Septembre 2012 - Gambit-list - mailman.iro.umontreal.ca

Efficient Compilation of Tail Calls and Continuations to JavaScript
by Marc Feeley 18 Sep '13

18 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 05 Avr '13

05 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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executable works, loadable module segfaults
by REPLeffect 30 Sep '12

30 Sep '12

I came across a strange behavior with Gambit Scheme on Windows (XP, in this case). I wrote a module to convert C++ std::string types to Gambit char-strings. I wanted to use that in a loadable module. This all works fine on Linux, but I also need to use it on Windows. I'm using MinGW's C++ compiler (g++ version 4.6.2 -- which I also used to compile Gambit). And I'm still on version 4.6.5 of Gambit Scheme. I've attached a zipped tar file with an example (6 files, including a build.windows script and a build.linux script). When I load the shared module in gsi on Windows XP, it segfaults in ___garbage_collect(long) -- I believe it was in the call to ___alloc_scmobj. When I load it on Linux it works just fine. The executable built by the scripts on both platforms works just fine. I would love to know what is causing this. I've spent many hours trying to find the source of the problem, and finally narrowed it down to this. Any help/explanations/suggestions would be much appreciated. repleffect

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How reset Gambit source dir? I.e. you did tar xvfz gambc*.tar.gz; cd gambc*; ./configure args; make and now you want to configure or make from scratch, what make command to use?
by Mikael 28 Sep '12

28 Sep '12

Hi, When after having tar xvfz gambc*.tar.gz; cd gambc*;./configure args;make , you want to wipe all binary output produced by make and also any results from configure as to start out all from the beginning, what make command do you use for this? "make clean" wipes something, but, it always fails as gsc-compat or sth like this is not around, so I suppose this means the make script wiped too much (as the gsc-compat invocation is to produce those C files anew, so I suppose they're missin) - also the C files the distro was bundled with, that are precompiled C versions of the system's scm files. What command use for this? Mikael

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Gambit and ØMQ
by Joshua Griffith 28 Sep '12

28 Sep '12

Would it be feasible to run gambit within its own thread and use ØMQ's inproc sockets to synchronously send and receive messages from other threads? I know gambit is not multithreaded, but could ØMQ be used to safely communicate with one gambit thread in a multithreaded application?

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Intermixing syntax-rules and define-macro
by Patrick Li 28 Sep '12

28 Sep '12

Hello, I am having some issues with the subtleties of the low-level define-macro system. The problem seems to be that the identifiers created by syntax-rules are not equivalent to the identifiers created by define-macro. I would really appreciate some help on this. Here is a small example: (define-syntax multi-let (syntax-rules () ((multi-let (vars ...) body ...) (let* [(vars '()) ...] ;; Declare the variables ($set vars) ... ;; Set them to "initial" body ...)))) (define-macro ($set var) `(set! ,var "initial")) ;; Set the variable to "initial" And here is what happens when I try to use it: > (multi-let (x y z) x) *** ERROR IN #<procedure #2> -- Unbound variable: x Thank you very much! For my use case, I am unable to stick completely to using define-syntax thus have to deal with how to intermix these two systems properly. -Patrick

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On cygwin, how compile Gambit with cygwin as target(host?) (as to rely on its libraries with its way of console and file access etc.) and not mingw?
by Mikael 22 Sep '12

22 Sep '12

So typically installation would more or less be ./configure --enable-single-host [--enable-cplusplus]; make; make install . Some months ago I did this on a Cygwin installation (using a nonstandard console driver i.e. not the Microsoft-provided console as used by cmd etc.), and the gsc binary ran within cygwin smoothly. Yesterday I did the same thing again, and what happened when starting gsc was that it created a new console window atop/beyond the Cygwin console window from where gsc was started (and in which it was supposed to execute), and also, the gsc binary seemed to use Windows- not Unix-naming, i.e. "c:\\dir\\dir\\etc." . The configure script's output was the following, that just makes it weirder: checking build system type... i686-pc-cygwin checking host system type... i686-pc-cygwin checking target system type... i686-pc-cygwin checking for gcc... gcc [...] Cygwin apparently made a 'major release' recently and at least now the default gcc distribution used, is called "gcc-mingw-" something, even though I switched to the "gcc-gcc4.4" or something, perhaps still there's something fish in there - which would be funny still, as I suppose Cygwin's gcc by default should produce Cygwin binaries. How resolve? Brgds

