December 2016 - Gambit-list - mailman.iro.umontreal.ca

Gambit versus Python+GMP: Timing for Chudnovskys' algorithm for pi
by Bradley Lucier 07 Apr '22

07 Apr '22

Bakul Shah wrote a particularly elegant Scheme program for Chudnovskys' algorithm for pi based on the Common Lisp program here: https://bitbucket.org/tarballs_are_good/numericl/src/5fe8fe7089f48ab1c8a388… Nick Craig-Wood wrote a Python program using the GMP multiprecision library that appears to use exactly the same algorithm here: http://www.craig-wood.com/nick/articles/pi-chudnovsky/ I modified both programs a bit and include them here. They time the calculation of $10^n$ digits of pi for $n=1,2,3,4,5,6,7$. The results are heine:~/programs/gambiteer/gambit> !py python pi_chudnovsky_bs_gmpy.py 31415926535897932384626433832795028841971693993751058209749445923078164062862089986280348253421170679 ('chudnovsky_gmpy_mpz_bs: digits', 10, 'time', 1.0967254638671875e-05) ('chudnovsky_gmpy_mpz_bs: digits', 100, 'time', 3.0040740966796875e-05) Last 5 digits 70679 OK ('chudnovsky_gmpy_mpz_bs: digits', 1000, 'time', 0.00025582313537597656) Last 5 digits 01989 OK ('chudnovsky_gmpy_mpz_bs: digits', 10000, 'time', 0.00386810302734375) Last 5 digits 75678 OK ('chudnovsky_gmpy_mpz_bs: digits', 100000, 'time', 0.0834801197052002) Last 5 digits 24646 OK ('chudnovsky_gmpy_mpz_bs: digits', 1000000, 'time', 1.655979871749878) Last 5 digits 58151 OK ('chudnovsky_gmpy_mpz_bs: digits', 10000000, 'time', 30.67442488670349) Last 5 digits 55897 OK heine:~/programs/gambiteer/gambit> gsi chud1.scm Chudnovsky's algorithm using binary splitting in Gambit Scheme: digits 10, CPU time: 0.. Last 5 digits 26535. Chudnovsky's algorithm using binary splitting in Gambit Scheme: digits 100, CPU time: 0.. Last 5 digits 70679. Chudnovsky's algorithm using binary splitting in Gambit Scheme: digits 1000, CPU time: .004. Last 5 digits 1989. Chudnovsky's algorithm using binary splitting in Gambit Scheme: digits 10000, CPU time: .028. Last 5 digits 75678. Chudnovsky's algorithm using binary splitting in Gambit Scheme: digits 100000, CPU time: .472. Last 5 digits 24646. Chudnovsky's algorithm using binary splitting in Gambit Scheme: digits 1000000, CPU time: 6.448. Last 5 digits 58151. Chudnovsky's algorithm using binary splitting in Gambit Scheme: digits 10000000, CPU time: 98.612. Last 5 digits 55897. So it appears that for this algorithm applied to large integers, GMP's bignum routines are about 3-4 times as fast as Gambit's bignum routines. Not so bad. For smaller bignums, GMP has a bigger advantage. The C program gmp-chudnovsky.c includes certain optimizations to this basic algorithm: http://gmplib.org/pi-with-gmp.html ftp://ftp.gmplib.org/pub/misc/gmp-chudnovsky.c On my machine, compiled with gcc -O3 -march=native -o gmp-chudnovsky gmp-chudnovsky.c -lgmp -lm the CPU times for 1,000,000 and 10,000,000 digits are 1.064 and 18.200 seconds, respectively. This is with a somewhat older machine model name : Intel(R) Core(TM)2 Quad CPU Q8200 @ 2.33GHz running Ubuntu 13.04 with heine:~/programs/gambiteer/gambit> gcc -v Using built-in specs. COLLECT_GCC=gcc COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/4.7/lto-wrapper Target: x86_64-linux-gnu Configured with: ../src/configure -v --with-pkgversion='Ubuntu/Linaro 4.7.3-1ubuntu1' --with-bugurl=file:///usr/share/doc/gcc-4.7/README.Bugs --enable-languages=c,c++,go,fortran,objc,obj-c++ --prefix=/usr --program-suffix=-4.7 --enable-shared --enable-linker-build-id --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --with-gxx-include-dir=/usr/include/c++/4.7 --libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --enable-gnu-unique-object --enable-plugin --with-system-zlib --enable-objc-gc --with-cloog --enable-cloog-backend=ppl --disable-cloog-version-check --disable-ppl-version-check --enable-multiarch --disable-werror --with-arch-32=i686 --with-abi=m64 --with-multilib-list=m32,m64,mx32 --with-tune=generic --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu Thread model: posix gcc version 4.7.3 (Ubuntu/Linaro 4.7.3-1ubuntu1) heine:~/programs/gambiteer/gambit> gsi -v v4.6.9 20130607151908 x86_64-unknown-linux-gnu "./configure '--enable-single-host' '--enable-multiple-versions' '--enable-shared'" and the Ubuntu-provided GMP 5.0.5. (I'm sure the GMP folks have a better way to build GMP on my machine than the "generic" 64-bit version provided by Ubuntu.) Brad

