# Questions & Answers **URL:** https://racket.discourse.group/c/questions/6.md [Latest](https://racket.discourse.group/latest.md) · [Categories](https://racket.discourse.group/categories.md) · [Tags](https://racket.discourse.group/tags.md) --- ## [About the Questions & Answers category](https://racket.discourse.group/t/about-the-questions-answers-category/72)
**Author:** [@jbclements](https://racket.discourse.group/u/jbclements)\ **Replies:** 0
Questions about the Racket, related languages, and tools. Got a problem? ask a question here! See also the Racket Frequently Asked Questions. --- ## [Thunk vs. lambda and doc confusion](https://racket.discourse.group/t/thunk-vs-lambda-and-doc-confusion/4388)
**Author:** [@gbellinoz](https://racket.discourse.group/u/gbellinoz)\ **Replies:** 13\ **Last updated:** [September 16, 2026, 11:56pm UTC](https://racket.discourse.group/t/thunk-vs-lambda-and-doc-confusion/4388 "2026-09-16T23:56:51Z")
Hi team, The Thunk glossary entry has a second example that is supposedly turning a function into a thunk, yet it uses the lambda keyword! But thunks exist as a keyword, so why use lambda? Am I missing something, or i… --- ## [PPA falling behind?](https://racket.discourse.group/t/ppa-falling-behind/4385)
**Author:** [@ToddOBryan](https://racket.discourse.group/u/ToddOBryan)\ **Replies:** 2\ **Last updated:** [September 16, 2026, 8:11pm UTC](https://racket.discourse.group/t/ppa-falling-behind/4385 "2026-09-16T20:11:00Z")
@samth The Racket PPA seems to have fallen behind by a couple of versions. Is it still working, or did a problem crop up? --- ## [CLI argument parser for Rhombus](https://racket.discourse.group/t/cli-argument-parser-for-rhombus/4386)
**Author:** [@halloleo](https://racket.discourse.group/u/halloleo)\ **Replies:** 1\ **Last updated:** [September 15, 2026, 3:58pm UTC](https://racket.discourse.group/t/cli-argument-parser-for-rhombus/4386 "2026-09-15T15:58:28Z")
I want to write a small CLI program in Rhombus. Does Rhombus have a CLI argument parser which can generate a help text and validate options and positional arguments? Many thanks for any help in advance. --- ## [How to require a submodule made with module\*?](https://racket.discourse.group/t/how-to-require-a-submodule-made-with-module/4380)
**Author:** [@joskoot](https://racket.discourse.group/u/joskoot)\ **Replies:** 3\ **Last updated:** [September 13, 2026, 8:09pm UTC](https://racket.discourse.group/t/how-to-require-a-submodule-made-with-module/4380 "2026-09-13T20:09:24Z")
trying to require a submodule made with module\* I get the following error: require: unknown module module name: (submod 'anonymous-module\[2096977\] aap) I have tried some variations on the line marked with \<---, but no… --- ## [Futures not running parallely](https://racket.discourse.group/t/futures-not-running-parallely/4366)
**Author:** [@joskoot](https://racket.discourse.group/u/joskoot)\ **Replies:** 9\ **Last updated:** [September 12, 2026, 9:58am UTC](https://racket.discourse.group/t/futures-not-running-parallely/4366 "2026-09-12T09:58:02Z")
\#| I Try to use futures for parallelization. I have 12 processors. The task manager (Windows) tells me that only one processor is used. Question: why aren't the futures run parallely? I Run from the definitions window of… --- ## [What do I need the Drawing Context for?](https://racket.discourse.group/t/what-do-i-need-the-drawing-context-for/4369)
**Author:** [@halloleo](https://racket.discourse.group/u/halloleo)\ **Replies:** 2\ **Last updated:** [September 3, 2026, 12:33pm UTC](https://racket.discourse.group/t/what-do-i-need-the-drawing-context-for/4369 "2026-09-03T12:33:00Z")
New here - and new to Rhombus! Via the pict module I generate little pictures. In the REPL they are displayed immediately. Now I try to write the pictures to a file, so that I can run the Rhombus program from a normal … --- ## [Rhombus : + on draw.Point](https://racket.discourse.group/t/rhombus-on-draw-point/4364)
