# Latest **URL:** https://racket.discourse.group/latest.md?page=11 [Latest](https://racket.discourse.group/latest.md) · [Categories](https://racket.discourse.group/categories.md) · [Tags](https://racket.discourse.group/tags.md) **Page:** 12 --- ## [Seeking custom \`#lang\`s for Resyntax](https://racket.discourse.group/t/seeking-custom-lang-s-for-resyntax/3922)
**Author:** [@notjack](https://racket.discourse.group/u/notjack)\ **Replies:** 0\ **Last updated:** [August 25, 2025, 11:08pm UTC](https://racket.discourse.group/t/seeking-custom-lang-s-for-resyntax/3922 "2025-08-25T23:08:54Z")
I've implemented experimental and rudimentary support in Resyntax for custom #langs, including non-s-expression #langs. This allows a language to configure Resyntax's default suggestions on code written in that language,… --- ## [New library: Compile time unit tests!](https://racket.discourse.group/t/new-library-compile-time-unit-tests/3919)
**Author:** [@pcn](https://racket.discourse.group/u/pcn)\ **Replies:** 0\ **Last updated:** [August 25, 2025, 6:05am UTC](https://racket.discourse.group/t/new-library-compile-time-unit-tests/3919 "2025-08-25T06:05:04Z")
Do you prefer a quicker test-driven development turnaround, and have battery and CPU cycles to spare? Check out this library that lets you have compile-time unit tests, whose failures are highlighted as syntax errors in … --- ## [Release Announcement for v8.18](https://racket.discourse.group/t/release-announcement-for-v8-18/3900)
**Author:** [@jbclements](https://racket.discourse.group/u/jbclements)\ **Replies:** 23\ **Last updated:** [August 22, 2025, 12:48pm UTC](https://racket.discourse.group/t/release-announcement-for-v8-18/3900 "2025-08-22T12:48:02Z")
The release announcement sketch that I have so far is below. Please mail me new items and/or edits. Please phrase announcements using complete sentences and avoid the word "now". As of this release: Racket uses Unic… --- ## [Racket v8.18 is now available](https://racket.discourse.group/t/racket-v8-18-is-now-available/3917)
**Author:** [@spdegabrielle](https://racket.discourse.group/u/spdegabrielle)\ **Replies:** 0\ **Last updated:** [August 21, 2025, 12:17am UTC](https://racket.discourse.group/t/racket-v8-18-is-now-available/3917 "2025-08-21T00:17:38Z")
We are pleased to announce Racket v8.18 is now available from https://download.racket-lang.org/. As of this release: The racket-lang.org website no longer distributes Racket BC bundles, but it includes pre-built bu… --- ## [Should changing a style% update derived style%'s?](https://racket.discourse.group/t/should-changing-a-style-update-derived-style-s/3904)
**Author:** [@jjsimpso](https://racket.discourse.group/u/jjsimpso)\ **Replies:** 3\ **Last updated:** [August 20, 2025, 8:45pm UTC](https://racket.discourse.group/t/should-changing-a-style-update-derived-style-s/3904 "2025-08-20T20:45:01Z")
I have some code to increase the font size in my application: (define (change-canvas-font-size canvas amount) (define standard (send (send canvas get-style-list) find-named-style "Standard")) (when standard … --- ## [FFI loading of raco-installed dynamic libraries](https://racket.discourse.group/t/ffi-loading-of-raco-installed-dynamic-libraries/3915)
**Author:** [@massung](https://racket.discourse.group/u/massung)\ **Replies:** 4\ **Last updated:** [August 20, 2025, 2:37pm UTC](https://racket.discourse.group/t/ffi-loading-of-raco-installed-dynamic-libraries/3915 "2025-08-20T14:37:46Z")
This might be better suited for "Internals", but being my first post to this forum... :wink: One particular issue that exists is that of being able to ffi-lib dynamic libraries that have been installed by raco. This is … --- ## [Racket threads and callbacks to another thread](https://racket.discourse.group/t/racket-threads-and-callbacks-to-another-thread/3905)