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Re: [gambit-list] JavaScript backend
by Marc Feeley 13 Feb '17

13 Feb '17

First of all, this change is for the universal backend. It is more of a temporary kludge to experiment with dynamically loading files generated by the universal backend. Here’s how it works… At the end of the link file, the Gambit linker generates a table of the Scheme modules required by the program. The table is passed as a parameter to the g_module_registry_init function of the Gambit runtime system. For example, the link command: gsc -link -l lib/_gambit.js a.js b.js will generate at the end of the link file “b_.js”: g_module_registry_init([new G_ModLinkInfo("_gambit",0), new G_ModLinkInfo("a",1), new G_ModLinkInfo("b",2)]); At then end of a file generated for the compilation of a module there is a call to a runtime system function that registers the module in the module registry. For example, when “a.scm” is compiled with the command “gsc -target js -c a.scm”, the file “a.js” generated ends with: g_module_register([g_make_interned_symbol("a"),g_bb1__20_a,1,null,false]); The parameter of g_module_register is a “module descriptor” giving information on the module: name, main function (g_bb1__20_a), preload flag (1), module meta information (null), and a dummy field (false) that is only interesting for the C backend. So when the files of generated code are loaded (incrementally) by the JS VM, g_module_register accumulates the modules in a table. When all the modules required by the program have beed loaded (in the example, _gambit, a and b) the function g_module_register will call the main function of the first module. This will run the Scheme code at the toplevel of the first module. The first module contains a loop, in Scheme, that iterates over the module registry and calls the main function of each of the remaining modules in the registry (this information is available in Scheme in the global variable ##program-descr). Specifically, the first module is the Gambit universal library (lib/_univlib.scm), which ends with a call to ##load-vm (a procedure defined in lib/_kernel.scm that runs each module other than the first). What my most recent change does is extend g_module_register so that any subsequent module that is loaded by the JS VM causes its immediate execution by calling the module's main function. In the C backend the mechanism is slightly different (and more flexible): the ##load-object-file procedure of the Gambit runtime library constructs a vector of module descriptors and this vector is passed to ##register-module-descrs-and-load! (defined in lib/_kernel.scm) which then runs the modules. It is more flexible because the loaded object file can contain more than one module, and also control goes through Scheme before the module is executed. Marc > On Jan 3, 2016, at 2:54 AM, Adam <adam.mlmb(a)gmail.com> wrote: > > Marc, > > Wait, what's the point? > > That is effectively C modules' default behavior isn't it? (even if it's the runtime or linker-generated code that actually does the actual run command.) > > So this way you create symmetrical behavior but the actual run command is in the module file itself rather than in runtime/linker - > > Is there any disadvantage.. could be, no, like, I need more modules loaded at the same time and with this model you introduced now, the global namespace in JS files is evaluated at load time so could cause a problem? > > > 2016-01-03 14:10 GMT+08:00 Marc Feeley <feeley(a)iro.umontreal.ca>: > I’ve just pushed a small change to the module registration method. Now, loading the generated .js file will run that file. > > Marc > > > On Jan 2, 2016, at 11:39 PM, Blake McBride <blake(a)mcbride.name> wrote: > > > > Yes, and I use jQuery get and html methods to load the html part. > > > > > > On Sat, Jan 2, 2016 at 8:43 PM, Marc Feeley <feeley(a)iro.umontreal.ca> wrote: > > That’s an interesting app! > > > > As I said, it shouldn’t be hard to do. In your app, how do you load new JS code? Are you using jQuery and the getScript method? > > > > Marc > > > > > On Jan 2, 2016, at 8:42 PM, Blake McBride <blake(a)mcbride.name> wrote: > > > > > > Hi Marc, > > > > > > Thanks for the reply. > > > > > > I started development of a Web based business application in 2006. The app is in production use. The front-end is about 450 screens written in Flash. The back-end is written in Java (over 9,000 classes) on top of an SQL database with 250 tables accessed through Hibernate. The front-end and back-end communicate through SOAP web services. > > > > > > Since Flash is now dead, I need to re-write at least parts of the front-end in JS to support tablets and phones at least. I have front-end JS code that communicates with the back-end SOAP Web services so I theoretically wouldn't need to touch the back-end. > > > > > > I have a preference to utilize scheme if I can, but the back-end is already written and works. It doesn't make sense to mess with it given the investment. > > > > > > The problems I had with Gambit (as well as many other systems) is as follows: > > > > > > Once a user logs in, my app has a consistent visual / UI framework. Beyond this framework, there are 450 different screens that appear within the framework (like in one of the div's). > > > > > > A. I cannot load all 450 screen at system startup. I must lazy load them as they are called up. > > > > > > B. The