# Latest **URL:** https://racket.discourse.group/latest.md?page=36 [Latest](https://racket.discourse.group/latest.md) · [Categories](https://racket.discourse.group/categories.md) · [Tags](https://racket.discourse.group/tags.md) **Page:** 37 --- ## [How to use union types?](https://racket.discourse.group/t/how-to-use-union-types/2537)
**Author:** [@Kalimehtar](https://racket.discourse.group/u/Kalimehtar)\ **Replies:** 5\ **Last updated:** [November 26, 2023, 6:00pm UTC](https://racket.discourse.group/t/how-to-use-union-types/2537 "2023-11-26T18:00:19Z")
If I try (: foo (-\> (U Positive-Exact-Rational Negative-Exact-Rational) Positive-Exact-Rational (U Positive-Exact-Rational Negative-Exact-Rational))) (define (foo a b) (\* a b)) I get type mismatch. But both … --- ## [Racket leaderboard for advent of code?](https://racket.discourse.group/t/racket-leaderboard-for-advent-of-code/2538)
**Author:** [@spdegabrielle](https://racket.discourse.group/u/spdegabrielle)\ **Replies:** 1\ **Last updated:** [November 26, 2023, 3:59pm UTC](https://racket.discourse.group/t/racket-leaderboard-for-advent-of-code/2538 "2023-11-26T15:59:37Z")
Is advent of code happening this year? Does the Racket Leaderboard have the same code as previous years? --- ## [Racket languages showcase! Nominate a language!](https://racket.discourse.group/t/racket-languages-showcase-nominate-a-language/2536)
**Author:** [@spdegabrielle](https://racket.discourse.group/u/spdegabrielle)\ **Replies:** 2\ **Last updated:** [November 26, 2023, 9:01am UTC](https://racket.discourse.group/t/racket-languages-showcase-nominate-a-language/2536 "2023-11-26T09:01:58Z")
I'd like to see a list of Racket languages on the Racket website to give people an idea of the power and possibilities for creating programming languages in Racket. You can search for #lang's in the Racket documentation… --- ## [\[feedback/help requested\] A practical introduction to kill-safe, concurrent programming in Racket](https://racket.discourse.group/t/feedback-help-requested-a-practical-introduction-to-kill-safe-concurrent-programming-in-racket/2534)
**Author:** [@nikhilm](https://racket.discourse.group/u/nikhilm)\ **Replies:** 5\ **Last updated:** [November 26, 2023, 6:12am UTC](https://racket.discourse.group/t/feedback-help-requested-a-practical-introduction-to-kill-safe-concurrent-programming-in-racket/2534 "2023-11-26T06:12:45Z")
I’ve written a long tutorial exploring the user of Racket’s Concurrent ML (CML) inspired concurrency paradigm to write an API wrapping git-cat-file. It is meant to serve as an introduction to kill-safety and CML concurre… --- ## [New installltion of Drracket does not work](https://racket.discourse.group/t/new-installltion-of-drracket-does-not-work/2527)
**Author:** [@greadey](https://racket.discourse.group/u/greadey)\ **Replies:** 1\ **Last updated:** [November 26, 2023, 4:55am UTC](https://racket.discourse.group/t/new-installltion-of-drracket-does-not-work/2527 "2023-11-26T04:55:36Z")
I recently re-installed my OS (Freebsd). I did it by wiping everything and starting again. As usual I installed DRRacket. In the past it has just worked! Now it starts up in typed racket and no #lang line in the defs … --- ## [Typed racket identifier in Refined type (or define type to length of vector)](https://racket.discourse.group/t/typed-racket-identifier-in-refined-type-or-define-type-to-length-of-vector/2533)
