# Latest **URL:** https://racket.discourse.group/latest.md?page=57 [Latest](https://racket.discourse.group/latest.md) · [Categories](https://racket.discourse.group/categories.md) · [Tags](https://racket.discourse.group/tags.md) **Page:** 58 --- ## [Why is lazy faster than memo here?](https://racket.discourse.group/t/why-is-lazy-faster-than-memo-here/1151)
**Author:** [@Grafcube](https://racket.discourse.group/u/Grafcube)\ **Replies:** 5\ **Last updated:** [July 15, 2022, 12:37pm UTC](https://racket.discourse.group/t/why-is-lazy-faster-than-memo-here/1151 "2022-07-15T12:37:25Z")
Hi. I'm new to Racket and I'm learning functional programming. I was reading about lazy evaluation and memoize and I was testing it on this program. #lang lazy ;; #lang racket/base ;; (require memo) ;; (define/memoize… --- ## [Email package maintainers when their packages are broken](https://racket.discourse.group/t/email-package-maintainers-when-their-packages-are-broken/1145)
**Author:** [@winny](https://racket.discourse.group/u/winny)\ **Replies:** 10\ **Last updated:** [July 15, 2022, 1:36am UTC](https://racket.discourse.group/t/email-package-maintainers-when-their-packages-are-broken/1145 "2022-07-15T01:36:04Z")
Would it be beneficial to send emails to pkgs.racket-lang.org package maintainers? I think this would enable maintainers to know about build problems such as undeclared dependencies, breakage due to a racket upgrade, or… --- ## [RacketCon 2022: Hotel information added](https://racket.discourse.group/t/racketcon-2022-hotel-information-added/1149)
**Author:** [@jesse](https://racket.discourse.group/u/jesse)\ **Replies:** 0\ **Last updated:** [July 14, 2022, 11:54am UTC](https://racket.discourse.group/t/racketcon-2022-hotel-information-added/1149 "2022-07-14T11:54:07Z")
RacketCon 2022 planning is picking up steam! In particular, we have managed to reserve blocks of rooms, at reasonable rates, at a couple of hotels near the conference venue. See the RacketCon homepage for details (scroll… --- ## [Is it possible to unsafely assume sub-types in Typed Racket?](https://racket.discourse.group/t/is-it-possible-to-unsafely-assume-sub-types-in-typed-racket/1140)
**Author:** [@pcn](https://racket.discourse.group/u/pcn)\ **Replies:** 1\ **Last updated:** [July 11, 2022, 2:41pm UTC](https://racket.discourse.group/t/is-it-possible-to-unsafely-assume-sub-types-in-typed-racket/1140 "2022-07-11T14:41:20Z")
Typed Racket exposes unsafe primitives that make it possible to unsafely cast a value to an arbitrary type. Is it also possible to use existing unsafe utilities to somehow make Typed Racket assume that one type is anothe… --- ## [What's the common idea to represent types in Racket's LOP?](https://racket.discourse.group/t/whats-the-common-idea-to-represent-types-in-rackets-lop/1144)
**Author:** [@doublex](https://racket.discourse.group/u/doublex)\ **Replies:** 2\ **Last updated:** [July 11, 2022, 11:17am UTC](https://racket.discourse.group/t/whats-the-common-idea-to-represent-types-in-rackets-lop/1144 "2022-07-11T11:17:24Z")
Hi all, I'm new to designing languages in Racket and need some help with general techniques. Suppose I want to build a statically typed language (s-exp) on top of Racket. In my opinion, For the surface language, what … --- ## [Laundry: \`#lang org\`](https://racket.discourse.group/t/laundry-lang-org/1142)
