# Questions & Answers **URL:** https://racket.discourse.group/c/questions/6.md?page=10 [Latest](https://racket.discourse.group/latest.md) · [Categories](https://racket.discourse.group/categories.md) · [Tags](https://racket.discourse.group/tags.md) **Page:** 11 --- ## [Generate XML with the xml library](https://racket.discourse.group/t/generate-xml-with-the-xml-library/3194)
**Author:** [@damien\_mattei](https://racket.discourse.group/u/damien_mattei)\ **Replies:** 7\ **Last updated:** [October 18, 2024, 1:32pm UTC](https://racket.discourse.group/t/generate-xml-with-the-xml-library/3194 "2024-10-18T13:32:44Z")
hello, i need to generate an XML document that start with things like that: \ \ **Author:** [@spdegabrielle](https://racket.discourse.group/u/spdegabrielle)\ **Replies:** 2\ **Last updated:** [October 13, 2024, 7:11pm UTC](https://racket.discourse.group/t/trying-out-raco-demod/3207 "2024-10-13T19:11:34Z") Hi Thought I’d try out raco demod but I’ve run into a little roadblock I’ve got a nice little module cli-command/hello.rkt at master · racket-templates/cli-command · GitHub I ran raco demod -o hellod -g hello.rkt and … --- ## [Best practices for tracing type information in a #lang](https://racket.discourse.group/t/best-practices-for-tracing-type-information-in-a-lang/3221)
**Author:** [@JoeyEremondi](https://racket.discourse.group/u/JoeyEremondi)\ **Replies:** 0\ **Last updated:** [October 12, 2024, 4:29am UTC](https://racket.discourse.group/t/best-practices-for-tracing-type-information-in-a-lang/3221 "2024-10-12T04:29:50Z")
I'm wondering what the "best" or recommended way to track type information in a statically typed #lang is, for things like showing type information on hover, printing the types of variables in a context, typing holes wit… --- ## [Best way to implement a "front controller" with Racket's web server](https://racket.discourse.group/t/best-way-to-implement-a-front-controller-with-rackets-web-server/3193)
**Author:** [@badkins](https://racket.discourse.group/u/badkins)\ **Replies:** 4\ **Last updated:** [October 9, 2024, 2:24pm UTC](https://racket.discourse.group/t/best-way-to-implement-a-front-controller-with-rackets-web-server/3193 "2024-10-09T14:24:02Z")
This question is primarily directed to @jeapostrophe , but anyone can feel free to comment :slight\_smile: I think back in 2019, Jay mentioned my use of web-server/dispatchers/dispatch-lift in Axio was less than ideal, a… --- ## [Harness for mutation testing](https://racket.discourse.group/t/harness-for-mutation-testing/3206)
**Author:** [@SamPhillips](https://racket.discourse.group/u/SamPhillips)\ **Replies:** 3\ **Last updated:** [October 9, 2024, 10:55am UTC](https://racket.discourse.group/t/harness-for-mutation-testing/3206 "2024-10-09T10:55:02Z")
Is there are harness to streamline some of the setup of mutation testing (using mutate) for a package? This seems like it could be a neat raco command... Tagging: @CharlieRay668 @jbclements @llazarek --- ## [Running handin server with systemd?](https://racket.discourse.group/t/running-handin-server-with-systemd/3205)
**Author:** [@jbclements](https://racket.discourse.group/u/jbclements)\ **Replies:** 1\ **Last updated:** [October 7, 2024, 10:37pm UTC](https://racket.discourse.group/t/running-handin-server-with-systemd/3205 "2024-10-07T22:37:24Z")
I've been running a handin server (that is, using the handin pkg) for ... uh .. 20 years? I'm still using Daniel J. Bernstein's daemontools to keep it runnning, but a conversation with @SamPhillips at 14th RacketCon conv… --- ## [WeScheme Editor](https://racket.discourse.group/t/wescheme-editor/3202)
