http://blog.gmane.org/gmane.comp.lang.racket.user hourly 1 1901-01-01T00:00+00:00 http://gmane.org/img/gmane-25t.png http://gmane.org http://comments.gmane.org/gmane.comp.lang.racket.user/12468 <pre>Hi all, In debugging my second display monitor issue I'm trying to make a little test utility from the Racket source. I've copied a snippet (pasted below) from &lt;somepath&gt;\collects\mred\private\wx\win32\frame.rkt into a new file in the same directory as frame.rkt. Although it will compile (with raco make) and execute from the command line (using racket), DrRacket refuses to compile or execute, failing with the error message: "cannot instantiate `racket/gui/base' a second time in the same process" I've tried changing the order of the files in the require with no success. Can anyone tell me if I'm doing something wrong or if I have a problem with my configuration? Cheers, Kieron. **** #lang racket/base (require ffi/unsafe "utils.rkt" "types.rkt" ) (define-user32 EnumDisplayMonitors (_wfun _HDC _pointer (_wfun #:atomic? #t _pointer _HDC _RECT-pointer _pointer -&gt; _BOOL) _pointer -&gt; _BOOL)) ____________________ Racket Users list: http://lists.racket-lang.org/users </pre> Kieron Hardy 2012-05-26T07:17:44 http://comments.gmane.org/gmane.comp.lang.racket.user/12467 <pre>I can use for/fold to loop through a sequence while having the current element and the previous element of the sequence still available by doing something like this. (for/fold ([previous-element-in-sequence '()][list-being-created '()]) ( [current-element-in-sequence sequence]) (do some stuff) .... (values current-element-in-sequence (cons something list-being-created))) But what I want is to be able to loop through a sequence while having the prior, the current and the next element available. I'm sequencing through a representation of lines of a black and white page of text showing where the black pixels are and from that producing a graph showing the connectivity of the black pixel strips on each line to the ones on the lines above and below it. Using for/fold I'm able to code the graph of connectedness of the black strips on each line to the prior line in a very straightforward way, but I'd like to graph in both directions both to the prior line and to the next line at the same time. Is there a simple way to loop through a sequence and have the prior, current and next element available at the same time. Thanks, Harry ____________________ Racket Users list: http://lists.racket-lang.org/users </pre> Harry Spier 2012-05-26T04:56:18 http://comments.gmane.org/gmane.comp.lang.racket.user/12464 <pre>Why are some Racket functions such a 'member' not designed as booleans? I would expect 'member' to be a boolean. I am inclined to write my own version of 'member' that is boolean. Before I do, I am wondering if the bright person who designed the Racket function: 'member', did so for some very good reason that is not obvious to me. I notice that there are a number of other Racket functions like this, where they return #t or the value of the argument passed to the function, not #t or #f. I am just looking for the concept so that I might be convinced that I should use the racket function as it is, rather than writing a boolean version. Thanks ____________________ Racket Users list: http://lists.racket-lang.org/users </pre> Don Green 2012-05-25T16:29:40 http://comments.gmane.org/gmane.comp.lang.racket.user/12462 <pre>Given the output of Racket's read-words/line function, which produces a list of lists. Each word is in a list, each group of words on a line is in a list, all within a list. Any ideas on how to sort on the car (first element) of each list that corresponds to a line? In other words, I want to sort lines based on the first word on a line. I want to keep the lines intact. Thanks. ____________________ Racket Users list: http://lists.racket-lang.org/users </pre> Don Green 2012-05-25T16:16:31 