May 2006 - Haskell - Haskell.org

ANNOUNCE: cpphs-1.2
by Malcolm Wallace 04 May '06

04 May '06

cpphs - 1.2 ----------- We would like to announce a new release of cpphs, the in-Haskell implementation of the C pre-processor. The major change in this release is that the source files have been re-arranged into a cabal-ised hierarchical library namespace, so you can use cpp functionality from within your own code, in addition to the stand-alone utility. * Re-arranged the source files into hierarchical libraries. * Exposed the library interface as an installable Cabal package, with Haddock documentation. * Added the --unlit option, for removing literate-style comments. The webpage is http://haskell.org/cpphs Darcs repo at http://www.cs.york.ac.uk/fp/darcs/cpphs On-line darcsweb browser at http://www.cs.york.ac.uk/fp/darcs Regards, Malcolm

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Re: FW: [Haskell] parallel seq
by Phil Trinder 04 May '06

04 May '06

Chad, > I was thinking about the dynamic behavior of par, and there's something > that's a little confusing to me. Am I right in understanding that (x > `par` y) evaluates to y, and may or may not evaluate x along the way? The reason that par doesn't necessarily evaluate it's 1st argument is that typical parallel Haskell programs contain vast amounts of potential parallelism. So rather than create a relatively heavyweight thread and be forced to administer it, e.g. schedule it for every possible expression that could be evaluated in parallel, the expression is 'sparked', i.e. a lightweight action that simply notes that the expression *could* be evaluated in parallel. > I think it would be easier to reason about if we knew that x would be > evaluated, either by a newly-spawned thread or by the parent thread. Yes, although we usually reason by saying trhat the 'potential parallelism' in two expressions is the same, i.e. making the assumption that all sparked expressions become threads. > If > I'm understanding this correctly, this could be done by defining > > x `pSeq` y = x `par` y `seq` x `seq` y This seems plausible. All the best, Phil > From: haskell-bounces(a)haskell.org [mailto:haskell-bounces@haskell.org] > On Behalf Of Scherrer, Chad > Sent: 25 April 2006 21:35 > To: haskell(a)haskell.org > Subject: [Haskell] parallel seq > > I was thinking about the dynamic behavior of par, and there's something > that's a little confusing to me. Am I right in understanding that (x > `par` y) evaluates to y, and may or may not evaluate x along the way? > > I think it would be easier to reason about if we knew that x would be > evaluated, either by a newly-spawned thread or by the parent thread. If > I'm understanding this correctly, this could be done by defining > > x `pSeq` y = x `par` y `seq` x `seq` y > (seq has higher precedence than par) > > When (x `pSeq` y) is evaluated, x may or may not be evaluated by a new > thread. The parent thread continues along evaluating y. Then the parent > makes sure x was evaluated before finally returning y. > > I've not seen this approach used before -- Is there something I'm > missing that makes using pSeq as above just silly? > > Thanks! > > Chad Scherrer > Computational Mathematics Group > Pacific Northwest National Laboratory > > "Time flies like an arrow; fruit flies like a banana." -- Groucho Marx > _______________________________________________ > Haskell mailing list > Haskell(a)haskell.org > http://www.haskell.org/mailman/listinfo/haskell > -------------------------------------------------- Phil Trinder School of Mathematical and Computer Sciences Heriot-Watt University Edinburgh, EH14 4AS E-mail: trinder(a)macs.hw.ac.uk Teleph: +44 (0)131 451 3435 Depart: +44 (0)131 451 3328 Fasmly: +44 (0)131 451 3327 Intrnt: http://www.macs.hw.ac.uk/~trinder

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ANNOUNCE: hmake-3.11
by Malcolm Wallace 03 May '06

03 May '06

hmake - 3.11 ------------ This announcement is for a bug-fix release of 'hmake', the compiler-independent project-building tool for Haskell programs. It automates recompilation analysis, based on import declarations in your files, to rebuild only those modules that are impacted by a change. It is rather like ghc's --make mode, but faster, less memory intensive, and it works with any compiler (e.g. hbc, nhc98). hmake also knows about preprocessors such as Happy, Alex, c2hs, gh, and Hat, and does the right things with modules that need them. This release is essentially just a refresh to counter bit-rot. * New: the #! runhs script interpreter. * Bugfix: now finds dependency B with explicit braces in module A where { import B; ... } * Bugfixes: for compatibility problems with gcc-4.0. * Re-organised the internal cpphs library. The webpage is at http://haskell.org/hmake Regards, Malcolm

