Gambit-list Juin 2011

gambit-list@iro.umontreal.ca

20 participants
24 discussions

Edge triggered I/O with libevent
by Adam Langley 04 Avr '13

04 Avr '13

Gambit uses the select call on POSIX systems to multiplex IO operations. This is fine for small numbers of file descriptors, but falls apart quickly with large numbers[1]. libevent[2] is a wrapper library around a number of modern IO multiplexing systems (epoll on Linux, kqueue on the BSDs as well as poll and select). Attached is a patch which converts Gambit to using edge triggered I/O with epoll and libevent. This also requires a patch (attached) of libevent since the standard distribution doesn't include edge triggering support and the upstream appears to be on holiday. (epoll is required because I don't have a BSD box on which to develop edge triggering support for kqueue) This patch (for Gambit) preprocesses away to nothing unless --enable-libevent is passed to the configure script. (Note that, since this patches the configure.ac script, you'll need to run autoconf to regenerate). I hope I've not broken anything, but at this stage I've only tested that the console and tcp ports work. This patch (in the future) should also allow people, who write programs which use socket calls directly, to integrate into the main event loop at some point. Testing is more than welcome and, if you find a form of IO which is broken, please email me. [1] http://monkey.org/~provos/libevent/libevent-benchmark2.jpg [2] http://monkey.org/~provos/libevent/ -- Adam Langley agl(a)imperialviolet.org http://www.imperialviolet.org (+44) (0)7906 332512 PGP: 9113 256A CC0F 71A6 4C84 5087 CDA5 52DF 2CB6 3D60

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How to pass a u8vector to the FFI
by Mikael 20 Sep '11

20 Sep '11

You do this, by declaring the passed u8vector as a scheme-object in the c-lambda definition. The memory pointer to the u8vector's contents in the C code is resolved by void *u8vectorptr = ___CAST(void*,&___FETCH_U8(___BODY(theu8vectorschemeobjectvariable),___INT(0))); Remember that the pointer is only to be kept until the next return to Scheme. Mikael 2010/3/30 Álvaro Castro-Castilla <alvaro.castro.castilla(a)gmail.com> > Hi! > > Is there a way to pass a u8-vector to a FFI interface somehow? > The way I expect this to work is through a (pointer unsigned-char), but it > obviously doesn't work, claiming a proper C pointer. I would like to be able > to build this arrays from Scheme code. Is there a way? > > Currently I have to call a FFI function to set char by char, calling the > c-lambda function too many times. > > One thing that could work is something that converts u8-vectors to unsigned > char* arrays, does that exist in Gambit? > > > Thanks, > > Álvaro > > _______________________________________________ > Gambit-list mailing list > Gambit-list(a)iro.umontreal.ca > https://webmail.iro.umontreal.ca/mailman/listinfo/gambit-list > >

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Reacquainting myself
by Hendrik Boom 21 Jul '11

21 Jul '11

New to Gambit, old to Scheme and Lisp (bit I've been away from actively using them for decades, and much has changed). I'm refamiliarising myself, taking a small project that I could write in several other languages in an hour, but doing it as learning project instead of a quickie implementation, finding out what's available nowadays. The project is to take some overly dictatorial HTML and liberate it. You know the kind of thing, take out all the excess <br>'s and &nbsp.'s, figure out the real structure they're hiding, and reemit it using <p> and <h5> and other proper tags. Now I can do all this from scratch, reading characters from ports and writing code to lex it and parse it and recognise idioms and such ... but that's so nose-to-the-grindstone. Isn't the whole point of these new Scheme systems that we can work at a more conceptual level? So I ask. What tools and libraries are already there to make this kind of task easier? Or more elaborate tasks of this kind -- because I will run into them later. I look in the web and find myself lost in beginner documentation. I guess I'm looking for links to heavier stuff. -- hendrik

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Re: [gambit-list] Gambit for Android Platform
by Steve Graham 28 Jui '11