**Author:** [@spdegabrielle](https://racket.discourse.group/u/spdegabrielle)\ **Replies:** 0\ **Last updated:** [July 10, 2022, 8:46pm UTC](https://racket.discourse.group/t/laundry-lang-org/1142 "2022-07-10T20:46:46Z")
Thanks to Tom (@tgbugs) for Laundry; An attempt to specify a formal grammar for Org syntax. The aim of Laundry is to support the Org Mode community; The primary objective of this work is to provide a reference gram… --- ## [Summer #lang party first entry: russian-lang / Programming language based on Russian language and Racket](https://racket.discourse.group/t/summer-lang-party-first-entry-russian-lang-programming-language-based-on-russian-language-and-racket/1138)
**Author:** [@spdegabrielle](https://racket.discourse.group/u/spdegabrielle)\ **Replies:** 0\ **Last updated:** [July 9, 2022, 4:27pm UTC](https://racket.discourse.group/t/summer-lang-party-first-entry-russian-lang-programming-language-based-on-russian-language-and-racket/1138 "2022-07-09T16:27:56Z")
Hi, We have our first submission, russian-lang thanks to Roman Klochkov Quoting Roman; The main purpose is to avoid a lot of parenthesis. The second — to add operators. The last — to make it easy to learn for Russian… --- ## [Languages dev category?](https://racket.discourse.group/t/languages-dev-category/1133)
**Author:** [@spdegabrielle](https://racket.discourse.group/u/spdegabrielle)\ **Replies:** 1\ **Last updated:** [July 10, 2022, 11:08am UTC](https://racket.discourse.group/t/languages-dev-category/1133 "2022-07-10T11:08:24Z")
Hi all Would it be ok for me to make a languages category? The intent is to cover any language design and/or implementation - not be specifically restricted to #lang's. Stay cool & keep hydrated Stephen PS; The Rack… --- ## [Teaching systematic program design to industry folks?](https://racket.discourse.group/t/teaching-systematic-program-design-to-industry-folks/1130)
**Author:** [@jschuster](https://racket.discourse.group/u/jschuster)\ **Replies:** 2\ **Last updated:** [July 9, 2022, 10:46am UTC](https://racket.discourse.group/t/teaching-systematic-program-design-to-industry-folks/1130 "2022-07-09T10:46:57Z")
Hello, Racketeers! I'm part of a new initiative to teach software design at Google, and HtDP's idea of systematic program design has been on my mind lately. I recommended the book recently in an internal mailing list th… --- ## [Questions about Plot / plot3d](https://racket.discourse.group/t/questions-about-plot-plot3d/1134)
**Author:** [@JustinZed](https://racket.discourse.group/u/JustinZed)\ **Replies:** 2\ **Last updated:** [July 9, 2022, 12:30am UTC](https://racket.discourse.group/t/questions-about-plot-plot3d/1134 "2022-07-09T00:30:49Z")
I have several questions about the Plot library, especially plot3d. When clicking and dragging a 3D plot, the altitude won't go below zero, so I can't view the plot from below. Setting the altitude to a negative numbe… --- ## [How can I keep a REPL alive during \`read-eval-print-loop\` + \`with-handlers\` + a contract violation?](https://racket.discourse.group/t/how-can-i-keep-a-repl-alive-during-read-eval-print-loop-with-handlers-a-contract-violation/1126)
**Author:** [@benknoble](https://racket.discourse.group/u/benknoble)\ **Replies:** 4\ **Last updated:** [July 7, 2022, 4:27pm UTC](https://racket.discourse.group/t/how-can-i-keep-a-repl-alive-during-read-eval-print-loop-with-handlers-a-contract-violation/1126 "2022-07-07T16:27:33Z")
I have a program that starts a REPL via (read-eval-print-loop) that happens to be dynamically inside a with-handlers clause. And I noticed something equivalent to the following that might be related to error-escape-handl… --- ## [Syntax of \`id\` in grammar for FEP](https://racket.discourse.group/t/syntax-of-id-in-grammar-for-fep/1109)