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Optimizing locking with MVars
by Bulat Ziganshin 03 May '06

03 May '06

Hello haskell, Main reason of slowness of existing Handle-based I/O in GHC is locking around each operation. it is especially bad for simple char-at-a-time I/O where 99% of time spent on locking and unlocking. To be exact, on my CPU, hPutChar for 100mb file requires 150 seconds, while hGetChar for the same file is "only" 100 seconds long. it seems that former use 3 locking operations and later 2 ones, because my own vGetChar/vPutChar implementations both requires 52 seconds, of those only about one second is real work and rest is just `withMVar` expenses. Until now, i thought that this 0.5 ms (about 1000 primitive CPU operations) on each withMVar is pure time required to perform takeMVar+putMVar operations. But yesterday i investigated this problem deeper and results was amazing! First, i just made local copy of `withMVar` and added INLINE to it: import Control.Exception as Exception {-# INLINE inlinedWithMVar #-} inlinedWithMVar :: MVar a -> (a -> IO b) -> IO b inlinedWithMVar m io = block $ do a <- takeMVar m b <- Exception.catch (unblock (io a)) (\e -> do putMVar m a; throw e) putMVar m a return b Second, i've developed my own simplified version of this procedure. Here i should say that my library uses "MVar ()" field to hold lock and separate immutable data field with actual data locked: data WithLocking h = WithLocking h !(MVar ()) This allowed me to omit block/unblock operation and develop the following faster analog of withMVar: lock (WithLocking h mvar) action = do Exception.catch (do takeMVar mvar result <- action h putMVar mvar () return res ) (\e -> do tryPutMVar mvar (); throw e) And as third variant i tried exception-unsafe variant of `withMVar`: unsafeWithMVar :: MVar a -> (a -> IO b) -> IO b unsafeWithMVar m io = do a <- takeMVar m b <- io a putMVar m a return b And now are results: withMVar 52 seconds inlinedWithMVar 38 seconds lock 20 seconds unsafeWithMVar 10 seconds So, 1) `withMVar` can be made significantly faster just by attaching INLINE pragma to it. until GHC includes this patch, you can just make local copy of this procedure (it's implementation is compiler-independent) and use INLINE pragma for this local copy 2) if MVar is used only to protect some immutable data from simultaneous access, it's use can be made significantly faster by using above-mentioned WithLocking type constructor together with 'lock' function. I hope that this mechanism will go into future Haskell implementations and in particular it will be used in my own Streams library and in new DiffArray implementation (that is a part of ArrayRef library) 3) For simple programs that don't catch exceptions anyway, this excessive protection is just meaningless. they can use 'unsafeWithMVar' to work as fast as possible. i mean in particular shootout-like benchmarks. it is also possible to develop fast & safe routines by using explicit unlocking (with 'tryPutMVar') in higher-level exception handlers and a more general conclusion. this case is a good demonstration of significant performance loss due to using of higher-order functions. i think that more aggressive inlining of high-order and polymorphic functions should significantly speed up GHC-compiled programs. -- Best regards, Bulat mailto:Bulat.Ziganshin@gmail.com

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Last call for papers: RULE-BASED PROGRAMMING 2006
by Ralf Lammel 02 May '06