initial UI framework code should contain all of the Gambit machinery and libraries so that each of the 450 screens can be small, light-weight, compiled separately yet have full access to the entire Gambit facility. > > > > > > With respect, my investigation into Gambit as a possible solution in the past led me to the conclusions at that time it was not possible to produce separately compiled modules that leveraged off of a single main module for the Gambit machinery and libraries. > > > > > > I suppose some time has passed and I wanted to see if the situation has changed. I can only use Gambit if: > > > > > > 1. I can compile and load each screen separately > > > > > > 2. I only have to have one copy of the Gambit machinery and library so that the separate screens are small. > > > > > > Thank you. > > > > > > Blake > > > > > > > > > On Sat, Jan 2, 2016 at 7:06 PM, Marc Feeley <feeley(a)iro.umontreal.ca> wrote: > > > asmjs is cool and Gambit has already been compiled to it thanks to emscripten (see “Gambit in the browser”: http://feeley.github.io/gambit-in-the-browser/) The performance is not bad, perhaps 10x to 20x slower than when Gambit is compiled by gcc to native code. The main problem is the size of the JS that is generated when compiling Gambit-C with emscripten to JS. The gsi interpreter yields roughly 10 MB of asmjs code. > > > > > > As far as code size is concerned, a better solution is to use Gambit's JS backend with the Gambit library. The code generated is roughly half the size when minimized (and it could be even less if some thought went into how identifiers are encoded). > > > > > > Even more savings can be had by doing away with the default Gambit library and writing a custom library specialized for the application. Gambit’s library has lots of functionality that is not normally needed by typical applications. For example, the predefined map procedure can handle an arbitrary number of list parameters. If the application only uses the single list version, then this definition would be sufficient: > > > > > > (define (map f lst) > > > (if (pair? lst) > > > (cons (f (car lst)) (map f (cdr lst))) > > > ‘())) > > > > > > That 4 line version is 1/20th the size of the map defined in the Gambit library (which handles multiple lists, has type checking, precise error messages, same list length checking and is safe for multithreading). > > > > > > So perhaps what’s needed for Gambit to be more successful for web dev is the creation of such a “slim” library for Gambit to replace the default feature-full library. Gambit’s “tree shaker” would also help to eliminate the unused procedures of the slim library (unfortunately this only works for “whole program” compilation, so separate compilation would only be used for the development phase). > > > > > > Anyway, if this interests you please let me know. > > > > > > Marc > > > > > > > On Jan 1, 2016, at 11:44 AM, Blake McBride <blake(a)mcbride.name> wrote: > > > > > > > > Just some opinions. > > > > > > > > asmjs.org defines a portable subset that allows JS platforms to compile into very fast code. Targeting that subset, and within their spec, is probably a good idea. > > > > > > > > JS has, and is becoming increasingly, a very, very important platform. With ajax and rest services, code increasingly independent from the back-end is being developed. So, in a very important sense, JS has become its own platform, just like X86, and X86_64, along with Linux, Windows, Mac, etc. > > > > > > > > Many apps consist of two major parts: the back-end processing, and the front-end human interface. While one can write the back-end processing in any of dozens of languages targeting X86 or a VM, and the OS, there is really only one target for the other half - the human interface - and that is JS. > > > > > > > > While many languages are now targeting the JS platform (I am using the word "platform" to mean X86, X86_64, either, plus the OS) including, believe it or not, Smalltalk, there are few that can, IMO, be used in a real world application for several reasons. But, these issues will likely be resolved soon. > > > > > > > > With respect, Gambit, at least in the past, was in many ways another toy solution - one with a functioning "Hello world" application but missing important features that make it usable in a real-world situation. I would love to be a part of that solution, but alas, life doesn't offer me that level of freedom. I am only capable of using a system that is reportedly working, reporting bugs, making small adjustments, and providing feedback. Regardless of my attitude, preferences, and intentions, I cannot provide more. > > > > > > > > Look at node (JS for the back-end) and its vastly increasing popularity. Since developers are being forced to use JS on the front-end, it's bleeding over to the back-end. I think solutions that take JS seriously at this stage will prosper greatly. > > > > > > > > Now, having said all that, I would love to see Gambit target JS as a high-priority, first-class target. If that were the case, I would be happy to contribute what I stated above. > > > > > > > > Thanks! > > > > > > > > Blake McBride > > > > > > > > _______________________________________________ > > > > 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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Computing pi with parallel gambit
by Bradley Lucier 06 Feb '17