http://comments.gmane.org/gmane.comp.lang.racket.user/12449 <pre> Hey there! So I'm trying to use racket/serialize according to http://docs.racket-lang.org/reference/serialization.html?q=serialize#(def._((lib._racket/private/serialize..rkt)._deserialize)) According to the third bullet point, custom serializable structure types include a "quoted module path" pointing to a module that provides the serialized structure's serialization info. It seems to be a full absolute filesystem path in my tests. Problem is, I want to send serializable structs across the network to a machine where the module path is different. Is there a sane way to, uh, strip off the absolute parts in that path? I could just mess around with the serialized info myself, but... oy, that just feels nasty. (If anyone's curious, my ultimate goal is to send serializable lambdas to other machines. Just like Distributed Places, but not as conceptually confusing and constraining.) http://blog.racket-lang.org/2009/06/serializable-closures-in-plt-scheme.html Thanks in advance. ____________________ Racket Users list: http://lists.racket-lang.org/users </pre> Michael Wilber 2012-05-25T00:14:20 http://comments.gmane.org/gmane.comp.lang.racket.user/12448 <pre>Hi all, On one of my client's laptops (Windows 7), the attached code detects the second display monitor (get-display-count returns 2), but prints exactly the same values for the location and size of the two displays. i.e. The top-left coordinate and size values returned ((0,0) and 1024 x 768) are the same for both monitors. This effectively maps the second monitor underneath(?) the main monitor, making it inaccessible to Racket. In this particular case the second monitor is a TV connected through the laptop's s-video port. Windows itself sees the two displays and is configured to extend the desktop over both of them and 'Identify monitors' works as expected. At least one other program can see and use the TV without problems. Racket has no problems seeing and using a second display monitor on this same laptop when that second monitor is a video converter box connected through the laptop's VGA port. Also Racket has no problems seeing and using a TV as a second display monitor when connected to my (Vista) laptop's HDMI port. What can I do to troubleshoot this problem? I have searched the source for both 'get-display-left-top-inset' and 'monitor' and only find something relevant in .html and .js document files. Where in the source should I be looking? Thanks in advance for any help. Cheers, Kieron. **** #lang racket/gui (printf "display-count:~a\n" (get-display-count)) (printf "display-depth:~a\n" (get-display-depth)) (for ([m (in-range 0 (get-display-count))]) (let-values ([(mx my) (get-display-left-top-inset #f #:monitor m)] [(mxwob mywob) (get-display-left-top-inset #t #:monitor m)] [(mw mh) (get-display-size #f #:monitor m)] [(mwfs mhfs) (get-display-size #t #:monitor m)] ) (printf "monitor:~a (~a ~a) (~a ~a) (~a ~a) (~a ~a)~n" m mx my mxwob mywob mw mh mwfs mhfs) ) ) ____________________ Racket Users list: http://lists.racket-lang.org/users </pre> Kieron Hardy 2012-05-25T00:08:07 http://comments.gmane.org/gmane.comp.lang.racket.user/12444 <pre>Hi All. I am attempting to get Noels bindings for libgsl working on my machine (OS X 64 bit). https://github.com/noelwelsh/mzgsl My problem is that it crashes DrRacket and I can't pinpoint where it happens. I downloaded gsl using port with sudo port install gsl This downloaded and installed version 1.15. Now racket is able to find and load the libraries. I can now allocated a gsl_vector with (gsl_vector-malloc n). Allas calling gslvector-fill! aka gsl_vector_set_all will crash Racket. The vector structure is defined as: (define-cstruct _gsl_vector ([size _size_t] [stride _size_t] [data _pointer] [block _pointer] [owner _int])) And the actual allocation functions as: (define (gsl_vector-malloc n) (define ptr (malloc _double n 