**Author:** [@Hazematman](https://racket.discourse.group/u/Hazematman)\ **Replies:** 1\ **Last updated:** [November 26, 2023, 1:16am UTC](https://racket.discourse.group/t/typed-racket-identifier-in-refined-type-or-define-type-to-length-of-vector/2533 "2023-11-26T01:16:11Z")
Hello, I'm trying to figure out a way I can use an identifier in a refined type. If this is not possible my end goal is to have a the range of an integer be restricted by some identifier that I can use else where in my … --- ## [What does "No instance for id: 1" mean in the Racket webserver?](https://racket.discourse.group/t/what-does-no-instance-for-id-1-mean-in-the-racket-webserver/2529)
**Author:** [@hendrikboom3](https://racket.discourse.group/u/hendrikboom3)\ **Replies:** 4\ **Last updated:** [November 25, 2023, 10:18pm UTC](https://racket.discourse.group/t/what-does-no-instance-for-id-1-mean-in-the-racket-webserver/2529 "2023-11-25T22:18:10Z")
Over the past few years I've been getting deeper into the Racket ecosystem, and encountering more obscure problems. Today I seem to be misusing the Racket webserver and failing to understand a message. I'm using the Ra… --- ## [Hyperlinks inside a scribble single file](https://racket.discourse.group/t/hyperlinks-inside-a-scribble-single-file/2519)
**Author:** [@hrvoje064](https://racket.discourse.group/u/hrvoje064)\ **Replies:** 16\ **Last updated:** [November 25, 2023, 4:26pm UTC](https://racket.discourse.group/t/hyperlinks-inside-a-scribble-single-file/2519 "2023-11-25T16:26:43Z")
I have a problem with my scribble docs for math-quiz. It is a very simple (single) file (my first attempt at this), and contains just a few sections and subsections. Nothing fancy. This all works, except after I introdu… --- ## [Class with static fields](https://racket.discourse.group/t/class-with-static-fields/2530)
**Author:** [@ceving](https://racket.discourse.group/u/ceving)\ **Replies:** 3\ **Last updated:** [November 24, 2023, 12:59am UTC](https://racket.discourse.group/t/class-with-static-fields/2530 "2023-11-24T00:59:14Z")
What is Rackets canonical way to define fields called in other languages "static", which means the value is shared among all instances of the class. I can use a closure, but I can not access the value without an object: … --- ## [Kerning Problem with Latin Modern Roman](https://racket.discourse.group/t/kerning-problem-with-latin-modern-roman/2525)
**Author:** [@ceving](https://racket.discourse.group/u/ceving)\ **Replies:** 4\ **Last updated:** [November 23, 2023, 9:56am UTC](https://racket.discourse.group/t/kerning-problem-with-latin-modern-roman/2525 "2023-11-23T09:56:49Z")
I have a kerning problem with the font "Latin Modern Roman" (maybe also with others). I wrote a program which draws "Hello, World!" (source at the bottom). Next I made a screenshot and imported the screenshot into Inksca… --- ## [Practical Common Lisp in Racket](https://racket.discourse.group/t/practical-common-lisp-in-racket/1890)
**Author:** [@shawnw](https://racket.discourse.group/u/shawnw)\ **Replies:** 8\ **Last updated:** [November 22, 2023, 6:49pm UTC](https://racket.discourse.group/t/practical-common-lisp-in-racket/1890 "2023-11-22T18:49:23Z")
I thought it would be interesting to rewrite some of the example programs in Peter Seibel's Practical Common Lisp in Racket to compare and contrast the two languages. An example from the spam filter in chapter 23: #lang… --- ## [Blog post: Racket Beyond Languages](https://racket.discourse.group/t/blog-post-racket-beyond-languages/2524)
**Author:** [@nikhilm](https://racket.discourse.group/u/nikhilm)\ **Replies:** 0\ **Last updated:** [November 21, 2023, 4:31pm UTC](https://racket.discourse.group/t/blog-post-racket-beyond-languages/2524 "2023-11-21T16:31:10Z")
@spdegabrielle suggested I share this here. I'd love to hear feedback, particularly if there are any corrections I can do. I am also writing another post about a practical use of Racket's CML-like concurrency mechanisms. … --- ## [Racket/gui canvas Hello World](https://racket.discourse.group/t/racket-gui-canvas-hello-world/2522)