06 Feb '17

Marc: Because of accumulated roundoff error in IEEE floating-point arithmetic, Gambit's FFT-based bignum multiplication algorithm is limited to multiplying two numbers each of which has <= 2^{29} bits (on a 64-bit machine). Multiplying larger numbers falls back on Karatsuba multiplication, which cuts the size of the multiplicands roughly in half in each step, until you get back down to numbers of <= 2^{29} bits again, in which case FFT is used again. So, in fact, to compute a billion decimal digits of pi, we rely on Karatsuba to do the largest multiplications (and divisions and square roots, since they all reduce to multiplication). On a machine with enough memory, all the "sub-multiplications" in Karatsuba can be done in parallel. I haven't figured out how much memory is needed; it takes a few GB of temporary RAM to multiply the largest numbers with the FFT algorithm. I believe it took about 16GB total to calculate a billion decimal digits of pi using the current serial algorithm. Once parallel gambit is usable, computing pi to a billion (or even 10 billion, who knows) digits by parallelizing the larger Karatsuba multiplications might be a good test of the system. Brad

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Building and using Gambit on windows
by Bill Six 02 Jan '17

02 Jan '17

I'm unable to figure out how to use Gambit on Windows successfully, and I'd like some help. (I'm plenty comfortable with Gambit on Linux/OSX). My general feeling is that I'm using configure's "prefix" argument incorrectly on Windows, which may be causing my problem. I can build gambit just fine using the msys2 environment with mingw64 as the compiler. (Here's the head of config.log "$ ./configure --prefix=/c/opt/gambit/bld --enable-single-host --enable-gcc-opts") I can do basic stuff in gsi, such as > (+ 1 2) 3 But the following doesn't work: > (include "~~/lib/_gambit#.scm") *** ERROR IN (console)(a)2.1 -- Can't open file "\\c\\opt\\gambit\\bld\\lib/_gambit#.scm" and I can't get "gsc -exe foo.scm" (for some trivial foo.scm) to not segfault. Any ideas? Thanks, Bill

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[ANN] Gambit v4.8.7 released
by gambit＠iro.umontreal.ca 28 Dec '16