'raw)) (define v (make-gsl_vector n 1 ptr #f 0)) (register-finalizer v (lambda (_) (free ptr))) v) Does this look right? The actual source file is here: https://github.com/noelwelsh/mzgsl/blob/master/low-level/gsl-vector.ss The error message after a crash: Process: DrRacket [62009] Path: /Applications/Racket Full v5.3.0.6/*/DrRacket.app/Contents/MacOS/DrRacket Identifier: org.racket-lang.DrRacket Version: 5.3.0.6 (5.3.0.6) Code Type: X86-64 (Native) Parent Process: bash [62005] Date/Time: 2012-05-24 20:56:26.374 +0200 OS Version: Mac OS X 10.7.3 (11D50b) Report Version: 9 Interval Since Last Report: 6884660 sec Crashes Since Last Report: 77 Per-App Interval Since Last Report: 776847 sec Per-App Crashes Since Last Report: 3 Anonymous UUID: 479A6BDE-6BDF-47B6-AB0F-194A795E4C53 Crashed Thread: 0 Dispatch queue: com.apple.main-thread Exception Type: EXC_BAD_ACCESS (SIGSEGV) Exception Codes: KERN_INVALID_ADDRESS at 0x0000000000000000 VM Regions Near 0: --&gt; __TEXT 0000000100000000-0000000100008000 [ 32K] r-x/rwx SM=COW /Applications/Racket Full v5.3.0.6/DrRacket.app/Contents/MacOS/DrRacket Application Specific Information: objc[62009]: garbage collection is OFF Thread 0 Crashed:: Dispatch queue: com.apple.main-thread 0 libgsl.dylib 0x000000010d152460 gsl_vector_set_all + 32 1 Racket 0x00000001002aee5c ffi_call_unix64 + 76 2 Racket 0x00000001002afa74 ffi_call + 644 3 Racket 0x00000001002a1c56 ffi_do_call + 1558 4 Racket 0x0000000100062282 scheme_do_eval + 9058 5 Racket 0x0000000100064fdc _scheme_apply_multi_from_native + 108 6 ??? 0x00000001007e4078 0 + 4303241336 7 Racket 0x0000000100061f19 scheme_do_eval + 8185 8 Racket 0x00000001000640d5 splice_execute + 229 9 Racket 0x000000010006111f scheme_do_eval + 4607 10 Racket 0x0000000100076754 force_values + 292 11 Racket 0x0000000100080452 scheme_force_value_same_mark + 114 12 ??? 0x00000001007cfdf7 0 + 4303158775 13 Racket 0x0000000100061f19 scheme_do_eval + 8185 14 Racket 0x00000001000822c9 scheme_finish_apply_for_prompt + 873 15 Racket 0x000000010008249c scheme_apply_for_prompt + 92 16 Racket 0x000000010008e062 call_with_prompt + 1282 17 Racket 0x00000001000650f9 _scheme_apply_multi_from_native + 393 18 ??? 0x00000001037e79b0 0 + 4353587632 19 ??? 0x00000001007d20fb 0 + 4303167739 20 ??? 0x00000001037e657c 0 + 4353582460 21 Racket 0x0000000100061f19 scheme_do_eval + 8185 22 Racket 0x00000001000822c9 scheme_finish_apply_for_prompt + 873 23 Racket 0x000000010008249c scheme_apply_for_prompt + 92 24 Racket 0x000000010008e062 call_with_prompt + 1282 25 Racket 0x00000001000650f9 _scheme_apply_multi_from_native + 393 26 ??? 0x00000001037e79b0 0 + 4353587632 27 ??? 0x00000001007c5264 0 + 4303114852 28 Racket 0x0000000100064fdc _scheme_apply_multi_from_native + 108 29 ??? 0x00000001037e699c 0 + 4353583516 30 Racket 0x0000000100061f19 scheme_do_eval + 8185 31 Racket 0x0000000100064fdc _scheme_apply_multi_from_native + 108 32 ??? 0x00000001007cfee0 0 + 4303159008 33 Racket 0x0000000100061f19 scheme_do_eval + 8185 34 Racket 0x00000001000822c9 scheme_finish_apply_for_prompt + 873 35 Racket 0x000000010008249c scheme_apply_for_prompt + 92 36 Racket 0x000000010008e062 call_with_prompt + 1282 37 ??? 0x00000001007c51f7 0 + 4303114743 38 Racket 0x0000000100061f19 scheme_do_eval + 8185 39 Racket 0x00000001000822c9 scheme_finish_apply_for_prompt + 873 40 Racket 0x000000010008249c scheme_apply_for_prompt + 92 41 Racket 0x000000010008e062 call_with_prompt + 1282 42 ??? 0x00000001007d01e5 0 + 4303159781 43 ??? 0x00000001007c5264 0 + 4303114852 44 Racket 0x0000000100076754 force_values + 292 45 Racket 0x0000000100080452 scheme_force_value_same_mark + 114 46 ??? 0x00000001007cfc39 0 + 4303158329 47 Racket 0x0000000100061f19 scheme_do_eval + 8185 48 Racket 0x00000001000822c9 scheme_finish_apply_for_prompt + 873 49 Racket 0x000000010008249c scheme_apply_for_prompt + 92 50 Racket 0x000000010008e062 call_with_prompt + 1282 51 ??? 