# Latest **URL:** https://racket.discourse.group/latest.md?page=56 [Latest](https://racket.discourse.group/latest.md) · [Categories](https://racket.discourse.group/categories.md) · [Tags](https://racket.discourse.group/tags.md) **Page:** 57 --- ## [How to measure an object size accurate](https://racket.discourse.group/t/how-to-measure-an-object-size-accurate/1202)
**Author:** [@dannypsnl](https://racket.discourse.group/u/dannypsnl)\ **Replies:** 8\ **Last updated:** [August 7, 2022, 7:00pm UTC](https://racket.discourse.group/t/how-to-measure-an-object-size-accurate/1202 "2022-08-07T19:00:18Z")
I make a draft macro called size which takes an object and measures the memory use: (define-syntax (size stx) (syntax-parse stx \[(\_ obj) #'(let (\[before-use (current-memory-use)\]) obj (defin… --- ## [The elegantest way to manipulate part of a list?](https://racket.discourse.group/t/the-elegantest-way-to-manipulate-part-of-a-list/1205)
**Author:** [@slbtty](https://racket.discourse.group/u/slbtty)\ **Replies:** 5\ **Last updated:** [August 6, 2022, 5:04pm UTC](https://racket.discourse.group/t/the-elegantest-way-to-manipulate-part-of-a-list/1205 "2022-08-06T17:04:08Z")
When I look at the “remove” functions of lisp, I noticed there are optional arguments :start :end to designate the part of the list you want to manipulate. http://clhs.lisp.se/Body/f\_rm\_rm.htm I cannot find an elegant … --- ## [Raise-argument-error](https://racket.discourse.group/t/raise-argument-error/1206)
**Author:** [@joskoot](https://racket.discourse.group/u/joskoot)\ **Replies:** 2\ **Last updated:** [August 6, 2022, 1:58pm UTC](https://racket.discourse.group/t/raise-argument-error/1206 "2022-08-06T13:58:56Z")
\#lang racket/base (raise-argument-error 'monkey "banana" 3 0 1 2 3 4 5 6 7 8 9) Yields error message monkey: contract violation expected: banana given: 3 argument position: 4th other arguments...: I want to see a… --- ## [Racket meet-up August 6th at 18:00 UTC :racket:](https://racket.discourse.group/t/racket-meet-up-august-6th-at-18-00-utc/1181)
**Author:** [@spdegabrielle](https://racket.discourse.group/u/spdegabrielle)\ **Replies:** 2\ **Last updated:** [August 6, 2022, 5:07am UTC](https://racket.discourse.group/t/racket-meet-up-august-6th-at-18-00-utc/1181 "2022-08-06T05:07:13Z")
Racket meet-up August 6th at 18:00 UTC :racket: Meet-up time at your location: 2022-08-06T18:00:00Z (UTC) Online In the Gather Town 'Racket Room': https://gather.town/app/wH1EDG3McffLjrs0/racket-users (thank you to … --- ## [How do I make Racket notice a SQLite update?](https://racket.discourse.group/t/how-do-i-make-racket-notice-a-sqlite-update/1201)
**Author:** [@dstorrs](https://racket.discourse.group/u/dstorrs)\ **Replies:** 3\ **Last updated:** [August 5, 2022, 5:53pm UTC](https://racket.discourse.group/t/how-do-i-make-racket-notice-a-sqlite-update/1201 "2022-08-05T17:53:34Z")
macOS Catalina comes with sqlite3 version 3.28. This version does not include the 'table\_list' pragma, so I upgraded to version 3.39.2 (the latest). I have checked the version number on the new version and verified tha… --- ## [How to run old version of racket and raco](https://racket.discourse.group/t/how-to-run-old-version-of-racket-and-raco/1200)
**Author:** [@marc](https://racket.discourse.group/u/marc)\ **Replies:** 3\ **Last updated:** [August 5, 2022, 2:42pm UTC](https://racket.discourse.group/t/how-to-run-old-version-of-racket-and-raco/1200 "2022-08-05T14:42:54Z")
I want to run some old code of mine that needs some racket version 7.7 code and relies on a bunch of packages. I am on Ubuntu and the current version I have is 8.5. First, should I still be able to run the old versions … --- ## [Tab-panel is not sized properly](https://racket.discourse.group/t/tab-panel-is-not-sized-properly/1196)
