Racket v6.7

Racket version 6.7 is now available from http://racket-lang.org/

• Racket supports building graphical applications on Android through the racket-android project: https://github.com/jeapostrophe/racket-android
• The Racket REPL comes with line-editing, command and result history, and various meta-commands out of the box, via the racket/interactive module. See the racket/interactive and xrepl documentation for details.
• The package system supports authentication when installing packages from git, using the raco pkg config git-checkout-credentials configuration option.
• HTTP libraries, as well as raco pkg, support proxying via HTTP CONNECT.
• Typed Racket provides typed versions of racket/os and racket/db/sqlite.
• The PLT_COMPILED_FILE_CHECK environment variable provides more fine-grained control over when .zo files are consulted.
• The documentation search supports searching for #langs and #readers via the "L:" and "R:" search prefixes.
• The file/glob module implements globbing for path-strings.
• Optimizations in the bytecode compiler improve performance for structure, list, string, and byte-string operations.

The following people contributed to this release:
Alex Knauth, Alex Harsanyi, Alexis King, Andrew Kent, Asumu Takikawa, Ben Greenman, Brian Lachance, Chongkai Zhu, Daniel Feltey, Georges Dupéron, Gustavo Massaccesi, Jay McCarthy, John Clements, Jonathan Schuster, Leif Andersen, Marc Burns, Matthew Butterick, Matthew Flatt,
Matthias Felleisen, Mike Sperber, Robby Findler, Rohin Shah, Ryan Culpepper, Sam Tobin-Hochstadt, Spencer Florence, Stephen Chang, Stephen De Gabrielle, Tim Brown, Tony Garnock-Jones, Vincent St-Amour, WarGrey Gyoudmon Ju, and William J. Bowman.

Feedback Welcome

Racket v6.6

Racket version 6.6 is now available from http://racket-lang.org/

• The new Macro Profiler command-line tool (`raco macro-profiler`) shows how macros contribute to the final expanded code size of a program.
• Typed Racket supports intersection types. This allows the type system to track more information, and for programmers to express more precise types.
• Typed Racket produces up to 4x smaller compiled files compared with Racket 6.5, reducing the size of the Racket distribution by 50M.
• Typed Racket issues warnings in cases where the contract generated for Any was not strict enough in the past. These warnings will become errors in a future release. Warnings are enabled via View -> Show Log in DrRacket, and shown by default on command-line Racket.
• Typed Racket enforces uses of cast more correctly, by checking both the "casted-to" and "casted-from" types. Previously, only the former were checked. In some cases, this will produce contract errors in programs that did not have errors before.
• syntax-parse raises an error when an ellipsis pattern has an empty match rather than diverging, and it logs a warning when it statically detects a nullable pattern, such as ((~seq) ...). In the next version of Racket, it will reject the pattern instead, and it will remove special handling that currently makes some uses of such patterns terminate.
• htdp/dir: The create-dir function delivers data information for files in a new field. The domain of its functions are backwards compatible.

The following people contributed to this release:
Alex Knauth, Alexander Shopov, Alexis King, Andrew Kent, Asumu Takikawa,
Ben Greenman, Bernardo Sulzbach, Brian Lachance, Chris Jester-Young, Dan
Feltey, Eric Dobson, Georges Dupéron, Gustavo Massaccesi, James Bornholt,
Jay McCarthy, John Clements, Leandro Facchinetti, Leif Andersen, Maksim
Kochkin, Matthew Flatt, Matthias Felleisen, Mike Sperber, Paul Stansifer,
Pedro Caldeira, Philip McGrath, Robby Findler, Ryan Culpepper, Sam
Tobin-Hochstadt, Spencer Florence, Stephen Chang, Stephen De Gabrielle,
Tim Brown, Tony Garnock-Jones, Vincent St-Amour, WarGrey Gyoudmon Ju,
William J. Bowman, and Zeina Migeed.