02 May '06

RULE'06, 7th International Workshop on Rule-Based Programming, 11th August, 2006, Seattle, USA, A Satellite Event of RTA http://www.dcs.kcl.ac.uk/events/RULE06/ ________________________________________ IMPORTANT DATES - 14th May, 2006 Deadline for electronic submission of papers - 15th June, 2006 Notification of acceptance of papers - 30th June, 2006 Deadline for final versions of accepted papers - 11th August, 2006 Workshop ________________________________________ INVITED SPEAKERS Joint RULE and WRS keynote speakers: - Dick Kieburtz, OHSU/OGI School of Science & Engineering - Claude Kirchner, INRIA and LORIA ________________________________________ RULE-BASED PROGRAMMING The rule-based programming paradigm is characterized by the repeated, localized transformation of a data object such as a term, graph, proof, constraint store, etc. The transformations are described by rules which separate the description of the object to be replaced (the pattern) from the calculation of the replacement. Optionally, rules can have further conditions that restrict their applicability. The transformations are controlled by explicit or implicit strategies. The basic concepts of rule-based programming appear throughout computer science, from theoretical foundations to practical implementations. Term rewriting is used in semantics in order to describe the meaning of programming languages, as well as in the implementation of program transformation systems. Rules are used implicitly or explicitly to perform computations, e.g., in Mathematica, OBJ, ELAN, Maude or to perform deductions, e.g., by using inference rules to describe or implement a logic, theorem prover or constraint solver. Mail clients and mail servers use complex rules to help users organising their email and sorting out spam. Language implementations use bottom-up rewrite systems for code generation (as in the BURG family of tools.) Constraint-handling rules (CHRs) are used to specify and implement constraint-based algorithms and applications. Rule-based programming idioms also give rise to multi-paradigm languages like Claire. ________________________________________ TOPICS We solicit original papers on all topics of rule-based programming, including: - Languages for rule-based programming * Expressivity, Idioms, Design patterns * Semantics, Type systems * Implementation techniques * System descriptions - Other foundations * Complexity results * Advances on rewriting logic * Advances on rewriting calculus * Static analyses of rule-based programs * Transformation of rule-based programs - Applications of rule-based programming, e.g.: * Program transformation * Software analysis and generation * System Control * Work-flow control * Knowledge engineering - Combination with other paradigms * Functional programming * Logic programming * OO programming * Language extensions * Language embeddings - System descriptions ________________________________________ SUBMISSIONS Papers (of at most 15 pages) should be submitted electronically via the web-based submission site. http://www.easychair.org/RULE2006/ Any problems with the submission procedure should be reported to one of the PC chairs: Maribel Fernandez (maribel(a)dcs.kcl.ac.uk) Ralf Lämmel (Ralf.Lammel(a)microsoft.com) ________________________________________ PROCEEDINGS Accepted papers will be published in the preliminary proceedings volume, which will be available during the workshop. The final proceedings will be published in Electronic Notes in Theoretical Computer Science (ENTCS), Elsevier. ________________________________________ PROGRAMME COMMITTEE - Mark van den Brand (TU Eindhoven, Netherlands) - Horatiu Cirstea (LORIA, France) - Pierre Deransart (INRIA Rocquencourt, France) - Michael L. Collard (Kent State University, USA) - Martin Erwig (Oregon State University, USA) - Francois Fages (INRIA Rocquencourt, France) - Maribel Fernandez (Co-Chair, King's College London, UK) - Jean-Pierre Jouannaud (LIX, Ecole Polytechnique, France) - Oleg Kiselyov (FNMOC, USA) - Ralf Lämmel (Co-Chair, Microsoft, USA) - Ugo Montanari (Universita di Pisa, Italy) - Pierre-Etienne Moreau (LORIA, France) - Tobias Nipkow (Technical University Munich, Germany) - Tom Schrijvers (K.U.Leuven, Belgium) - Martin Sulzmann (National University of Singapore, Singapore) - Victor Winter (University of Nebraska at Omaha, USA)

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(GHC) Boot files and instance declarations
by David House 02 May '06

02 May '06

Hi all. A quick bootfiles question. The GHC docs specify not to put instance decls in bootfiles. However, what if i need to? For example, say I have a module A where I'm importing a module B with the {-# SOURCE #-} pragma. Module A needs to know that the types in module B are instances of some typeclasses (instance declarations for which are given in module B). How would I manage this? Thanks in advance. -- -David House, dmhouse(a)gmail.com, http://xmouse.ithium.net

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Call for papers: FM-Ed'06 - Formal Methods in the Teaching Lab
by J.N. Oliveira 02 May '06