**Author:** [@rogert](https://racket.discourse.group/u/rogert)\ **Replies:** 5\ **Last updated:** [October 7, 2024, 2:36pm UTC](https://racket.discourse.group/t/wescheme-editor/3202 "2024-10-07T14:36:05Z")
Attempting to use the WeScheme Editor at https://www.bootstrapworld.org/materials/fall2024/en-us/lessons/hoc-wescheme-intro/index.shtml# , the second page states In the editor, we've written a simple program in the D… --- ## [2 versions of Racket code shared accross network disks](https://racket.discourse.group/t/2-versions-of-racket-code-shared-accross-network-disks/3196)
**Author:** [@damien\_mattei](https://racket.discourse.group/u/damien_mattei)\ **Replies:** 0\ **Last updated:** [October 3, 2024, 9:04am UTC](https://racket.discourse.group/t/2-versions-of-racket-code-shared-accross-network-disks/3196 "2024-10-03T09:04:27Z")
hello, i share on a Dropbox my Racket code between MacOS and Linux (and even i have 2 versions of Racket different) so i got message: loading code: version mismatch expected: "8.13" found: "8.14" in: /Users/matte… --- ## [Confused about tab-panel usage with mred-designer's code](https://racket.discourse.group/t/confused-about-tab-panel-usage-with-mred-designers-code/3189)
**Author:** [@shakeshuck](https://racket.discourse.group/u/shakeshuck)\ **Replies:** 2\ **Last updated:** [October 1, 2024, 10:43pm UTC](https://racket.discourse.group/t/confused-about-tab-panel-usage-with-mred-designers-code/3189 "2024-10-01T22:43:23Z")
I'm using mred-designer, and am confused as to how I am supposed to get children under the appropriate tabs. All the areas I have added appear under tabs-panel, but under the first tab only. The generated code looks like… --- ## [A typewriter problem (and colors...)](https://racket.discourse.group/t/a-typewriter-problem-and-colors/3190)
**Author:** [@damien\_mattei](https://racket.discourse.group/u/damien_mattei)\ **Replies:** 0\ **Last updated:** [October 1, 2024, 10:54am UTC](https://racket.discourse.group/t/a-typewriter-problem-and-colors/3190 "2024-10-01T10:54:11Z")
hello, this could be a joke (and i like that :wink: ) but it is not one... i have a SRFI-105 curly infix reader that works in Racket GUI and CLI (command line interface) too... but for a weird reason the same code doe… --- ## [Predicate Inconsistency in with List, Listof in Polymorphic Functions](https://racket.discourse.group/t/predicate-inconsistency-in-with-list-listof-in-polymorphic-functions/3187)
**Author:** [@wolfraam](https://racket.discourse.group/u/wolfraam)\ **Replies:** 3\ **Last updated:** [September 28, 2024, 11:50pm UTC](https://racket.discourse.group/t/predicate-inconsistency-in-with-list-listof-in-polymorphic-functions/3187 "2024-09-28T23:50:04Z")
Hello, If I define a function taking a heterogeneous list (List A ... A) and try to coerce the argument to a pair with (assert lst pair?) or an unless guard, the program typechecks, but the assertion fails even when I p… --- ## [Writing to output port from GUI callback function stalls event handling on windows](https://racket.discourse.group/t/writing-to-output-port-from-gui-callback-function-stalls-event-handling-on-windows/3185)
**Author:** [@jjsimpso](https://racket.discourse.group/u/jjsimpso)\ **Replies:** 3\ **Last updated:** [September 28, 2024, 5:49pm UTC](https://racket.discourse.group/t/writing-to-output-port-from-gui-callback-function-stalls-event-handling-on-windows/3185 "2024-09-28T17:49:05Z")
I've run into a strange issue while testing my application on Windows. This does not occur on Linux. It is a racket/gui app that uses a custom subclass of canvas% that I wrote. When dragging the scroll bar on Windows, i… --- ## [Getting going with gsl-integration](https://racket.discourse.group/t/getting-going-with-gsl-integration/3164)
