# Show & Tell **URL:** https://racket.discourse.group/c/show-and-tell/7.md?page=1 [Latest](https://racket.discourse.group/latest.md) · [Categories](https://racket.discourse.group/categories.md) · [Tags](https://racket.discourse.group/tags.md) **Page:** 2 --- ## [Custom and simple 3D opengl engine written with racket](https://racket.discourse.group/t/custom-and-simple-3d-opengl-engine-written-with-racket/3663)
**Author:** [@g0zar](https://racket.discourse.group/u/g0zar)\ **Replies:** 1\ **Last updated:** [February 19, 2026, 7:12pm UTC](https://racket.discourse.group/t/custom-and-simple-3d-opengl-engine-written-with-racket/3663 "2026-02-19T19:12:25Z")
Hello racket folks. I thought about sharing my latest project with you. It's a 3D game engine I am making for very simple games. The whole thing was done in about 3 to 4 weeks. I've made 2 whole videos of what it looks … --- ## [Color theory - generate color palettes](https://racket.discourse.group/t/color-theory-generate-color-palettes/4084)
**Author:** [@MickeyKnox](https://racket.discourse.group/u/MickeyKnox)\ **Replies:** 2\ **Last updated:** [January 17, 2026, 5:38pm UTC](https://racket.discourse.group/t/color-theory-generate-color-palettes/4084 "2026-01-17T17:38:36Z")
I've created a small tool to generate color palettes: --- ## [A happy path for Racket in the Collatz benchmark](https://racket.discourse.group/t/a-happy-path-for-racket-in-the-collatz-benchmark/4081)
**Author:** [@gus-massa](https://racket.discourse.group/u/gus-massa)\ **Replies:** 0\ **Last updated:** [January 16, 2026, 2:23pm UTC](https://racket.discourse.group/t/a-happy-path-for-racket-in-the-collatz-benchmark/4081 "2026-01-16T14:23:39Z")
I made a short post about making a "benchmark" published by @awiersdorf faster. The original code is nice, but it's posible to make it faster using some tricks or improving (in the future) the compiler to do the tricks f… --- ## [Inside-out Procedures with Bruijn](https://racket.discourse.group/t/inside-out-procedures-with-bruijn/4028)
**Author:** [@bakgatviooldoos](https://racket.discourse.group/u/bakgatviooldoos)\ **Replies:** 1\ **Last updated:** [December 5, 2025, 5:11pm UTC](https://racket.discourse.group/t/inside-out-procedures-with-bruijn/4028 "2025-12-05T17:11:03Z")
Hi, Racket Discourse. I have been tinkering with the syntax of the bruijn language recently, and I thought I'd share some of the bits I've found interesting so far. The language uses De Bruijn index-notation to name va… --- ## [Amazing Lisp/Scheme](https://racket.discourse.group/t/amazing-lisp-scheme/4031)
**Author:** [@damien\_mattei](https://racket.discourse.group/u/damien_mattei)\ **Replies:** 0\ **Last updated:** [November 29, 2025, 9:07am UTC](https://racket.discourse.group/t/amazing-lisp-scheme/4031 "2025-11-29T09:07:20Z")
I never really understood all the power of Lisp/Scheme syntax associated with the quote facility to represent and use data in a human readable way. We often talk about homoiconicity as the first quality of Lisp/Scheme. … --- ## [TOML library with writer](https://racket.discourse.group/t/toml-library-with-writer/2495)
**Author:** [@bzyeung](https://racket.discourse.group/u/bzyeung)\ **Replies:** 4\ **Last updated:** [November 28, 2025, 5:47pm UTC](https://racket.discourse.group/t/toml-library-with-writer/2495 "2025-11-28T17:47:59Z")
Don't know how many of you are interested in TOML, but the Racket TOML library has been updated and is v1.0 compliant now. An eye is on the upcoming TOML v1.1 so that it shouldn't take too long to update it once the spe… --- ## [BibTeX language](https://racket.discourse.group/t/bibtex-language/4023)
**Author:** [@dominik.pantucek](https://racket.discourse.group/u/dominik.pantucek)\ **Replies:** 2\ **Last updated:** [November 24, 2025, 4:14pm UTC](https://racket.discourse.group/t/bibtex-language/4023 "2025-11-24T16:14:51Z")
Hello fellow Racketeers, as a part of my research, my BibTeX bibliography file started quickly growing both in terms of the number of entries and also in terms of the content included in each entry (for example all the … --- ## [SMathML: A Set of Programs to Write Math on the Web](https://racket.discourse.group/t/smathml-a-set-of-programs-to-write-math-on-the-web/2444)
