# Latest **URL:** https://racket.discourse.group/latest.md?page=42 [Latest](https://racket.discourse.group/latest.md) · [Categories](https://racket.discourse.group/categories.md) · [Tags](https://racket.discourse.group/tags.md) **Page:** 43 --- ## [Python string indexes](https://racket.discourse.group/t/python-string-indexes/2175)
**Author:** [@matteo-daddio](https://racket.discourse.group/u/matteo-daddio)\ **Replies:** 10\ **Last updated:** [August 7, 2023, 10:43am UTC](https://racket.discourse.group/t/python-string-indexes/2175 "2023-08-07T10:43:47Z")
Hello, I learned some Python and I discovered that it uses negative indexes when dealing with strings. Something like this: (substring “racket.discourse.group” 7 -6) =\> “discourse” (substring “racket.discourse.group”… --- ## [Refactoring homepage](https://racket.discourse.group/t/refactoring-homepage/2121)
**Author:** [@sorawee](https://racket.discourse.group/u/sorawee)\ **Replies:** 18\ **Last updated:** [August 6, 2023, 1:00am UTC](https://racket.discourse.group/t/refactoring-homepage/2121 "2023-08-06T01:00:21Z")
Per @jbclements's suggestion, I attempted to make sections in the homepage of racket-lang.org linkable. As a part of this effort, I refactored the home page (I am yak shaving, am I not?). See more details at \[WIP\] homepa… --- ## [Racket meet-up Sat, 5 August 2023 at 18:00 UTC :Racket:](https://racket.discourse.group/t/racket-meet-up-sat-5-august-2023-at-18-00-utc/2082)
**Author:** [@spdegabrielle](https://racket.discourse.group/u/spdegabrielle)\ **Replies:** 7\ **Last updated:** [August 5, 2023, 11:07pm UTC](https://racket.discourse.group/t/racket-meet-up-sat-5-august-2023-at-18-00-utc/2082 "2023-08-05T23:07:44Z")
Racket meet-up Sat, 5 August 2023 at 18:00 UTC :racket: At this meet-up: RacketCon!! Show and tell News & rumours AOB This meet-up will be held at https://meet.jit.si/Racketmeet-up Meet-up time at your location: 202… --- ## [Functor, Natural tranformation, and Monad in Racket](https://racket.discourse.group/t/functor-natural-tranformation-and-monad-in-racket/1930)
**Author:** [@NoahStoryM](https://racket.discourse.group/u/NoahStoryM)\ **Replies:** 14\ **Last updated:** [August 4, 2023, 6:06am UTC](https://racket.discourse.group/t/functor-natural-tranformation-and-monad-in-racket/1930 "2023-08-04T06:06:21Z")
\#lang racket ;; Functor F : (-\> (-\> A B) (-\> (F A) (F B))) ;; f : (-\> A B) ;; g : (-\> B C) #;(== (compose (F g) (F f)) (F (compose g f))) ;; Natural transformation α F-\>G : (-\> (-\> (F A) (F B)) (-\> (F A) (G B))) … --- ## [Racket - first language in a primary school](https://racket.discourse.group/t/racket-first-language-in-a-primary-school/2188)
**Author:** [@gour](https://racket.discourse.group/u/gour)\ **Replies:** 4\ **Last updated:** [August 2, 2023, 5:10am UTC](https://racket.discourse.group/t/racket-first-language-in-a-primary-school/2188 "2023-08-02T05:10:09Z")
Hello, I've graduated software engineering many years ago and was considering to learn & use Racket for a full-fledged desktop (GUI) application. However, due to several reasons, had to abandon the project... Our kid i… --- ## [Reading a web directory (slow) vs. reading a file (quick)](https://racket.discourse.group/t/reading-a-web-directory-slow-vs-reading-a-file-quick/2182)
**Author:** [@gknauth](https://racket.discourse.group/u/gknauth)\ **Replies:** 9\ **Last updated:** [August 1, 2023, 7:04pm UTC](https://racket.discourse.group/t/reading-a-web-directory-slow-vs-reading-a-file-quick/2182 "2023-08-01T19:04:25Z")
I'm reading a couple of NOAA directories on the web, just to find out what the latest data is. But that is taking forever, like 500 seconds (!). Whereas once I find the file I need, I can read its 28756136 bytes in 6 s… --- ## [DrRacket 8.5 glitches in combined presentation mode](https://racket.discourse.group/t/drracket-8-5-glitches-in-combined-presentation-mode/2161)
**Author:** [@srikumarks](https://racket.discourse.group/u/srikumarks)\ **Replies:** 5\ **Last updated:** [August 1, 2023, 1:16pm UTC](https://racket.discourse.group/t/drracket-8-5-glitches-in-combined-presentation-mode/2161 "2023-08-01T13:16:10Z")
Hi Racketeers, I'm using DrRacket in class where it is full screen on my laptop, being projected to students in class and also shared with online attendees via Zoom screenshare (I teach CS at Krea University). In this … --- ## [Making nested vectors with build-vector in typed/racket](https://racket.discourse.group/t/making-nested-vectors-with-build-vector-in-typed-racket/2183)