**Author:** [@ceving](https://racket.discourse.group/u/ceving)\ **Replies:** 5\ **Last updated:** [November 21, 2023, 3:59pm UTC](https://racket.discourse.group/t/racket-gui-canvas-hello-world/2522 "2023-11-21T15:59:14Z")
Can anybody give me a simple hello-world example using the racket/gui canvas? Just a very minimal program opening a window with a canvas and drawing a text in the middle. I am a newbie and could not find something simila… --- ## [Error: no pattern variables before ellipsis in template](https://racket.discourse.group/t/error-no-pattern-variables-before-ellipsis-in-template/2520)
**Author:** [@ceving](https://racket.discourse.group/u/ceving)\ **Replies:** 3\ **Last updated:** [November 20, 2023, 4:05pm UTC](https://racket.discourse.group/t/error-no-pattern-variables-before-ellipsis-in-template/2520 "2023-11-20T16:05:42Z")
The following code throws the error: no pattern variables before ellipsis in template I do not understand why ::f\* is no pattern variable. Can anybody explain? #lang racket (define undefined (when #f #f)) (define … --- ## [Racket v8.11.1 Release Thread](https://racket.discourse.group/t/racket-v8-11-1-release-thread/2518)
**Author:** [@jbclements](https://racket.discourse.group/u/jbclements)\ **Replies:** 0\ **Last updated:** [November 19, 2023, 11:08pm UTC](https://racket.discourse.group/t/racket-v8-11-1-release-thread/2518 "2023-11-19T23:08:14Z")
The release process for v8.11.1 has started. Racket 8.11.1 is a bugfix release to address issues in Racket 8.11. Specifically, it turns out that we need to repair a problem with building from source using the built-pac… --- ## [Documentation feedback : Continuations](https://racket.discourse.group/t/documentation-feedback-continuations/2516)
**Author:** [@dehidehidehi](https://racket.discourse.group/u/dehidehidehi)\ **Replies:** 8\ **Last updated:** [November 18, 2023, 8:24pm UTC](https://racket.discourse.group/t/documentation-feedback-continuations/2516 "2023-11-18T20:24:32Z")
Good afternoon, There are a couple points I found difficult to follow in the Racket documentation about continuations; the difficulty is not about understanding continuations (even though that also is the case), but mai… --- ## [Vendoring racket packages](https://racket.discourse.group/t/vendoring-racket-packages/2478)
**Author:** [@db7](https://racket.discourse.group/u/db7)\ **Replies:** 8\ **Last updated:** [November 17, 2023, 8:29pm UTC](https://racket.discourse.group/t/vendoring-racket-packages/2478 "2023-11-17T20:29:06Z")
Hi, I'm looking for a practical way to "vendor" dependencies in a project. We are building a Docker container with Racket and some packages (eg, quickcheck). During the docker build process, we would need to download t… --- ## [Discourse housekeeping: registration/authentication options, GitHub, plugins, oh my](https://racket.discourse.group/t/discourse-housekeeping-registration-authentication-options-github-plugins-oh-my/2515)
**Author:** [@spdegabrielle](https://racket.discourse.group/u/spdegabrielle)\ **Replies:** 0\ **Last updated:** [November 17, 2023, 7:14pm UTC](https://racket.discourse.group/t/discourse-housekeeping-registration-authentication-options-github-plugins-oh-my/2515 "2023-11-17T19:14:57Z")
Log in services In addition to traditional username and password, the discourse supports login using Apple, Discord, Facebook, Google and Twitter. please let me know if this is desirable and I'll look into enabling it… --- ## ["Log in with GitHub" doesn't seem to work on this discourse instance](https://racket.discourse.group/t/log-in-with-github-doesnt-seem-to-work-on-this-discourse-instance/2510)