**Author:** [@dstorrs](https://racket.discourse.group/u/dstorrs)\ **Replies:** 0\ **Last updated:** [August 1, 2022, 8:00pm UTC](https://racket.discourse.group/t/tab-panel-is-not-sized-properly/1196 "2022-08-01T20:00:09Z")
Given this code: #lang racket/gui (define frame (new frame% \[label "Example"\])) (define panel (new vertical-panel% \[parent frame\] )) (define tab-panel (new tab-panel% … --- ## [Racket/gui fullscreen and parameters](https://racket.discourse.group/t/racket-gui-fullscreen-and-parameters/1190)
**Author:** [@dominik.pantucek](https://racket.discourse.group/u/dominik.pantucek)\ **Replies:** 4\ **Last updated:** [August 1, 2022, 12:52pm UTC](https://racket.discourse.group/t/racket-gui-fullscreen-and-parameters/1190 "2022-08-01T12:52:20Z")
I have a simple program like: #lang racket/gui (define current-width (make-parameter #f)) (define (run-fullscreen proc) (define window (new (class frame% (super-new) (define/override (on-size … --- ## [I can not close window completely created by racket on macOS 13 beta](https://racket.discourse.group/t/i-can-not-close-window-completely-created-by-racket-on-macos-13-beta/1166)
**Author:** [@ixnij](https://racket.discourse.group/u/ixnij)\ **Replies:** 21\ **Last updated:** [August 1, 2022, 10:04am UTC](https://racket.discourse.group/t/i-can-not-close-window-completely-created-by-racket-on-macos-13-beta/1166 "2022-08-01T10:04:13Z")
My racket version is 8.5. For example, when I opened the about window, I can't close it neither by clicking the red button nor by press C-w. other windows have the same problem. GUI - problem with delete-child - #5 … --- ## [RacketCon 2022: Friday afternoon hackathon planning](https://racket.discourse.group/t/racketcon-2022-friday-afternoon-hackathon-planning/1195)
**Author:** [@jesse](https://racket.discourse.group/u/jesse)\ **Replies:** 0\ **Last updated:** [August 1, 2022, 9:24am UTC](https://racket.discourse.group/t/racketcon-2022-friday-afternoon-hackathon-planning/1195 "2022-08-01T09:24:23Z")
Greetings RacketCon 2022 participant! (Wait, you haven't registered yet? Just go here to register! That way, the rest of this message will make sense.) This year, we're going to have Friday afternoon available to us for… --- ## [Qi 3.0 Released](https://racket.discourse.group/t/qi-3-0-released/1194)
**Author:** [@countvajhula](https://racket.discourse.group/u/countvajhula)\ **Replies:** 0\ **Last updated:** [July 30, 2022, 8:21pm UTC](https://racket.discourse.group/t/qi-3-0-released/1194 "2022-07-30T20:21:22Z")
It's my pleasure to announce that Qi 3.0 is now available. Upgrade now via: raco pkg update qi This ended up being a big release with contributions from many people. I will do my best to summarize the improvements. The… --- ## ["Deleting" a package?](https://racket.discourse.group/t/deleting-a-package/1191)
**Author:** [@greghendershott](https://racket.discourse.group/u/greghendershott)\ **Replies:** 2\ **Last updated:** [July 31, 2022, 2:18pm UTC](https://racket.discourse.group/t/deleting-a-package/1191 "2022-07-31T14:18:40Z")
This recent discussion reminded me I have an old package echonest that has failing tests -- and the tests can't ever pass again because the company no longer supplies that web API (IIRC Spotify bought them and shut down … --- ## [Syntax-local-introduce and module boundaries](https://racket.discourse.group/t/syntax-local-introduce-and-module-boundaries/1157)