**Author:** [@ulambda](https://racket.discourse.group/u/ulambda)\ **Replies:** 4\ **Last updated:** [November 21, 2025, 3:40am UTC](https://racket.discourse.group/t/smathml-a-set-of-programs-to-write-math-on-the-web/2444 "2025-11-21T03:40:05Z")
SMathML Recently I decide to translate Hoffman & Kunze into Chinese. And I also want to put it on my homepage. Then I write down these programs to generate html, mathml, svg, and so on. Here is an example I pick up from… --- ## [An Array Language](https://racket.discourse.group/t/an-array-language/3980)
**Author:** [@ulambda](https://racket.discourse.group/u/ulambda)\ **Replies:** 0\ **Last updated:** [October 21, 2025, 8:50pm UTC](https://racket.discourse.group/t/an-array-language/3980 "2025-10-21T20:50:25Z")
miscellaneous/array0.rkt at main · alpha-beta-eta/miscellaneous Basically, I follow the idea in the link below: Image Processing Playground with Array Languages (faithfully) translate the OCaml code into Racket and ma… --- ## [Scheme+ documentation in Scribble Racket format and new release](https://racket.discourse.group/t/scheme-documentation-in-scribble-racket-format-and-new-release/3957)
**Author:** [@damien\_mattei](https://racket.discourse.group/u/damien_mattei)\ **Replies:** 0\ **Last updated:** [September 26, 2025, 9:50am UTC](https://racket.discourse.group/t/scheme-documentation-in-scribble-racket-format-and-new-release/3957 "2025-09-26T09:50:44Z")
Hi, i wrote the documentation of Scheme+ in Scribble, the official Racket format for documentation: https://docs.racket-lang.org/Scheme-PLUS-for-Racket/index.html It contains also many short examples from my codes for… --- ## [Illustrate "anonymous recursive functions" à la PowerShell](https://racket.discourse.group/t/illustrate-anonymous-recursive-functions-a-la-powershell/3932)
**Author:** [@spdegabrielle](https://racket.discourse.group/u/spdegabrielle)\ **Replies:** 1\ **Last updated:** [September 6, 2025, 7:12pm UTC](https://racket.discourse.group/t/illustrate-anonymous-recursive-functions-a-la-powershell/3932 "2025-09-06T19:12:52Z")
Wrote up a nice little macro in @racketlang to illustrate "anonymous recursive functions" à la PowerShell. GitHub - shriram/anonymous-recursive-function: Anonymous recursive functions in Racket https://discord.com/ch… --- ## [μKanren Learnings](https://racket.discourse.group/t/kanren-learnings/3916)
**Author:** [@bakgatviooldoos](https://racket.discourse.group/u/bakgatviooldoos)\ **Replies:** 7\ **Last updated:** [August 31, 2025, 12:15am UTC](https://racket.discourse.group/t/kanren-learnings/3916 "2025-08-31T00:15:01Z")
Hi, Racket Discourse. I am busy researching μKanren to see if it would be suited to some tasks at work, and I thought to share some of my observations on the subject. So, the papers I am reading, are: µKanren: A Mini… --- ## [Melting prefix and infix expression with scheme+ for racket](https://racket.discourse.group/t/melting-prefix-and-infix-expression-with-scheme-for-racket/3802)
**Author:** [@damien\_mattei](https://racket.discourse.group/u/damien_mattei)\ **Replies:** 4\ **Last updated:** [August 27, 2025, 4:08am UTC](https://racket.discourse.group/t/melting-prefix-and-infix-expression-with-scheme-for-racket/3802 "2025-08-27T04:08:11Z")
Hi "Racketeers" :slight\_smile: , i present the lastest feature of scheme+ for racket that allow the melting in an expression of both infix and prefix sub-expressions. There is a disambiguating algorithm based on a fini… --- ## [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 … --- ## [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 … --- ## [Out-parameters in Racket](https://racket.discourse.group/t/out-parameters-in-racket/3855)
**Author:** [@bakgatviooldoos](https://racket.discourse.group/u/bakgatviooldoos)\ **Replies:** 1\ **Last updated:** [July 16, 2025, 12:07pm UTC](https://racket.discourse.group/t/out-parameters-in-racket/3855 "2025-07-16T12:07:17Z")
Hi, Racket Discourse. Long time no see. I have C# coming out my ears, lately, so I thought to make a bit of a racket to clear the air... :drum:. I really enjoy using out-parameters in C#, and I think they make some nic… --- ## [Lazily flattening trees with a gopher](https://racket.discourse.group/t/lazily-flattening-trees-with-a-gopher/3842)