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Build fails with --enable-shared on Mac OS X 10.6.8
by Bradley Lucier 22 Sep '12

22 Sep '12

Commands: 28 22:01 git clone https://github.com/feeley/gambit.git 29 22:01 cd gambit 31 22:02 ./configure CC='/pkgs/gcc-4.7.2/bin/gcc -march=core2 -fschedule-insns' --enable-single-host --enable-multiple-versions --enable-shared 32 22:03 make -j 2 bootstrap 33 22:06 make bootclean 34 22:07 make -j 2 Result: DYLD_LIBRARY_PATH=..: ../gsc-boot -:~~bin=../bin,~~lib=../lib,~~include=../include -f -c -check _io.scm DYLD_LIBRARY_PATH=..: ../gsc-boot -:~~bin=../bin,~~lib=../lib,~~include=../include -f -c -check _num.scm make[1]: *** [_num.c] Segmentation fault make[1]: *** Waiting for unfinished jobs.... make[1]: *** [_io.c] Segmentation fault make: *** [all-recursive] Error 1 It builds fine without the --enable-shared. Brad

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module system with letrec
by Cyrille Duret 19 Sep '12

19 Sep '12

hello, I want to make a portable module system using lexical scoping (1). By using a letrec form, one can write (define my-module (lambda () (letrec ((private-fun (lambda () ..)) (public-fun (lambda () ..))) (list 'public-fun public-fun)))) I use the let () form wich I believe is equivalent : (define my-module (lambda () (let () (define private-fun (lambda () ..)) (define public-fun (lambda () ..)) (list 'public-fun public-fun)))) But I have an annoying limitation with letrec. For letrec, each init expression must evaluate without referencing or assigning the value of any of the vars. That is a problem when I want this code to be encapsulated in a module : (define private-fun (lambda (x) ...) (define public-var (private-fun 'a-value)) by putting these expression into a let () form violate the scheme rules (2) The letrec* macro does exactly what I want, unfortunately it is not available in a r5rs system as gambit-c The solution I see is tracking the backward references to variables or functions declared earlier and add a new closure each time a reference is made. The preceding code would be translated by : (define my-module (lambda () (let () (define private-fun (lambda (x) ..)) (let () (define public-var (private-fun 'a-value)) (list 'public-var public-var))))) Is it the best strategy to deal with this problem ? Does the letrec* macro can be written for gambit-c ? thanks cyrille references : 1. Using letrec and lambda to Implement Modules : http://icem-www.folkwang-hochschule.de/~finnendahl/cm_kurse/doc/schintro/sc… 2. letrec in the interpreter : https://mercure.iro.umontreal.ca/pipermail/gambit-list/2005-September/00041…

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Re: [gambit-list] MeroonV3 cause Xcode random freeze on iPhone real device
by Shihpin Tseng 01 Sep '12

01 Sep '12

For now I haven't. It freeze before debugger attach it, without debug info. On Sep 1, 2012, at 3:18 AM, Mikael <mikael.rcv(a)gmail.com> wrote: > Did you find the reason? > > 2012/7/13 Shihpin Tseng <deftsp(a)gmail.com> > I noticed that if run app with MeroonV3 on iPhone real device, Xcode will random freeze, simulator is fine. > > It costs me lots of time to find it out. To someone suffering from this problem also. :) > > ENV: > gambit 4.6.6 + cpp project > MeroonV3-2012Jan20.tar.bz2 > Xcode 4.3.3 > > _______________________________________________ > Gambit-list mailing list > Gambit-list(a)iro.umontreal.ca > https://webmail.iro.umontreal.ca/mailman/listinfo/gambit-list >

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