# Latest **URL:** https://racket.discourse.group/latest.md?page=53 [Latest](https://racket.discourse.group/latest.md) · [Categories](https://racket.discourse.group/categories.md) · [Tags](https://racket.discourse.group/tags.md) **Page:** 54 --- ## [404 error when attempting to create a new topic?](https://racket.discourse.group/t/404-error-when-attempting-to-create-a-new-topic/1383)
**Author:** [@spdegabrielle](https://racket.discourse.group/u/spdegabrielle)\ **Replies:** 2\ **Last updated:** [October 17, 2022, 5:51pm UTC](https://racket.discourse.group/t/404-error-when-attempting-to-create-a-new-topic/1383 "2022-10-17T17:51:13Z")
Does anyone else get a 404 error if you attempt to create a new topic on racket discourse ? --- ## [The red white blue banner with links is an eyesore especially in dark mode](https://racket.discourse.group/t/the-red-white-blue-banner-with-links-is-an-eyesore-especially-in-dark-mode/1390)
**Author:** [@simonls](https://racket.discourse.group/u/simonls)\ **Replies:** 4\ **Last updated:** [October 16, 2022, 7:02pm UTC](https://racket.discourse.group/t/the-red-white-blue-banner-with-links-is-an-eyesore-especially-in-dark-mode/1390 "2022-10-16T19:02:11Z")
If it would only show me certain links once and never show me those again, if I already clicked on them, then it would be acceptable for me, because then it would just be temporary. But instead it seems to be permanent… --- ## [Multiple bibliographies in a scribble document](https://racket.discourse.group/t/multiple-bibliographies-in-a-scribble-document/1373)
**Author:** [@brittAnderson](https://racket.discourse.group/u/brittAnderson)\ **Replies:** 2\ **Last updated:** [October 16, 2022, 1:10pm UTC](https://racket.discourse.group/t/multiple-bibliographies-in-a-scribble-document/1373 "2022-10-16T13:10:35Z")
I am writing a scribble document for a class I am teaching and am including references. The document is rather long and I would like the references to appear in the sections where they are referred to. Thus there will be… --- ## [Create new Events category?](https://racket.discourse.group/t/create-new-events-category/1386)
**Author:** [@jesse](https://racket.discourse.group/u/jesse)\ **Replies:** 3\ **Last updated:** [October 16, 2022, 12:06am UTC](https://racket.discourse.group/t/create-new-events-category/1386 "2022-10-16T00:06:14Z")
There are all sorts of Racket-y events going on: meet ups, livestreams, Racket-friendly conference calls for papers/participation (e.g., BOB, PLDI), not to mention more official things like RacketCon and the Racket Summe… --- ## [RacketCon 2022: The closing stretch](https://racket.discourse.group/t/racketcon-2022-the-closing-stretch/1385)
**Author:** [@jesse](https://racket.discourse.group/u/jesse)\ **Replies:** 0\ **Last updated:** [October 15, 2022, 9:45am UTC](https://racket.discourse.group/t/racketcon-2022-the-closing-stretch/1385 "2022-10-15T09:45:10Z")
This is a test. I'm having trouble posting on Discourse. Please ignore this message. --- ## [When might \`(find-lib-dir)\` return \`#f\`?](https://racket.discourse.group/t/when-might-find-lib-dir-return-f/1377)
**Author:** [@LiberalArtist](https://racket.discourse.group/u/LiberalArtist)\ **Replies:** 1\ **Last updated:** [October 14, 2022, 10:42pm UTC](https://racket.discourse.group/t/when-might-find-lib-dir-return-f/1377 "2022-10-14T22:42:54Z")
Functions like find-lib-dir from setup/dirs document that: The result is #f if no such directory is available. What does "available" mean in this context? From experiments, it seems that the functions don't return #f … --- ## [Is there a PB decompiler?](https://racket.discourse.group/t/is-there-a-pb-decompiler/1381)
**Author:** [@jbclements](https://racket.discourse.group/u/jbclements)\ **Replies:** 1\ **Last updated:** [October 14, 2022, 10:25pm UTC](https://racket.discourse.group/t/is-there-a-pb-decompiler/1381 "2022-10-14T22:25:55Z")
I'm hoping this doesn't have an obvious documented answer: is there a way to decompile PB (portable bytecode) files? I see that the pb implementation went in around 2020, with substantial additions earlier this year in o… --- ## [Enable discourse-math plugin for rendering LaTeX-style equations](https://racket.discourse.group/t/enable-discourse-math-plugin-for-rendering-latex-style-equations/1372)