**Author:** [@shawnw](https://racket.discourse.group/u/shawnw)\ **Replies:** 0\ **Last updated:** [July 8, 2025, 1:06pm UTC](https://racket.discourse.group/t/lazily-flattening-trees-with-a-gopher/3842 "2025-07-08T13:06:44Z")
One of the bits of Scheme code on Oleg Kiselyov's site is an implementation of flatten that uses delay to lazily do its thing: (define (flatten x) (define (does-flatten x) (if (not (pair? x)) x (cond … --- ## [Recspecs: an expect testing library](https://racket.discourse.group/t/recspecs-an-expect-testing-library/3796)
**Author:** [@samth](https://racket.discourse.group/u/samth)\ **Replies:** 10\ **Last updated:** [June 18, 2025, 4:00pm UTC](https://racket.discourse.group/t/recspecs-an-expect-testing-library/3796 "2025-06-18T16:00:48Z")
I wanted to try some of the new AI programming tools, so I (or really Codex) wrote a new testing library: GitHub - samth/recspecs: Expect testing for Racket It's "expect testing" which Jane Street has advocated for in t… --- ## [Rhombus on Rosetta Code](https://racket.discourse.group/t/rhombus-on-rosetta-code/3787)
**Author:** [@avrame](https://racket.discourse.group/u/avrame)\ **Replies:** 3\ **Last updated:** [June 17, 2025, 7:58pm UTC](https://racket.discourse.group/t/rhombus-on-rosetta-code/3787 "2025-06-17T19:58:20Z")
In order to learn Rhombus, I’ve been creating small programs and figured I might as well add them to Rosetta Code. So I added a Rhombus page with a few simple examples. I plan to add more when I have the time, but I thou… --- ## [John Conway's FRACTRAN in Racket](https://racket.discourse.group/t/john-conways-fractran-in-racket/3768)
**Author:** [@shawnw](https://racket.discourse.group/u/shawnw)\ **Replies:** 0\ **Last updated:** [June 2, 2025, 12:20pm UTC](https://racket.discourse.group/t/john-conways-fractran-in-racket/3768 "2025-06-02T12:20:28Z")
Recently in a Hacker News post, I learned about the existence of Conway's FRACTRAN, an esoteric programming language based on multiplying integers with rational numbers until the result is an integer (Then repeat). One o… --- ## [C(a|d)ⁿr 1.1: Future-proofing RacketCon](https://racket.discourse.group/t/c-a-d-r-1-1-future-proofing-racketcon/3715)
**Author:** [@Eutro](https://racket.discourse.group/u/Eutro)\ **Replies:** 1\ **Last updated:** [May 4, 2025, 11:09pm UTC](https://racket.discourse.group/t/c-a-d-r-1-1-future-proofing-racketcon/3715 "2025-05-04T23:09:44Z")
With (fifteenth RacketCon) coming up, we will once again be running out of list accessors in racket/list soon. Fortunately, with the new c(a|d)ⁿr release now providing list accessors into the millions and beyond, this pr… --- ## [Game of Life using math/array](https://racket.discourse.group/t/game-of-life-using-math-array/584)
**Author:** [@alexh](https://racket.discourse.group/u/alexh)\ **Replies:** 4\ **Last updated:** [April 19, 2025, 6:39pm UTC](https://racket.discourse.group/t/game-of-life-using-math-array/584 "2025-04-19T18:39:57Z")
Since the use of math/array came up recently in a topic here, I thought, I'll have a look at the package and see how difficult it would be to implement the game of life (Conway's Game of Life - Wikipedia) using it. Turn… --- ## [Decomposing factorial of 300K as the product of 300K factors larger than 100K](https://racket.discourse.group/t/decomposing-factorial-of-300k-as-the-product-of-300k-factors-larger-than-100k/3683)
**Author:** [@gus-massa](https://racket.discourse.group/u/gus-massa)\ **Replies:** 1\ **Last updated:** [April 10, 2025, 4:00am UTC](https://racket.discourse.group/t/decomposing-factorial-of-300k-as-the-product-of-300k-factors-larger-than-100k/3683 "2025-04-10T04:00:00Z")
This is a reply to a challenge proposed by Terence Tao, as a small step to try to prove a conjeture. I solved it with Racket. Not my prettiest code, a lot of single letter variables, a few unnecessary set!. I rewrote … --- ## [Auto Rename Transformers](https://racket.discourse.group/t/auto-rename-transformers/3671)