**Author:** [@hnmdijkema](https://racket.discourse.group/u/hnmdijkema)\ **Replies:** 8\ **Last updated:** [August 19, 2025, 12:22pm UTC](https://racket.discourse.group/t/racket-threads-and-callbacks-to-another-thread/3905 "2025-08-19T12:22:20Z")
I'm wondering how the Gui of racket works. There must be some thread that processes events from the widget set (wxwidgets afaik). However, callbacks of e.g. buttons are processed in the main (repl) thread. How is this… --- ## [Question on Racket Guide 5.2 statement](https://racket.discourse.group/t/question-on-racket-guide-5-2-statement/3903)
**Author:** [@Dashman](https://racket.discourse.group/u/Dashman)\ **Replies:** 3\ **Last updated:** [August 16, 2025, 10:34pm UTC](https://racket.discourse.group/t/question-on-racket-guide-5-2-statement/3903 "2025-08-16T22:34:06Z")
"The struct-copy form clones a structure and optionally updates specified fields in the clone. This process is sometimes called a functional update, because the result is a structure with updated field values. but the or… --- ## [RacketCon tickets!](https://racket.discourse.group/t/racketcon-tickets/3902)
**Author:** [@spdegabrielle](https://racket.discourse.group/u/spdegabrielle)\ **Replies:** 0\ **Last updated:** [August 14, 2025, 10:04pm UTC](https://racket.discourse.group/t/racketcon-tickets/3902 "2025-08-14T22:04:54Z")
(fifteenth RacketCon) October 4-5, 2025, UMass Boston To register, buy a ticket via Eventbrite. If you cannot attend in-person, there is an option to help support the livestream for remote participants. --- ## [Differences between for/fold and explicit car/cdr recursion?](https://racket.discourse.group/t/differences-between-for-fold-and-explicit-car-cdr-recursion/3891)
**Author:** [@ddrake](https://racket.discourse.group/u/ddrake)\ **Replies:** 14\ **Last updated:** [August 13, 2025, 9:10pm UTC](https://racket.discourse.group/t/differences-between-for-fold-and-explicit-car-cdr-recursion/3891 "2025-08-13T21:10:45Z")
I solved one of the katas on codewars: it's called "are they the same?". The key thing is deciding if two lists have equal elements. My solution used for/fold; one of the other solutions used first and rest and explicit… --- ## [Tab Style in DrRacket controlled by env var?](https://racket.discourse.group/t/tab-style-in-drracket-controlled-by-env-var/3899)
**Author:** [@jbclements](https://racket.discourse.group/u/jbclements)\ **Replies:** 5\ **Last updated:** [August 13, 2025, 3:07pm UTC](https://racket.discourse.group/t/tab-style-in-drracket-controlled-by-env-var/3899 "2025-08-13T15:07:38Z")
DrRacket has two different graphical tab styles for its editor windows. One looks like this: ... and the other looks like this: I have two related questions. The first is probably pretty simple: what controls thi… --- ## [Racket FFI and cstruct bit-fields](https://racket.discourse.group/t/racket-ffi-and-cstruct-bit-fields/3898)
**Author:** [@hnmdijkema](https://racket.discourse.group/u/hnmdijkema)\ **Replies:** 1\ **Last updated:** [August 13, 2025, 1:22am UTC](https://racket.discourse.group/t/racket-ffi-and-cstruct-bit-fields/3898 "2025-08-13T01:22:35Z")
Hello, Does anyone have experience with the racket FFI and bit fields in C structures? I'm encountering one here: typedef struct { FLAC\_\_uint64 offset; FLAC\_\_byte number; char isrc\[13\]; uint32\_t type:1… --- ## [Any prior art/existing libs/ideas for localising Racket languages?](https://racket.discourse.group/t/any-prior-art-existing-libs-ideas-for-localising-racket-languages/3895)
