June 2009 - Haskell-Cafe

BostonHaskell: Next meeting - June 23rd at MIT CSAIL Reading Room (32-G882)
by Ravi Nanavati 16 Jun '09

16 Jun '09

I'm pleased to announce the second meeting of the Boston Area Haskell Users' Group. The meeting is scheduled for Tuesday, June 23rd from 6:30pm - 8:30pm (*). It will be held in the MIT CSAIL Reading Room (32-G882, i.e. a room on the 8th floor of the Gates Tower of the MIT's Stata Center at 32 Vassar St in Cambridge, MA). We have the following two talks scheduled (each intended to be 30-45 minutes each): "Automagic Font Conversion with Haskell Typeclasses" by Frank Berthold "Intermediate Language Representations via GADTs" by Nirav Dave As in the last meeting there will be a break between the talks for discussion and mingling. As we are an informal, unsponsored group, there are no current plans to provide refreshments during the break, but I encourage people to volunteer to provide them (please contact me at ravi(a)bluespec.com so I can keep track of what to expect). I'll make sure to appropriately thank any refreshment volunteers at the meeting. If you have any questions about the meeting please send them to the BostonHaskell mailing list: bostonhaskell(a)googlegroups.com or contact me directly. I look forward to seeing many Boston area Haskellers next Tuesday! - Ravi Nanavati (*) I interpreted the silence in response to my previous email proposing June 23rd as assent. If this was a bad time or date to pick, please send your scheduling comments to the BostonHaskell list (i.e. bostonhaskell(a)googlegroups.com) so we can do a better job of picking a date and time in the future.

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PEPM'10 - First Call for Papers
by Janis Voigtlaender 16 Jun '09

16 Jun '09

=============================================================== CALL FOR PAPERS ACM SIGPLAN 2010 Workshop on Partial Evaluation and Program Manipulation (PEPM'10) Madrid, January 18-19, 2010 (Affiliated with POPL'10) http://www.program-transformation.org/PEPM10 =============================================================== IMPORTANT DATES: * Paper submission: Tue, October 6, 2009, 23:59, Apia time * Author notification: Thu, October 29, 2009 * Camera-ready papers: Mon, November 9, 2009 To facilitate smooth organization of the review process, authors are asked to submit a short abstract by October 1, 2009. SUBMISSION CATEGORIES: * Regular research papers (max. 10 pages in ACM Proceedings style) * Tool demonstration papers (max. 4 pages plus max. 6 pages appendix) SCOPE: The PEPM Symposium/Workshop series aims to bring together researchers and practitioners working in the areas of program manipulation, partial evaluation, and program generation. PEPM focuses on techniques, theory, tools, and applications of analysis and manipulation of programs. The 2010 PEPM workshop will be based on a broad interpretation of semantics-based program manipulation and continue previous years' effort to expand the scope of PEPM significantly beyond the traditionally covered areas of partial evaluation and specialization and include practical applications of program transformations such as refactoring tools, and practical implementation techniques such as rule-based transformation systems. In addition, the scope of PEPM covers manipulation and transformations of program and system representations such as structural and semantic models that occur in the context of model-driven development. In order to reach out to practitioners, there is a separate category of tool demonstration papers. Topics of interest for PEPM'10 include, but are not limited to: * Program and model manipulation techniques such as transformations driven by rules, patterns, or analyses, partial evaluation, specialization, program inversion, program composition, slicing, symbolic execution, refactoring, aspect weaving, decompilation, and obfuscation. * Program analysis techniques that are used to drive program/model manipulation such as abstract interpretation, static analysis, binding-time analysis, dynamic analysis, constraint solving, type systems, automated testing and test case generation. * Analysis and transformation for programs/models with advanced features such as objects, generics, ownership types, aspects, reflection, XML type systems, component frameworks, and middleware. * Techniques that treat programs/models as data objects including meta-programming, generative programming, deep embedded domain-specific languages, program synthesis by sketching and inductive programming, staged computation, and model-driven program generation and transformation. * Application of the above techniques including experimental studies, engineering needed for scalability, and benchmarking. Examples of application domains include legacy program understanding and transformation, DSL implementations, visual languages and end-user programming, scientific computing, middleware frameworks and infrastructure needed for distributed and web-based applications, resource-limited computation, and security. We especially encourage papers that break new ground including descriptions of how program/model manipulation tools can be integrated into realistic software development processes, descriptions of robust tools capable of effectively handling realistic applications, and new areas of application such as rapidly evolving systems, distributed and web-based programming including middleware manipulation, model-driven development, and on-the-fly program adaptation driven by run-time or statistical analysis. PROCEEDINGS: There will be formal proceedings published by ACM Press. In addition to printed proceedings, accepted papers will be included in the ACM Digital Library. Selected papers may later on be invited for a journal special issue dedicated to PEPM'10. SUBMISSION GUIDELINES: Papers should be submitted electronically via the workshop web site. Regular research papers must not exceed 10 pages in ACM Proceedings style. Tool demonstration papers must not exceed 4 pages in ACM Proceedings style, and authors will be expected to present a live demonstration of the described tool at the workshop (tool papers should include an additional appendix of up to 6 additional pages giving the outline, screenshots, examples, etc. to indicate the content of the proposed live demo at the workshop). Authors using Latex to prepare their submissions should use the new improved SIGPLAN proceedings style (sigplanconf.cls). PROGRAM CO-CHAIRS: * John Gallagher (Roskilde University, Denmark, and IMDEA Software, Spain) * Janis Voigtländer (Technische Universität Dresden, Germany) PROGRAM COMMITTEE MEMBERS: * Wei-Ngan Chin (National University of Singapore, Singapore) * Michael Codish (Ben-Gurion University of the Negev, Israel) * Jim Cordy (Queen's University, Canada) * Nate Foster (University of Pennsylvania, USA) * Haifeng Guo (University of Nebraska at Omaha, USA) * Patricia Johann (University of Strathclyde, UK) * Oleg Kiselyov (FNMOC, USA) * Günter Kniesel (University of Bonn, Germany) * Viktor Kuncak (Ecole Polytechnique Fédérale de Lausanne, Switzerland) * Yanhong Annie Liu (State University of New York at Stony Brook, USA) * Andres Löh (Utrecht University, Netherlands) * Jan Midtgaard (Roskilde University, Denmark) * David Monniaux (National Center for Scientific Research (CNRS) and VERIMAG laboratory, France) * Akimasa Morihata (University of Tokyo, Japan) * Alberto Pettorossi (Università di Roma Tor Vergata, Italy) * João Saraiva (Universidade do Minho, Portugal) * Ganesh Sittampalam (Credit Suisse, UK) * Fausto Spoto (Università di Verona, Italy) * Harald Søndergaard (University of Melbourne, Australia) * Walid Taha (Rice University, USA)