**Author:** [@AlexG](https://racket.discourse.group/u/AlexG)\ **Replies:** 4\ **Last updated:** [September 21, 2024, 1:32am UTC](https://racket.discourse.group/t/getting-going-with-gsl-integration/3164 "2024-09-21T01:32:32Z")
I am trying to set up the gsl-integration package. I have installed the package itself, and I have (I think) installed the GNU GSL libraries too. I am using DrRacket 8.6 under Ubuntu 22.04 I tried to install the C lib… --- ## [I want to break free :-) : break in my code with call/cc does not return a value](https://racket.discourse.group/t/i-want-to-break-free-break-in-my-code-with-call-cc-does-not-return-a-value/3169)
**Author:** [@damien\_mattei](https://racket.discourse.group/u/damien_mattei)\ **Replies:** 5\ **Last updated:** [September 19, 2024, 9:48pm UTC](https://racket.discourse.group/t/i-want-to-break-free-break-in-my-code-with-call-cc-does-not-return-a-value/3169 "2024-09-19T21:48:52Z")
i have for (for\_next\_step.rkt) that allow C style for with break and continue. Example: Welcome to DrRacket, version 8.14 \[cs\]. Language: racket, with debugging; memory limit: 8192 MB. \> (require Scheme+/for\_next\_step)… --- ## [For/sum in typed/racket](https://racket.discourse.group/t/for-sum-in-typed-racket/3166)
**Author:** [@ken](https://racket.discourse.group/u/ken)\ **Replies:** 10\ **Last updated:** [September 17, 2024, 6:40pm UTC](https://racket.discourse.group/t/for-sum-in-typed-racket/3166 "2024-09-17T18:40:25Z")
I'm experimenting with typed/racket to see if it can speed up some lengthy numerical calculations. As a first step, I tried to sum all the square roots up to a million, first in plain Racket: (for/sum (\[i 1000000\]) (… --- ## [Importing all struct features? \[inverse of struct-out\]](https://racket.discourse.group/t/importing-all-struct-features-inverse-of-struct-out/3104)
**Author:** [@Greg\_Davidson](https://racket.discourse.group/u/Greg_Davidson)\ **Replies:** 2\ **Last updated:** [September 12, 2024, 7:03pm UTC](https://racket.discourse.group/t/importing-all-struct-features-inverse-of-struct-out/3104 "2024-09-12T19:03:09Z")
I can conveniently provide all of a structure's features, including its id, with a struct-out clause inside of a provide form. Is there an inverse for importing such in a require form without importing everything unrela… --- ## ["path+anchor-\>tag", or, get bluebox given path+anchor](https://racket.discourse.group/t/path-anchor-tag-or-get-bluebox-given-path-anchor/3165)
**Author:** [@greghendershott](https://racket.discourse.group/u/greghendershott)\ **Replies:** 1\ **Last updated:** [September 11, 2024, 7:21pm UTC](https://racket.discourse.group/t/path-anchor-tag-or-get-bluebox-given-path-anchor/3165 "2024-09-11T19:21:00Z")
There exists xref-tag-\>path+anchor. I don't see the reverse -- anything like "xref-path+anchor-\>tag". Is it possible for me to write this myself, and if so, how? Why I ask: Given a documentation path + anchor, I want… --- ## [Hard to get Packages without documentation](https://racket.discourse.group/t/hard-to-get-packages-without-documentation/3157)
**Author:** [@Zeb](https://racket.discourse.group/u/Zeb)\ **Replies:** 9\ **Last updated:** [September 11, 2024, 5:02am UTC](https://racket.discourse.group/t/hard-to-get-packages-without-documentation/3157 "2024-09-11T05:02:15Z")
I want to talk about getting packages installed without their docs. I tried the binary and binary lib options of raco setup and they always tell me the package isn't compatible. I've often had to resort to manually stri… --- ## [Streams questions](https://racket.discourse.group/t/streams-questions/3147)