**Author:** [@lectia](https://racket.discourse.group/u/lectia)\ **Replies:** 6\ **Last updated:** [August 12, 2025, 7:39pm UTC](https://racket.discourse.group/t/any-prior-art-existing-libs-ideas-for-localising-racket-languages/3895 "2025-08-12T19:39:23Z")
For custom langs I imagine this would be somewhat more complicated, but for any s-exp based language certainly and for the base Racket language in particular it's certainly very possible to have "localised lisps" with lo… --- ## [Uploaded package has documentation but not generated on https://pkgd.racket-lang.org/pkgn/](https://racket.discourse.group/t/uploaded-package-has-documentation-but-not-generated-on-https-pkgd-racket-lang-org-pkgn/3890)
**Author:** [@hnmdijkema](https://racket.discourse.group/u/hnmdijkema)\ **Replies:** 8\ **Last updated:** [August 12, 2025, 4:39pm UTC](https://racket.discourse.group/t/uploaded-package-has-documentation-but-not-generated-on-https-pkgd-racket-lang-org-pkgn/3890 "2025-08-12T16:39:21Z")
Hi, I've created a package 'ellipsis-msg' and uploaded it to Racket Package Index. It has the same setup as 'columns-pane', but somehow the documentation is generated for 'columns-pane', but not for 'ellipsis-msg'. St… --- ## [Does Racket have a way of defining a constant or immutable variable?](https://racket.discourse.group/t/does-racket-have-a-way-of-defining-a-constant-or-immutable-variable/3874)
**Author:** [@Dashman](https://racket.discourse.group/u/Dashman)\ **Replies:** 19\ **Last updated:** [August 7, 2025, 10:15pm UTC](https://racket.discourse.group/t/does-racket-have-a-way-of-defining-a-constant-or-immutable-variable/3874 "2025-08-07T22:15:06Z")
I don't see anything in the index about a constant variable declaration. --- ## [Testing for the v8.18 release](https://racket.discourse.group/t/testing-for-the-v8-18-release/3876)
**Author:** [@jbclements](https://racket.discourse.group/u/jbclements)\ **Replies:** 0\ **Last updated:** [July 27, 2025, 12:27pm UTC](https://racket.discourse.group/t/testing-for-the-v8-18-release/3876 "2025-07-27T12:27:14Z")
(using the v8.17.900 release candidate build) Search for your name on the checklist page to find relevant items, either reply when you finish an item (please indicate which item/s is/are done), or check it off yoursel… --- ## [Layout does not automatically adjust. What can I do?](https://racket.discourse.group/t/layout-does-not-automatically-adjust-what-can-i-do/3887)
**Author:** [@hnmdijkema](https://racket.discourse.group/u/hnmdijkema)\ **Replies:** 1\ **Last updated:** [August 6, 2025, 9:00pm UTC](https://racket.discourse.group/t/layout-does-not-automatically-adjust-what-can-i-do/3887 "2025-08-06T21:00:32Z")
Hi, I've got following code (as a spike): (require racket/gui) (define win (new frame% \[label "Hi there!"\])) (define grid-group (new group-box-panel% \[label "My group"\] \[parent win\] \[horiz-margin 10\] \[vert-margin 10\])… --- ## [RacketFest 2026 (Spring)](https://racket.discourse.group/t/racketfest-2026-spring/3838)
**Author:** [@dominik.pantucek](https://racket.discourse.group/u/dominik.pantucek)\ **Replies:** 4\ **Last updated:** [August 6, 2025, 12:48pm UTC](https://racket.discourse.group/t/racketfest-2026-spring/3838 "2025-08-06T12:48:53Z")
Hello fellow Racketeers, last RacketFest took place more than two years ago and I think it is time to Make Europe Great Again by organizing another one. It looks like we might be able to get a decent venue here in Pragu… --- ## [I can't seem to understand the output of the following code:](https://racket.discourse.group/t/i-cant-seem-to-understand-the-output-of-the-following-code/3886)