**Author:** [@Kalimehtar](https://racket.discourse.group/u/Kalimehtar)\ **Replies:** 7\ **Last updated:** [July 28, 2022, 5:47pm UTC](https://racket.discourse.group/t/syntax-local-introduce-and-module-boundaries/1157 "2022-07-28T17:47:38Z")
If I use syntax-local-introduce inside one module, then it works: (define-syntax (require-macro stx) (syntax-local-introduce #'(require racket/math))) (define-syntax (define-macro stx) (syntax-local-introduce #'(de… --- ## [Possible bug in parser-tools lexer-srcloc](https://racket.discourse.group/t/possible-bug-in-parser-tools-lexer-srcloc/1189)
**Author:** [@jjsimpso](https://racket.discourse.group/u/jjsimpso)\ **Replies:** 0\ **Last updated:** [July 27, 2022, 3:59pm UTC](https://racket.discourse.group/t/possible-bug-in-parser-tools-lexer-srcloc/1189 "2022-07-27T15:59:31Z")
Using both Drracket and Emacs racket-mode, the error highlighting is sometimes incorrect in my custom lang(#lang magic). I finally found that the issue is that a literal '\\r' in the file's text leads to what appears to b… --- ## [Converting Scribble-generated single HTML to EPUB via Pandoc](https://racket.discourse.group/t/converting-scribble-generated-single-html-to-epub-via-pandoc/1188)
**Author:** [@ds26gte](https://racket.discourse.group/u/ds26gte)\ **Replies:** 3\ **Last updated:** [July 27, 2022, 3:29pm UTC](https://racket.discourse.group/t/converting-scribble-generated-single-html-to-epub-via-pandoc/1188 "2022-07-27T15:29:04Z")
Greetings, friiends. I've been trying to use Pandoc to create a readable EPUB from a Scribble-generated single HTML page. It works fine for everything except the math bits, which show up as verbatim LaTeX source inthe E… --- ## [Macro Template Syntax Quasi-Quote with Ellipses](https://racket.discourse.group/t/macro-template-syntax-quasi-quote-with-ellipses/1179)
**Author:** [@Liam.Gaudy](https://racket.discourse.group/u/Liam.Gaudy)\ **Replies:** 5\ **Last updated:** [July 25, 2022, 10:57pm UTC](https://racket.discourse.group/t/macro-template-syntax-quasi-quote-with-ellipses/1179 "2022-07-25T22:57:33Z")
I'm using the below as an example to ask the question. Please recall that case works like this: (case (+ 7 5) \[( 1 2 3) 'small\] \[( 10 11 12) 'big\]) Let's say I never need more than one match for the same body.… --- ## [Is that possible to create a "purely functional" language with #lang?](https://racket.discourse.group/t/is-that-possible-to-create-a-purely-functional-language-with-lang/1186)
**Author:** [@z2gr8339](https://racket.discourse.group/u/z2gr8339)\ **Replies:** 1\ **Last updated:** [July 25, 2022, 7:11pm UTC](https://racket.discourse.group/t/is-that-possible-to-create-a-purely-functional-language-with-lang/1186 "2022-07-25T19:11:25Z")
Please have a look on these questions: How to execute deterministic code from an untrusted third party safely? Defining a "purely functional" R5RS env in Racket Is that possible to create a new language (something lik… --- ## [Summer #lang party 8pm UTC on Racket Discord](https://racket.discourse.group/t/summer-lang-party-8pm-utc-on-racket-discord/1184)
**Author:** [@spdegabrielle](https://racket.discourse.group/u/spdegabrielle)\ **Replies:** 0\ **Last updated:** [July 25, 2022, 4:50pm UTC](https://racket.discourse.group/t/summer-lang-party-8pm-utc-on-racket-discord/1184 "2022-07-25T16:50:56Z")
2022-07-25T20:00:00Z (UTC)→2022-07-25T21:00:00Z (UTC) Event invite link https://discord.gg/9Ed2tEzG?event=1001171820671680593 Racket Discord in #streaming come join me - tell me about your language - or your ideas for… --- ## [How we optimized pruning in Herbie](https://racket.discourse.group/t/how-we-optimized-pruning-in-herbie/1182)