**Author:** [@matteo-daddio](https://racket.discourse.group/u/matteo-daddio)\ **Replies:** 22\ **Last updated:** [September 9, 2024, 11:49am UTC](https://racket.discourse.group/t/streams-questions/3147 "2024-09-09T11:49:23Z")
Hi, I need to work with streams, I'm reading the racket reference and I have some questions. Why stream-map doesn't accept more than one stream? I read that the one in SRFI-41 does. Why the function f is sometimes pro… --- ## [List of syntaxes objects becomes syntax of a list of objects when porting code from Racket/R6RS to Racket](https://racket.discourse.group/t/list-of-syntaxes-objects-becomes-syntax-of-a-list-of-objects-when-porting-code-from-racket-r6rs-to-racket/3158)
**Author:** [@damien\_mattei](https://racket.discourse.group/u/damien_mattei)\ **Replies:** 3\ **Last updated:** [September 9, 2024, 10:34am UTC](https://racket.discourse.group/t/list-of-syntaxes-objects-becomes-syntax-of-a-list-of-objects-when-porting-code-from-racket-r6rs-to-racket/3158 "2024-09-09T10:34:19Z")
hello, i'm having a bug i have found no explanation for now.... I'm porting my code from Racket/R6RS to Racket. For now i just have to translate R6RS library into Racket module for each files , so there is only the he… --- ## [Migrate packages from 8.13 to 8.14 on Debian](https://racket.discourse.group/t/migrate-packages-from-8-13-to-8-14-on-debian/3151)
**Author:** [@Cyrille](https://racket.discourse.group/u/Cyrille)\ **Replies:** 13\ **Last updated:** [September 8, 2024, 8:15pm UTC](https://racket.discourse.group/t/migrate-packages-from-8-13-to-8-14-on-debian/3151 "2024-09-08T20:15:34Z")
Can't update. Here is the error message open-output-file: error opening file path: /usr/share/racket/pkgs/.LOCKpkgs.rktd system error: Permission non accordée; errno=13 context...: /usr/share/racket/collects/ra… --- ## [Impossible to use gui package installer even after recompile from source](https://racket.discourse.group/t/impossible-to-use-gui-package-installer-even-after-recompile-from-source/3154)
**Author:** [@damien\_mattei](https://racket.discourse.group/u/damien_mattei)\ **Replies:** 1\ **Last updated:** [September 6, 2024, 5:15pm UTC](https://racket.discourse.group/t/impossible-to-use-gui-package-installer-even-after-recompile-from-source/3154 "2024-09-06T17:15:59Z")
hello, having constant crash when using the GUI package manager from a binary install i decided to compile from source the 8.14 version but the compilation finish apparently with this warning: compiler/cm: finish-com… --- ## [When there is " in XML, how to get the whole string?](https://racket.discourse.group/t/when-there-is-quot-in-xml-how-to-get-the-whole-string/3144)
**Author:** [@luistung](https://racket.discourse.group/u/luistung)\ **Replies:** 10\ **Last updated:** [September 3, 2024, 5:44pm UTC](https://racket.discourse.group/t/when-there-is-quot-in-xml-how-to-get-the-whole-string/3144 "2024-09-03T17:44:25Z")
I have a xml file. \ \\{"key1":"value1"}\\ \\{"key2":"value2"}\\ \ read it using (print (xml-\>xexpr (document-element (read-xml (open-input-file "prob… --- ## [Is there a procedure for combinations of list elements?](https://racket.discourse.group/t/is-there-a-procedure-for-combinations-of-list-elements/3148)
**Author:** [@joskoot](https://racket.discourse.group/u/joskoot)\ **Replies:** 3\ **Last updated:** [September 4, 2024, 4:23pm UTC](https://racket.discourse.group/t/is-there-a-procedure-for-combinations-of-list-elements/3148 "2024-09-04T16:23:52Z")
Looking around I could not find a procedure that given a list lst and a natural number n returns a list of all (expt (length lst) n) combinations of the elements of the lst. I have concocted the following, but probably a… --- ## [R6RS and optional arguments with keywords (plot for example)](https://racket.discourse.group/t/r6rs-and-optional-arguments-with-keywords-plot-for-example/3141)