28 Jui '11

Not sure what else or how else to test. On Tue Jun 28th, 2011 5:25 AM EDT Keith Flower wrote: >I have some automated JUnit/Robotium tests to drive the app. Repeated (1000x) evaluation of your example expression permuted with other test expressions and programs don't cause problems on a 1.6 emulator (the closest thing I have to your device). However, such tests won't fully exercise my fairly simpleminded Android REPL window code, so bug(s) may lie there. Any further details you note may be helpful. > >Many thanks for the feedback. > >On Jun 27, 2011, at 5:51 PM, Steve Graham wrote: > >> Thanks, Keith. >> >> Thought I should mention that sometimes even simple code causes the app to abort to the desktop. I noticed this happening with "(* (+ 35 31.5) 45)". Sometimes this works and sometimes it aborts. Not sure why. >> >> Steve >> >> On Tue Jun 21st, 2011 1:12 PM EDT Keith Flower wrote: >> >>> Hi Steve, >>> >>> Thanks again for trying out the little app and providing feedback. >>> >>> Depending on the kind of app you want to write, it might not currently be the most efficient process to try to use Gambit, but there are a couple of approaches one might take. If you look in the source for the app, you'll see Scheme code working with HTML for the app's "Edit Scripts" page. Another alternative would be adding Java-Native (JNI) functions to allow Gambit to make the actual Java/Android function calls you desire. You could also use Gambit to generate C code that you compile with Android's Native Development Toolkit and call from Java using JNI. >>> >>> The tree recursive fibonacci example is designed to consume lots of memory (~7-8 megs), so your phone (and mine) with limited memory resources has to thrash around to satisfy those memory needs. >>> >>> Regards, >>> >>> Keith >>> >>> >>> On Jun 21, 2011, at 7:52 AM, Steve Graham wrote: >>> >>>> Keith, >>>> >>>> I like your implementation, including the features beyond plain Gambit. I wonder if someone could use it as a basis of a system for coding Android apps. >>>> >>>> Question: On the fib function, why do you suppose it was so resource hungry and experienced the faults? I am using a G-1 running version 1.6 . >>>> >>>> Thanks, Steve >>>> >>>> --- >>>> >>>> Gambit v4.6.1 >>>> >>>>> (time (fib 25)) >>>> 47258 ms real time >>>> 8010 ms cpu time (7950 user, 60 system) >>>> 47 collections accounting for 566 ms real time (550 user, 10 system) >>>> 8377804 bytes allocated >>>> 124 minor faults >>>> no major faults >>>> 75025 >>>> >>>> >>>> On Sat Jun 18th, 2011 7:04 PM EDT Keith Flower wrote: >>>> >>>>> Inspired by Marc's iOS Gambit REPL, an alpha Android release and source are available at: >>>>> >>>>> http://apps.keithflower.org/?page_id=152 >>>>> >>>>> Requires Android 2.2. Comments, criticism, suggestions are welcome. >>>>> >>>>> Thanks to all for a great Scheme environment. >>>>> >>>>> Keith >>>>> _______________________________________________ >>>>> Gambit-list mailing list >>>>> Gambit-list(a)iro.umontreal.ca >>>>> https://webmail.iro.umontreal.ca/mailman/listinfo/gambit-list >>>> >>> >> >

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Re: [gambit-list] Gambit for Android Platform
by Steve Graham 28 Jui '11

