- Haskell - Haskell.org

(no subject)
by Boyko Bantchev 05 Jun '07

05 Jun '07

Hi all! The List module provides isPrefixOf, isSuffixOf, and -- since recently -- isInfixOf, to check whether a list is a prefix, a suffix, or an infix to another list. Similarly, we have inits and tails to obtain the prefixes and the suffixes of a list, but there is no standard function that would return a list of infixes. For reasons of symmetry, perhaps it is worth having a function in List returning, say, a list of infixes of fixed length, such as e.g., infixes n as = map (take n) $ take (length as - n + 1) (tails as) Or, instead, there might be included a function that lists all infixes lexicographically (map (tail . inits) . tails) or perhaps otherwise, e.g. in the order of increasing/decreasing lengths. (In the latter case, the result might be a list of lists of same-length infixes each.) What do you think? Regards, Boyko

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Haskell on Beowulf?
by Johannes Waldmann 04 Jun '07

04 Jun '07

What tool/compiler support is there for compiling Haskell code to run on a Beowulf cluster? Any pointers appreciated. -- Johannes Waldmann, Leipzig, Germany.

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[IAT 2007] Deadline Extended: June 16, 2007!
by Jia Hu 02 Jun '07

02 Jun '07

[Apologies if you receive this more than once] Dear Colleague, In response to many requests for an extension, we are pleased to extend the paper submission deadline for IAT 2007 to ** June 16, 2007 **. Submission can be done online at: http://www.cs.sjsu.edu/wi07/iat/ We look forward to receiving your submissions soon. With best regards, Tsau Young (T.Y.) Lin PC chair of WI-IAT'07 ##################################################################### IEEE/WIC/ACM Intelligent Agent Technology 2007 CALL FOR PAPERS ##################################################################### 2007 IEEE/WIC/ACM International Conference on Intelligent Agent Technology (IAT'07) Silicon Valley, USA, November 2-5, 2007 Official: http://www.cs.sjsu.edu/wi07/iat/ Mirror: http://www.maebashi-it.org/wi07/iat/ (to be collocated with WI'07, BIBM'07 and GrC'07) Sponsored By IEEE Computer Society Web Intelligence Consortium (WIC) Association for Computing Machinery (ACM) ##################################################################### # Conference Chair # Andrei Broder, VP, Yahoo Fellow, Yahoo! Research # # Program Chair and Co-Chairs # T.Y. Lin, San Jose State University/UC Berkeley, USA # Jeffrey M. Bradshaw, UWF/Institute for Human and Machine Cognition, USA # Matthias Klusch, German Research Center for AI, Germany # Chengqi Zhang, University of Technology, Sydney, Australia # # Organizing Chair # Howard Ho, Manager, IBM Almaden Research Center # # IAT-WI Joint Keynote Speakers (Tentative) # # Vinton G. Cerf, Turing Award Winner, # VP and Chief Internet Evangelist, Google # Richard M. Karp, Turing Award Winner, # University of California Berkeley # Anant Jhingran, VP and CTO, IBM Silicon Valley Laboratory # # (More IAT Invited Speakers will be announced) # # (Papers Due: ** June 1 **, 2007) # Accepted papers will be published in the conference proceedings # by the IEEE Computer Society Press, which are indexed by EI. ###################################################################### The 2007 IEEE/WIC/ACM International Conference on Intelligent Agent Technology (IAT'07) will be jointly held with the 2007 IEEE/WIC/ACM International Conference on Web Intelligence (WI'07), the 2007 IEEE International Conference on Bioinformatics and Biomedicine (BIBM'07), and the 2007 IEEE International Conference on Granular Computing (GrC'07) for providing synergism among the four research areas. It will provide opportunities for technical collaboration beyond that of previous conferences. The four conferences will have a joint opening, keynote, reception, and banquet. Attendees only need to register for one conference and can attend workshops, sessions and tutorials across the four conferences. We are also planning a joint panel and joint paper sessions that