**Author:** [@pmatos](https://racket.discourse.group/u/pmatos)\ **Replies:** 13\ **Last updated:** [July 7, 2022, 7:22am UTC](https://racket.discourse.group/t/syntax-of-id-in-grammar-for-fep/1109 "2022-07-07T07:22:19Z")
If I look at the documentation for a linklet grammar here: 14.14 Linklets and the Core Compiler it says: The grammar of an defn-or-expr is similar to the expander’s grammar of fully expanded expressions (see Fully Exp… --- ## [\`with-editor-sequence\`](https://racket.discourse.group/t/with-editor-sequence/1125)
**Author:** [@benknoble](https://racket.discourse.group/u/benknoble)\ **Replies:** 1\ **Last updated:** [July 6, 2022, 10:24pm UTC](https://racket.discourse.group/t/with-editor-sequence/1125 "2022-07-06T22:24:38Z")
I almost can't believe this isn't in the standard library, so here it is: (define (call-with-editor-sequence editor f) (send editor begin-edit-sequence) (f) (send editor end-edit-sequence)) (require syntax/parse/… --- ## [Noob with noob questions](https://racket.discourse.group/t/noob-with-noob-questions/1124)
**Author:** [@Alex](https://racket.discourse.group/u/Alex)\ **Replies:** 9\ **Last updated:** [July 6, 2022, 6:35pm UTC](https://racket.discourse.group/t/noob-with-noob-questions/1124 "2022-07-06T18:35:58Z")
Hi, I'm currently planning to write a DSL for a project, and am evaluating different ways to do this. Racket came up as a good language for writing languages, and I have some questions I couldn't find answers to from si… --- ## [Intervals: Trivial questions from an absolute beginner](https://racket.discourse.group/t/intervals-trivial-questions-from-an-absolute-beginner/1099)
**Author:** [@late\_bloomer](https://racket.discourse.group/u/late_bloomer)\ **Replies:** 12\ **Last updated:** [July 6, 2022, 5:33pm UTC](https://racket.discourse.group/t/intervals-trivial-questions-from-an-absolute-beginner/1099 "2022-07-06T17:33:01Z")
Hi there. I bought the HTDP book over a year ago as a newbie with no background in programming, gave it a little try, but then had to stop for a while... Now I'm back at it with plenty of motivation, and I'm over the 1… --- ## [Zero clause in a \`match\` expression](https://racket.discourse.group/t/zero-clause-in-a-match-expression/1120)
**Author:** [@capfredf](https://racket.discourse.group/u/capfredf)\ **Replies:** 6\ **Last updated:** [July 5, 2022, 5:41pm UTC](https://racket.discourse.group/t/zero-clause-in-a-match-expression/1120 "2022-07-05T17:41:29Z")
according to the documentation for the match form, we don't need to supply a clause to a match expression. For example: (define (g x) (match x)) However, this does not seem very useful to me, because calling g with… --- ## [Scribble to PDF pain](https://racket.discourse.group/t/scribble-to-pdf-pain/1076)
**Author:** [@danprager](https://racket.discourse.group/u/danprager)\ **Replies:** 15\ **Last updated:** [July 5, 2022, 4:45pm UTC](https://racket.discourse.group/t/scribble-to-pdf-pain/1076 "2022-07-05T16:45:34Z")
I'm struggling to get my scribble setup working to produce pdfs. System: Mac M1 Racket: 8.3 CS LaTex: MacTex 2022 With the mouse example from the docs #lang scribble/base @title{On the Cookie-Eating Habits of Mice… --- ## [Are there any 'Developer Evangelist' on the plane?](https://racket.discourse.group/t/are-there-any-developer-evangelist-on-the-plane/1108)
**Author:** [@spdegabrielle](https://racket.discourse.group/u/spdegabrielle)\ **Replies:** 2\ **Last updated:** [July 3, 2022, 2:58pm UTC](https://racket.discourse.group/t/are-there-any-developer-evangelist-on-the-plane/1108 "2022-07-03T14:58:51Z")
Are there any 'Developer Evangelist' on the plane? or does anyone know one who might be up for providing a little advice? I'd like to take up a half hour of the time of someone who knows what they are doing to see if t… --- ## [A tool generating coverage badges](https://racket.discourse.group/t/a-tool-generating-coverage-badges/1118)