02 May '06

Call for Papers -- Submission deadline: June 9, 2006 FORMAL METHODS IN THE TEACHING LAB Examples, Cases, Assignments and Projects Enhancing Formal Methods Education http://www.di.uminho.pt/FME-SoE/FMEd06/ A Workshop at the Formal Methods 2006 Symposium Workshop: Saturday, August 26, 2006 Symposium: August 21 - 27, 2006 McMaster University, Hamilton, Ontario, Canada I. ORGANIZATION This workshop is organized by the Formal Methods Europe Subgroup on Education. Dines Bjørner (JAIST, Japan) Eerke Boiten (University of Kent, UK) Raymond Boute (Universiteit Gent, Belgium) Andrew Butterfield (Trinity College, Dublin) John Fitzgerald (University of Newcastle upon Tyne, UK) Randolph Johnson Steve King (University of York, UK) Peter Lucas Michael Mac an Airchinnigh (Trinity College, Dublin) Dino Mandrioli (Politecnico di Milano, Italy) Andrew Martin (Oxford University, UK) José Oliveira (Universidade do Minho, Portugal) -- Convenor Kees Pronk (Technische Universiteit Delft, NL) Simão Melo de Sousa (Universidade da Beira Interior, Portugal) Wolfgang Reisig (Humboldt-Universität zu Berlin, Germany) Workshop Co-Chairs Raymond Boute Formal Methods Group, Department of Information Technology (INTEC), Ghent University, Ghent (Belgium) E-mail: boute(a)intec.UGent.be José Oliveira Departamento de Informatica Universidade do Minho, Braga, Portugal E-mail: jno(a)di.uminho.pt II. CONCEPT OF THE WORKSHOP Motivation Quoting Dines Dines Bjørner: "Formal Methods Education is currently facing a `trichotomy': - On the one hand, industries dealing with the design of complex and critical systems have an increasing need for methods that provide a certain degree of confidence in the result, and are often looking for external assistance in the area of formal methods from consulting companies and academia. - On the other hand, a growing number of university staff enjoys the intellectual challenge of research in this area and teaching formal techniques to students. - On the "third hand", an increasing number of students de-select formal methods in the curriculum, due to various causes and trends." One cause of the problem is a general mathphobic trend in society and education. Another cause is that, intellectually, Information Technology is the victim of its own success. Indeed, the rapid growth creates so many design and implementation tasks that can be done and, more importantly, are being done with negligible educational or scientific background that it is difficult to argue convincingly in favor of formal methods on the basis of immediate everyday necessities. Critical systems, of course, are a notable exception. These trends are so pervasive that the small minority of FM educators has little hope to curb them in the near future. More effective in the long term is instilling a higher degree of professionalism in the next generation. This requires in particular a directed, positive action towards motivating students. Theme This workshop solicits short papers, presentations, demonstrations and evaluations describing sharp classroom or lab experiments which have proved particularly beneficial to the students' understanding and motivation for formal methods. The emphasis is not on (new) theories or methods but on specific illustrations and exercises that can be used by colleagues in their own courses, perhaps applying their own formalisms. The main goals are: - to share knowledge and experience on the practicalities of teaching and learning formal methods; - to build a collection of interesting cases, examples, assignments and projects that FM teachers can use in educational activities. Format The workshop will be a forum-like event, with short presentations, demos and informal discussion slots. After the workshop, if the evaluation committee decides that there is a sufficient number of high-quality submissions, an agreement will be sought with Springer Lecture Notes in Computer Science about publishing a special volume, and authors will be invited to submit their contribution for refereeing. III. SUBMISSIONS Call for Contributions This workshop solicits papers, presentations, demonstrations and evaluations describing such material in detail and how it has been beneficial to the students' understanding and motivation. The emphasis should not be primarily on new theories or methods but on specific illustrations and exercises that can be used by colleagues in their own courses, perhaps applying their own formalisms. The central problem(s) should be clearly stated and a typical solution outline provided (using the author's preferred method), accompanied by a discussion of what educational aspect is meant to be enhanced. Contributors should motivate their techniques with a discussion of the desired knowledge and skill outcomes of the examples/case studies or projects, and a frank appraisal of their effectiveness, insofar as such an appraisal is meaningful and instructive, which we expect to be the case for most topics. Papers should be kept short (maximum 6 pages). They should be prepared preferably in LaTeX, and a pdf-file should be sent to jno(a)di.uminho.pt. Submitted papers will be evaluated by the Subgroup on Education. Timings Submission deadline: Friday, June 9, 2006 Acceptance notification: Friday, July 1, 2006 IV. REPOSITORY AND FOLLOW-UP The organization will produce a web-based resource of output from the workshop housed under http://www.fmeurope.org. Contributors willing to allow their teaching materials to be made publicly available for the community are invited to send source files, links or tools and other information that would be suitable for such an on-line repository, which the organization will keep alive on a wiki-like basis. The collected material will form the start of a compendium of examples, cases, assignments and projects, according to the following (rough) categorization. Examples are shorter items, ranging in length from a single observation to over a full page. An example is aimed at clarifying a single aspect where the essence is captured in a somewhat condensed form, with minimal clutter from side-issues. Cases are taken from situations encountered in practice, where the problems may appear in various forms: from immediately appealing (and hence motivating) but not very challenging to subtly hidden and requiring major research. Side-issues and secondary problems may be included to clarify the setting or to illustrate the need for abstraction. Assignments and projects correspond to examples and cases respectively, but the difference is that they are elaborated by the students rather than the instructors. The repository is expected to evolve in at least 3 dimensions: new items are added in their original form as time proceeds; existing items are reworked in various formalisms; experience in teaching is reported. Every one or two years, people who submit the most suitable contributions will be invited to join forces for combining their work into a "laboratory notebook". Any further suggestions are welcome.