discuss common problems in the four areas. IAT 2007 provides a leading international forum to bring together researchers and practitioners from diverse fields, such as computer science, information technology, business, education, human factors, systems engineering, and robotics, to (1) examine the design principles and performance characteristics of various approaches in intelligent agent technology, and (2) increase the cross-fertilization of ideas on the development of autonomous agents and multi-agent systems among different domains. By encouraging idea-sharing and discussions on the underlying logical, cognitive, physical, and sociological foundations as well as the enabling technologies of intelligent agents, IAT 2007 will foster the development of novel paradigms and advanced solutions in agent-based computing. +++++++++++ Highlights +++++++++++ The conference will be held in Silicon Valley, California. Many high-tech companies and three distinguished universities (Stanford, UC Berkely and UCSC) are just around the corner. The highlight of the conference is that a unique forum consisting of a half-day demo session and free discussion will be organized to link industries and academics. Leading IT companies like IBM, Google, and Yahoo etc will present at the conference. The area now known as Silicon Valley has been a center of technological development since the 1950's. The name Silicon Valley stems from the early 1970's, when the area had become the center for many semiconductor companies. While still hosting semiconductor and microprocessor companies, the region now hosts the headquarters of high tech companies of every kind, including many of the best known and most prestigious names in personal computers, Web search, Internet auctions, networking, storage, databases, etc. +++++++++++++++++++ Topics of Interest +++++++++++++++++++ The topics and areas include, but not limited to: * Autonomy-Oriented Computing (AOC) - Agent-Based Complex Systems Modeling and Development - Agent-Based Simulation - Autonomy-Oriented Modeling and Computation Methods - Behavioral Self-Organization - Complex Behavior Characterization and Engineering - Emergent Behavior - Hard Computational Problem Solving - Nature-Inspired Paradigms - Self-Organized Criticality - Self-Organized Intelligence - Swarm Intelligence * Autonomous Knowledge and Information Agents - Agent-Based Distributed Data Mining - Agent-Based Knowledge Discovery And Sharing - Autonomous Information Services - Distributed Knowledge Systems - Emergent Natural Law Discovery in Multi-Agent Systems - Evolution of Knowledge Networks - Human-Agent Interaction - Information Filtering Agents - Knowledge Aggregation - Knowledge Discovery - Ontology-Based Information Services * Agent Systems Modeling and Methodology - Agent Interaction Protocols - Cognitive Architectures - Cognitive Modeling of Agents - Emotional Modeling - Fault-Tolerance in Multi-Agent Systems - Formal Framework for Multi-Agent Systems - Information Exchanges in Multi-Agent Systems - Learning and Self-Adaptation in Multi-Agent Systems - Mobile Agent Languages and Protocols - Multi-Agent Autonomic Architectures - Multi-Agent Coordination Techniques - Multi-Agent Planning and Re-Planning - Peer-to-Peer Models for Multi-Agent Systems - Reinforcement Learning - Social Interactions in Multi-Agent Systems - Task-Based Agent Context - Task-Oriented Agents * Distributed Problem Solving - Agent-Based Grid Computing - Agent Networks in Distributed Problem Solving - Collective Group Behavior - Coordination and Cooperation - Distributed Intelligence - Distributed Search - Dynamics of Agent Groups and Populations - Efficiency and Complexity Issues - Market-Based Computing - Problem-Solving in Dynamic Environments * Autonomous Auctions and Negotiation - Agent-Based Marketplaces - Auction Markets - Combinatorial Auctions - Hybrid Negotiation - Integrative Negotiation - Mediating Agents - Pricing Agents - Thin Double Auctions * Applications - Agent-Based Assistants - Agent-Based Virtual Enterprise - Embodied Agents and Agent-Based Systems