28 Jui '11

Thanks, Marc. Keith: I added my code as a script and ran it repeatedly from there without a hitch. Steve On Tue Jun 28th, 2011 11:40 AM EDT Marc Feeley wrote: >I suspect that it might be related to garbage collection. If the foreign code (in C) in "Gambit for Android" keeps a reference to a movable Scheme object (or to a still object whose reference count is 0), then if a GC is started from the C code, or from Scheme code called from C, then you will get a dangling reference problem. These GC related problems tend to occur at unpredictable times. > >Here's a suggestion... add a trace at the top of ___garbage_collect (in lib/mem.c) and see if the app aborts soon after a garbage collection. > >Marc > >On 2011-06-28, at 11:02 AM, Steve Graham wrote: > >> Not sure what else or how else to test. >> >> On Tue Jun 28th, 2011 5:25 AM EDT Keith Flower wrote: >> >>> I have some automated JUnit/Robotium tests to drive the app. Repeated (1000x) evaluation of your example expression permuted with other test expressions and programs don't cause problems on a 1.6 emulator (the closest thing I have to your device). However, such tests won't fully exercise my fairly simpleminded Android REPL window code, so bug(s) may lie there. Any further details you note may be helpful. >>> >>> Many thanks for the feedback. >>> >>> On Jun 27, 2011, at 5:51 PM, Steve Graham wrote: >>> >>>> Thanks, Keith. >>>> >>>> Thought I should mention that sometimes even simple code causes the app to abort to the desktop. I noticed this happening with "(* (+ 35 31.5) 45)". Sometimes this works and sometimes it aborts. Not sure why. >>>> >>>> Steve >>>> >>>> On Tue Jun 21st, 2011 1:12 PM EDT Keith Flower wrote: >>>> >>>>> Hi Steve, >>>>> >>>>> Thanks again for trying out the little app and providing feedback. >>>>> >>>>> Depending on the kind of app you want to write, it might not currently be the most efficient process to try to use Gambit, but there are a couple of approaches one might take. If you look in the source for the app, you'll see Scheme code working with HTML for the app's "Edit Scripts" page. Another alternative would be adding Java-Native (JNI) functions to allow Gambit to make the actual Java/Android function calls you desire. You could also use Gambit to generate C code that you compile with Android's Native Development Toolkit and call from Java using JNI. >>>>> >>>>> The tree recursive fibonacci example is designed to consume lots of memory (~7-8 megs), so your phone (and mine) with limited memory resources has to thrash around to satisfy those memory needs. >>>>> >>>>> Regards, >>>>> >>>>> Keith >>>>> >>>>> >>>>> On Jun 21, 2011, at 7:52 AM, Steve Graham wrote: >>>>> >>>>>> Keith, >>>>>> >>>>>> I like your implementation, including the features beyond plain Gambit. I wonder if someone could use it as a basis of a system for coding Android apps. >>>>>> >>>>>> Question: On the fib function, why do you suppose it was so resource hungry and experienced the faults? I am using a G-1 running version 1.6 . >>>>>> >>>>>> Thanks, Steve >>>>>> >>>>>> --- >>>>>> >>>>>> Gambit v4.6.1 >>>>>> >>>>>>> (time (fib 25)) >>>>>> 47258 ms real time >>>>>> 8010 ms cpu time (7950 user, 60 system) >>>>>> 47 collections accounting for 566 ms real time (550 user, 10 system) >>>>>> 8377804 bytes allocated >>>>>> 124 minor faults >>>>>> no major faults >>>>>> 75025 >>>>>> >>>>>> >>>>>> On Sat Jun 18th, 2011 7:04 PM EDT Keith Flower wrote: >>>>>> >>>>>>> Inspired by Marc's iOS Gambit REPL, an alpha Android release and source are available at: >>>>>>> >>>>>>> http://apps.keithflower.org/?page_id=152 >>>>>>> >>>>>>> Requires Android 2.2. Comments, criticism, suggestions are welcome. >>>>>>> >>>>>>> Thanks to all for a great Scheme environment. >>>>>>> >>>>>>> Keith >>>>>>> _______________________________________________ >>>>>>> Gambit-list mailing list >>>>>>> Gambit-list(a)iro.umontreal.ca >>>>>>> https://webmail.iro.umontreal.ca/mailman/listinfo/gambit-list >>>>>> >>>>> >>>> >>> >> >> _______________________________________________ >> Gambit-list mailing list >> Gambit-list(a)iro.umontreal.ca >> https://webmail.iro.umontreal.ca/mailman/listinfo/gambit-list >

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Re: [gambit-list] Gambit for Android Platform
by Steve Graham 28 Jui '11

28 Jui '11

Thanks, Keith. Thought I should mention that sometimes even simple code causes the app to abort to the desktop. I noticed this happening with "(* (+ 35 31.5) 45)". Sometimes this works and sometimes it aborts. Not sure why. Steve On Tue Jun 21st, 2011 1:12 PM EDT Keith Flower wrote: >Hi Steve, > >Thanks again for trying out the little app and providing feedback. > >Depending on the kind of app you want to write, it might not currently be the most efficient process to try to use Gambit, but there are a couple of approaches one might take. If you look in the source for the app, you'll see Scheme code working with HTML for the app's "Edit Scripts" page. Another alternative would be adding Java-Native (JNI) functions to allow Gambit to make the actual Java/Android function calls you desire. You could also use Gambit to generate C code that you compile with Android's Native Development Toolkit and call from Java using JNI. > >The tree recursive fibonacci example is designed to consume lots of memory (~7-8 megs), so your phone (and mine) with limited memory resources has to thrash around to satisfy those memory needs. > >Regards, > >Keith > > >On Jun 21, 2011, at 7:52 AM, Steve Graham wrote: > >> Keith, >> >> I like your implementation, including the features beyond plain Gambit. I wonder if someone could use it as a basis of a system for coding Android apps. >> >> Question: On the fib function, why do you suppose it was so resource hungry and experienced the faults? I am using a G-1 running version 1.6 . >> >> Thanks, Steve >> >> --- >> >> Gambit v4.6.1 >> >>> (time (fib 25)) >> 47258 ms real time >> 8010 ms cpu time (7950 user, 60 system) >> 47 collections accounting for 566 ms real time (550 user, 10 system) >> 8377804 bytes allocated >> 124 minor faults >> no major faults >> 75025 >> >> >> On Sat Jun 18th, 2011 7:04 PM EDT Keith Flower wrote: >> >>> Inspired by Marc's iOS Gambit REPL, an alpha Android release and source are available at: >>> >>> http://apps.keithflower.org/?page_id=152 >>> >>> Requires Android 2.2. Comments, criticism, suggestions are welcome. >>> >>> Thanks to all for a great Scheme environment. >>> >>> Keith >>> _______________________________________________ >>> Gambit-list mailing list >>> Gambit-list(a)iro.umontreal.ca >>> https://webmail.iro.umontreal.ca/mailman/listinfo/gambit-list >> >