**Author:** [@dannypsnl](https://racket.discourse.group/u/dannypsnl)\ **Replies:** 0\ **Last updated:** [July 3, 2022, 1:07am UTC](https://racket.discourse.group/t/a-tool-generating-coverage-badges/1118 "2022-07-03T01:07:11Z")
GitHub - racket-tw/cover-badge: A badge generator for coverage generating coverage badges, which is fully independent of any CI service, you can simply use shell and host your information anywhere! The only not-in-contro… --- ## [Extends existed module?](https://racket.discourse.group/t/extends-existed-module/1117)
**Author:** [@dannypsnl](https://racket.discourse.group/u/dannypsnl)\ **Replies:** 7\ **Last updated:** [July 2, 2022, 9:53pm UTC](https://racket.discourse.group/t/extends-existed-module/1117 "2022-07-02T21:53:09Z")
I'm unsure how to express this problem precisely. Thus, I give some examples. In Racket, a stx module in syntax module can be imported like (require syntax/stx) If I make something related to syntax, and named it a, c… --- ## [The self-hosting \`derive\` macro](https://racket.discourse.group/t/the-self-hosting-derive-macro/1116)
**Author:** [@slg](https://racket.discourse.group/u/slg)\ **Replies:** 0\ **Last updated:** [July 1, 2022, 7:22pm UTC](https://racket.discourse.group/t/the-self-hosting-derive-macro/1116 "2022-07-01T19:22:04Z")
I came up with a derive macro that specializes match as a refactoring tool for self-hosted programs. I built it on top of blossoms I think it's fun to use because any position in expression context can reflect on its ro… --- ## [Racket meet-up Saturday, 2 July 2022 at 18:00 UTC :racket:](https://racket.discourse.group/t/racket-meet-up-saturday-2-july-2022-at-18-00-utc/1094)
**Author:** [@spdegabrielle](https://racket.discourse.group/u/spdegabrielle)\ **Replies:** 6\ **Last updated:** [July 2, 2022, 11:25am UTC](https://racket.discourse.group/t/racket-meet-up-saturday-2-july-2022-at-18-00-utc/1094 "2022-07-02T11:25:27Z")
Racket meet-up Saturday, 2 July 2022 at 18:00 UTC :racket: 2022-07-02T18:00:00Z (UTC) Online: https://gather.town/app/wH1EDG3McffLjrs0/racket-users When: First Saturday EVERY month at UTC: 18:00 Show and tell … --- ## [For/first, for\*/first, for/and, for\*/and, for/last in Typed Racket](https://racket.discourse.group/t/for-first-for-first-for-and-for-and-for-last-in-typed-racket/1002)
**Author:** [@scolobb](https://racket.discourse.group/u/scolobb)\ **Replies:** 3\ **Last updated:** [July 1, 2022, 11:36pm UTC](https://racket.discourse.group/t/for-first-for-first-for-and-for-and-for-last-in-typed-racket/1002 "2022-07-01T23:36:14Z")
Hi, I tried using for/first in Typed Racket in many different ways, in particular like this: (for/first : Integer (\[i : Integer '(1 2 3)\]) (ann i Integer)) As you can see, I put in all type annotations I could think o… --- ## [Setting the koyo port](https://racket.discourse.group/t/setting-the-koyo-port/1103)
**Author:** [@robertpostill](https://racket.discourse.group/u/robertpostill)\ **Replies:** 4\ **Last updated:** [July 1, 2022, 6:14am UTC](https://racket.discourse.group/t/setting-the-koyo-port/1103 "2022-07-01T06:14:31Z")
I have a couple of forms in my config.rkt that I believe set the IP and port of the racket web server: (define-option http-host #:default "127.0.0.1") (define-option http-port #:default (or (getenv "PORT") "8000") (st… --- ## [Punct: Markdown/Racket authoring environment](https://racket.discourse.group/t/punct-markdown-racket-authoring-environment/1106)