Applications - Interface Agents - Knowledge and Data Intensive Systems - Perceptive Animated Interfaces - Scalability - Social Simulation - Socially Situated Planning - Software and Pervasive Agents - Tools and Standards - Ubiquitous Systems and E-Technology Agents - Ubiquitous Software Services - Virtual Humans - XML-Based Agent Systems ++++++++++++++++++++++++++++++++++++ On-Line Submissions and Publication ++++++++++++++++++++++++++++++++++++ High-quality papers in all IAT related areas are solicited. Paper submissions should be limited to a maximum of 7 pages in the IEEE 2-column format, the same as the camera-ready format (see the Author Guidelines of last year at http://www.computer.org/portal/pages/cscps/cps/final/iat06.xml) All submitted papers will be reviewed by the Program Committee on the basis of technical quality, relevance, significance, and clarity. Note that IAT'07 will accept ONLY on-line submissions, containing PDF versions. Please use the Submission Form on the IAT'07 website to submit your paper. Accepted papers will be published in the conference proceedings by the IEEE Computer Society Press that are indexed by EI. Submissions accepted as regular papers will be allocated 7 pages in the proceedings and accorded oral presentation times in the main conference. Submissions accepted as short papers will be allocated 4 pages in the proceedings and will have a shorter presentation time at the conference than regular papers. All co-authors will be notified at all time, for the submission, notification, and confirmation on the attendance. Submitting a paper to the conference and workshops means that, if the paper is accepted, at least one author should attend the conference to present the paper. The acceptance list and no-show list will be openly published on-line. For no-show authors, their affiliations will receive a notification. A selected number of IAT'07 accepted papers will be expanded and revised for inclusion in Web Intelligence and Agent Systems: An International Journal (http://wi-consortium.org/journal.html) and in Annual Review of Intelligent Informatics (http://www.wi-consortium.org/annual.html) More detailed instructions and the On-Line Submission Form can be found from the IAT'07 homepage: http://www.cs.sjsu.edu/wi07/iat/. +++++++++++++++++++++++++ IAT'07 Best Paper Awards +++++++++++++++++++++++++ The best paper awards will be conferred at the conference on the authors of (1) the best research paper and (2) the best application paper. Application-oriented submissions will be considered for the best application paper award. The full author list and paper title will be announced on the Web Intelligence Consortium homepage: http://wi-consortium.org/html/wicawards.html ++++++++++++++++++++ Industry/Demo-Track ++++++++++++++++++++ We solicit Industry/Demo-Track papers by the following methods. (1) Industry papers of 4 pages can be submitted on the same schedule as the research track. (2) Separate 2 page demo proposals can submitted at a later schedule. (3) Full regular paper submissions can include a demo option. That is, a full paper submissions will be asked to specify if they would like to give a demonstration; choice of demonstrations (while utilizing information from the regular reviewing process) will be selected based on value as a demonstration. For options (1) and (2), please find more detailed instructions at the homepage: http://www.cs.sjsu.edu/wi07/wi/ We are planning to arrange the Industry/Demo track in the afternoon of November 3 (before and during the conference reception), jointly with the IAT'07 Demo sessions. Leading IT companies in Silicon Valley will be invited to attend this track. ++++++++++ Workshops ++++++++++ As an important part of the conference, the workshop program will focus on new research challenges and initiatives. All papers accepted for workshops will be included in the Workshop Proceedings published by the IEEE Computer Society Press that are indexed by EI, and will be available at the workshops. Detailed information is available at the conference homepage. Note: