Gambit-list Novembre 2012

gambit-list@iro.umontreal.ca

12 participants
15 discussions

Efficient Compilation of Tail Calls and Continuations to JavaScript
by Marc Feeley 17 Sep '13

17 Sep '13

Eric Thivierge is in Copenhagen today, at the Scheme Workshop, presenting our latest paper: "Efficient Compilation of Tail Calls and Continuations to JavaScript" You can get the paper on the Scheme Worshop web page: http://users-cs.au.dk/danvy/sfp12/programme-sfp12.html It describes the implementation of tail calls and continuations in Gambit-JS and evaluates its performance. Even if you are not specifically interested in the JavaScript back-end the paper may be interesting to read as it provides a brief explanation of the Gambit Virtual Machine (GVM) and compiler front-end, and a complete example of compilation from Scheme, to GVM, to JavaScript. The performance evaluation (see attached tables) shows that the approach used by Gambit-JS is consistently faster than Scheme2JS and Spock. Marc Execution times using V8 (Chrome 21.0.1180.89): Gambit-JS Scheme2JS Spock fib35 .80 1.54 1.9x 2.40 3.0x nqueens12 .72 .76 1.1x 2.33 3.3x oddeven .83 1.92 2.3x 5.62 6.8x ctak .18 17.64 95.9x .59 3.2x contfib30 1.17 106.01 90.9x 3.38 2.9x btsearch2000 1.35 25.40 18.8x 7.93 5.9x threads10 1.34 24.68 18.5x 4.40 3.3x Execution times using JagerMonkey (Firefox 15.0.1): Gambit-JS Scheme2JS Spock fib35 1.07 7.66 7.2x 20.73 19.4x nqueens12 1.49 2.62 1.8x 12.97 8.7x oddeven 1.09 1.93 1.8x 33.91 31.1x ctak 1.25 30.38 24.3x 1.86 1.5x contfib30 5.88 156.79 26.7x 10.61 1.8x btsearch2000 11.19 27.16 2.4x 16.54 1.5x threads10 6.97 34.36 4.9x 22.11 3.2x Execution times using Nitro (Safari 6.0): Gambit-JS Scheme2JS Spock fib35 1.32 6.53 4.9x 84.69 64.2x nqueens12 1.31 1.89 1.4x 45.15 34.4x oddeven 2.52 1.55 .6x 143.97 57.1x ctak .30 52.88 177.4x 4.18 14.0x contfib30 1.60 2311.69 1443.0x 25.98 16.2x btsearch2000 3.46 102.98 29.7x 92.02 26.6x threads10 3.03 74.21 24.5x 74.88 24.7x

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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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Does Gambit have any dependencies whatsoever?
by Mikael 02 Jan '13

02 Jan '13

Guys, While that Gambit makes platform-independent C code is great, isn't something related we could give attention to more about Gambit, that it has no required dependencies, or how is it? Thinking about it and browsing through ./configure's code I can't see any. I think I noticed it's quite common among Scheme implementations to require quite many dependencies, sometimes even for as central stuff as garbage collection, and obviously there needs to be architectural and performance benefits of making these things customized in one piece, as well as saving some resources and making deployment in any kind of unusual environment exponentially easier, thus giving weight to the identification of the software as 'system software'. There are indeed many times when users quite strongly intuitively prefer slimmer internal software designs that have no effect on how UI:s actually look. Things like load time, UI latency, the direct and indirect effects of CPU and RAM consumption such as RAM fragmentation, and grade of leaky abstractions causing arbitrary small and big errors during installation and runtime would be typical such things, in my understanding. This kind of contrast ought also to be reflected in the very strong enthusiasm found regarding certain computer manufacturers. The only thing even close to a dep I could think of as being relevant for Gambit would be optional bindings for libgmp even though it has a somewhat weird license, now that Brad has been clear that there's so much differentiated algorithms and architecture-specific custom-written assembly in there that it not is feasible to maintain top-notch bignum functionality on a per-language-implementation basis today. Libgmp's interface in it's present state is averse to deep integration though, in the respect that all of its small memory allocations are immovable, so working through its sourcecode and resolving that would be of big benefit for actually taking it in use. In all cases Gambit's built-in bignum library will always be of use as it's neat in all ways. Now, which are the deps - C compiler is optional, and file/process/OS thread/time/network handling is OS-internal so those are not deps. Are there any deps at all? Any thoughts? Brgds, Mikael

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Something like ##device-port-eof? available?
by Mikael 18 Déc '12