28 Dec '16

1 0

Call for Papers: ICFP 2017
by Lindsey Kuper 23 Dec '16

23 Dec '16

ICFP 2017 The 22nd ACM SIGPLAN International Conference on Functional Programming Oxford, United Kingdom http://icfp17.sigplan.org/ Call for Papers ### Important dates Submissions due: Monday, February 27, Anywhere on Earth https://icfp17.hotcrp.com Author response: Monday, April 17, 2017, 15:00 (UTC) - Thursday, April 20, 2017, 15:00 (UTC) Notification: Monday, 1 May, 2017 Final copy due: Monday, 5 June 2017 Early registration: TBA Conference: Monday, 4 September - Wednesday, 6 September, 2017 ### New this year Those familiar with previous ICFP conferences should be aware of two significant changes that are being introduced in 2017: 1. Papers selected for ICFP 2017 will be published as the ICFP 2017 issue of a new journal, Proceedings of the ACM on Programming Languages (PACMPL), which replaces the previous ICFP conference proceedings. The move to PACMPL will have two noticeable impacts on authors: * A new, two-phase selection and reviewing process that conforms to ACM’s journal reviewing guidelines. * A new, single-column format for submissions. 2. Authors of papers that are conditionally accepted in the first phase of the reviewing process will have the option to submit materials for Artifact Evaluation. Further details on each of these changes are included in the following text. ### Scope ICFP 2017 seeks original papers on the art and science of functional programming. Submissions are invited on all topics from principles to practice, from foundations to features, and from abstraction to application. The scope includes all languages that encourage functional programming, including both purely applicative and imperative languages, as well as languages with objects, concurrency, or parallelism. Topics of interest include (but are not limited to): * *Language Design*: concurrency, parallelism, and distribution; modules; components and composition; metaprogramming; type systems; interoperability; domain-specific languages; and relations to imperative, object-oriented, or logic programming. * *Implementation*: abstract machines; virtual machines; interpretation; compilation; compile-time and run-time optimization; garbage collection and memory management; multi-threading; exploiting parallel hardware; interfaces to foreign functions, services, components, or low-level machine resources. * *Software-Development Techniques*: algorithms and data structures; design patterns; specification; verification; validation; proof assistants; debugging; testing; tracing; profiling. * *Foundations*: formal semantics; lambda calculus; rewriting; type theory; monads; continuations; control; state; effects; program verification; dependent types. * *Analysis and Transformation*: control-flow; data-flow; abstract interpretation; partial evaluation; program calculation. * *Applications*: symbolic computing; formal-methods tools; artificial intelligence; systems programming; distributed-systems and web programming; hardware design; databases; XML processing; scientific and numerical computing; graphical user interfaces; multimedia and 3D graphics programming; scripting; system administration; security. * *Education*: teaching introductory programming; parallel programming; mathematical proof; algebra. Submissions will be evaluated according to their relevance, correctness, significance, originality, and clarity. Each submission should explain its contributions in both general and technical terms, clearly identifying what has been accomplished, explaining why it is significant, and comparing it with previous work. The technical content should be accessible to a broad audience. ICFP 2017 also welcomes submissions in two separate categories — Functional Pearls and Experience Reports — that must be marked as such at the time of submission and that need not report original research results. Detailed guidelines on both categories are given at the end of this call. Please contact the program chair if you have questions or are concerned about the appropriateness of a topic. ### Preparation of submissions **Deadline**: The deadline for submissions is Monday, February 27, 2017, Anywhere on Earth (<https://en.wikipedia.org/wiki/Anywhere_on_Earth>). This deadline will be strictly enforced. **Formatting**: (NOTE: NEW FORMAT REQUIREMENTS FOR ICFP 2017) Submissions must be in PDF format, printable in black and white on US Letter sized paper, and interpretable by common PDF tools. All submissions must adhere to the "ACM Large" template that is available (in both LaTeX and Word formats) from <http://www.acm.org/publications/proceedings-template>. For authors using LaTeX, a lighter-weight package, including only the essential files, is available from <http://sigplan.org/Resources/Author/#acmart-format>. There is a limit of 24 pages for a full paper or 12 pages for an Experience Report; in either case, the bibliography will not be counted against these limits. These page limits have been chosen to allow essentially the same amount of content with the new single-column format as was possible with the two-column format used in past ICFP conferences. Submissions that exceed the page limits or, for other reasons, do not meet the requirements for formatting, will be summarily rejected. **Submission**: Submissions will be accepted at <https://icfp17.hotcrp.com/> (in preparation at the time of writing). Improved versions of a paper may be submitted at any point before the submission deadline using the same web interface. **Author Response Period**: Authors will have a 72-hour period, starting at 15:00 UTC on Monday, April 17, 2017, to read reviews and respond to them. **Supplementary Materials**: Authors have the option to attach supplementary material to a submission, on the understanding that reviewers may choose not to look at it. The material should be uploaded at submission time, as a single pdf or a tarball, not via a URL. This supplementary material may or may not be anonymized; if not anonymized, it will only be revealed to reviewers after they have submitted their review of the paper and learned the identity of the author(s). **Authorship Policies**: All submissions are expected to comply with the ACM Policies for Authorship that are detailed at <https://www.acm.org/publications/authors/information-for-authors>. **Republication Policies**: Each submission must adhere to SIGPLAN's republication policy, as explained on the web at <http://www.sigplan.org/Resources/Policies/Republication>. **Resubmitted Papers**: Authors who submit a revised version of a paper that has previously been rejected by another conference have the option to attach an annotated copy of the reviews of their previous submission(s), explaining how they have addressed these previous reviews in the present submission. If a reviewer identifies him/herself as a reviewer of this previous submission and wishes to see how his/her comments have been addressed, the program chair will communicate to this reviewer the annotated copy of his/her previous review. Otherwise, no reviewer will read the annotated copies of the previous reviews. ### Review Process This section outlines the two-stage process with lightweight double-blind reviewing that will be used to select papers for presentation at ICFP 2017. We anticipate that there will be a need to clarify and expand on this process, and we will maintain a list of frequently asked questions and answers on the conference website to address common concerns. **ICFP 2017 will employ a two-stage review process.