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CFP: 2nd Int'l Workshop on Automated Specification and Verification of Web Systems (WWV'06)
by Santiago Escobar 01 May '06

01 May '06

[ We apologize for multiple copies ] ******************************************************************* 2nd International Workshop on Automated Specification and Verification of Web Systems (WWV'06) Cyprus, November 15-19, 2006 (Track of ISoLA 2006) http://www.dsic.upv.es/workshops/wwv06 ******************************************************************* SCOPE The increased complexity of Web sites and the explosive growth of Web-based applications has turned their design and construction into a challenging problem. Nowadays, many companies have diverted their Web sites into interactive, completely-automated, Web-based applications (such as Amazon, on-line banking, or travel agencies) with a high complexity that requires appropriate specification and verification techniques and tools. Systematic, formal approaches to the analysis and verification can address the problems of this particular domain with automated and reliable tools that also incorporate semantic aspects. We solicit paper on formal methods and techniques applied to Web sites, Web services or Web-based applications, such as: * rule-based approaches to Web site analysis, certification, specification, verification, and optimization * formal models for describing and reasoning about Web sites * model-checking, synthesis and debugging of Web sites * abstract interpretation and program transformation applied to the semantic Web * intelligent tutoring and advisory systems for Web applications and Web specifications authoring The WWV series provides a forum for researchers from the communities of Rule-based programming, Automated Software Engineering, and Web-oriented research to facilitate the cross-fertilization and the advancement of hybrid methods that combine the three areas. LOCATION WWV'06 will be held in November in Cyprus as a Special Track of the 2006 International Symposium on Leveraging Applications of Formal Methods, Verification, and Validation (ISoLA 2006). HISTORY The first WWV'05 edition was held in Valencia, Spain, during March 14-15, 2005. The workshop was attended by 42 participants from universities, research institutes, and companies from 11 countries: Austria, Canada, France, Germany, India, Italy, Japan, Mexico, Spain, UK, and USA. A selection of the papers appeared as a volume of the Elsevier series Electronic Notes in Theoretical Computer Science (ENTCS). PUBLICATION Accepted papers will be published in a preliminary proceedings volume, which will be available during the workshop. Publication of the workshop post-proceedings in the Springer series Lecture Notes in Computer Science (LNCS) is envisaged. PROGRAM CO-CHAIRS Maria Alpuente (Technical University of Valencia, Spain) Moreno Falaschi (University of Siena, Italy) WORKSHOP CHAIR Santiago Escobar (Technical University of Valencia, Spain) PROGRAM COMMITTEE Jose Julio Alferes (Universidade Nova de Lisboa, Portugal) Maria Alpuente (Technical University of Valencia, Spain) Demis Ballis (University of Udine, Italy) Francois Bry (University of Munich, Germany) Santiago Escobar (Technical University of Valencia, Spain) Francois Fages (INRIA Rocquencourt, France) Moreno Falaschi (University of Siena, Italy) Gopal Gupta (University of Texas at Dallas, USA) Shriram Krishnamurthi (Brown University, USA) Tiziana Margaria (University of Potsdam, Germany) I.V. Ramakrishnan (State University of New York at Stony Brook, USA) Leon van der Torre (University of Luxembourg, Luxembourg) IMPORTANT DATES Abstract Submission July 3, 2006 Full Paper Submission July 16, 2006 Acceptance Notification September 17, 2006 Camera Ready October 15, 2006 Workshop November 15-19, 2006 (one day)