we will not have a separate workshop registration fee (i.e., only one conference registration covers everything). ---------------------- WI-IAT 2007 Workshops: ---------------------- Title: Educating the Web-Generation (Edu4WebGen 2007) Organisers: Elisabeth Heinemann Email: elisabeth.heinemann(a)googlemail.com Web page: http://www.effactory.com/Edu4WebGen/ Title: Collective Intelligence on Semantic Web (CISW 2007) Organisers: Geun Sik Jo; Jason J. Jung; Ngoc Thanh Nguyen Email: gsjo(a)inha.ac.kr; j2jung(a)intelligent.pe.kr; thanh(a)pwr.wroc.pl Web page: http://intelligent.pe.kr/CISW07/ Title: New Computing Paradigms for Web Intelligence and Brain Informatics (WImBI 2007) Organisers: Dr. Yuefeng Li; Dr. Yulin Qin, Prof. Dieter Fensel Email: y2.li(a)qut.edu.au; dieter.fensel(a)deri.org Web page: http://www.maebashi-it.org/wimbi07/WImBI2007.htm Title: Web Personalization and Recommender Systems (WPRS 2007) Organisers: Yue Xu Email: yue.xu(a)qut.edu.au Web page: http://www.wprs07.fit.qut.edu.au/ Title: Service Composition & SWS Challenge (SerComp & SWS Challenge 2007) Organisers: M. Brian Blake; Dumitru Roman; Charles Petrie Email: blakeb(a)cs.georgetown.edu; dumitru.roman(a)deri.org Web page: http://events.deri.at/sercomp2007/ Title: Biomedicine Applications of Web technologies (BMWT 2007) Organisers: Chun-Nan Hsu; Vincent Shin-Mu Tseng; Wen-Hsiang Lu Email: chunnan(a)iis.sinica.edu.tw; tsengsm(a)mail.ncku.edu.tw; whlu(a)mail.ncku.edu.tw Web page: http://chunnan.iis.sinica.edu.tw/BMWT2007.html Title: Intelligent Web Interaction (IWI 2007) 1st Organiser: Prof. Seiji YAMADA Email: seiji(a)nii.ac.jp Web site: http://ymd.ex.nii.ac.jp/ws/iwi/07/ Title: Cyberinfrastucture for e-Science (CyIneS 2007) Organisers: Prof. Vasant Honavar; A/prof. Kei Cheung Email: honavar(a)cs.iastate.edu; kei.cheung(a)yale.edu Web page: http://www.cild.iastate.edu/events/CyIneS2007/ Title: Social Media Analysis (SMA 2007) Organisers: Chun-hung Li, William K. Cheung, Quoping Qiu Email: sma(a)comp.hkbu.edu.hk Web page: http://www.comp.hkbu.edu.hk/~sma/ Title: Web Security, Integrity, Privacy and Trust (WSIPT 2007) Organisers: Dr. Yiuming Cheung, Prof. Michael Chau, and Prof. Yong Zhang Email: ymc(a)Comp.HKBU.Edu.HK; mchau(a)business.hku.hk; zhangyong076(a)gmail.com Web page: http://isec.hitsz.edu.cn/wsipt07/ Title: Communication between Human and Artificial Agents (CHAA 2007) Organisers: Christel Kemke Email: ckemke(a)cs.umanitoba.ca Web page: http://www.cs.umanitoba.ca/~ckemke/CHAA-07/ Title: Rational, Robust, and Secure Negotiations in Multi-Agent Systems (RRS 2007) Organisers: Takayuki Ito Email: ito.takayuki(a)nitech.ac.jp Web page: http://www-itolab.mta.nitech.ac.jp/RRS2007/ Title: P2P Computing and Autonomous Agents (P2PAA 2007) Organisers: Tarek Helmy, Khaled Ragab Email: helmy(a)ccse.kfupm.edu.sa; helmy(a)kfupm.edu.sa Web Page: http://www.ccse.kfupm.edu.sa/~helmy/P2PAA2007_WI.html Title: (Multi-)Agent Systems in E-Business: Concepts, Technologies and Applications (MASeB 2007) Organisers: Costin Badica; Maria Ganzha; Marcin Paprzycki Email: badica_costin(a)software.ucv.ro; ganzha(a)euh-e.edu.pl; marcin.parzycki(a)swps.edu.pl Web page: http://software.ucv.ro/~badica_costin/maseb2007/ Title: Agent & Data Mining Interaction (ADMI 2007) Organisers: Pericles A. Mitkas, Longbing Cao, Vladimir Gorodetsky, Justin Zhan Email: mitkas(a)eng.auth.gr; lbcao(a)it.uts.edu.au Web page: http://issel.ee.auth.gr/ADMI For more information, please visit the conference website at http://www.maebashi-it.org/wi07/iat/?index=workshop. ++++++++++ Tutorials ++++++++++ IAT'07 also welcomes Tutorial proposals. IAT'07 will include tutorials providing in-depth background on subjects that are of broad interest to the intelligent agent community. Both short (2 hours) and long (half day) tutorials will be considered. The tutorials will be part of the main conference technical program. Detailed information is available at the conference homepage. Note: we will not have a separate tutorials registration fee (i.e., only one conference registration covers everything). ++++++++++++++++ Important