**Author:** [@dharmatech](https://racket.discourse.group/u/dharmatech)\ **Replies:** 3\ **Last updated:** [September 3, 2026, 12:29am UTC](https://racket.discourse.group/t/rhombus-on-draw-point/4364 "2026-09-03T00:29:25Z")
Hey y'all :man\_raising\_hand: Is there a way to use + on draw.Point? So, something like this: #lang rhombus/static import: draw open operator ((a :: Point) + (b :: Point)): Point(a.x + b.x, a.y + b.y) def a = Po… --- ## [Output of drawings to files](https://racket.discourse.group/t/output-of-drawings-to-files/4139)
**Author:** [@jsampson45](https://racket.discourse.group/u/jsampson45)\ **Replies:** 7\ **Last updated:** [August 3, 2026, 9:42am UTC](https://racket.discourse.group/t/output-of-drawings-to-files/4139 "2026-08-03T09:42:46Z")
Is it possible to output a drawing made with the draw module or Metapict or the turtle graphics library to a file such as png or jpeg? --- ## [Make-variable-like-transformer](https://racket.discourse.group/t/make-variable-like-transformer/4323)
**Author:** [@joskoot](https://racket.discourse.group/u/joskoot)\ **Replies:** 2\ **Last updated:** [July 20, 2026, 3:09pm UTC](https://racket.discourse.group/t/make-variable-like-transformer/4323 "2026-07-20T15:09:59Z")
Why does the following give an error? state-a: undefined; cannot reference an identifier before its definition in module: 'anonymous-module Wrong use of datum-\>syntax? How to fix this? #lang racket (require (for-s… --- ## [How to reinstall raylib?](https://racket.discourse.group/t/how-to-reinstall-raylib/4320)
**Author:** [@MickeyKnox](https://racket.discourse.group/u/MickeyKnox)\ **Replies:** 1\ **Last updated:** [July 17, 2026, 10:02pm UTC](https://racket.discourse.group/t/how-to-reinstall-raylib/4320 "2026-07-17T22:02:20Z")
I recently upgraded my system, which also upgraded racket from version 8.18 to 9.2. Now I want to run my project, which requires recompiling, but it doesn't seem to find raylib. When running raco setup raylib, I get thi… --- ## [Nanopass installation failed](https://racket.discourse.group/t/nanopass-installation-failed/4319)
**Author:** [@Antigen-11](https://racket.discourse.group/u/Antigen-11)\ **Replies:** 2\ **Last updated:** [July 16, 2026, 12:03pm UTC](https://racket.discourse.group/t/nanopass-installation-failed/4319 "2026-07-16T12:03:51Z")
Hello everyone! The following errors occurred when I tried to install nanopass. How should I install it correctly? # raco pkg install nanopass Resolving "nanopass" via https://download.racket-lang.org/releases/9.2/cata… --- ## [State of a viewport of graphics/graphics](https://racket.discourse.group/t/state-of-a-viewport-of-graphics-graphics/4309)
**Author:** [@joskoot](https://racket.discourse.group/u/joskoot)\ **Replies:** 2\ **Last updated:** [July 7, 2026, 3:38pm UTC](https://racket.discourse.group/t/state-of-a-viewport-of-graphics-graphics/4309 "2026-07-07T15:38:23Z")
Would it be possible to add a procedure to library graphics/graphics showing the state of a viewport (open, hidden or closed)? When closing a viewport in the title bar (upper right corner) while the program is waiting f… --- ## [Can't I use symbols in case?](https://racket.discourse.group/t/cant-i-use-symbols-in-case/4310)
**Author:** [@MickeyKnox](https://racket.discourse.group/u/MickeyKnox)\ **Replies:** 4\ **Last updated:** [July 6, 2026, 11:39pm UTC](https://racket.discourse.group/t/cant-i-use-symbols-in-case/4310 "2026-07-06T23:39:07Z")
Check out this small snippet from the REPL: \> (define (foo p) (case p (('bar) 1) (else 2))) \> (foo 'bar) 2 I expected to the call (foo 'bar) would return 1. Why is 'bar not matched? --- ## [Https://github.com/joskoot/hanoi](https://racket.discourse.group/t/https-github-com-joskoot-hanoi/4306)
**Author:** [@joskoot](https://racket.discourse.group/u/joskoot)\ **Replies:** 2\ **Last updated:** [July 3, 2026, 6:52pm UTC](https://racket.discourse.group/t/https-github-com-joskoot-hanoi/4306 "2026-07-03T18:52:35Z")
I have a repository: GitHub - joskoot/hanoi: GUI for playing the game of The Tower of Hanoi · GitHub It depends on graphics/graphics. When I try to install it with DrRackets package manager I get the following error: … --- ## [HtDP speed curiosity](https://racket.discourse.group/t/htdp-speed-curiosity/4302)