**Author:** [@srikumarks](https://racket.discourse.group/u/srikumarks)\ **Replies:** 4\ **Last updated:** [August 1, 2023, 4:22am UTC](https://racket.discourse.group/t/making-nested-vectors-with-build-vector-in-typed-racket/2183 "2023-08-01T04:22:23Z")
I can't seem to get how to get the use of build-vector in the following code to pass the Racket type checker. I've reduced this from an existing untyped function that constructs an "image" as a "vector of vector of color… --- ## [Racket-money email list](https://racket.discourse.group/t/racket-money-email-list/2176)
**Author:** [@spdegabrielle](https://racket.discourse.group/u/spdegabrielle)\ **Replies:** 0\ **Last updated:** [July 30, 2023, 1:35pm UTC](https://racket.discourse.group/t/racket-money-email-list/2176 "2023-07-30T13:35:53Z")
racket-money email list The racket-money email list is for a relatively candid discussion about making money with the Racket programming language. For more information, rules and signup procedure see: https://p.ocmatos… --- ## [Qi meet-up 28-July](https://racket.discourse.group/t/qi-meet-up-28-july/2169)
**Author:** [@spdegabrielle](https://racket.discourse.group/u/spdegabrielle)\ **Replies:** 0\ **Last updated:** [July 28, 2023, 3:41pm UTC](https://racket.discourse.group/t/qi-meet-up-28-july/2169 "2023-07-28T15:41:10Z")
Today at 2023-07-28T17:00:00Z (UTC) Posted by @countvajhula on Racket discord yesterday: Invite: https://discord.gg/au5jagbw?event=1134274179856859156 ok folks, we're going to try doing this on Discord tomorrow (in t… --- ## [Trying the PLT Games collection?](https://racket.discourse.group/t/trying-the-plt-games-collection/2156)
**Author:** [@late\_bloomer](https://racket.discourse.group/u/late_bloomer)\ **Replies:** 3\ **Last updated:** [July 27, 2023, 6:36pm UTC](https://racket.discourse.group/t/trying-the-plt-games-collection/2156 "2023-07-27T18:36:22Z")
\[Solved\] Sorry about all this. I just needed to stick with the name of the package actually shown in the list of installed ones (so "games" instead of plt-games), and not add anything beyond (require games), before I run… --- ## [Best way of drawing with turtles](https://racket.discourse.group/t/best-way-of-drawing-with-turtles/2166)
**Author:** [@absalom](https://racket.discourse.group/u/absalom)\ **Replies:** 9\ **Last updated:** [July 27, 2023, 5:23pm UTC](https://racket.discourse.group/t/best-way-of-drawing-with-turtles/2166 "2023-07-27T17:23:18Z")
Hi, I have to teach functional programming and I chose Scheme as the main language I will use for that course. I chose DrRacket as the IDE my students will use for obvious practical reasons. I will stick to R5RS and wil… --- ## [Call for Participation, Functional Software Architecture (Sep 8, Seattle)](https://racket.discourse.group/t/call-for-participation-functional-software-architecture-sep-8-seattle/2167)
**Author:** [@mike](https://racket.discourse.group/u/mike)\ **Replies:** 0\ **Last updated:** [July 26, 2023, 1:33pm UTC](https://racket.discourse.group/t/call-for-participation-functional-software-architecture-sep-8-seattle/2167 "2023-07-26T13:33:21Z")
====================================================================== \*\*\* FUNARCH 2023 -- CALL FOR PARTICIPATION \*\*\* The First ACM SIGPLAN Workshop on Functional Software Architecture - FP in the Large … --- ## [Use symbol \_ or not if \_ (underscore) is reserved already](https://racket.discourse.group/t/use-symbol-or-not-if-underscore-is-reserved-already/2116)
**Author:** [@damien\_mattei](https://racket.discourse.group/u/damien_mattei)\ **Replies:** 5\ **Last updated:** [July 24, 2023, 5:58pm UTC](https://racket.discourse.group/t/use-symbol-or-not-if-underscore-is-reserved-already/2116 "2023-07-24T17:58:19Z")
hello, i needed a single symbol to define a new syntax but almost all those that can be directly typed on an US keyboard are already used. i wanted to use the underscore \_ as a keyword (i think of / but my syntax can u… --- ## [What should we do for the summer event this year?](https://racket.discourse.group/t/what-should-we-do-for-the-summer-event-this-year/2039)