**Author:** [@tonyg](https://racket.discourse.group/u/tonyg)\ **Replies:** 2\ **Last updated:** [November 17, 2023, 6:28pm UTC](https://racket.discourse.group/t/log-in-with-github-doesnt-seem-to-work-on-this-discourse-instance/2510 "2023-11-17T18:28:12Z")
When signed out, click "Log in" at the top right of the site. Then click "Log in with GitHub" on the modal that appears. Nothing seems to happen. In console, I see: 15:09:40.043 Uncaught (in promise) TypeError: this.log… --- ## [My aspirational Social Podcast Webapp](https://racket.discourse.group/t/my-aspirational-social-podcast-webapp/2513)
**Author:** [@thrilway](https://racket.discourse.group/u/thrilway)\ **Replies:** 0\ **Last updated:** [November 17, 2023, 5:39pm UTC](https://racket.discourse.group/t/my-aspirational-social-podcast-webapp/2513 "2023-11-17T17:39:50Z")
As a way to expand my Racket skills, I started writing a webapp that I thought needed writing—https://github.com/thrilway/dolphin-pod The core functionality would be that of a podcatcher—allow users to subscribe to, lis… --- ## [Upgrade instructions](https://racket.discourse.group/t/upgrade-instructions/1655)
**Author:** [@hendrikboom3](https://racket.discourse.group/u/hendrikboom3)\ **Replies:** 3\ **Last updated:** [November 17, 2023, 9:09am UTC](https://racket.discourse.group/t/upgrade-instructions/1655 "2023-11-17T09:09:07Z")
The page Racket v8.7 contains links to https://download.racket-lang.org/ . At least for the Linux version that page explains how to install Racket 8.7. Perhaps it should also explain how to upgrade to 8.7 from a previou… --- ## [Updating Racket](https://racket.discourse.group/t/updating-racket/2508)
**Author:** [@taeknibunadur](https://racket.discourse.group/u/taeknibunadur)\ **Replies:** 3\ **Last updated:** [November 17, 2023, 9:07am UTC](https://racket.discourse.group/t/updating-racket/2508 "2023-11-17T09:07:51Z")
I installed Racket on Linux using the bash script provided on the website. I'd like to update it to the latest version but am not sure how. Can anyone advise me please? --- ## [Rebuild package with dependancies problem](https://racket.discourse.group/t/rebuild-package-with-dependancies-problem/2506)
**Author:** [@damien\_mattei](https://racket.discourse.group/u/damien_mattei)\ **Replies:** 3\ **Last updated:** [November 16, 2023, 5:35pm UTC](https://racket.discourse.group/t/rebuild-package-with-dependancies-problem/2506 "2023-11-16T17:35:11Z")
hello, i have two questions related to https://pkgs.racket-lang.org i put a module: Scheme-PLUS-for-Racket (it allow special syntax in Racket, see example: https://github.com/damien-mattei/AI\_Deep\_Learning/blob/main/e… --- ## [Getting closer to a "normal" distribution from a minimal build](https://racket.discourse.group/t/getting-closer-to-a-normal-distribution-from-a-minimal-build/2502)
**Author:** [@abhillman](https://racket.discourse.group/u/abhillman)\ **Replies:** 2\ **Last updated:** [November 16, 2023, 2:19pm UTC](https://racket.discourse.group/t/getting-closer-to-a-normal-distribution-from-a-minimal-build/2502 "2023-11-16T14:19:00Z")
github.com/racket/racket has two principal ways of building: running make from the root of the repository with appropriate additional flags (e.g. make unix-style PREFIX=\ as documented in build.md) running make fro… --- ## [Racket version 8.11 is now available](https://racket.discourse.group/t/racket-version-8-11-is-now-available/2499)