**Author:** [@GregVernon](https://racket.discourse.group/u/GregVernon)\ **Replies:** 11\ **Last updated:** [October 13, 2022, 6:27pm UTC](https://racket.discourse.group/t/enable-discourse-math-plugin-for-rendering-latex-style-equations/1372 "2022-10-13T18:27:41Z")
There's an official Discourse plugin (link below) that would allow for users to post LaTeX style equations and have them rendered. As far as I can tell, this plugin is not enabled on this Discourse (test: $x^2$ ). Would… --- ## [Plotting a lambda that returns a (math/matrix) vector](https://racket.discourse.group/t/plotting-a-lambda-that-returns-a-math-matrix-vector/1365)
**Author:** [@GregVernon](https://racket.discourse.group/u/GregVernon)\ **Replies:** 3\ **Last updated:** [October 11, 2022, 4:20pm UTC](https://racket.discourse.group/t/plotting-a-lambda-that-returns-a-math-matrix-vector/1365 "2022-10-11T16:20:13Z")
I'm writing a text where I'm needing to plot polynomial bases and operations on them. The bases are often represented in a vector form, e.g., \\mathbf{N}^p(\\xi) = \[ N\_0^p(\\xi), N\_1^p(\\xi), \\dots, N\_p^p(\\xi) \]^T Where… --- ## [How to use \`head-extra\` in scribble?](https://racket.discourse.group/t/how-to-use-head-extra-in-scribble/1371)
**Author:** [@KDr2](https://racket.discourse.group/u/KDr2)\ **Replies:** 6\ **Last updated:** [October 11, 2022, 12:35pm UTC](https://racket.discourse.group/t/how-to-use-head-extra-in-scribble/1371 "2022-10-11T12:35:28Z")
I want to add a favicon to my website which is built with scribble, but when I put something like (make-head-extra ...) into my scribble file, it tells me that: not valid in document body (need a pre-part for decode) i… --- ## [The Wolf, the Goat, and the Cabbage](https://racket.discourse.group/t/the-wolf-the-goat-and-the-cabbage/1366)
**Author:** [@alexh](https://racket.discourse.group/u/alexh)\ **Replies:** 0\ **Last updated:** [October 10, 2022, 10:43pm UTC](https://racket.discourse.group/t/the-wolf-the-goat-and-the-cabbage/1366 "2022-10-10T22:43:36Z")
I was always fascinated by relational programming, but I never had any real-world opportunities to use it myself, so I tried to use it to solve some simple puzzles. Below is my attempt to solve the "Wolf, Goat, and Cabb… --- ## [Does Racket run on Windows 7?](https://racket.discourse.group/t/does-racket-run-on-windows-7/1351)
**Author:** [@alexh](https://racket.discourse.group/u/alexh)\ **Replies:** 4\ **Last updated:** [October 10, 2022, 3:52pm UTC](https://racket.discourse.group/t/does-racket-run-on-windows-7/1351 "2022-10-10T15:52:45Z")
A user of ActivityLog2 reported that the application fails to run on Window7, and the application is built using Racket 8.6 CS. Since the application itself does not load additional DLLs except for what Racket librarie… --- ## [Racket now available on Compiler Explorer](https://racket.discourse.group/t/racket-now-available-on-compiler-explorer/1356)
**Author:** [@jryans](https://racket.discourse.group/u/jryans)\ **Replies:** 7\ **Last updated:** [October 7, 2022, 5:25pm UTC](https://racket.discourse.group/t/racket-now-available-on-compiler-explorer/1356 "2022-10-07T17:25:05Z")
Over the last few weeks, I've been working on adding Racket to Compiler Explorer (sometimes called Godbolt because of the domain name which is also the creator's last name). If you've never encountered it before, Compil… --- ## [Running Racket in the cloud](https://racket.discourse.group/t/running-racket-in-the-cloud/878)
**Author:** [@spdegabrielle](https://racket.discourse.group/u/spdegabrielle)\ **Replies:** 6\ **Last updated:** [October 7, 2022, 3:46pm UTC](https://racket.discourse.group/t/running-racket-in-the-cloud/878 "2022-10-07T15:46:14Z")
Sometimes you are away you preferred machine for running Racket, or maybe you are a student and need to share computing resources. In these scenarios and others it can be useful to have other options. Fortunately there … --- ## [RacketCon 2022!](https://racket.discourse.group/t/racketcon-2022/1102)
**Author:** [@jesse](https://racket.discourse.group/u/jesse)\ **Replies:** 12\ **Last updated:** [October 7, 2022, 4:06am UTC](https://racket.discourse.group/t/racketcon-2022/1102 "2022-10-07T04:06:39Z")
I'm pleased to announce the RacketCon 2022 is cleared for takeoff! Mark your calendars: October 28-30, 2022 at the Department of Computer Science at Brown University in Providence, Rhode Island, USA. This will be an in-… --- ## [Racket meet-up October 1st at 18:00 UTC :racket:](https://racket.discourse.group/t/racket-meet-up-october-1st-at-18-00-utc/1272)