**Author:** [@spdegabrielle](https://racket.discourse.group/u/spdegabrielle)\ **Replies:** 6\ **Last updated:** [July 24, 2023, 5:45pm UTC](https://racket.discourse.group/t/what-should-we-do-for-the-summer-event-this-year/2039 "2023-07-24T17:45:49Z")
What should we do for the summer event this year? In past years we have done Pictures Quickscripts Macros Languages I'm quite aware Racket the Platform are different things for different people. I'd like the event t… --- ## [Struggling with trivial command line program](https://racket.discourse.group/t/struggling-with-trivial-command-line-program/2152)
**Author:** [@lewisl](https://racket.discourse.group/u/lewisl)\ **Replies:** 2\ **Last updated:** [July 24, 2023, 12:48am UTC](https://racket.discourse.group/t/struggling-with-trivial-command-line-program/2152 "2023-07-24T00:48:14Z")
Both versions work. Which would you use? It's surprising how hard this is and how inconsistent across schemes (and, of course, common lisp). Which would you use? #lang cli (program (square n) (let ((num (string-\>n… --- ## [Closing DrRacket 8.9 takes time](https://racket.discourse.group/t/closing-drracket-8-9-takes-time/2151)
**Author:** [@joskoot](https://racket.discourse.group/u/joskoot)\ **Replies:** 0\ **Last updated:** [July 23, 2023, 4:31pm UTC](https://racket.discourse.group/t/closing-drracket-8-9-takes-time/2151 "2023-07-23T16:31:29Z")
Closing DrRacket 8.9 (both BC and cs) may take up to a second. Not a big problem, of course, but I wonder what DrRacket is doing in that time. --- ## [\#lang cli doesn't work or no longer is part of Racket](https://racket.discourse.group/t/lang-cli-doesnt-work-or-no-longer-is-part-of-racket/2137)
**Author:** [@lewisl](https://racket.discourse.group/u/lewisl)\ **Replies:** 2\ **Last updated:** [July 22, 2023, 11:19pm UTC](https://racket.discourse.group/t/lang-cli-doesnt-work-or-no-longer-is-part-of-racket/2137 "2023-07-22T23:19:56Z")
I followed an example in the doc: In order to use the language to write a command line script, simply declare the module as #lang cli at the top of the file. #lang cli (program (hello name) (displayln (string-appen… --- ## [Revising READMEs](https://racket.discourse.group/t/revising-readmes/2120)
**Author:** [@sorawee](https://racket.discourse.group/u/sorawee)\ **Replies:** 4\ **Last updated:** [July 21, 2023, 4:42pm UTC](https://racket.discourse.group/t/revising-readmes/2120 "2023-07-21T16:42:04Z")
I'm planning to revise READMEs of many repos under the Racket organization (Racket · GitHub). The goal is to make it easier for people to understand what the repo is about. It would be nice to get a brainstorm on what to… --- ## [Squash when merging?](https://racket.discourse.group/t/squash-when-merging/2105)
**Author:** [@jbclements](https://racket.discourse.group/u/jbclements)\ **Replies:** 22\ **Last updated:** [July 21, 2023, 1:25pm UTC](https://racket.discourse.group/t/squash-when-merging/2105 "2023-07-21T13:25:10Z")
Do we have a policy on whether to squash when merging a PR to the racket repo? My knee-jerk inclination is not to squash, it loses information, but I can see the case for squashing as well. Opinions? Thanks! John --- ## [How hard would it be to build a api as a service company using racket?](https://racket.discourse.group/t/how-hard-would-it-be-to-build-a-api-as-a-service-company-using-racket/2115)
**Author:** [@Jobhdez](https://racket.discourse.group/u/Jobhdez)\ **Replies:** 2\ **Last updated:** [July 21, 2023, 12:46am UTC](https://racket.discourse.group/t/how-hard-would-it-be-to-build-a-api-as-a-service-company-using-racket/2115 "2023-07-21T00:46:23Z")
hey, I have always gotten excited about starting a company with lisp or haskell. Was wondering if it would be a good decision choosing racket if I happen to start something. thanks --- ## [Very interesting racket research papers](https://racket.discourse.group/t/very-interesting-racket-research-papers/2114)
**Author:** [@Jobhdez](https://racket.discourse.group/u/Jobhdez)\ **Replies:** 3\ **Last updated:** [July 21, 2023, 12:43am UTC](https://racket.discourse.group/t/very-interesting-racket-research-papers/2114 "2023-07-21T00:43:40Z")
Here are some papers I read today that I found fascinating: macros for dsls migratory typing: 10 years later --- ## [Syntax parameter encapsulation](https://racket.discourse.group/t/syntax-parameter-encapsulation/2119)