Feedback Welcome

Racket v6.5

Racket version 6.5 is now available from http://racket-lang.org/

• Typed Racket and the racket/contract library generate code with lower overhead, speeding up typed/untyped interaction in a number of gradual typing programs we studied.
• Macros written using syntax-parse automatically emit more accurate error messages.
• The contract profiler captures costs from more contract combinators, including all those in the main distribution.
• Hash table and set iteration, via both existing and new non-generic sequences, is more performant, up to twice as fast on microbenchmarks.
• The Racket optimizer detects many more optimization opportunities, including when variables always hold numbers.
• The db library supports single-result CALL statements in MySQL.
• The net/dns library supports SRV records.
• The racket/unix-socket library supports listen and accept operations.

The following people contributed to this release:
Adrien Tateno, Alex Knauth, Alexander Shopov, Alexis King, Andrew Kent, Asumu Takikawa, Ben Greenman, Chen Xiao, Chris Jester-Young, Daniel Feltey, Eric Dobson, Georges Dupéron, Gustavo Massaccesi, Ian Harris, Jay McCarthy, Jens Axel Søgaard, John Clements, Leandro Facchinetti, Lehi Toskin, Leif Andersen, Łukasz Dąbek, Marc Kaufmann, Matthew Flatt, Matthias Felleisen, Michael McConville, Mike Sperber, Paul Stansifer, Philippe Meunier, Robby Findler, Rodrigo Setti, Ryan Culpepper, Sam Caldwell, Sam Tobin-Hochstadt, Sorawee Porncharoenwase, Spencer Florence, Stephen Chang, Tony Garnock-Jones, Vincent St-Amour, WarGrey Gyoudmon Ju, and William J. Bowman.

Feedback Welcome

Racket Web Server Security Vulnerability

We recently discovered a serious security vulnerability in the Racket web server, which can lead to unintended disclosure of files on the machine running the web server. This vulnerability is fixed in Racket version 6.4, just released, and we encourage people to upgrade to that version.

The vulnerability affects web servers that serve static files using the #:extra-files-paths option, including the default value of this option. If you do not use the Racket web serve to serve static files, or you do so via a mechanism that does not use the make-url->path function, then you are likely not vulnerable. Affected web serves will allow specially-crafted URLs to access files outside of the specified paths, potentially exposing any file that the web server process is able to read.

If you cannot immediately upgrade to version 6.4, we have provided a package catalog with updated versions of the "web-server-lib" package for versions of Racket back to 6.0. That catalog is located at

 http://download.racket-lang.org/patches/web-server-1/

To use it to upgrade your Racket installation, add it as a catalog using raco pkg config. To make this process easier, you can download the Racket script available here. Then run:

  $ racket add-catalog.rkt
  $ raco pkg update -i web-server-lib

If you need advice on updating Racket installations older than version 6.0, please let us know and we will provide them.

To test that your Racket installation is fixed, you can run the program here. It will print whether your installation is out of date.

Racket v6.4

Racket version 6.4 is now available from http://racket-lang.org/

• We fixed a security vulnerability in the web server. The existing web server is vulnerable to a navigation attack if it is also enabled to serve files statically; that is, any file readable by the web server is accessible remotely. For more information, see this post.
• DrRacket's scrolling is faster.
• Incremental garbage-collection mode can eliminate long pauses in a program. For example, incremental mode is useful for avoiding pauses in games and animations.
  Programs must specifically request incremental mode with (collect-garbage 'incremental), but libraries such as 2htdp/universe include the request as part of the library's implementation.
• The default package catalog is an HTTPS address instead of HTTP, and package operations properly validate server certificates when using HTTPS.
• Documentation may define their own categories for the manual top-level page by using strings, rather than only symbols that name pre-defined categories.
• The Racket cheat sheet is included in the main distribution.
• DrRacket is available in Bulgarian, thanks to Alexander Shopov.
• The contract Typed Racket generates for the Any type is more permissive, allowing more typed/untyped programs to work without contract errors.
• Redex supports binding specifications; describe which variables bind in which expressions and your metafunctions and reduction relations automatically become scope-sensitive. Thanks to Paul Stansifer for this improvement.
• All pict functions accept pict-convertibles. This allows for transparent interoperability between pict and libraries like 2htdp/image.
• The raco profile and raco contract-profile commands provide easy access to profiling tools, without requiring program modifications.

Feedback Welcome