**Author:** [@pavpanchekha](https://racket.discourse.group/u/pavpanchekha)\ **Replies:** 1\ **Last updated:** [July 25, 2022, 4:05pm UTC](https://racket.discourse.group/t/how-we-optimized-pruning-in-herbie/1182 "2022-07-25T16:05:31Z")
Stephen asked me to repost here a blog post I wrote about about some optimization work I did in the Herbie project, including some nice profile exploration tools I've built in Racket: https://pavpanchekha.com/blog/optim… --- ## [How can I generate WXME files from some other external files?](https://racket.discourse.group/t/how-can-i-generate-wxme-files-from-some-other-external-files/1176)
**Author:** [@etaoinbe](https://racket.discourse.group/u/etaoinbe)\ **Replies:** 2\ **Last updated:** [July 24, 2022, 12:47pm UTC](https://racket.discourse.group/t/how-can-i-generate-wxme-files-from-some-other-external-files/1176 "2022-07-24T12:47:16Z")
how can I generate WXME files from some other external files? the decoding wxme chapter appearst to assume you already have a wxme file, I want to GENERATE a wxme file that can be edited afterwards in drracket --- ## [Am I barking up the wrong tree with HtDP?](https://racket.discourse.group/t/am-i-barking-up-the-wrong-tree-with-htdp/1169)
**Author:** [@okeefe77](https://racket.discourse.group/u/okeefe77)\ **Replies:** 7\ **Last updated:** [July 23, 2022, 4:18pm UTC](https://racket.discourse.group/t/am-i-barking-up-the-wrong-tree-with-htdp/1169 "2022-07-23T16:18:57Z")
I've been programming on and off both professionally and as a hobby for years and recently realized that the design and architecture of programs is a huge weakness for me. I tend to learn a language and then not know wh… --- ## [Language makers meet-up / how to get started](https://racket.discourse.group/t/language-makers-meet-up-how-to-get-started/1172)
**Author:** [@spdegabrielle](https://racket.discourse.group/u/spdegabrielle)\ **Replies:** 0\ **Last updated:** [July 22, 2022, 9:19pm UTC](https://racket.discourse.group/t/language-makers-meet-up-how-to-get-started/1172 "2022-07-22T21:19:31Z")
Hi, As part of the Summer #lang Party I’m hosting two short meet-ups on Saturday to help people get started on their own language. In the spirit of the event I’ll be working through a tutorial on making my own #lang and… --- ## [What is the best book for learning racket(scheme)?](https://racket.discourse.group/t/what-is-the-best-book-for-learning-racket-scheme/1008)
**Author:** [@devosalain](https://racket.discourse.group/u/devosalain)\ **Replies:** 14\ **Last updated:** [July 22, 2022, 1:29pm UTC](https://racket.discourse.group/t/what-is-the-best-book-for-learning-racket-scheme/1008 "2022-07-22T13:29:52Z")
Probably the most obvious question. Buy do i need a 1000 pager or a 100 pager ? After a book you need to be productive ... --- ## [GUI - problem with delete-child](https://racket.discourse.group/t/gui-problem-with-delete-child/1160)
**Author:** [@jtp](https://racket.discourse.group/u/jtp)\ **Replies:** 5\ **Last updated:** [July 21, 2022, 9:01pm UTC](https://racket.discourse.group/t/gui-problem-with-delete-child/1160 "2022-07-21T21:01:31Z")
Below is a simple example of something which I am having trouble with. I want to be able to delete all the children of a frame, regardless of what they are. It seems like this should work but it errors out as shown be… --- ## [Newbie issue with read/write and SQL-NULL](https://racket.discourse.group/t/newbie-issue-with-read-write-and-sql-null/1162)