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Fwd: Re[2]: [Haskell] speed of Binary serialization libraries
by Bulat Ziganshin 01 May '06

01 May '06

continuing theme of fast serialization library, i should say that this library, Streams, also implements much faster general (text) I/O. below is it's results comparing to well-known Handles: ===8<==============Original message text=============== > Do you have a URL or darcs repository? http://freearc.narod.ru/Streams.tar.gz http://haskell.org/haskellwiki/Library/Streams - docs AltBinary is not yet documented, but al least you can do import Data.AltBinary import Data.Binary.ByteAligned and use the well-known NewBinary (GHC Binary) interface with openBinMem, get, put_ and all other functions. One more Streams-advertizing is the following table of text I/O speeds. It constructed, again, using 100 mb in each test. Strings I/O was tested using 15-char and 80-char lines (see conclusion at the end): Handle: vPutChar: 150.336 secs (user: 566.974 secs) vGetChar: 100.905 secs (user: 92.864 secs) vPutStrLn15: 34.310 secs (user: 31.165 secs) vGetLine15 : 18.397 secs (user: 16.914 secs) vPutStrLn80: 9.874 secs (user: 8.843 secs) vGetLine80 : 10.955 secs (user: 9.974 secs) vGetContents: 16.255 secs (user: -381.408 secs) Streams: File with locking: vPutChar: 48.900 secs (user: -384.632 secs) vGetChar: 48.029 secs (user: 44.304 secs) vPutStrLn15: 10.986 secs (user: 9.854 secs) vGetLine15 : 11.316 secs (user: 10.355 secs) vPutStrLn80: 5.618 secs (user: 4.987 secs) vGetLine80 : 8.672 secs (user: 8.032 secs) vGetContents: 14.571 secs (user: 13.379 secs) Streams: File: vPutChar: 3.065 secs (user: 1.222 secs) vGetChar: 1.232 secs (user: 1.082 secs) vPutStrLn15: 5.388 secs (user: 4.737 secs) vGetLine15 : 8.523 secs (user: 7.791 secs) vPutStrLn80: 4.687 secs (user: 4.076 secs) vGetLine80 : 7.822 secs (user: 7.200 secs) vGetContents: 14.831 secs (user: 13.640 secs) Streams: Memory-mapped file: vPutChar: 1.022 secs (user: 1.021 secs) vGetChar: 0.882 secs (user: 0.861 secs) vPutStrLn15: 4.667 secs (user: 4.246 secs) vGetLine15 : 7.451 secs (user: 6.920 secs) vPutStrLn80: 3.926 secs (user: 3.705 secs) vGetLine80 : 8.443 secs (user: 6.800 secs) Streams: File with UTF-8 encoding: vPutChar: 8.853 secs (user: 8.042 secs) vGetChar: 9.113 secs (user: 8.312 secs) vPutStrLn15: 10.005 secs (user: 8.933 secs) vGetLine15 : 13.770 secs (user: 12.518 secs) vPutStrLn80: 9.683 secs (user: 8.442 secs) vGetLine80 : 13.219 secs (user: 12.198 secs) vGetContents: 24.616 secs (user: 22.613 secs) Streams: MemBuf: vPutChar: 0.951 secs (user: 0.851 secs) vGetChar: 0.711 secs (user: 0.591 secs) vPutStrLn15: 4.446 secs (user: 4.166 secs) vGetLine15 : 7.130 secs (user: 6.599 secs) vPutStrLn80: 3.746 secs (user: 3.575 secs) vGetLine80 : 7.161 secs (user: 6.479 secs) vGetContents: 14.361 secs (user: 13.329 secs) as you can see, now, after all my optimizations, text I/O speeds are seriously limited by speed of lazy strings itself (getline/putline/getcontents are several times slower than getchar/putchar although it should be vice versa - much faster!). i foresee that Streams + Fast Packed Strings together will yield a breakthrough in GHC I/O speed, and this can be implemented even without waiting for GHC 6.6 ===8<===========End of original message text=========== -- Best regards, Bulat mailto:Bulat.Ziganshin@gmail.com