**Author:** [@spdegabrielle](https://racket.discourse.group/u/spdegabrielle)\ **Replies:** 5\ **Last updated:** [October 6, 2022, 1:47pm UTC](https://racket.discourse.group/t/racket-meet-up-october-1st-at-18-00-utc/1272 "2022-10-06T13:47:38Z")
Racket meet-up October 1st at 18:00 UTC :racket: At this meet-up: Build your own Lightsaber: Ben Knoble will show us how to configure Vim as a powerful Racket development environment. Show and tell News & rumours AO… --- ## [FFI: Converting from \_pointer to byte string](https://racket.discourse.group/t/ffi-converting-from-pointer-to-byte-string/1349)
**Author:** [@jA\_cOp](https://racket.discourse.group/u/jA_cOp)\ **Replies:** 8\ **Last updated:** [October 6, 2022, 12:59pm UTC](https://racket.discourse.group/t/ffi-converting-from-pointer-to-byte-string/1349 "2022-10-06T12:59:23Z")
I have a C struct like so: (define-cstruct \_foo (\[data \_pointer\] \[len \_int32\])) I then get an instance of this struct as an output parameter of a C function. data points to a non-null-terminated array of bytes, of leng… --- ## [Scribble: How to wrap a subsection in a custom \`div\` element?](https://racket.discourse.group/t/scribble-how-to-wrap-a-subsection-in-a-custom-div-element/1340)
**Author:** [@sschwarzer](https://racket.discourse.group/u/sschwarzer)\ **Replies:** 5\ **Last updated:** [October 6, 2022, 12:06pm UTC](https://racket.discourse.group/t/scribble-how-to-wrap-a-subsection-in-a-custom-div-element/1340 "2022-10-06T12:06:22Z")
I'm trying to write a function that wraps a subsection, i.e. the subsection and the content belonging to the subsection, in a div element with a custom class. The function without the div wrapping currently looks like t… --- ## [Package dependency cycles](https://racket.discourse.group/t/package-dependency-cycles/1353)
**Author:** [@LiberalArtist](https://racket.discourse.group/u/LiberalArtist)\ **Replies:** 1\ **Last updated:** [October 6, 2022, 3:51am UTC](https://racket.discourse.group/t/package-dependency-cycles/1353 "2022-10-06T03:51:59Z")
While working on support for Racket packages in Guix, I learned that packages can have cyclic dependencies. Cycles seem rare, but, since one cycle involves base and racket-lib, they have to be accounted for from the begi… --- ## [Education: online vs in-person](https://racket.discourse.group/t/education-online-vs-in-person/1350)
**Author:** [@jestarray](https://racket.discourse.group/u/jestarray)\ **Replies:** 3\ **Last updated:** [October 5, 2022, 9:29pm UTC](https://racket.discourse.group/t/education-online-vs-in-person/1350 "2022-10-05T21:29:25Z")
Since a sizable chunk of the Racket community are teachers and academics, what are the pros and cons of online instruction? What do the stats tell? Are students doing better in-person or online(compared to previous semes… --- ## [2htdp save-movie analog of save-image?](https://racket.discourse.group/t/2htdp-save-movie-analog-of-save-image/1352)
**Author:** [@jasonhemann](https://racket.discourse.group/u/jasonhemann)\ **Replies:** 2\ **Last updated:** [October 5, 2022, 7:48pm UTC](https://racket.discourse.group/t/2htdp-save-movie-analog-of-save-image/1352 "2022-10-05T19:48:37Z")
2htdp/image includes save-image, a built-in way to easily export an image to disk. Is there a comparably easy way to save a movie that you'd produce with the run-movie function? --- ## [How to use the profiler?](https://racket.discourse.group/t/how-to-use-the-profiler/1345)
**Author:** [@dstorrs](https://racket.discourse.group/u/dstorrs)\ **Replies:** 4\ **Last updated:** [October 4, 2022, 8:35pm UTC](https://racket.discourse.group/t/how-to-use-the-profiler/1345 "2022-10-04T20:35:29Z")
I'm looking at the docs on the profiler and having some trouble. What I see is the following: profile will accept some expressions, run them, gather timing data, analyze it, and render it. It's a macro wrapper around… --- ## [Compiling Racket to LLVM](https://racket.discourse.group/t/compiling-racket-to-llvm/1336)
**Author:** [@jbclements](https://racket.discourse.group/u/jbclements)\ **Replies:** 3\ **Last updated:** [September 30, 2022, 3:52pm UTC](https://racket.discourse.group/t/compiling-racket-to-llvm/1336 "2022-09-30T15:52:28Z")
I found myself in a conversation today with Adam Perlin about compiling racket to LLVM, and I found myself wondering why there was no LLVM back-end for Racket\[\*\]. After thinking about it for a while, I decided that the m… --- ## [New module: message-loop](https://racket.discourse.group/t/new-module-message-loop/1337)