18 Déc '12

Dear Marc, How do I know if a device port reached EOF? Is there a flag internally in Gambit somewhere I suppose there is a flag internally somewhere in Gambit that keeps track of this. |wait-for-input|just returns immediately. Of course I could do something like (read-subu8vector v 0 1 port 0) though in this particular application I'd much prefer to only do the socket reading and writing completely outside the scope of Gambit's IO system. If it's not in Gambit then please just say so, there's always another implementation path, though I'd appreciate not to go into higher complexity than needed. Thanks! (define (port-wait-for-input port) (##wait-for-io! (device-port-rdevice-condvar port) (port-rtimeout port)))

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TCP socket never read from/written to using Gambit API:s is completely untouched by Gambit so one can do reads&writes directly with OS on them uninterferedly, right?
by Mikael 18 Déc '12

18 Déc '12

Dear Marc, If I open a TCP port by either |open-tcp-client|, or by (read (open-tcp-server .. )), and then I just let the object remain referenced to as not to GC and do not perform any Gambit IO operations on them whatsoever except for |port-wait-for-input|, |port-wait-for-output| and |force-output|, then I can do any IO operations on the socket that I want to (i.e. reading and writing) directly with the OS and Gambit will *not* interfere with those by by reading in prebuffering purposes or alike? (I do the direct socket access by extracting the TCP port's socket integer from the port object.) Thanks, Mikael (define (port-wait-for-input port) (##wait-for-io! (device-port-rdevice-condvar port) (port-rtimeout port))) (define (port-wait-for-output port) (##wait-for-io! (device-port-wdevice-condvar port) (port-wtimeout port)))

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Current situation of macro systems in Gambit
by Álvaro Castro-Castilla 18 Déc '12

18 Déc '12

Hi, In the past I've used Blackhole, the bundled syntax-case implementation and Alexpander. Each one has its own advantages and disadvantages: blackhole - A: it works well, and not only syntax-rules, but also sc-macro-transformer and er-macro-transformer - D: forces you to use its module system. I think this is a mistake, since is not standard, but anyway it has some current limitations for my work that I tried to fix in my own branch but stem from deep parts of blackhole that would require a deep understanding and rewrite. I tried that already and spent a fair amount of time working with Per these issues and decided to drop it. syntax-case - A: installed with Gambit, easy to setup, supports syntax-case? (I guess so, but haven't tried this last point as I don't really care at the moment) - D: incompatible with DSSSL and other Gambit functionality. I really don't understand why the bundled implementation doesn't support it... Alexpander - A: it is supposed to support DSSSL and be nicer to Gambit - D: I still get errors related to define-macros, even if they are not mixed with define-syntax macros. Taking into account that some of my macros work with both blackhole and syntax-case but not with alexpander, I assume this implementation is less mature/stable. The point is: is there any stable, good implementation of R5RS syntax-rules that is fully-compatible and nice to all of Gambit's functionality? I believe this should be a basic feature of the Gambit ecosystem, but maybe I'm missing something. Any help, ideas or opinions? Best regards, Álvaro Castro-Castilla

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Are flonums passed around within Gambit by value or reference? What's their bit width on 32 & 64bir archs?
by Mikael 18 Déc '12

18 Déc '12

Dear Marc, Something I was curious about for long: So fixnums are passed around in Gambit by value and all objects like closures, pairs, vectors and bignums are passed around by reference. What about flonums? Also, what's the flonum bit width (exponent & fraction respectively) on 32 and 64bit architectures? Thanks, Mikael

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ELS13
by Marc Feeley 29 Nov '12