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Haskell Weekly News: May 1, 2006
by dons＠cse.unsw.edu.au 01 May '06

01 May '06

Haskell Weekly News: May 1, 2006 Welcome to issue 34 of HWN, a weekly newsletter covering developments in the Haskell community. Each Monday, new editions are posted to [1]the Haskell mailing list as well as to [2]the Haskell Sequence and [3]Planet Haskell. [4]RSS is also available, and headlines appear on [5]haskell.org. 1. http://www.haskell.org/mailman/listinfo/haskell 2. http://sequence.complete.org/ 3. http://planet.haskell.org/ 4. http://sequence.complete.org/node/feed 5. http://haskell.org/ A double-plus episode this week, as last week's HWN went missing during a furious hack fest. Announcements * GHC 6.4.2. Simon Marlow [6]announced the release of the Glasgow Haskell Compiler, version 6.4.2. GHC is a state-of-the-art programming suite for Haskell. Included is an optimising compiler generating good code for a variety of platforms, together with an interactive system for convenient, quick development. The distribution includes space and time profiling facilities, a large collection of libraries, and support for various language extensions, including concurrency, exceptions, and foreign language interfaces (C, whatever). GHC is distributed under a BSD-style open source license. For more information, see: + [7]GHC home + [8]Release notes + [9]GHC developers' home 6. http://article.gmane.org/gmane.comp.lang.haskell.general/13576 7. http://www.haskell.org/ghc/ 8. http://haskell.org/ghc/docs/6.4.2/html/users_guide/release-6-4-2.html 9. http://hackage.haskell.org/trac/ghc/ * Communities and Activities Report. Andres Loeh [10]released the call for contributions to the 10th (!) Haskell Communities and Activities Report. If you are working on any project that is in some way related to Haskell, write a short entry and submit it to Andres. The Haskell Communities and Activities Report is a bi-annual overview of the state of Haskell as well as Haskell-related projects over the last, and possibly the upcoming 6 months. If you have only recently been exposed to Haskell, it might be a good idea to browse the [11]November 2005 edition -- you will find interesting topics described as well as several starting points and links that may provide answers to many questions. 10. http://article.gmane.org/gmane.comp.lang.haskell.general/13578 11. http://haskell.org/communities/11-2005/html/report.html * Haskell' Status Report. Isaac Jones [12]released a [13]Haskell' status report. Currently the committee is focused on two issues, standardising [14]concurrency and extensions to [15]the class system. 12. http://article.gmane.org/gmane.comp.lang.haskell.general/13603 13. http://hackage.haskell.org/trac/haskell-prime 14. http://hackage.haskell.org/trac/haskell-prime/wiki/Concurrency 15. http://hackage.haskell.org/trac/haskell-prime/wiki/ClassSystem * Google Summer of Code. Paolo Martini [16]announced that Haskell.org would have a presence as an official mentoring organisation for this year's Google Summer of Code. Several members of the Haskell community have volunteered as mentors, and a large number of proposals have been listed. If you're interested in mentoring, suggesting projects, or applying as a student to spend your summer writing Haskell code, check it out! + [17]The official SoC site + [18]The Haskell.org SoC page 16. http://article.gmane.org/gmane.comp.lang.haskell.cafe/12496 17. http://code.google.com/soc/ 18. http://hackage.haskell.org/trac/summer-of-code/ * 2006 GHC Hackathon. Simon Marlow [19]writes that the GHC team is considering the possibility of organising a GHC Hackathon around ICFP this year. Tentative details are on [20]the wiki page. 19. http://article.gmane.org/gmane.comp.lang.haskell.general/13618 20. http://hackage.haskell.org/trac/ghc/wiki/Hackathon * Data.ByteString. Don Stewart [21]announced new versions of [22]FPS/Data.ByteString, the fast, packed strings library for Haskell. 