**Author:** [@matteo-daddio](https://racket.discourse.group/u/matteo-daddio)\ **Replies:** 2\ **Last updated:** [June 28, 2026, 7:37pm UTC](https://racket.discourse.group/t/htdp-speed-curiosity/4302 "2026-06-28T19:37:49Z")
Hello, I'm reading HtDP, a very interesting and well written book. I’m on chapter VI about accumulators. The note on speed compares two different functions, one with an accumulator and one with natural recursion. Su… --- ## [DrRacket Package Manager Question](https://racket.discourse.group/t/drracket-package-manager-question/4291)
**Author:** [@ndykman](https://racket.discourse.group/u/ndykman)\ **Replies:** 8\ **Last updated:** [June 24, 2026, 10:38pm UTC](https://racket.discourse.group/t/drracket-package-manager-question/4291 "2026-06-24T22:38:15Z")
On Windows 11 here. When I install or update package via the "Package Manager..." menu item, it opens up a console window that stays after the operation is done. If the window is closed, DrRacket closes. Is this a known… --- ## [Rhombus version of HtDP student languages](https://racket.discourse.group/t/rhombus-version-of-htdp-student-languages/4300)
**Author:** [@nadeemabdulhamid](https://racket.discourse.group/u/nadeemabdulhamid)\ **Replies:** 0\ **Last updated:** [June 24, 2026, 7:44pm UTC](https://racket.discourse.group/t/rhombus-version-of-htdp-student-languages/4300 "2026-06-24T19:44:53Z")
I'm curious if there is thought of eventually developing a Rhombus version of the HtDP student languages? I know Pyret is syntactically similar, but it's completely isolated from the Racket ecosystem and libraries. I su… --- ## [Percentage sign \[Characters added to make the required 15 here\]](https://racket.discourse.group/t/percentage-sign-characters-added-to-make-the-required-15-here/4284)
**Author:** [@jsampson45](https://racket.discourse.group/u/jsampson45)\ **Replies:** 7\ **Last updated:** [June 22, 2026, 3:47pm UTC](https://racket.discourse.group/t/percentage-sign-characters-added-to-make-the-required-15-here/4284 "2026-06-22T15:47:11Z")
Being very new to Racket, I see in the documentation percentage-sign suffixes "%" or "\<%\>". What do these mean? Are there any documents explaining these? --- ## [Rackup provision for generated scripts (?) (\`\`racket-launcher-names\`\`)](https://racket.discourse.group/t/rackup-provision-for-generated-scripts-racket-launcher-names/4272)
**Author:** [@aanastasiou](https://racket.discourse.group/u/aanastasiou)\ **Replies:** 2\ **Last updated:** [June 8, 2026, 5:58pm UTC](https://racket.discourse.group/t/rackup-provision-for-generated-scripts-racket-launcher-names/4272 "2026-06-08T17:58:17Z")
In a given info.rkt, I am making use of racket-launcher-names which creates a launching script within the current racket installation's bin/ directory. This means that if that directory is in the current PATH, the genera… --- ## [Thead-safe streams](https://racket.discourse.group/t/thead-safe-streams/4196)
**Author:** [@bdeket](https://racket.discourse.group/u/bdeket)\ **Replies:** 9\ **Last updated:** [June 1, 2026, 5:05pm UTC](https://racket.discourse.group/t/thead-safe-streams/4196 "2026-06-01T17:05:04Z")
Hi, the following triggers a "Stream: reentrant or broken delay" error: #lang racket/base (require racket/stream) (define K (stream-cons 1 (for/stream (\[a (in-stream K)\]) … --- ## [Posn in graphics/graphics](https://racket.discourse.group/t/posn-in-graphics-graphics/4273)
**Author:** [@joskoot](https://racket.discourse.group/u/joskoot)\ **Replies:** 4\ **Last updated:** [June 1, 2026, 4:02pm UTC](https://racket.discourse.group/t/posn-in-graphics-graphics/4273 "2026-06-01T16:02:21Z")
Hi posn-s of graphics/graphics are structs with two reals. They are used to locate objects in a viewport. I would expect locations to be identified by two exact nonnegative integers pointing to a pixel. We don't have fr… --- ## [Macro that expands to (module .. (provide (all-defined-out)) ..)](https://racket.discourse.group/t/macro-that-expands-to-module-provide-all-defined-out/4270)