29 Nov '12

;; ______ _ _____ _ __ ____ ;; | ____| | | / ____| ( ) /_ | |___ \ ;; | |__ | | | (___ |/ | | __) | ;; | __| | | \___ \ | | |__ < ;; | |____ | |____ ____) | | | ___) | ;; |______| |______| |_____/ |_| |____/ ;; ;; European Lisp Symposium 2013 - ELS'13 ;; Madrid, Spain ;; ;; June 1-4, 2013 ;; ;; http://els2013.european-lisp-symposium.org/ The purpose of the European Lisp Symposium is to provide a forum for the discussion and dissemination of all aspects of design, implementation and application of any of the Lisp and Lisp-inspired dialects, including Common Lisp, Scheme, Emacs Lisp, AutoLisp, ISLISP, Dylan, Clojure, ACL2, ECMAScript, Racket, SKILL, Hop and so on. We encourage everyone interested in Lisp to participate. The main theme of the 2013 European Lisp Symposium is on the use of these languages with respect to the current grand challenges: big tables, open data, semantic web, network programming, discovery, robustness, runtime failures, etc. The European Lisp Symposium 2013 solicits the submission of papers with these specific themes in mind, alongside the more traditional tracks which have appeared in the past editions. We invite submissions in the following forms: Papers: Technical papers of up to 15 pages that describe original results or explain known ideas in new and elegant ways. Demonstrations: Abstracts of up to 4 pages for demonstrations of tools, libraries, and applications. Tutorials: Abstracts of up to 4 pages for in-depth presentations about topics of special interest for at least 90 minutes and up to 180 minutes. Lightning talks: Abstracts of up to one page for talks to last for no more than 5 minutes. All submissions should be formatted following the ACM SIGS guidelines and include ACM classification categories and terms. For more information on the submission guidelines and the ACM keywords, see: http://www.acm.org/sigs/publications/proceedings-templates and http://www.acm.org/about/class/1998. Invited speakers: Florian Loitsch, Google: Dart, why you should care. GÈrard Assayag, Ircam: Lisp and Music Research. Important dates: March, 1st 2013: submission deadline April, 5th 2013: acceptance results June, 1-4 2013: symposium Program Commitee: Pascal Costanza, Belgium Ludovic Courtes, INRIA, France Theo D'Hondt, Vrije Universiteit Brussel, Belgium Florian Loitsch, Google, Denmark Christian Queinnec, UPMC, France Kurt Noermark, Denmark Olin Shivers, Northeastern University, USA Manuel Serrano, INRIA, France Didier Verna, EPITA, France Chair: Juan Jose Garcia-Ripoll, local organizer Christian Queinnec, PC co-chair Manuel Serrano, PC co-chair

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(Good til ~Feb or so:) Complete guide to how to set up Black Hole non-syntactictower version, the "std bundled libs" directory, and the Sack web server and client middleware , inclusive of all .tar.gz files required (copy kept on Dumping Grounds as long as relevant).
by Mikael 28 Nov '12