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Logo fun
by Thomas Davie 16 Jun '09

16 Jun '09

We had a lot of "fun" deciding Haskell's new logo, and while I don't agree with the final result, it would be nice if we could now start consistently using it. With that in mind, I realised that the Haskell Platform's logo is totally different, and did a quick mock up of a version reflecting the current Haskell logo. It needs someone with the original vector graphics to have a play and improve it a little bit, but hopefully you'll se a concept you like. Here's the logo, continuing on the batteries included theme: http://www.cs.kent.ac.uk/people/rpg/tatd2/HaskellBatteries.png I'd appreciate comments, suggestions, and possibly either access to the vector version of our current logo, or someone producing a nice version of this. Bob

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Parametrized monads
by Miguel Mitrofanov 16 Jun '09

16 Jun '09

Hi! Suppose I want to create a specific monad as a combination of monad transformers - something like "StateT smth1 (ReaderT smth2 Identity)". As you can see, each transformer is parametrized with a type of kind *. I want to abstract these parameters, so that instead of "StateT smth..." I can write something like Zip (ConsT StateT (ConsT ReaderT NilT)) (ConsA smth1 (ConsA smth2 NilA)) Identity and it would be a type isomorphic to the first one. I mean, I want (ConsT StateT (ConsT ReaderT NilT))" to be a separate entity of fixed kind, so that I can, say, create a class instance for it or something. I'd be quite happy if list length appears as a separate parameter, like Zip (Succ (Succ Zero)) (ConsT ... I would NOT be happy with something like Zip (List_2 StateT ReaderT) (Arg_2 smth1 smth2) If haskell had polymorphic kinds, I'd be able to do it easily; unfortunately, it doesn't have them. Thanks

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Running Hoogle as a cgi script.
by Erik de Castro Lopo 16 Jun '09

16 Jun '09

Hi all, I'd like to run my own version of Hoogle: http://hackage.haskell.org/package/hoogle as a CGI script much like this: http://www.haskell.org/hoogle/ but there doesn't seem to be any documentation on how to do this. Clues anyone? Cheers, Erik -- ---------------------------------------------------------------------- Erik de Castro Lopo http://www.mega-nerd.com/

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Fwd: [Haskell-cafe] Logo
by Robert Greayer 15 Jun '09