21. http://article.gmane.org/gmane.comp.lang.haskell.general/13577 22. http://www.cse.unsw.edu.au/~dons/fps.html * Debian from Scratch. John Goerzen [23]announced Debian From Scratch (DFS), a single, full rescue linux CD capable of working with all major filesystems, LVM, software RAID, and even compiling a new kernel. The tool that generates the ISO images (dfsbuild) is written in Haskell. The generated ISO images also contain full, working GHC and Hugs environments. 23. http://article.gmane.org/gmane.comp.lang.haskell.general/13585 * Hazakura - search-based MUA. Jun Mukai [24]announced the first release of hazakura, a search-based mail client, written in Haskell. + [25]Web + [26]Source + [27]Darcs 24. http://article.gmane.org/gmane.comp.lang.haskell.general/13620 25. http://www.city5.org/hazakura/ 26. http://www.city5.org/haskellprog/hazakura/ 27. http://www.city5.org/haskellprog/hazakura/ * (HS)XML queries. Oleg Kiselyov [28]published a note demonstrating [29]Scrap your boilerplate 3 style generic term processing for transformations and selections from (HS)XML-like documents. 28. http://article.gmane.org/gmane.comp.lang.haskell.general/13589 29. http://www.cwi.nl/~ralf/syb3/ Haskell' This section covers activity on [30]Haskell' standardisation process. * [31]Class system status * [32]Termination for FDs and ATs * [33]Associated types and two-way functional dependencies * [34]unsafePerformIO and cooperative concurrency * [35]Concurrency guarantees * [36]Control of C headers 30. http://hackage.haskell.org/trac/haskell-prime 31. http://article.gmane.org/gmane.comp.lang.haskell.prime/1437 32. http://thread.gmane.org/gmane.comp.lang.haskell.prime/1450/focus=1450 33. http://thread.gmane.org/gmane.comp.lang.haskell.prime/1478/focus=1478 34. http://thread.gmane.org/gmane.comp.lang.haskell.prime/1452/focus=1452 35. http://thread.gmane.org/gmane.comp.lang.haskell.prime/1460/focus=1460 36. http://thread.gmane.org/gmane.comp.lang.haskell.prime/1438/focus=1438 Discussion * Global IORefs. Brian Hulley [37]forked a long running thread on the use of top level mutable variables in an application he's developing, leading to many contributions on how to rewrite the code in a functional style. 37. http://thread.gmane.org/gmane.comp.lang.haskell.cafe/12454/focus=12454 * cabal-get. Isaac Jones [38]released a note discussing some changes to Cabal, including integration of the cabal-get tool into the main branch. 38. http://article.gmane.org/gmane.comp.lang.haskell.libraries/4692 * Fast serialisation. Bulat Ziganshin [39]published some result of a test of various serialization libraries speed, comparing his AltBinary code against the standard Binary implementations, with very encouraging results. 39. http://article.gmane.org/gmane.comp.lang.haskell.general/13619 * Gigabyte strings. Don Stewart [40]posted the results of some experiments into using gigabyte strings (as ByteStrings) in GHC, with good results. 40. http://article.gmane.org/gmane.comp.lang.haskell.cafe/12446 Darcs corner * Darcs patcher. Nicholas FitzRoy-Dale [41]announced Darcs patcher, a tool to take a darcs patch file in the and applies it to the source tree in your current working directory. It was written as a tool to keep Bazaar repositories in sync with Darcs, with the Darcs repo being the master. Nicholas writes that he finds darcs much easier to use and less prone to failure. 41. http://article.gmane.org/gmane.comp.version-control.darcs.user/9861 Contributing to HWN You can help us create new editions of this newsletter. Please see the [42]contributing information, send stories to dons -at- cse.unsw.edu.au. The darcs repository is available at darcs get http://www.cse.unsw.edu.au/~dons/code/hwn 42. http://haskell.org/haskellwiki/HWN

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