**Author:** [@damien\_mattei](https://racket.discourse.group/u/damien_mattei)\ **Replies:** 4\ **Last updated:** [September 1, 2024, 2:02pm UTC](https://racket.discourse.group/t/r6rs-and-optional-arguments-with-keywords-plot-for-example/3141 "2024-09-01T14:02:00Z")
hello, i can not find a way to use all the feature of plot library in R6RS because i can not pass all the options. : is forbiden in R6RS and so #:something too for example, this works: #!r6rs (library (test-plot) … --- ## [Is it possible to match a set?](https://racket.discourse.group/t/is-it-possible-to-match-a-set/3142)
**Author:** [@dstorrs](https://racket.discourse.group/u/dstorrs)\ **Replies:** 2\ **Last updated:** [September 1, 2024, 4:12pm UTC](https://racket.discourse.group/t/is-it-possible-to-match-a-set/3142 "2024-09-01T16:12:07Z")
I can't believe I've never noticed this before, but is there a way to use match with set? (match (set 1 2 3) \[(set 1 2 3) 'matched\] \[\_ 'not-matched\]) ;; Error: syntax error in pattern in: (set 1 2 3) I suppose it… --- ## [Mutable mpair vs immutable pair, how to port code](https://racket.discourse.group/t/mutable-mpair-vs-immutable-pair-how-to-port-code/3135)
**Author:** [@damien\_mattei](https://racket.discourse.group/u/damien_mattei)\ **Replies:** 4\ **Last updated:** [August 31, 2024, 3:12pm UTC](https://racket.discourse.group/t/mutable-mpair-vs-immutable-pair-how-to-port-code/3135 "2024-08-31T15:12:41Z")
hello again, i have a serious problem porting code from Racket that use immutable list to r6rs at some point i got this error i do not understand and do not know how to solve: \<- : #'parsed-args=.#\ **Author:** [@damien\_mattei](https://racket.discourse.group/u/damien_mattei)\ **Replies:** 3\ **Last updated:** [August 31, 2024, 8:02am UTC](https://racket.discourse.group/t/module-inter-depandancies/3133 "2024-08-31T08:02:46Z") hello, In R6RS code i have a module A (assignment) that needs a module B (set-values-plus) and B also needs module A. Should i put all code in the same module? or is there a way to solve this problem otherwise,because … --- ## [(require plot) not working](https://racket.discourse.group/t/require-plot-not-working/3132)
**Author:** [@AlexG](https://racket.discourse.group/u/AlexG)\ **Replies:** 2\ **Last updated:** [August 30, 2024, 1:33am UTC](https://racket.discourse.group/t/require-plot-not-working/3132 "2024-08-30T01:33:42Z")
I am trying to add some plotting to a program that uses malt - (require malt) - the library that is provided as support to The Little Learner. When I add (require plot), I get the error: . module: identifier already r… --- ## [Trouble finishing installation with racket cs on a raspberry pi](https://racket.discourse.group/t/trouble-finishing-installation-with-racket-cs-on-a-raspberry-pi/3131)
**Author:** [@Zeb](https://racket.discourse.group/u/Zeb)\ **Replies:** 5\ **Last updated:** [August 29, 2024, 6:45pm UTC](https://racket.discourse.group/t/trouble-finishing-installation-with-racket-cs-on-a-raspberry-pi/3131 "2024-08-29T18:45:16Z")
Is this possible? I'm currently trying to build racket and it's hung up on a package that's failing to compile. The error message is completely unhelpful. I'd like to just skip it for now if possible. I also have a hunc… [Previous page](https://racket.discourse.group/c/questions/6.md?page=9) [Next page](https://racket.discourse.group/c/questions/6.md?page=11)