0x00000001007d01e5 0 + 4303159781 52 Racket 0x0000000100061f19 scheme_do_eval + 8185 53 Racket 0x00000001000802d3 apply_k + 179 54 Racket 0x0000000100080f86 scheme_top_level_do_worker + 1046 55 Racket 0x0000000100280321 start_child + 1153 56 Racket 0x000000010028467a make_subprocess + 570 57 Racket 0x000000010028495e scheme_thread_w_details + 446 ____________________ Racket Users list: http://lists.racket-lang.org/users </pre> Jens Axel Søgaard 2012-05-24T19:21:50 http://comments.gmane.org/gmane.comp.lang.racket.user/12432 <pre>I want to restrict to setting up just the collection I'm developing. I've created a development link `raco planet link dsheap vis-eval 1 0 &lt;path-to-package-dir&gt;`, and now I'd like to generate documentation (or at least see just the errors generated when I do), so I try raco setup -l dsheap/vis-eval:1:0 ...but this generates an error, as does raco setup -l &lt;path-to-package-dir&gt; </pre> Danny Heap 2012-05-23T21:04:54 http://comments.gmane.org/gmane.comp.lang.racket.user/12424 <pre>In the Module Browser, has anyone tried annotating the graph edges with imported symbols that are actually referenced by the importing module? Maybe further annotate those symbols with phases? Neil V. ____________________ Racket Users list: http://lists.racket-lang.org/users </pre> Neil Van Dyke 2012-05-23T18:13:09 http://comments.gmane.org/gmane.comp.lang.racket.user/12422 <pre>Hi, I'm following "The Reasoned Schemer" and implementing the answers in Racket, but for one answer Racket seems to be returning the results in the wrong order. It's number 52, commented out here: https://github.com/rodnaph/the-reasoned-schemer/blob/master/01-playthings.rkt#L215 The answer the book gives is: (tea #t) (cup #t) (#f #t) but the answer Racket gives is (#f #t) (cup #t) (tea #t) Can anyone spot what I've done wrong, or possibly explain the different behaviours? Thanks, rod. ____________________ Racket Users list: http://lists.racket-lang.org/users </pre> rod 2012-05-23T12:44:04 http://comments.gmane.org/gmane.comp.lang.racket.user/12419 <pre>I'm pretty keen to try out some of the new data structures&lt;http://www.ccs.neu.edu/scheme/pubs/sfp10-kth.pdf&gt;for typed Racket, but they haven't landed yet--either in 5.2.1, or in the repo last I checked. Is there any notion of when I might be able to get my hands on them? </pre> Simon Haines 2012-05-23T01:48:42 http://comments.gmane.org/gmane.comp.lang.racket.user/12415 <pre>Hi, I created a planet archive locally with raco planet create, then I installed it into my local cache with raco planet fileinject. All I've written in Dr Racket so far is: (require (planet "something.rkt" ("shawnps" "something-racket.plt" 1 1))) and it runs fine. I can see it in the module browser (View -&gt; Show Module Browser), and when I double click on it, it opens the correct file. But I get "unbound identifier" whenever I try to use any of its functions or structs. Any help is appreciated. Shawn ____________________ Racket Users list: http://lists.racket-lang.org/users </pre> Shawn Smith 2012-05-22T18:28:12 http://comments.gmane.org/gmane.comp.lang.racket.user/12414 <pre>Currently Typed/Racket does not recognized submodules. Type Checker: cannot typecheck unknown form : (module util typed/racket/base ... Will they be supported in the near future. Thanks, Ray ____________________ Racket Users list: http://lists.racket-lang.org/users </pre> Ray Racine 2012-05-22T17:13:23 http://comments.gmane.org/gmane.comp.lang.racket.user/12407 <pre>I've entered the following example from the Racket Guide into DrRacket #lang racket (define-syntax-rule (swap X Y) (let ([tmp X]) (set! X Y) (set! Y tmp))) (let ([tmp 5] [other 6]) (swap tmp other) (list tmp other)) It gives me the correct result: But when I stepped through it with the macro expander I got: [Macro transformation] (module anonymous-module racket (#%module-begin (define-syntax-rule (swap X Y) (let ([tmp X]) (set! X