** The first stage in the review process will assess submitted papers using the criteria stated above and will allow for feedback and input on initial reviews through the author response period mentioned previously. At the PC meeting, a set of papers will be conditionally accepted and all other papers will be rejected. Authors will be notified of these decisions on May 1, 2017. Authors of conditionally accepted papers will be provided with committee reviews (just as in previous conferences) along with a set of mandatory revisions. After five weeks (June 5, 2017), the authors will provide a second submission. The second and final reviewing phase assesses whether the mandatory revisions have been adequately addressed by the authors and thereby determines the final accept/reject status of the paper. The intent and expectation is that the mandatory revisions can be addressed within five weeks and hence that conditionally accepted papers will in general be accepted in the second phase. The second submission should clearly identify how the mandatory revisions were addressed. To that end, the second submission must be accompanied by a cover letter mapping each mandatory revision request to specific parts of the paper. The cover letter will facilitate a quick second review, allowing for confirmation of final acceptance within two weeks. Conversely, the absence of a cover letter will be grounds for the paper’s rejection. This process is intended as a refinement of the review process that has been used in previous ICFP conferences. By incorporating a second stage, the process will conform to ACM’s journal reviewing guidelines for PACMPL. **ICFP 2017 will employ a lightweight double-blind reviewing process.** To facilitate this, submitted papers must adhere to two rules: 1. **author names and institutions must be omitted**, and 2. **references to authors' own related work should be in the third person** (e.g., not "We build on our previous work ..." but rather "We build on the work of ..."). The purpose of this process is to help the PC and external reviewers come to an initial judgement about the paper without bias, not to make it impossible for them to discover the authors if they were to try. Nothing should be done in the name of anonymity that weakens the submission or makes the job of reviewing the paper more difficult (e.g., important background references should not be omitted or anonymized). In addition, authors should feel free to disseminate their ideas or draft versions of their paper as they normally would. For instance, authors may post drafts of their papers on the web or give talks on their research ideas. ### Information for Authors of Accepted Papers * As a condition of acceptance, final versions of all papers must adhere to the new ACM Large format. The page limits for final versions of papers will be increased to ensure that authors have space to respond to reviewer comments and mandatory revisions. * Authors of accepted submissions will be required to agree to one of the three ACM licensing options: copyright transfer to ACM; retaining copyright but granting ACM exclusive publication rights; or open access on payment of a fee. Further information about ACM author rights is available from <http://authors.acm.org>. * At least one author of each accepted submissions will be expected to attend and present their paper at the conference. The schedule for presentations will be determined and shared with authors after the full program has been selected. Presentations will be videotaped and released online if the presenter consents. * We intend that the proceedings will be freely available for download from the ACM Digital Library in perpetuity via the OpenTOC mechanism. * ACM Author-Izer is a unique service that enables ACM authors to generate and post links on either their home page or institutional repository for visitors to download the definitive version of their articles from the ACM Digital Library at no charge. Downloads through Author-Izer links are captured in official ACM statistics, improving the accuracy of usage and impact measurements. Consistently linking to the definitive version of an ACM article should reduce user confusion over article versioning. After an article has been published and assigned to the appropriate ACM Author Profile pages, authors should visit <http://www.acm.org/publications/acm-author-izer-service> to learn how to create links for free downloads from the ACM DL. * The official publication date is the date the proceedings are made available in the ACM Digital Library. This date may be up to *two weeks prior* to the first day of the conference. The official publication date affects the deadline for any patent filings related to published work. ### Artifact Evaluation Authors of papers that are conditionally accepted in the first phase of the review process will be encouraged (but not required) to submit supporting materials for Artifact Evaluation. These items will then be reviewed by a committee, separate from the program committee, whose task is to assess how the artifacts support the work described in the associated paper. Papers that go through the Artifact Evaluation process successfully will receive a seal of approval printed on the papers themselves. Authors of accepted papers will be encouraged to make the supporting materials publicly available upon publication of the proceedings, for example, by including them as "source materials" in the ACM Digital Library. An additional seal will mark papers whose artifacts are made available, as outlined in the ACM guidelines for artifact badging. Participation in Artifact Evaluation is voluntary and will not influence the final decision regarding paper acceptance. Further information about the motivations and expectations for Artifact Evaluation can be found at <http://icfp17.sigplan.org/track/icfp-2017-Artifacts>. ### Special categories of papers In addition to research papers, ICFP solicits two kinds of papers that do not require original research contributions: Functional Pearls, which are full papers, and Experience Reports, which are limited to half the length of a full paper. Authors submitting such papers should consider the following guidelines. #### Functional Pearls A Functional Pearl is an elegant essay about something related to functional programming. Examples include, but are not limited to: * a new and thought-provoking way of looking at an old idea * an instructive example of program calculation or proof * a nifty presentation of an