**Author:** [@joeld](https://racket.discourse.group/u/joeld)\ **Replies:** 1\ **Last updated:** [June 30, 2022, 9:21am UTC](https://racket.discourse.group/t/punct-markdown-racket-authoring-environment/1106 "2022-06-30T09:21:50Z")
Punct began as sort of a lightweight Pollen replacement, and then became a way of combining CommonMark-flavored Markdown with Racket. It is extremely derivative of both Pollen and Alexis King‘s CommonMark library. I pla… --- ## [Writing the Zuo version number](https://racket.discourse.group/t/writing-the-zuo-version-number/1105)
**Author:** [@LiberalArtist](https://racket.discourse.group/u/LiberalArtist)\ **Replies:** 1\ **Last updated:** [June 30, 2022, 12:13am UTC](https://racket.discourse.group/t/writing-the-zuo-version-number/1105 "2022-06-30T00:13:03Z")
How should Zuo's version number be written? I know that, in Zuo, (hash-ref (runtime-env) 'version) produces 1, but 1 is not a valid-version? in the sense of version/utils. I also know that Racket and Chez Scheme pack th… --- ## [FFI cannot find symbol in shared library despite nm utility saying otherwise](https://racket.discourse.group/t/ffi-cannot-find-symbol-in-shared-library-despite-nm-utility-saying-otherwise/1098)
**Author:** [@kurinoku](https://racket.discourse.group/u/kurinoku)\ **Replies:** 2\ **Last updated:** [June 27, 2022, 3:16pm UTC](https://racket.discourse.group/t/ffi-cannot-find-symbol-in-shared-library-despite-nm-utility-saying-otherwise/1098 "2022-06-27T15:16:39Z")
I'm trying to create a dynamic library out of sxiv since I need to have a programmatically controllable image viewer, I don't really have much experience with shared libraries so it might be an error outside of Racket, b… --- ## [Function and macro to define unique values](https://racket.discourse.group/t/function-and-macro-to-define-unique-values/1097)
**Author:** [@sschwarzer](https://racket.discourse.group/u/sschwarzer)\ **Replies:** 9\ **Last updated:** [June 27, 2022, 5:29am UTC](https://racket.discourse.group/t/function-and-macro-to-define-unique-values/1097 "2022-06-27T05:29:33Z")
I've seen the idiom (struct unique-value ()) to create unique values, for example as default arguments in a function to check with (eq? argument unique-value) if anything was passed for the argument. Since I have only… --- ## [Enable syntax highlighting for REPL in terminal](https://racket.discourse.group/t/enable-syntax-highlighting-for-repl-in-terminal/1096)
**Author:** [@kurinoku](https://racket.discourse.group/u/kurinoku)\ **Replies:** 3\ **Last updated:** [June 24, 2022, 11:22pm UTC](https://racket.discourse.group/t/enable-syntax-highlighting-for-repl-in-terminal/1096 "2022-06-24T23:22:20Z")
Recently my university lends us a VM for a course, I installed racket there and the REPL has colors, I know this is a bit off-topic and has to do with my configuration, but I didn't find any dot file or installation file… --- ## [Nightly builds size of download](https://racket.discourse.group/t/nightly-builds-size-of-download/1095)
**Author:** [@spdegabrielle](https://racket.discourse.group/u/spdegabrielle)\ **Replies:** 1\ **Last updated:** [June 24, 2022, 7:19pm UTC](https://racket.discourse.group/t/nightly-builds-size-of-download/1095 "2022-06-24T19:19:46Z")
Why do the nightly Snapshot Builds from University of Utah and Northwestern University vary so much in size? I tend to use the University of Utah snapshots because they are usually smaller. best wishes Stephen [Previous page](https://racket.discourse.group/latest.md?page=56) [Next page](https://racket.discourse.group/latest.md?page=58)