**Author:** [@wluker](https://racket.discourse.group/u/wluker)\ **Replies:** 10\ **Last updated:** [June 1, 2026, 2:30pm UTC](https://racket.discourse.group/t/macro-that-expands-to-module-provide-all-defined-out/4270 "2026-06-01T14:30:21Z")
I'm attempting to create a macro that expands to a submodule, but I can't seem to figure out how to use the (provide (all-defined-out)) form indroduced by the macro. Here is an example: #lang racket/base (module defpkg… --- ## [How can I build a racket package "offline"?](https://racket.discourse.group/t/how-can-i-build-a-racket-package-offline/4230)
**Author:** [@panaeon](https://racket.discourse.group/u/panaeon)\ **Replies:** 3\ **Last updated:** [May 26, 2026, 7:30pm UTC](https://racket.discourse.group/t/how-can-i-build-a-racket-package-offline/4230 "2026-05-26T19:30:16Z")
Hi, I'm trying to build a rash with nix. Obviously standard raco pkg install fails with http errors (this is intentional by nix). Then I tried to link and call setup, but it failed.... Is there any standard way to ach… --- ## [About the youtube procedure in scribble-embedding package](https://racket.discourse.group/t/about-the-youtube-procedure-in-scribble-embedding-package/4162)
**Author:** [@encomer](https://racket.discourse.group/u/encomer)\ **Replies:** 14\ **Last updated:** [May 8, 2026, 10:06pm UTC](https://racket.discourse.group/t/about-the-youtube-procedure-in-scribble-embedding-package/4162 "2026-05-08T22:06:14Z")
Hello Racket friends: Please, if possible: could you verify\*\* if the youtube procedure in the very useful scribble-embedding package is working fine for you?\*\* In my installation (Racket v9.1, under Windows 10 and the … --- ## [Different behavior racket/base vs. racket/hash](https://racket.discourse.group/t/different-behavior-racket-base-vs-racket-hash/4198)
**Author:** [@alsch](https://racket.discourse.group/u/alsch)\ **Replies:** 6\ **Last updated:** [May 8, 2026, 3:07am UTC](https://racket.discourse.group/t/different-behavior-racket-base-vs-racket-hash/4198 "2026-05-08T03:07:12Z")
How come: #lang racket (define h (make-hash (list (list "a" 1) ) ) ) (hash-ref h "a") returns '(1) \[a list of one element\], but in Advanced Student Language: (define h (ma… --- ## [Callback from OS Thread in FFI lib](https://racket.discourse.group/t/callback-from-os-thread-in-ffi-lib/4188)
**Author:** [@hnmdijkema](https://racket.discourse.group/u/hnmdijkema)\ **Replies:** 3\ **Last updated:** [April 10, 2026, 9:53pm UTC](https://racket.discourse.group/t/callback-from-os-thread-in-ffi-lib/4188 "2026-04-10T21:53:03Z")
A question about callbacks from a C library, where the callback will be initiated from a OS thread. I'd like to initiate a callback as a kind of signal from a C library. The signal will carry one integer value. The ca… --- ## [\#lang htdp/bsl doesn't show coverage info](https://racket.discourse.group/t/lang-htdp-bsl-doesnt-show-coverage-info/4100)
**Author:** [@ToddOBryan](https://racket.discourse.group/u/ToddOBryan)\ **Replies:** 7\ **Last updated:** [April 6, 2026, 6:14pm UTC](https://racket.discourse.group/t/lang-htdp-bsl-doesnt-show-coverage-info/4100 "2026-04-06T18:14:33Z")
I've been transitioning my classes this year to use #lang htdp/bsl instead of picking a language under the menu. But I've just noticed that doing this prevents DrRacket from screaming at them about code missing coverage… --- ## [Conditional define-syntax](https://racket.discourse.group/t/conditional-define-syntax/4181)
**Author:** [@hnmdijkema](https://racket.discourse.group/u/hnmdijkema)\ **Replies:** 2\ **Last updated:** [April 5, 2026, 9:41pm UTC](https://racket.discourse.group/t/conditional-define-syntax/4181 "2026-04-05T21:41:57Z")
I'm trying to not load an FFI and define all functions when it's not available, defining the functions to be something like 'error' on call. Is it possible to do a define-syntax based on the value of a variable? e.g., s… --- ## [Images in scribbles](https://racket.discourse.group/t/images-in-scribbles/4178)
**Author:** [@hnmdijkema](https://racket.discourse.group/u/hnmdijkema)\ **Replies:** 7\ **Last updated:** [April 5, 2026, 11:51am UTC](https://racket.discourse.group/t/images-in-scribbles/4178 "2026-04-05T11:51:21Z")
I’ve got an image in a scribble, and it works in my local setup,but when I try to distributie my package, jt fails,because raco does not find it. What can I do to solve this? [Next page](https://racket.discourse.group/c/questions/6.md?page=1)