28 Nov '12

(Per: Message for you at the bottom!) Hi Matthew and anyone interested in getting BH non-syntactictower + std-bundled libs + Sack going, *Objective* To make you get going in a Black Hole environment that's been proven by experience to work very very well, giving a rapid start with 'batteries included'-style nicety, which is of value for those who are at a beginner level in these particular tools and libraries. *Note on **validity duration of this email* Basically this email ought to be as good as the last said word, until ~February 2013. Regarding BH, this email and files referred to here will be valid until the BH repos and docs online have been tweaked and a bit restructured. A separate annoncement will be made when this has happened. Regarding Sack, this email and files referred to here are valid currently. The work needed to make the Sack github repo<https://github.com/pereckerdal/sack/> support both Black Hole versions out of the box is almost nil but has not been done. I'll do this personally at latest at the time the step above is done. For anyone interested, there's a production-quality HTTPS server extension to Sack. The next days as from this writing, the HTTPS client functionality is tweaked, as well as an asynchronous http* client API introduced, similar to XmlHttpRequest. If you want this, ask for it. This is a limited-purpose snapshot and for the Black Hole + bundled libs archive, GIT repo files have been duly omitted. *Prerequisites *Super-basic knowledge of Gambit, in particular naturally understanding when ,q = quit Gambit, is needed. Gambit installed on your system. Paths here are written from a Unix point of view but making it go on Windows is straightforward. Optional: Gambit compiled from source, and the source still available in your home directory (~/gambc-v4*). *To install these software components, please follow the following installation steps:* * * Download the archive with non-syntactictower Black Hole and the "bundled libs", + archive overview:* * Download 2012-11-28-bh-non-syntactictower+bundled-libs.tar.gzavailable for direct download at Gambit's Dumping Grounds page<http://dynamo.iro.umontreal.ca/wiki/index.php/Dumping_Grounds#Module_systems> . It will be available there for as long as it's not clearly obsolete. This is a file set that has two parts: * In the root directory: BH, that equals the legacy branch with pull request 45 linked to above included, though I'm sending it to you separately also just to be really safe you get the right thing. * In the std/ directory: The "bundled libraries" found on https://github.com/pereckerdal/std , though in a more tested and tried version, and with some extensions. * Untar this file in your home directory (~), i.e. cd ~; tar xvfz bh-non-syntactictower+bundled-libs.tar.gz . * Compile Black Hole: cd blackhole; gsc build * * Set up Black Hole:* * Make a /usr/bin/bsc file: cat > /usr/bin/bsc #!/bin/sh gsc -:dar,t8,l30,m20000,-n,tn,f8 -e '(load "~~/lib/blackhole/build.o1")(set! module#*compiler-options* (list (string->symbol "debug")))' $@ - [ctrl+D] chmod +x /usr/bin/bsc * Make ~~/lib/blackhole/build.o1 link to ~/blackhole/build.o1: ln -s /usr/local/Gambit-C/lib/blackhole ~/blackhole * For the package resolver for the std package to find module files, which it looks for in ~~/lib/modules/std : ln -s /usr/local/Gambit-C/lib/modules ~/blackhole * * * * Set up the bundled libraries:* * the (std net/tcp-ip) module has some lowlevel dependencies, if you want access to it, copy lib/*.h of your Gambit source distribution into /usr/local/Gambit-C/lib/ i.e. something like: cd ~/gambc-v4[tab] cd lib cp *.h /usr/local/Gambit-C/lib/ * Compile the bundle libraries: bsc (modules-compile! (modules-in-dir "~~/lib/modules"))) Please note that compiling the (std string/digest) module may occupy ~1.5-2GB memory. The others should be require much less though. * * Set up the Sack web server and client middleware:* * Create a project directory for yourself, say ~/proj : mkdir ~/proj; cd ~/proj * Download the 2012-11-28-sack-current-for-BH-non-syntactictower.tar.gzfile from Gambit's Dumping Grounds page<http://dynamo.iro.umontreal.ca/wiki/index.php/Dumping_Grounds#Networking_2>. It will be available there for as long as it's not clearly obsolete. * Unpack Sack into ~/proj/lib : mkdir ~/proj/lib; cd ~/proj/lib; tar xvfz ../sack-current-2012-11-28-for-BH-non-syntactictower.tar.gz; cd .. * Optional: Compile Sack: bsc (modules-compile! (modules-in-dir "lib/sack"))) *Done!* * * You can now run Gambit with Black Hole from your shell anytime under the name bsc . It's nicely pre-setup with UTF-8 encoding, clear exception reporting, and per-line output buffering for performance (note, invoking |force-output| after any |display| etc. may be needed). * * *Example HTTP server:* (presuming you're in ~/proj :) bsc (import (std misc/u8v) lib/sack/src/server) (define (simple-webserver! server #!rest rest) (apply sack-start! (cons (lambda (env) (let ((first? #t)) (values 200 '(("Content-Type" . "text/html")) (lambda () (let ((r (and first? (string->utf8-u8vector (server))))) (set! first? #f) r))))) rest))) (simple-webserver! (lambda () "Hello World!") port-number: 5000) *Example HTTP client:* (presuming you're in ~/proj :) bsc (import (std misc/u8v) lib/sack/src/http-client) (utf8-u8vector->string (http-response-get-content (http-get-url " http://dynamo.iro.umontreal.ca/wiki/index.php/Main_Page"))) If you have any queries please don't hesitate to ask. Mikael (*Per:* Dear Per, Through this email I'm providing a temporary workaround for the following, though, can you please include this pull request https://github.com/pereckerdal/blackhole/pull/45 in the legacy BH repo? Matthew and anyone downloading legacy BH from github is experiencing complete malfunction until this pull request is included. Thanks!) 2012/11/28 Matthew Phillips <matthew(a)phillipsoft.biz> > > > On Wed, Nov 28, 2012 at 3:26 PM, Mikael <mikael.rcv(a)gmail.com> wrote: > >> Ah, noted Sack uses the syntactictower branch's module naming scheme for >> SRFI:s. Let me know if I should email over one with the non-syntactictower >> branch's. >> >> >> Apart from what's released online yet, Sack has stable HTTPS server >> support, let me know if you want it. >> >> >> Release of improved HTTPS client support as well as an asynchronous HTTP* >> client API (akin to the API exported by the web browser XHR object) is >> underway. >> >> Brgds >> >> >> > If you could send me the Sack that works with the legacy branch, that > would be wonderful. >

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Http Client confusion
by Matthew Phillips 28 Nov '12

28 Nov '12

Must be a user error, according to the Black Hole documentation there is an http client in std, but that doesn't seem to the case: Gambit Scheme w/ Black Hole (import (std net/http-client)) *** ERROR IN ##execute-program -- No such file or directory (with-input-from-file "/home/matthew/.blackhole/pkgs/std-v0.0.4/net/http-client.scm" '#<procedure #2 bh#read-all-expr>) matthew@notebook-server:~/Downloads/gambtest/sack/src$ ls ~/.blackhole/pkgs/std- v0.0.4/net/ tcpip.ol tcpip.scm So I decide to try Sack, looks to be still developed. Gambit Scheme w/ Black Hole (import http-client) *** ERROR IN ##execute-program -- These variables are undefined: (string->u8vector write-urlencoded) #<module-reference #9 loader: #<loader #10 name: local> path: "/home/matthew... So no luck on this one either. I'm close to doing the dreaded right-it-yourself but would rather not, so far I'm not having luck with BH.

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Gambit-list Novembre 2012