Y) (set! Y tmp))) (let ([tmp 5] [other 6]) (let ([tmp tmp]) (set! tmp other) (set! other tmp)) (list tmp other)))) I was expecting to see something like the Racket Guide description in section 16.1 I.e: "Racket doesn’t produce the naive expansion for the above use of swap. Instead, it produces (let ([tmp 5] [other 6]) (let ([tmp_1 tmp]) (set! tmp other) (set! other tmp_1)) (list tmp other)) " While I do get the correct result, why does the macro expander show me (let ([tmp tmp] ..... instead of (let ([tmp_1 tmp] .... as the Racket Guide says I should. Thanks, Harry ____________________ Racket Users list: http://lists.racket-lang.org/users </pre> Harry Spier 2012-05-22T03:13:48 http://comments.gmane.org/gmane.comp.lang.racket.user/12398 <pre>Hi all, A couple of my students are toying with the idea of generating pseudorandom numbers from ambient sources, and want to try using audio as a source. They are doing it on Linux and not concerned about portability, and they just need to be able to grab some input on demand, so my initial off-the-cuff suggestion (advertised to them as such) was to open /dev/dsp for reading, read the number of bytes they want, and close it. I don't know enough about Linux audio (or audio hacking in general) to know this is a workable way to get it done in Racket, so if any of you have done enough audio I/O work to confirm or refute this idea, or offer a better way, please let me know. Thanks! Best, Jordan ____________________ Racket Users list: http://lists.racket-lang.org/users </pre> Jordan Johnson 2012-05-21T23:59:39 http://comments.gmane.org/gmane.comp.lang.racket.user/12397 <pre>I've been frustrated with trying to compose lexers together. The situation is that I'd like to define a lexer that knows how to give up gracefully, and to give another lexer a go at processing a port. Ideally, I'd like to say something like this: ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; (define lexer-1 (lexer ... [else (lexer-2 ip)])) (define lexer-2 (lexer ... [else (error 'i-dunno)])) ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; As far as I can tell from reading the documentation, I can't make this work nicely. That is, I do not want lexer-1 to consume a character when taking an alternative. So putting: ;;;;;; (define lexer-1 (lexer ... [any-char (lexer-2 ip)])) ;;;;;; despite what the documentation says about how this helps me handle the error condition, is not a solution that sits right with me. It creates a non-composable situation with any other lexers I'd like to work with. To make it compose, I need to somehow get that character back into the port. I don't know how to efficiently push that character back into the port besides using something like racket/port's input-port-append, which is a solution, but not a simple one nor one that immediately comes to mind. The design of the parser-tools/lex library feels like it values simplicity, so I'm wondering: is there a technical reason why parser-tools/lex doesn't have an "else"? ____________________ Racket Users list: http://lists.racket-lang.org/users </pre> Danny Yoo 2012-05-21T23:54:34 http://comments.gmane.org/gmane.comp.lang.racket.user/12392 <pre>Can I get Racket's graphics capability with lazy Scheme? Michael ____________________ Racket Users list: http://lists.racket-lang.org/users </pre> Michael Rice 2012-05-21T20:02:31 http://comments.gmane.org/gmane.comp.lang.racket.user/12391 <pre>I am trying to include a small manual page with my (also small) PLaneT module. Scribble doesn't see the bindings for the functions introduced in my module, judging by the warnings generated by 'raco setup...' --- errors which are also generated when the module is required from the PLanet repository. I was also unable to use &lt; at &gt;examples[], presumably for the same reason. I suppose I could work around the alarming error messages by omitting the documentation, but that seems counter-productive. Any