**Author:** [@dstorrs](https://racket.discourse.group/u/dstorrs)\ **Replies:** 0\ **Last updated:** [September 29, 2022, 7:50pm UTC](https://racket.discourse.group/t/new-module-message-loop/1337 "2022-09-29T19:50:51Z")
A simple message-handling loop. Listeners can watch for/react to multiple types of messages and multiple listeners can react to the same message, although order of processing is not guaranteed. I'm currently using this… --- ## [How to get handin to work with 2htdp/image?](https://racket.discourse.group/t/how-to-get-handin-to-work-with-2htdp-image/1333)
**Author:** [@jestarray](https://racket.discourse.group/u/jestarray)\ **Replies:** 2\ **Last updated:** [September 28, 2022, 5:42pm UTC](https://racket.discourse.group/t/how-to-get-handin-to-work-with-2htdp-image/1333 "2022-09-28T17:42:16Z")
; problem1.rkt (require 2htdp/image) (check-expect (myadd1 1) 2) (define (myadd1 n) (+ n 1)) ; checker.rkt (check: :language '(special intermediate) :requires '(2htdp/image 2htdp/universe)) ; I get this e… --- ## [Speed-up issue with futures (CS)](https://racket.discourse.group/t/speed-up-issue-with-futures-cs/1328)
**Author:** [@Laurent.O](https://racket.discourse.group/u/Laurent.O)\ **Replies:** 12\ **Last updated:** [September 28, 2022, 6:55am UTC](https://racket.discourse.group/t/speed-up-issue-with-futures-cs/1328 "2022-09-28T06:55:08Z")
I have a naive softmax-like function that is decently sped-up by futures (10x on the machine I'm using), but is numerically unstable. When I try to use the standard "subtract the max" trick, it does become stable, but fu… --- ## [Elemtag and elemref advice for Scribble documents](https://racket.discourse.group/t/elemtag-and-elemref-advice-for-scribble-documents/1329)
**Author:** [@brittAnderson](https://racket.discourse.group/u/brittAnderson)\ **Replies:** 2\ **Last updated:** [September 27, 2022, 11:29am UTC](https://racket.discourse.group/t/elemtag-and-elemref-advice-for-scribble-documents/1329 "2022-09-27T11:29:56Z")
I am trying to figure out if I can use, and how to use, elemtag and elemref to create hyperlinks to equations. I would like to do something like: @elemtag{eqn1 @($$ "1 + 1 = 2")} and later be able to create a link with… --- ## [Open .rkt files in gedit (linux mint)](https://racket.discourse.group/t/open-rkt-files-in-gedit-linux-mint/1324)
**Author:** [@j831526](https://racket.discourse.group/u/j831526)\ **Replies:** 2\ **Last updated:** [September 25, 2022, 6:05pm UTC](https://racket.discourse.group/t/open-rkt-files-in-gedit-linux-mint/1324 "2022-09-25T18:05:00Z")
When I open a .rkt file there is no markup on the source; it's all white. If I tell gedit it's a scheme file, I get the markup, but gedit doesn't seem to have an option for recognizing racket source file:( --- ## [How to prevent Compiled Racket GUI program opening a black terminal window?](https://racket.discourse.group/t/how-to-prevent-compiled-racket-gui-program-opening-a-black-terminal-window/1320)
**Author:** [@hrvoje064](https://racket.discourse.group/u/hrvoje064)\ **Replies:** 11\ **Last updated:** [September 24, 2022, 6:25am UTC](https://racket.discourse.group/t/how-to-prevent-compiled-racket-gui-program-opening-a-black-terminal-window/1320 "2022-09-24T06:25:57Z")
I find this problem very strange because it does not behave the same on all OS that I tested. The problem is following (actually not really a problem, just annoyance): I compile #lang racket/gui source file with follow… --- ## [(expt 2 #large) gives different results/aborts](https://racket.discourse.group/t/expt-2-large-gives-different-results-aborts/1325)
**Author:** [@Dominique](https://racket.discourse.group/u/Dominique)\ **Replies:** 1\ **Last updated:** [September 23, 2022, 7:44pm UTC](https://racket.discourse.group/t/expt-2-large-gives-different-results-aborts/1325 "2022-09-23T19:44:56Z")
Hi newbie here, I was playing around with racket and tried: (Every next large number has the last digit removed from the previous one) (expt 2 1234567890123456789) ash: out of memory \[,bt for context\] then \> (exp… [Previous page](https://racket.discourse.group/latest.md?page=52) [Next page](https://racket.discourse.group/latest.md?page=54)