**Author:** [@KenMax](https://racket.discourse.group/u/KenMax)\ **Replies:** 2\ **Last updated:** [July 21, 2022, 1:42pm UTC](https://racket.discourse.group/t/newbie-issue-with-read-write-and-sql-null/1162 "2022-07-21T13:42:20Z")
My objective is to backup and restore a MYSQL table. I am selecting all of the rows with (define sql-rows (query-rows... I am dumping them to a file with (with-output-to-file "backup.dat" (lambda () (write sql-rows)... … --- ## [Functional Geekery Episode 141 - Shriram Krishnamurthi](https://racket.discourse.group/t/functional-geekery-episode-141-shriram-krishnamurthi/1164)
**Author:** [@spdegabrielle](https://racket.discourse.group/u/spdegabrielle)\ **Replies:** 0\ **Last updated:** [July 20, 2022, 5:13pm UTC](https://racket.discourse.group/t/functional-geekery-episode-141-shriram-krishnamurthi/1164 "2022-07-20T17:13:36Z")
Functional Geekery Episode 141 - Shriram Krishnamurthi Racket and other things functional programming are discussed The host @Proctor also posted the following list of previous racket related interviews Other Racke… --- ## [Newish Racket videos (that I had not seen before)](https://racket.discourse.group/t/newish-racket-videos-that-i-had-not-seen-before/1159)
**Author:** [@spdegabrielle](https://racket.discourse.group/u/spdegabrielle)\ **Replies:** 0\ **Last updated:** [July 19, 2022, 5:22pm UTC](https://racket.discourse.group/t/newish-racket-videos-that-i-had-not-seen-before/1159 "2022-07-19T17:22:39Z")
Hi, I came across some Racket videos recently and thought I'd share Functional Programming (Racket) (12 videos) Why learn Racket? (10 minutes) by Eric Clack on the Racketfest YouTube channel Why Racket? Interview w… --- ## [Hydromel: \`#lang hydromel\`](https://racket.discourse.group/t/hydromel-lang-hydromel/1156)
**Author:** [@ben\_greenman](https://racket.discourse.group/u/ben_greenman)\ **Replies:** 0\ **Last updated:** [July 18, 2022, 2:00am UTC](https://racket.discourse.group/t/hydromel-lang-hydromel/1156 "2022-07-18T02:00:46Z")
Thanks to Guillaume (@aumouvantsillage) for Hydromel: Hydromel is a hardware description language inspired by VHDL, Verilog and Clash. More details: https://github.com/lang-party/Summer2022/issues/4 Related blog pos… --- ## [How can I redefine defintions in typed racket top level (repl)](https://racket.discourse.group/t/how-can-i-redefine-defintions-in-typed-racket-top-level-repl/1155)
**Author:** [@Inc0n](https://racket.discourse.group/u/Inc0n)\ **Replies:** 3\ **Last updated:** [July 16, 2022, 10:47pm UTC](https://racket.discourse.group/t/how-can-i-redefine-defintions-in-typed-racket-top-level-repl/1155 "2022-07-16T22:47:22Z")
Edit: I have realised, the details in my post is flawed (the example) and incomplete, please see my reply here in this samep post, for the additional details I have put in. What version of Racket are you using? Racket 8… --- ## [How to speed up array indexing from untyped Racket](https://racket.discourse.group/t/how-to-speed-up-array-indexing-from-untyped-racket/430)
**Author:** [@soegaard](https://racket.discourse.group/u/soegaard)\ **Replies:** 11\ **Last updated:** [July 16, 2022, 12:20pm UTC](https://racket.discourse.group/t/how-to-speed-up-array-indexing-from-untyped-racket/430 "2022-07-16T12:20:45Z")
The arrays from the math library performs best when using operations that work on an entire axis (think row or column) at a time. Using array-ref and array-set! in a loop will be slower than using array-ref and array-set… [Previous page](https://racket.discourse.group/latest.md?page=55) [Next page](https://racket.discourse.group/latest.md?page=57)