suggestions? I attach my info.rkt, main.rkt, manual.scrbl files, and the errors generated when the module is required. I made a development link to the directory containing those files, ran 'raco setup', created a repository with 'racket planet create...', and then uploaded the repository. </pre> Danny Heap 2012-05-21T19:36:41 http://comments.gmane.org/gmane.comp.lang.racket.user/12384 <pre>If I want to "require" a module for multiple phases, is there a shortcut for that? For example, right now, I have this in a real-world file: (require (for-syntax racket/base syntax/parse "html-template-generate.rkt" "html-template-parse.rkt" "planet-neil-html-writing.rkt") (for-template "html-template-generate.rkt" "html-template-parse.rkt" "planet-neil-html-writing.rkt") syntax/parse "html-template-generate.rkt" "html-template-parse.rkt" "planet-neil-html-writing.rkt" "planet-neil-mcfly.rkt") I would prefer less duplicated text for modules that I know I need to "require" 3 different ways: (require (for-darned-near-every-phase "html-template-generate.rkt" "html-template-parse.rkt" "planet-neil-html-writing.rkt") (for-syntax racket/base syntax/parse) syntax/parse "planet-neil-mcfly.rkt") Unless I'm doing something wrong, needing a module 3 different ways doesn't seem too unusual with the new-fangled syntax transformers. (I don't know whether I'll need quite as many "require"s once submodules make it into the Racket release.) Neil V. ____________________ Racket Users list: http://lists.racket-lang.org/users </pre> Neil Van Dyke 2012-05-21T17:39:19 http://comments.gmane.org/gmane.comp.lang.racket.user/12374 <pre>There was a question on SO on flymake -- an Emacs thing that runs your file through a "syntax checker" and highlights errors. The syntax checker usually means compile the file, which in racket's case is simple: I got it working using "racket -qf &lt;file&gt;" which will show syntax errors without actually running the code. The only caveat is that this true only for module files. It could easily be improved by some naive check that there's a "#lang" in the file. If anyone wants to play with it, here's how to use it: 1. Load flymake as usual (get from the website and add as an autoloaded function or just load directly). 2. Add this code somewhere: (defun flymake-racket-init () (let* ((temp-file (flymake-init-create-temp-buffer-copy 'flymake-create-temp-inplace)) (local-file (file-relative-name temp-file (file-name-directory buffer-file-name)))) (list "racket" (list "-qf" local-file)))) (push '("\\.rkt\\'" flymake-racket-init) flymake-allowed-file-name-masks) 3. Open some "*.rkt" file. </pre> Eli Barzilay 2012-05-21T13:51:36 http://comments.gmane.org/gmane.comp.lang.racket.user/12373 <pre>Hi, I would like to use scriblib/bibtex which looks like a wonderful tool, but I can't seem to have it work: #lang racket (require scriblib/bibtex) (define-bibtex-cite "biblio.bib" ~cite citet generate-bibliography) fails with: ../../usr/lib/racket-5.3.0.8/collects/scriblib/bibtex.rkt:84:9: read-entry: Parsing entry, expected , or }, got #\return; label is "hochreiter_long_1997"; atag is "pages"; aval is "1735--1780" &lt; at &gt; line 9 column 0 byte 219 The offending bib entry, which is the first in the file, is: &lt; at &gt;article{hochreiter_long_1997, author = {Hochreiter, S. and Schmidhuber, J.}, title = {Long {Short-Term} Memory}, volume = {9}, number = {8}, journal = {Neural Computation}, year = {1997}, pages = {1735--1780} } but all other entries I tested alone failed too. I tried adding "," after the pages, after the last "}", change {} to "", but no success. Do I use it incorrectly? (Plus I'd like to use it in slideshow, if anyone has something for that...) Laurent ____________________ Racket Users list: http://lists.racket-lang.org/users </pre> Laurent 2012-05-21T13:46:54 Search the mailing list at Gmane query http://search.gmane.org/?group=$group=gmane.comp.lang.racket.user