**Author:** [@Eutro](https://racket.discourse.group/u/Eutro)\ **Replies:** 1\ **Last updated:** [April 2, 2025, 6:43pm UTC](https://racket.discourse.group/t/auto-rename-transformers/3671 "2025-04-02T18:43:39Z")
Have you ever been frustrated with the naming conventions of libraries? Perhaps you are a British person frustrated with programming norms that dictate the use of incorrectly-spelled words like color and normalize? Perha… --- ## [Grego - An very simple stacker lang](https://racket.discourse.group/t/grego-an-very-simple-stacker-lang/3666)
**Author:** [@wilsonSants](https://racket.discourse.group/u/wilsonSants)\ **Replies:** 1\ **Last updated:** [April 2, 2025, 6:28pm UTC](https://racket.discourse.group/t/grego-an-very-simple-stacker-lang/3666 "2025-04-02T18:28:56Z")
This is my first language in racket, it's called grego. It's very simple and silly, you type an greek letter and it returns the letter name in greek. I based it on the Stacker language we learned in Beautiful Racket. … --- ## [Generating image from science for web with curly infix syntax reader and library](https://racket.discourse.group/t/generating-image-from-science-for-web-with-curly-infix-syntax-reader-and-library/3646)
**Author:** [@damien\_mattei](https://racket.discourse.group/u/damien_mattei)\ **Replies:** 0\ **Last updated:** [March 24, 2025, 11:32am UTC](https://racket.discourse.group/t/generating-image-from-science-for-web-with-curly-infix-syntax-reader-and-library/3646 "2025-03-24T11:32:23Z")
Hi, recently i generated image from science data to be integrated in a web page. The special thing being those image and html code was generated with Racket with and extension reader allowing some infix syntax and other… --- ## [Define Paths Pithily](https://racket.discourse.group/t/define-paths-pithily/3606)
**Author:** [@bakgatviooldoos](https://racket.discourse.group/u/bakgatviooldoos)\ **Replies:** 4\ **Last updated:** [March 24, 2025, 8:50am UTC](https://racket.discourse.group/t/define-paths-pithily/3606 "2025-03-24T08:50:12Z")
Hi, Racket Discourse. I thought I'd quickly share this little macro for defining paths originating from a single root (or home), which I've been using for easily referencing paths when writing scripts. Perhaps there is … --- ## [Maybe definitely?](https://racket.discourse.group/t/maybe-definitely/3639)
**Author:** [@bakgatviooldoos](https://racket.discourse.group/u/bakgatviooldoos)\ **Replies:** 0\ **Last updated:** [March 20, 2025, 11:42am UTC](https://racket.discourse.group/t/maybe-definitely/3639 "2025-03-20T11:42:42Z")
Hi, Racket Discourse. It is a public holiday in RSA tomorrow, so today is Friday, haha. I thought I would share a riff on a pattern-expander. From the phc-toolkit, there is a pattern-expander called ~maybe that looks l… --- ## [Make your own Racket 🥁](https://racket.discourse.group/t/make-your-own-racket/3485)
**Author:** [@spdegabrielle](https://racket.discourse.group/u/spdegabrielle)\ **Replies:** 1\ **Last updated:** [March 18, 2025, 5:34pm UTC](https://racket.discourse.group/t/make-your-own-racket/3485 "2025-03-18T17:34:35Z")
Did you know you can make your own Racket installer? Racket has so many options, and I have a habit of destroying my configuration file. As some point in the past I started thinking about creating an installer that inst… --- ## [Exponentiation (n-ary)](https://racket.discourse.group/t/exponentiation-n-ary/3611)
**Author:** [@damien\_mattei](https://racket.discourse.group/u/damien_mattei)\ **Replies:** 5\ **Last updated:** [March 17, 2025, 10:30am UTC](https://racket.discourse.group/t/exponentiation-n-ary/3611 "2025-03-17T10:30:38Z")
Hi, for this end of week i present an n-ary version of the classic expt of Scheme. I needed it because i use n-ary procedures in infix and it worked with +,-,\*,/ which are n-ary but not with expt. I did not know why S… [Previous page](https://racket.discourse.group/c/show-and-tell/7.md) [Next page](https://racket.discourse.group/c/show-and-tell/7.md?page=2)