old or new data structure * an interesting application of functional programming techniques * a novel use or exposition of functional programming in the classroom While pearls often demonstrate an idea through the development of a short program, there is no requirement or expectation that they do so. Thus, they encompass the notions of theoretical and educational pearls. Functional Pearls are valued as highly and judged as rigorously as ordinary papers, but using somewhat different criteria. In particular, a pearl is not required to report original research, but, it should be concise, instructive, and entertaining. A pearl is likely to be rejected if its readers get bored, if the material gets too complicated, if too much specialized knowledge is needed, or if the writing is inelegant. The key to writing a good pearl is polishing. A submission that is intended to be treated as a pearl must be marked as such on the submission web page, and should contain the words "Functional Pearl" somewhere in its title or subtitle. These steps will alert reviewers to use the appropriate evaluation criteria. Pearls will be combined with ordinary papers, however, for the purpose of computing the conference's acceptance rate. #### Experience Reports The purpose of an Experience Report is to help create a body of published, refereed, citable evidence that functional programming really works — or to describe what obstacles prevent it from working. Possible topics for an Experience Report include, but are not limited to: * insights gained from real-world projects using functional programming * comparison of functional programming with conventional programming in the context of an industrial project or a university curriculum * project-management, business, or legal issues encountered when using functional programming in a real-world project * curricular issues encountered when using functional programming in education * real-world constraints that created special challenges for an implementation of a functional language or for functional programming in general An Experience Report is distinguished from a normal ICFP paper by its title, by its length, and by the criteria used to evaluate it. * Both in the proceedings and in any citations, the title of each accepted Experience Report must begin with the words "Experience Report" followed by a colon. The acceptance rate for Experience Reports will be computed and reported separately from the rate for ordinary papers. * Experience Report submissions can be at most 12 pages long, excluding bibliography. * Each accepted Experience Report will be presented at the conference, but depending on the number of Experience Reports and regular papers accepted, authors of Experience reports may be asked to give shorter talks. * Because the purpose of Experience Reports is to enable our community to accumulate a body of evidence about the efficacy of functional programming, an acceptable Experience Report need not add to the body of knowledge of the functional-programming community by presenting novel results or conclusions. It is sufficient if the Report states a clear thesis and provides supporting evidence. The thesis must be relevant to ICFP, but it need not be novel. The program committee will accept or reject Experience Reports based on whether they judge the evidence to be convincing. Anecdotal evidence will be acceptable provided it is well argued and the author explains what efforts were made to gather as much evidence as possible. Typically, more convincing evidence is obtained from papers which show how functional programming was used than from papers which only say that functional programming was used. The most convincing evidence often includes comparisons of situations before and after the introduction or discontinuation of functional programming. Evidence drawn from a single person's experience may be sufficient, but more weight will be given to evidence drawn from the experience of groups of people. An Experience Report should be short and to the point: it should make a claim about how well functional programming worked on a particular project and why, and produce evidence to substantiate this claim. If functional programming worked in this case in the same ways it has worked for others, the paper need only summarize the results — the main part of the paper should discuss how well it worked and in what context. Most readers will not want to know all the details of the project and its implementation, but the paper should characterize the project and its context well enough so that readers can judge to what degree this experience is relevant to their own projects. The paper should take care to highlight any unusual aspects of the project. Specifics about the project are more valuable than generalities about functional programming; for example, it is more valuable to say that the team delivered its software a month ahead of schedule than it is to say that functional programming made the team more productive. If the paper not only describes experience but also presents new technical results, or if the experience refutes cherished beliefs of the functional-programming community, it may be better off submitted it as a full paper, which will be judged by the usual criteria of novelty, originality, and relevance. The program chair will be happy to advise on any concerns about which category to submit to. ### Organizers General Chair: Jeremy Gibbons (University of Oxford, UK) Program Chair: Mark Jones (Portland State University, USA) Artifact Evaluation Chair: Ryan R. Newton (Indiana University, USA) Industrial Relations Chair: Ryan Trinkle (Obsidian Systems LLC, USA) Programming Contest Organiser: Sam Lindley (University of Edinburgh, UK) Publicity and Web Chair: Lindsey Kuper (Intel Labs, USA) Student Research Competition Chair: Ilya Sergey (University College London, UK) Video Chair: Jose Calderon (Galois, Inc., USA) Workshops Co-Chair: Andres Löh (Well-Typed LLP) Workshops Co-Chair: David Christiansen (Indiana University, USA) Program Committee: Bob Atkey (University of Strathclyde, Scotland) Adam Chlipala (MIT, USA) Dominique Devriese (KU Leuven, Belgium) Martin Erwig (Oregon State, USA) Matthew Flatt (University of Utah, USA) Ronald Garcia (University of British Columbia, Canada) Kathryn Gray (University of Cambridge, England) John Hughes (Chalmers University and Quvik, Sweden) Chung-Kil Hur (Seoul National University, Korea) Graham Hutton (University of Nottingham, England) Alan Jeffrey (Mozilla Research, USA) Ranjit Jhala (University of California, San Diego, USA) Shin-ya Katsumata (Kyoto University, Japan) Lindsey Kuper (Intel Labs, USA) Dan Licata (Wesleyan University, USA) Ben Lippmeier (Digital Asset, Australia) Gabriel Scherer (Northeastern University, USA) Alexandra Silva (University College London, England) Nikhil Swamy (Microsoft Research, USA) Sam Tobin-Hochstadt (Indiana University, USA) Nicolas Wu (University of Bristol, England) Beta Ziliani (CONICET and FAMAF, Universidad Nacional de Córdoba, Argentina)