**Author:** [@Rugged](https://racket.discourse.group/u/Rugged)\ **Replies:** 3\ **Last updated:** [August 4, 2025, 10:50am UTC](https://racket.discourse.group/t/i-cant-seem-to-understand-the-output-of-the-following-code/3886 "2025-08-04T10:50:52Z")
\#lang racket ;; Use '() instead of the 'empty' alias (define board #("X" "0" empty empty)) (for/vector (\[val board\] #:when (empty? val)) val) ; this returns '#() I would expect it to return '#(empty emp… --- ## [Exercism's "Pythagorean triplets with given perimeter" problem](https://racket.discourse.group/t/exercisms-pythagorean-triplets-with-given-perimeter-problem/3858)
**Author:** [@ddrake](https://racket.discourse.group/u/ddrake)\ **Replies:** 10\ **Last updated:** [August 3, 2025, 9:17pm UTC](https://racket.discourse.group/t/exercisms-pythagorean-triplets-with-given-perimeter-problem/3858 "2025-08-03T21:17:25Z")
I went down a rabbit hole coming up with a good algorithm to solve this Exercism Racket problem but in the end, their system doesn't let you (require math). But my algorithm is much faster than brute-force search, and I … --- ## [New Discourse auto-formatting: Anyone else find this annoying?](https://racket.discourse.group/t/new-discourse-auto-formatting-anyone-else-find-this-annoying/3883)
**Author:** [@greghendershott](https://racket.discourse.group/u/greghendershott)\ **Replies:** 8\ **Last updated:** [August 3, 2025, 9:01pm UTC](https://racket.discourse.group/t/new-discourse-auto-formatting-anyone-else-find-this-annoying/3883 "2025-08-03T21:01:02Z")
The new Discourse UI here to compose a reply or post is pretty annoying, especially when using inline code via backticks. Try typing: \`module-\>namespace\` You get: module→namespace. Some auto-ligature thing kicks in. T… --- ## [Module and namespace: how to use module-\>namespace](https://racket.discourse.group/t/module-and-namespace-how-to-use-module-namespace/3881)
**Author:** [@lylgithub2021](https://racket.discourse.group/u/lylgithub2021)\ **Replies:** 3\ **Last updated:** [July 30, 2025, 12:39pm UTC](https://racket.discourse.group/t/module-and-namespace-how-to-use-module-namespace/3881 "2025-07-30T12:39:53Z")
\#lang racket (module m racket/base (provide x) (define x 11)) (require 'm) (define ns (module-\>namespace ''m)) (eval 'x ns) error meassage is given when running the above code: module-\>namespace: unknown module i… --- ## [Would it make sense to add a function for inverting a hash table to the standard library?](https://racket.discourse.group/t/would-it-make-sense-to-add-a-function-for-inverting-a-hash-table-to-the-standard-library/3869)
**Author:** [@ddrake](https://racket.discourse.group/u/ddrake)\ **Replies:** 8\ **Last updated:** [July 30, 2025, 12:24am UTC](https://racket.discourse.group/t/would-it-make-sense-to-add-a-function-for-inverting-a-hash-table-to-the-standard-library/3869 "2025-07-30T00:24:26Z")
If you have a hash table, there's a pretty reasonable "inverse" to that table: in the original, you have keys mapping to values. The obvious inverse would be a hash table whose keys are the values in the original table, … --- ## [String format does not work](https://racket.discourse.group/t/string-format-does-not-work/3871)
**Author:** [@lylgithub2021](https://racket.discourse.group/u/lylgithub2021)\ **Replies:** 9\ **Last updated:** [July 29, 2025, 9:42am UTC](https://racket.discourse.group/t/string-format-does-not-work/3871 "2025-07-29T09:42:56Z")
\#lang racket (printf "width1: |~6d|~6d|\\n" 12 345) Why dose it cause error message " printf: ill-formed pattern string explanation: tag ~6 not allowed; arguments were: 12 345"? Ps: on Drracket v8.17 --- ## [Different rendering when using image-snip and pict](https://racket.discourse.group/t/different-rendering-when-using-image-snip-and-pict/3878)
