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 under the name 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 7.9 of Racket, with the following announcement:
Release Announcement for Version 7.9:
Racket CS may become the default Racket implementation in the next release. If, between this release and the next, no bugs are discovered in Racket CS that are more serious than those typically discovered in Racket BC, then Racket CS will become the default for the next release. (Serious Racket CS bugs were found since the v7.8 release, but they’re ever fewer and farther between.)
Various improvements to Check Syntax arrows and renaming, thanks to Sorawee Porncharoenwase.
Full support for struct type properties in Typed Racket, developed by Fred Fu.
Racket CS now supports parallel garbage collection, along with improvements for place-local-allocation and incremental promotion.
Unix platforms now use the XDG filesystem conventions for the locations of per-user configuration and library files by default, but legacy paths are still used where they exist already.
Scribble improvements by Sorawee Porncharoenwase, William Bowman, and Shu-Hung You.
Improvements to the plot library from Alex Harsányi and Bert De Ketelaere.
The datumform from syntax/datumworks with syntax pattern variables and syntax-parseattributes.
Unicode input works with recent versions of libedit in addition to libreadline. On Mac OS, a compatible version of libedit is included with Racket.