Dates ++++++++++++++++ Workshop proposal submission: March 20, 2007 Electronic submission of full papers: ** June 1, 2007 ** Tutorial proposal submission: June 15, 2007 Notification of paper acceptance: July 22, 2007 Camera-ready copies of accepted papers: August 17, 2007 Conference: November 2-5, 2007 ++++++++++++++++++++++++ Conference Organization ++++++++++++++++++++++++ Conference Chair: * Andrei Broder, Yahoo! Research, USA Program Chair: * Tsau Young (T.Y.) Lin, San Jose State University/UC Berkeley, USA IAT Program Co-Chairs: * Jeffrey M. Bradshaw, UWF/Institute for Human and Machine Cognition, USA * Matthias Klusch, German Research Center for AI, Germany * Chengqi Zhang, University of Technology, Sydney, Australia IAT Program Vice Co-chairs * Longbing cao University of Technology Sydney Australia * Joseph A. Giampapa Carnegie Mellon University USA * Maria Gini University of Minnesota USA * Vladimir Gorodetsky St. Petersburg Institute for Informatics and Automation Russia * Alessio Lomuscio Imperial College London UK * Zbigniew Ras University of North Carolina USA * Marius C. Silaghi Florida Institute of Technology USA * Makoto Yokoo Kyushu University Japan WI Program Co-Chairs: * Laura Haas, IBM Almaden Research Center, USA * Janusz Kacprzyk, Polish Academy of Science, Poland * Rajeev Motwani, Stanford University, USA WI Program Vice Co-chairs * Ajith Abraham Yonsei University South Korea * Peter Brusilovsky University of Pittsburgh USA * Ashish Goel Stanford University USA * Ramanathan V. Guha Google USA * Jane Yung-jen Hsu National Taiwan University Taiwan * Ravi Kumar Yahoo! Research USA * Jie Lu University of Technology Sydney Australia * Tsuyoshi Murata Tokyo Institute of Technology Japan * York Sure Institute AIFB, University of Karlsruhe Germany * Pang-Ning Tan Michigan State University USA * Bhavani Thuraisingham University of Texas at Dallas USA * Mohammed Zaki Rensselaer Polytechnic Institute USA Organizing Chair: * Howard Ho, IBM Almaden Research Center, USA Workshop Co-Chairs: * Vijay Raghavan, University of Louisiana, USA * Yuefeng Li, Queensland University of Technology, Australia Tutorial Chair: * Pawan Lingras, Saint Mary's University, Canada Industry/Demo-Track Chair: * Jianchang Mao, Yahoo! Inc., USA Local Accommodations Co-Chairs: * David Scot Taylor, San Jose State University, USA * Tom Qi Zhang, Google, USA Publicity Chair: * James Wang, Clemson University, USA (chair) Publicity Co-Chairs: * Martine De Cock, Ghent University, Belgium * Jia Hu, International WIC Institute, China * Debajyoti Mukhopadhyay, West Bengal University of Technology, India IEEE-CS-TCII Chair: * Ning Zhong, Maebashi Institute of Technology, Japan ACM-SIGART Chair * Maria Gini, University of Minnesota, USA WIC Co-Chairs/Directors: * Ning Zhong, Maebashi Institute of Technology, Japan * Jiming Liu, University of Windsor, Canada WIC Advisory Board: * Edward A. Feigenbaum, Stanford University, USA * Setsuo Ohsuga, Waseda University, Japan * Benjamin Wah, University of Illinois, Urbana-Champaign, USA * Philip Yu, IBM Thomas J. Watson Research Center, USA * L.A. Zadeh, University of California Berkeley, USA WIC Tech. Committee & WI/IAT Steering Committee: * Jeffrey Bradshaw, UWF/Institute for Human and Machine Cognition, USA * Nick Cercone, York University, Canada * Dieter Fensel, University of Innsbruck/Digital Enterprise Research Institute, Austria * Georg Gottlob, Oxford University, UK * Lakhmi Jain, University of South Australia, Australia * Jianchang Mao, Yahoo! Inc., USA * Pierre Morizet-Mahoudeaux, Compiegne University of Technology, France * Hiroshi Motoda, Osaka University, Japan * Toyoaki Nishida, Kyoto University, Japan * Andrzej Skowron, Warsaw University, Poland * Jinglong Wu, Kagawa University, Japan * Xindong Wu, University of Vermont, USA * Yiyu Yao, University of Regina, Canada Webmaster: * Albert Sutojo, San Jose State University, USA Abbreviation: IAT 2007, IAT2007, IAT'2007, IAT'07, IAT07, IAT 07, IAT-07, IAT-2007 *** Contact Information *** Jia Hu International WIC Institute, China E-mail: hujia(a)kis-lab.com