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Using a function in a macro
by Benjohn Barnes 20 Jui '11

20 Jui '11

Hi, I think I must not be understanding something basic about macro expansion. I've reduced a more complex failure with macros that I am having to this simple example: > ; Define a function. > (define (inc x) (+ 1 x)) > > ;Define a macro using the function. > (define-macro (macro-inc x) (inc x)) > > ; This works okay. > (define two (inc 1)) > > ; This fails on load with: > ; *** ERROR IN #<procedure #2>, "macro-test.scm"@5.30 -- Unbound variable: inc > (define macro-two (macro-inc 1)) If I try to load this in to gsc (or if I import in to bsc), then when I try and use (expand) macro-inc (as shown in the last line), I get an error. It's as if I'm not allowed to use functions I have defined in the expansion of a macro? Thanks, Benjohn -- benjohn(a)fysh.org - Twitter @benjohnbarnes - Skype benjohnbarnes - Mobile +44 (0) 7968 851 636

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keyword argument: unspecified, or specified to #f?
by Matthew Koichi Grimes 19 Jui '11

19 Jui '11

When a keyword argument is left unspecified, it is initialized to #f. This can get weird for optional boolean arguments. For example: Example: > (define (my-func #!key bool-arg) (if bool-arg bool-arg "bool-arg unspecified")) > (my-func bool-arg: #t) #t > (my-func) "bool-arg unset" > (my-func bool-arg: #f) "bool-arg unset" Is there any way to distinguish between keyword arguments that were never set, and keyword arguments that were set to #f?

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Re: [gambit-list] Gambit for Android Platform
by Steve Graham 19 Jui '11

19 Jui '11

Thanks for the help. However that option is checked. This reminds me of trying to download pdf files before I installed a pdf reader. Same download unsuccessful message. It's like the phone does not know how to handle the file. Steve On Sun Jun 19th, 2011 3:15 AM EDT Keith Flower wrote: >Ah, you may also have to indicate on your phone that you allow installation from "unknown sources". Try Menu->Settings->Applications and make sure the "Unknown sources" box is checked…."Allow installation from non-Market applications". > >On Jun 19, 2011, at 12:02 AM, Steve Graham wrote: > >> Thanks, I have 1.6 >> >> I did as you suggested and it did try to download. The notification, however, stated that the downloaded had been unsuccessful. >> >> Guess the phone does not know how to handle .apk files - other than in the Market app. >> >> Suggestions? >> >> On Sun Jun 19th, 2011 2:06 AM EDT Keith Flower wrote: >> >>> Probably easiest to just use your phone's browser: browse to the link provided, and click on it. The apk should download, after which (on my phone at least) you will get a notification in the menu bar saying "Download complete". Click on that notification, and it should then ask if you want to install the app. >>> >>> What version of Android do you have? >>> >>> Keith >>> >>> On Jun 18, 2011, at 10:42 PM, Steve Graham wrote: >>> >>>> I tried selecting the link and it initiated a download which was unsuccessful. How does one install this apk? >>>> >>>> Thanks, Steve >>>> >>>> --- On Sun, 6/19/11, Keith Flower <keith(a)keithflower.org> wrote: >>>> >>>> From: Keith Flower <keith(a)keithflower.org> >>>> Subject: Re: [gambit-list] Gambit for Android Platform >>>> To: "Steve Graham" <jsgrahamus(a)yahoo.com> >>>> Cc: gambit-list(a)iro.umontreal.ca >>>> Date: Sunday, June 19, 2011, 1:11 AM >>>> >>>> >>>> On Jun 18, 2011, at 8:59 PM, Steve Graham wrote: >>>> >>>>> Can it not run on earlier versions of Android? >>>>> >>>>> >>>> >>>> Hi Steve, >>>> >>>> No particular reason it shouldn't run on earlier versions…I had a device running 2.2 for which I developed, and don't have easy access to other devices for testing. >>>> >>>> I just created a version that may work ok for Android 1.6+. The only source change was in an XML file for layout. A download link can be found here: >>>> >>>> http://apps.keithflower.org/?page_id=152#comment-6 >>>> >>>> Any feedback you have would be most welcome. >>>> >>>> Regards, >>>> >>>> Keith >>>> _______________________________________________ >>>> Gambit-list mailing list >>>> Gambit-list(a)iro.umontreal.ca >>>> https://webmail.iro.umontreal.ca/mailman/listinfo/gambit-list >>> >> >

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Gambit for Android Platform
by Keith Flower 19 Jui '11

19 Jui '11

Inspired by Marc's iOS Gambit REPL, an alpha Android release and source are available at: http://apps.keithflower.org/?page_id=152 Requires Android 2.2. Comments, criticism, suggestions are welcome. Thanks to all for a great Scheme environment. Keith

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Gambit-list Juin 2011