**Author:** [@notjack](https://racket.discourse.group/u/notjack)\ **Replies:** 5\ **Last updated:** [July 20, 2023, 4:44pm UTC](https://racket.discourse.group/t/syntax-parameter-encapsulation/2119 "2023-07-20T16:44:58Z")
For a long time now, when I've wanted an "anaphoric macro" I've used syntax parameters. Consider a library that defines a define/return macro for defining functions that can be short circuited using return. The way I'd … --- ## [Does DrRacket 8.7 start on Windows 7?](https://racket.discourse.group/t/does-drracket-8-7-start-on-windows-7/1637)
**Author:** [@jbclements](https://racket.discourse.group/u/jbclements)\ **Replies:** 25\ **Last updated:** [July 19, 2023, 12:04am UTC](https://racket.discourse.group/t/does-drracket-8-7-start-on-windows-7/1637 "2023-07-19T00:04:22Z")
This github issue: ... suggests that Racket 8.7 does not start on Windows 7. Does anyone here have a test machine, or know of a trustworthy VPS provider that supports Windows 7 instances? --- ## [Surprising (?) type error](https://racket.discourse.group/t/surprising-type-error/2110)
**Author:** [@bkc39](https://racket.discourse.group/u/bkc39)\ **Replies:** 1\ **Last updated:** [July 18, 2023, 4:58pm UTC](https://racket.discourse.group/t/surprising-type-error/2110 "2023-07-18T16:58:42Z")
I have been going through the typed/racket guide and encountered code like the following #lang typed/racket (: prop:foo (Struct-Property (-\> Self Number))) (: foo-pred (-\> Any Boolean : (Has-Struct-Property prop:foo)))… --- ## [How to add a search box to a scrrible document](https://racket.discourse.group/t/how-to-add-a-search-box-to-a-scrrible-document/2112)
**Author:** [@jmj](https://racket.discourse.group/u/jmj)\ **Replies:** 4\ **Last updated:** [July 18, 2023, 3:13pm UTC](https://racket.discourse.group/t/how-to-add-a-search-box-to-a-scrrible-document/2112 "2023-07-18T15:13:14Z")
Hello everyone, I am making study notes with scrrible. I hope the notes can be searched, just like Racket documents. How to do that? --- ## [Vim-racket: improved indentexpr](https://racket.discourse.group/t/vim-racket-improved-indentexpr/1908)
**Author:** [@benknoble](https://racket.discourse.group/u/benknoble)\ **Replies:** 5\ **Last updated:** [July 17, 2023, 4:12pm UTC](https://racket.discourse.group/t/vim-racket-improved-indentexpr/1908 "2023-07-17T16:12:50Z")
Been working on an improved indentexpr for vim-racket; if anyone is interesting in helping me dogfood it, please LMK and I'll clean it up and push a branch. Vim 9+ required. Current improvements: handles {} and #\<\ **Author:** [@spdegabrielle](https://racket.discourse.group/u/spdegabrielle)\ **Replies:** 6\ **Last updated:** [July 17, 2023, 9:09am UTC](https://racket.discourse.group/t/documentation-categories/2065 "2023-07-17T09:09:10Z") Hi all I recently noticed that we have documentation for many collections/packages listed in the Miscellaneous Libraries section of https://docs.racket-lang.org/ There are lots of useful categories available so if you … --- ## [Frog on larger sites](https://racket.discourse.group/t/frog-on-larger-sites/2099)
**Author:** [@bremner](https://racket.discourse.group/u/bremner)\ **Replies:** 3\ **Last updated:** [July 16, 2023, 10:40pm UTC](https://racket.discourse.group/t/frog-on-larger-sites/2099 "2023-07-16T22:40:06Z")
I have a moderate sized ikiwiki install (~1500 sub-pages) that I am considering converting to some other static site generator. Frog seems like a candidate, since I like racket, and I've used it for some toy projects.… --- ## [Type and object in Racket](https://racket.discourse.group/t/type-and-object-in-racket/2091)
**Author:** [@damien\_mattei](https://racket.discourse.group/u/damien_mattei)\ **Replies:** 23\ **Last updated:** [July 16, 2023, 3:26pm UTC](https://racket.discourse.group/t/type-and-object-in-racket/2091 "2023-07-16T15:26:20Z")
Hello, what is the best way to define a class and to be able to derive a type associated with it? example : creating a matrix object and having a matrix? predicate to check it type. i want to create a matrix that will… [Previous page](https://racket.discourse.group/latest.md?page=41) [Next page](https://racket.discourse.group/latest.md?page=43)