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Paper draft: "Applicative Data-Driven Computation"
by Conal Elliott 02 Jun '07

02 Jun '07

I would love to get comments on a short (4.5 page) paper draft called "Applicative Data-Driven Computation", which describes a very simple approach to data-driven (push-based) computation and its application to GUI programming. Please see http://www.haskell.org/haskellwiki/Applicative_Data-Driven_Programming. There's a "Talk Page" link for comments, or if you prefer you could email me instead. I'm also very interested in suggestions and (better yet) collaboration on other applications of data-driven computation beyond GUIs, say push-based internet apps. Thanks, - Conal

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ST vs State
by Federico Squartini 31 May '07

31 May '07

Hello dear Haskellers, Could someone be kind and explain with some detail what are the differences between the two monads: Control.Monad.ST And Control.Monad.State ? They are both meant to model stateful computation but they are not the same monad. The first one represents state with in place update? Regards, Federico

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ANNOUNCE: Haskell Communities & Activities Report (12th ed., May 2007)
by Andres Loeh 31 May '07

31 May '07

On behalf of the many, many contributors, I am pleased to announce that the Haskell Communities and Activities Report (12th edition, May 2007) http://www.haskell.org/communities/ is now available from the Haskell Communities home page in several PDF and HTML formats. Many thanks go to all the people that contributed to this report, both directly, by sending in descriptions, and indirectly, by doing all the interesting things that are reported. I hope you will find it as interesting a read as we did. If you haven't encountered the Haskell Communities and Activities Reports before, you may like to know that the first of these reports was published in November 2001. Their goal is to improve the communication between the increasingly diverse groups, projects and individuals working on, with, or inspired by Haskell. The idea behind these reports is simple: Every six months, a call goes out to all of you enjoying Haskell to contribute brief summaries of your own area of work. Many of you respond (eagerly, unprompted, and well in time for the actual deadline ;) ) to the call. The editor collects all the contributions into a single report and feeds that back to the community. When we try for the next update, six months from now, you might want to report on your own work, project, research area or group as well. So, please put the following into your diaries now: ---------------------------------------- End of October 2007: target deadline for contributions to the November 2007 edition of the HC&A Report ---------------------------------------- Unfortunately, many Haskellers working on interesting projects are so busy with their work that they seem to have lost the time to follow the Haskell related mailing lists and newsgroups, and have trouble even finding time to report on their work. If you are a member, user or friend of a project so burdened, please find someone willing to make time to report and ask them to `register' with the editor for a simple e-mail reminder in the middle of April (you could point me to them as well, and we can then politely ask if they want to contribute, but it might work better if you do the initial asking). Of course, they will still have to find the ten to fifteen minutes to draw up their report, but maybe we can increase our coverage of all that is going on in the community. Feel free to circulate this announcement further in order to reach people who might otherwise not see it. Enjoy! Andres Loeh <hcar at haskell.org> -- Haskell Communities and Activities Report (http://haskell.org/communities)

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ANNOUNCE: xmonad 0.2
by Spencer Janssen 31 May '07

31 May '07

The xmonad dev team is pleased to announce the 0.2 release of: xmonad: a tiling window manager http://xmonad.org About: Xmonad is a tiling window manager for X. Windows are arranged automatically to tile the screen without gaps or overlap, maximising screen use. All features of the window manager are accessible from the keyboard: a mouse is strictly optional, greatly increasing productivity in X. Xmonad is written and extensible in Haskell, and custom layout algorithms, and other extesions, may be implemented by the user in config files. Layouts may be applied dynamically, and separate layouts can be used on each workspace. A guiding principle of the user interface is predictability: users should know in advance precisely the window arrangement that will result from any action, leading to an intuitive user interface. Features: * Automatic window tiling and management * First class keyboard support: a mouse is unnecessary * Full multihead/Xinerama support * XRandR support to rotate, add or remove monitors * Per-workspace layout algorithms * Per-screen non-built in status bars, with arbitrary geometry * Dynamic restart/reconfigure preserving workspace state * Tiny code base (~500 lines of Haskell) * Fast, small and simple. No interpreters, no heavy extension languages Since 0.1, the following notable features and bug fixes have appeared: New features: * XRandR support, for dynamically adding, removing or rotating monitors * State-preserving dynamic restart * Popup, customisable status bar support * Multiple clients may appear in the master pane * mod-shift-j/k, to swap windows with their neighbours * mod-n, to resize windows * User-specified layout algorithms may be written in config files * All layouts may be 'mirrored' (rotated) * configurable window border size and colour Design changes: * Reimplemented core of xmonad with a 'zipper' data type to track focus by construction. We believe this is a first. * Use of Neil Mitchell's 'catch' program to verify pattern match safety * Use of ReaderT and StateT to partition read-only and modifiable values * Custom layout messages handled with open data type simulation * More QuickCheck properties Bug fixes: * numlock handling is fixed More information, screenshots, documentation and community resources are available from: http://xmonad.org Xmonad is available from hackage, and via darcs. Happy hacking! The Xmonad Team: Spencer Janssen Don Stewart Jason Creighton Xmonad has also received patches from: Alec Berryman Chris Mears Daniel Wagner David Glasser David Lazar David Roundy Joe Thornber Miikka Koskinen Neil Mitchell Nick Burlett Robert Marlow Sam Hughes Shae Erisson