15 Jun '09

Meant this to go to the list... ---------- Forwarded message ---------- From: Robert Greayer <robgreayer(a)gmail.com> To: Ashley Yakeley <ashley(a)semantic.org> For anyone concerned the Hackage icon (http://hackage.haskell.org/favicon.ico) is still the old blue lambda, not the sparkling new icon (http://haskell.org/favicon.ico) On Mon, Jun 15, 2009 at 2:39 AM, Ashley Yakeley<ashley(a)semantic.org> wrote: > Thomas Davie wrote: >> >> We had a lot of "fun" deciding Haskell's new logo, and while I don't agree >> with the final result, it would be nice if we could now start consistently >> using it. With that in mind, I realised that the Haskell Platform's logo is >> totally different, and did a quick mock up of a version reflecting the >> current Haskell logo. It needs someone with the original vector graphics to >> have a play and improve it a little bit, but hopefully you'll se a concept >> you like. > > I rather like the fact that the Haskell Platform logo is distinct from the > Haskell logo. I think it helps prevent confusion (even though the Platform > logo is based on one of the Haskell logo competition entrants). > > http://haskell.org/haskellwiki/Haskell_Platform > > By the way, when I came to replace the Haskell logo on the wiki site, since > the colours had not and still have not been officially decided on, I just > picked the same colours as the Haskell Platform logo. So for the time being, > there is a visual link between the two logos. > > -- > Ashley Yakeley > _______________________________________________ > Haskell-Cafe mailing list > Haskell-Cafe(a)haskell.org > http://www.haskell.org/mailman/listinfo/haskell-cafe >

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force evaluation beginners question
by Nico Rolle 15 Jun '09

15 Jun '09

Hi there I'm trying to compile a code snipped that i've go from a tutorial which uses the function "force". But when I'm trying to compile it ghc reports an error that it couldn't find the defenition of force. my ghc verion is 6.10.3 Did they moved force out of Prelude in one of the latest updates? regards

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Re: [Haskell-cafe] Backpropagation implementation for a neural net library
by Alp Mestan 15 Jun '09

15 Jun '09

On Mon, Jun 15, 2009 at 5:00 PM, Trin Trin <trin.cz(a)gmail.com> wrote: > Hi Alp, > - even with correctly programmed back-propagation, it is usually hard to > make the net converge. > Yeah, I know, that's why we're training it until the quadratic error goes under 0.1. > - usually you initialize neuron weights with somewhat random values, when > working with back-propagation. > Yeah, that'll be done too, once the algorithm will be ready. I'll provide fancy and easy functions to create a neural net just giving the numbers of layers and their sizes. > - do some debug prints of the net error while training to see how it is > going > Good idea, yeah. > - xor function cannot be trained with a single layer neural net !!! > That's why there are 2 layers there, one hidden and the output one. I consider the "inputs" as ... inputs, not as a first layer of the NN. Thanls for your time. If you have any clues when reading the code, don't hesitate of course. -- Alp Mestan http://blog.mestan.fr/ http://alp.developpez.com/

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ANN: Haskell protocol-buffers version 1.5.0
by Chris Kuklewicz 15 Jun '09

15 Jun '09

Hello all, I have just uploaded version 1.5.0 of the Haskell version to hackage. The links for the three pieces are: http://hackage.haskell.org/package/protocol-buffers http://hackage.haskell.org/package/protocol-buffers-descriptor http://hackage.haskell.org/package/hprotoc This catches up to Google's version 2.1.0, as described below: * Support for "repeated" fields for primitive type (good arrays!). Note that using on an invalid field type will generate an error. * NO support yet for the *_FIELD_NUMBER style constants * It is now an error to define a default value for a repeated field. * Fields can now be marked deprecated (does nothing) * The type name resolver will no longer resolve type names to fields. Note that this applies to type of normal and extension fields. A lexer bug was founds and fixed by George van den Driessche, when a numeric literal in a proto file was followed immediately by a newline character. Cheers, Chris

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Backpropagation implementation for a neural net library
by Alp Mestan 15 Jun '09

15 Jun '09

Dear List, I'm working with a friend of mine on a Neural Net library in Haskell. There are 3 files : neuron.hs, layer.hs and net.hs. neuron.hs defines the Neuron data type and many utility functions, all of which have been tested and work well. layer.hs defines layer-level functions (computing the output of a whole layer of neurons, etc). Tested and working. net.hs defines net-level functions (computing the output of a whole neural net) and the famous -- but annoying -- back-propagation algorithm. You can find them there : http://mestan.fr/haskell/nn/html/ The problem is that here when I ask for final_net or test_output (anything after the train call, in net.hs), it seems to loop and loop around, as if it never gets the error under 0.1. So I was just wondering if there was one or more Neural Nets and Haskell wizard in there to check the back-propagation implementation, given in net.hs, that seems to be wrong. Thanks a lot ! -- Alp Mestan

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