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Linkage order will affect behavior of same code?
by Meng Zhang 09 Dec '16

09 Dec '16

I have three scm files: main.scm: (display "Hello from main.scm.") (newline) (f1a-func) (f2-func) f1a.scm: (define (f1a-func) (display "f1a-func was called") (f2-func) (newline)) f2.scm: (define (f2-func) (display "Hello from f2.scm") (newline)) With gcc f1a.o f2.o main.o main_.o -lgambit, it compiles and generate expected output. With gcc main.o f1a.o f2.o main_.o -lgambit, it compiles but will raise an exception on missing f1a-func / f2-func. Is this expected behavior? Any workaround exist? My testing environment is OSX El Captain Thanks Meng -- Meng

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Emscripten compiled gambit-c app can not be executed in web browser environment
by 周宇 02 Dec '16

02 Dec '16

Hi Marc, I was frustrated trying to run emscripten powered gambit-c program on web browser. The attachment gsi.scm is my program, there's an explicitly main function delcare here to make sure the js code was completely loaded before calling gambit-c _setup() function. I put ##repl-debug-main in primordial thread and call _setup() in main to bring up the whole gambit-c system. I use the attachment my-build-script to generate the ultimate gsi.js file. I issue echo "(load \"fib\") (pp (time (fib 20)))" | /usr/bin/time node gsi.js, and everything is fine. Unfortunately gsi.js was stuck in a web browser environment. Through some experiment, I found the _setup() function never return, the comment in the code said it will create a service thread which executes the rest of the program. I think it is the reason why it hung the web browser. I also did another experiment, explicitly make the primordial thread exit. said issue echo "(load \"fib\") (pp (time (fib 20))) ,q" | /usr/bin/time node gsi.js, but the web_trampoline function throw an exception, I trace the exception was threw from macro-run-queue of ##next-heartbeat-interval function The reason I don't want to use recent gambit to build with emscripten is I am afraid the ultimate js file would be tremendious large. Looking forward your reply and help

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