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ANNOUNCE: The Reduceron
by Matthew Naylor 31 May '07

31 May '07

Dear Haskellers, You may be interested in the Reduceron: http://www-users.cs.york.ac.uk/~mfn/reduceron/index.html Here is a flavour: "The Reduceron is a processor for executing Haskell programs on FPGA with the aim of exploring how custom architectural features can improve the speed in which Haskell functions are evaluated. Being described entirely in Haskell (using Lava), the Reduceron also serves as an interesting application of functional languages to the design of complex control circuits such as processors. To program the Reduceron we provide a basic Haskell compiler, called Tred, that translates Yhc.Core programs into codes of the Reduceron's instruction set. The Tred compiler and Reduceron processor are in the early stages of development: they are both fairly naive, inefficient, and lacking in many important features. But they represent a good start, already capable of correctly compiling and executing (on FPGA) a reasonable range of Haskell programs." See webpage for more details. Matthew.

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Re: [Haskell] Doubt about recursive functions
by Jim Burton 29 May '07

29 May '07

Eduardo01 wrote: > > Hi! First, nice to meet you guys. > My name's Eduardo(or call me Edward, easier for you). > Hi Eduardo, > I'm brazilian and computation science student. > I'm at first period and the main language i'm learning is Haskell and i > will learn C 'till the end of this period. > Great! Please use the haskell-cafe mailing list for these kind of questions, this one is used more for announcements and that sort of thing. > So, as the title suggest, my doubt about haskell is on recursive > functions, especifically where you have two arguments. Like this: > > Build a function that sum all the even numbers between the interval of n > and k, where n < k. > > I was doing this: > > somapar :: Int -> Int -> Int > somapar n k = if even n && even k > then somapar (n+1) (k-1) + n + k > else if even n && not(even k) > then somapar (n+1) (k-1) + n > else if not (even n) && even k > then somapar (n+1) (k-1) + k > else somapar (n+1) (k-1) > > I checked this out and think that is allright, but I don't have the stop > condition. So when i execute it, the function falls into an infinite loop. > The other thing is that I think that there are a lot of "ifs" in the > function, tell me if i could remove some of them. > You're right, somapar never returns a value -- at what point do you think it should? Try to work it out on pencil and paper for some small values. How do you keep track of what the current sum is? Also, check out some Haskell list functions, if you're allowed to use them for this -> http://www.haskell.org/ghc/docs/latest/html/libraries/base/Data-List.html . You can do away with the "ifs" with guards like f x | x > 0 = 1 | otherwise = 0 > > Well, that's it. Sorry by the so so english and thank you. > -- View this message in context: http://www.nabble.com/Doubt-about-recursive-functions-tf3831290.html#a10851… Sent from the Haskell - Haskell mailing list archive at Nabble.com.

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ambiguous record field names which actually aren’t ambigious
by Wolfgang Jeltsch 28 May '07

28 May '07

Hello, I have the following modules: module A where data A = A { label :: Int } module B where data B = B { label :: Int } b :: B b = B { label = 0 } x :: B -> () x B { label = 0 } = () GHC reports an ambiguity for both usages of label. However, it should be clear that both usages can only refer to B.label since a field name in record syntax can only be one that is defined in the same module as the corresponding record type. Hugs accepts the above code. Is there a way to make GHC accept it too? Best wishes, Wolfgang

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