7.4

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 (beta)” instead of “regular” from the “Variant” popup menu.
• Single-precision floating-point literals, aka 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 WM, 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