**Author:** [@spdegabrielle](https://racket.discourse.group/u/spdegabrielle)\ **Replies:** 2\ **Last updated:** [November 15, 2023, 10:02pm UTC](https://racket.discourse.group/t/racket-version-8-11-is-now-available/2499 "2023-11-15T22:02:09Z")
Racket version 8.11 is now available from https://download.racket-lang.org/ Note: use raco pkg migrate 8.10 to update your packages As of this release: Match clauses can include a #:do option to allow evaluation … --- ## [My Racket AI book is available to read online](https://racket.discourse.group/t/my-racket-ai-book-is-available-to-read-online/2501)
**Author:** [@mark-watson](https://racket.discourse.group/u/mark-watson)\ **Replies:** 0\ **Last updated:** [November 15, 2023, 9:27pm UTC](https://racket.discourse.group/t/my-racket-ai-book-is-available-to-read-online/2501 "2023-11-15T21:27:41Z")
I wrote a short Racket AI projects book that you can read online using the link Practical Artificial Intelligence Development With Racket that contains many short AI examples including LLMs, vector datastore, NLP, semant… --- ## [Package dependency problem](https://racket.discourse.group/t/package-dependency-problem/2490)
**Author:** [@matteo-daddio](https://racket.discourse.group/u/matteo-daddio)\ **Replies:** 5\ **Last updated:** [November 13, 2023, 6:32pm UTC](https://racket.discourse.group/t/package-dependency-problem/2490 "2023-11-13T18:32:22Z")
Hi, as an exercise I developed a data structure, a double linked ring. I create a github repository and I put it in the Racket catalog. I took Ring Buffer and Priority Queues as examples. Everything is fine except th… --- ## [Why would \`second\` being unbound identifier inside \`syntax-\>datum\`?](https://racket.discourse.group/t/why-would-second-being-unbound-identifier-inside-syntax-datum/2497)
**Author:** [@JohnSnow](https://racket.discourse.group/u/JohnSnow)\ **Replies:** 3\ **Last updated:** [November 13, 2023, 11:45am UTC](https://racket.discourse.group/t/why-would-second-being-unbound-identifier-inside-syntax-datum/2497 "2023-11-13T11:45:16Z")
In this program, ok and ok2 only differs at cadr & second #lang racket (second '(1 2 3)) (define-syntax (ok stx) (datum-\>syntax stx (let (\[s (syntax-\>datum stx)\]) (cadr s)))) (ok 1 2 3) (define-syntax (ok2 stx)… --- ## [Private \`racket-advocacy\`category (anyone can join)](https://racket.discourse.group/t/private-racket-advocacy-category-anyone-can-join/2473)
**Author:** [@spdegabrielle](https://racket.discourse.group/u/spdegabrielle)\ **Replies:** 1\ **Last updated:** [November 13, 2023, 11:35am UTC](https://racket.discourse.group/t/private-racket-advocacy-category-anyone-can-join/2473 "2023-11-13T11:35:13Z")
Hi All, I've created a (racket)advocacy channel on the Racket Discord for chat about letting others know about Racket. I chose discord because it was easy - I could make it with a few clicks on my phone while on the tr… --- ## [Python Tokenizer with \`libpython\` via \`pyffi\`](https://racket.discourse.group/t/python-tokenizer-with-libpython-via-pyffi/2493)
**Author:** [@abhillman](https://racket.discourse.group/u/abhillman)\ **Replies:** 0\ **Last updated:** [November 11, 2023, 6:45am UTC](https://racket.discourse.group/t/python-tokenizer-with-libpython-via-pyffi/2493 "2023-11-11T06:45:30Z")
If you're looking for a way to tokenize python using its canonical tokenizer implementation, but wish to have the results in racket, this library may be useful. Source code here GitHub - abhillman/py-tokenizer-rkt: Pyth… [Previous page](https://racket.discourse.group/latest.md?page=35) [Next page](https://racket.discourse.group/latest.md?page=37)