**Author:** [@spdegabrielle](https://racket.discourse.group/u/spdegabrielle)\ **Replies:** 1\ **Last updated:** [July 27, 2025, 10:11pm UTC](https://racket.discourse.group/t/different-rendering-when-using-image-snip-and-pict/3878 "2025-07-27T22:11:09Z")
Hi, I'm getting different rendering when I use image-snip% compared to pict's dc. I think the difference is the rendering is assuming a different resolution display but I am not entirely sure. I've included a simple d… --- ## [Please pull Scribble PRs 523 and 525 for v8.18](https://racket.discourse.group/t/please-pull-scribble-prs-523-and-525-for-v8-18/3877)
**Author:** [@stevebyan](https://racket.discourse.group/u/stevebyan)\ **Replies:** 0\ **Last updated:** [July 27, 2025, 12:37pm UTC](https://racket.discourse.group/t/please-pull-scribble-prs-523-and-525-for-v8-18/3877 "2025-07-27T12:37:30Z")
PR 523 updates some documation for closed PRs 512 and 520. PR 525 fixes bugs in the manual style CSS caused by closed PR 512. --- ## [Racket meet-up: Saturday, 2 August 2025](https://racket.discourse.group/t/racket-meet-up-saturday-2-august-2025/3872)
**Author:** [@spdegabrielle](https://racket.discourse.group/u/spdegabrielle)\ **Replies:** 0\ **Last updated:** [July 25, 2025, 1:49pm UTC](https://racket.discourse.group/t/racket-meet-up-saturday-2-august-2025/3872 "2025-07-25T13:49:32Z")
Everyone is welcome to join us for the :racket: Racket meet-up: Saturday, 2 August 2025 at 18:00 UTC image by @pard In your timezone: 2025-08-02T18:00:00Z (UTC). (converter). At this meet-up: in-person meet-ups i… --- ## [Macro expansion: evaluating a pattern variable that could be a number or a function](https://racket.discourse.group/t/macro-expansion-evaluating-a-pattern-variable-that-could-be-a-number-or-a-function/3862)
**Author:** [@ddrake](https://racket.discourse.group/u/ddrake)\ **Replies:** 14\ **Last updated:** [July 24, 2025, 7:36pm UTC](https://racket.discourse.group/t/macro-expansion-evaluating-a-pattern-variable-that-could-be-a-number-or-a-function/3862 "2025-07-24T19:36:10Z")
This is related to my struggles with getting a new #lang to work. I've discovered a bug in my code, but I am not sure how to modify my macro to make it work as expected. The key parts of my macro and supporting code are… --- ## [Visible notes in Scribble bibliography](https://racket.discourse.group/t/visible-notes-in-scribble-bibliography/3868)
**Author:** [@Fare](https://racket.discourse.group/u/Fare)\ **Replies:** 2\ **Last updated:** [July 23, 2025, 4:24pm UTC](https://racket.discourse.group/t/visible-notes-in-scribble-bibliography/3868 "2025-07-23T16:24:44Z")
I would like to include some reader-visible notes in the foo.bib bibliography for an article written using Scribble's LaTeX / PDF backend. How do I do that? I might require some lower-level LaTeX hacking. --- ## [Prelude Modules](https://racket.discourse.group/t/prelude-modules/3864)
**Author:** [@bakgatviooldoos](https://racket.discourse.group/u/bakgatviooldoos)\ **Replies:** 6\ **Last updated:** [July 22, 2025, 12:28pm UTC](https://racket.discourse.group/t/prelude-modules/3864 "2025-07-22T12:28:29Z")
Hi, Racket Discourse. I was reading @notjack's post about what they call prelude modules, and I find the term to be an interesting addition to the nomenclature, should it take hold. One can become friends with a named c… [Previous page](https://racket.discourse.group/latest.md?page=10) [Next page](https://racket.discourse.group/latest.md?page=12)