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Re: [Haskell] Re: Help : A problem with IO
by abdullah abdul Khadir 27 Nov '08

27 Nov '08

Thanks all, I got it working finally. What did i learn ? a) I need to put a do after else for more than one instruction (?) b) All similar type of questions are to be redirected to haskell-beginner and haskell-cafe Points noted. Thank you once again, Abdullah Abdul Khadir On Wed, Nov 26, 2008 at 10:56 PM, wman <666wman(a)gmail.com> wrote: > if it should really read whole line, it must try to somehow chain the > values into the string / list of chars (using (:) ) > > getMyLine :: IO [Char] > getMyLine = do > c <- getChar > if (c == '\n') > then return "" -- imho [] looks nicer ;-) > else do > rest <- getMyLine > return $ c : rest > > -- or > > getMyLine :: IO [Char] > getMyLine = do > c <- getChar > if (c == '\n') > then return "" -- imho [] looks nicer ;-) > else getMyLine >>= return . (c:) > > -- or even shorter and still equivalent ;-) > > getMyLine :: IO [Char] > getMyLine = getChar >>= (\c -> if (c == '\n') then return [] else fmap > (c:) getMyLine) > > > > 2008/11/26 abdullah abdul Khadir <abdullah.ak2002(a)gmail.com> > >> Hi, >> >> The function getMyLine written by me is intended for getting a >> complete string from the standard input. >> >> import IO >> >> getMyLine :: IO [Char] >> getMyLine = do >> c <- getChar >> if(c == '\n') >> then return "" >> else cs <- getMyLine >> return [c] >> >> However I keep getting the following error: >> >> io.hs:14:2: Parse error in pattern >> Failed, modules loaded: none. >> >> I fail to understand what the error is. I tried out various things >> such as changing the alignment and so on to no avail. The following program, >> however, compiled successfully though it has the same structure as the >> previous program. >> >> checkd :: IO Bool >> checkd = do >> c <- getChar >> if(c=='d') >> then return True >> else return False >> >> Prelude> :load ./io.hs >> [1 of 1] Compiling Main ( io.hs, interpreted ) >> Ok, modules loaded: Main. >> *Main> checkd >> d >> True >> >> >> _______________________________________________ >> Haskell mailing list >> Haskell(a)haskell.org >> http://www.haskell.org/mailman/listinfo/haskell >> >> >

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Wait for *either* MVar to be set
by Peter Verswyvelen 27 Nov '08

27 Nov '08

Maybe this is not the correct mailing list to ask this question, but as a similar question was asked seemingly unanswered by Duncan Coutts in 2002 (http://markmail.org/message/kftpnulks7mbz2ij) and as this most likely has to do with the GHC runtime, I might have more luck to get an answer here... Sorry for the spam if this is inappropriate; please say so and I will resubscribe to the Haskell Cafe mailing list, not polluting this main list anymore... So here's my question. GHC provides MVar for nice lightweight concurrency synchronization. However, preemptive multitasking operating systems offer support for waiting for multiple "MVars", until *either* one of them returns (or timeouts). I see no way of achieving this with GHC's MVar, unless using Conal Elliott's unamb package on Hackage that emulates this by spawning and killing two threads (which might be an expensive operation, I'm not sure) Am I wrong in this? If so, is this something that might be considered as a future enhancement in the GHC libraries and runtime? Thanks very much, Peter Verswyvelen CTO - Anygma

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ANNOUNCE: Turbinado V0.2 "Still Ugly"
by Alson Kemp 26 Nov '08

26 Nov '08

Progress continues on Turbinado. Turbinado can be found at: http://www.turbinado.org The source can be found at: http://github.com/alsonkemp/turbinado/tree/master (see the /App directory for the code for www.turbinado.org) New in V0.2: * A better "Environment" type (rather than using Dynamics) (-> a 50% speed boost? That's unpossible!); * A functional early version of an ORM for PostgreSQL (note: still needs to handle updates; hdbc-postgresql has a bug with sensing nullable columns); * A prettier website; * Licensing -> BSD. Expect V0.3 in the next week or so with: * More view helpers; * An ORM which handles INSERT/UPDATE...; * A little CMS built using the ORM. Future release: * Separate the website out from the framework. For now, they're evolving together, so live together.

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ANN: "Real World Haskell", now shipping
by Bryan O'Sullivan 26 Nov '08

26 Nov '08

Good evening - John Goerzen, Don Stewart and I are delighted to announce the availability of our book, "Real World Haskell". It is 710 pages long, and published by O'Reilly Media. This is the first book to comprehensively cover modern Haskell programming. From an introduction to functional programming, it focuses on teaching through many worked examples. We discuss the "awkward squad" of I/O, concurrency, and exceptions. We cover network programming, databases, and system hacking. We motivate and work with monoids, applicative functors, monads, and monad transformers. We show you how to debug code, and how to ship well-tested software. Better yet, the book is available under a Creative Commons license, so you can read as much of it as you please before you buy: http://book.realworldhaskell.org/ We developed this book with the enthusiastic and voluble support of the Haskell community, and we are proud to share our work in a fashion that will help newcomers to our field. And best of all, if you order now (at least in North America), you can have a copy of the book in your hands in a matter of days. Thank you from all of us to our friends in the Haskell world who have been so generous with their feedback and kind words!

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Help : A problem with IO
by abdullah abdul Khadir 26 Nov '08

26 Nov '08

Hi, getMyLine :: IO [Char] getMyLine = do c <- getChar if(c == '\n') then return "" else cs <- getMyLine return [c]

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First CFP: WWV 2009
by demis＠dimi.uniud.it 26 Nov '08

26 Nov '08

[Apologies if you receive multiple copies] *********************************************************** * CALL FOR PAPERS * * * * WWV 2009 * * Automated Specification and Verification of Web Systems * * 5th International Workshop * * * * Castle of Hagenberg, Austria. July 17, 2009 * * http://www.risc.uni-linz.ac.at/conferences/wwv09/ * * * * Part of the RISC Summer 2009 * * http://www.risc.uni-linz.ac.at/conferences/summer2009/ * *********************************************************** IMPORTANT DATES Abstract Submission February 2, 2009 Full Paper Submission February 9, 2009 Acceptance Notification April 20, 2009 Camera Ready June 1, 2009 Workshop July 17, 2009 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 original papers 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 * algebraic methods for verification and certification of Web systems * 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 specifications authoring * Web quality and Web metrics * Web usability and accessibility * Testing and evaluation of Web systems and applications 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. The previous WWV editions were: WWV'08 (Siena, Italy), WWV'07 (Venice, Italy), WWV'06 (Paphos, Cyprus), and WWV'05 (Valencia, Spain). LOCATION WWV'09 will be held at the Research Institute for Symbolic Computation (RISC), which is an institute of the Johannes Kepler University in Linz. It is located in the Castle of Hagenberg, a romantic, medieval castle amidst the lovely, hilly landscape of the Mühlviertel region, 20 km north east of Linz, the provincial capital of Upper Austria, located halfway between Salzburg and Vienna. For more information about RISC, please visit: http://www.risc.uni-linz.ac.at/ The workshop is a part of the RISC Summer 2009 conference series: http://www.risc.uni-linz.ac.at/about/conferences/summer2009/ SUBMISSION PROCEDURE Submissions must be received by February 9, 2009. In addition, an ASCII version of the title and abstract must be submitted by February 2, 2009. Submitted papers should be prepared in LaTeX, formatted according to the Springer llncs style, and should not exceed 15 pages. Submission is web-based via this link: http://www.easychair.org/conferences/?conf=wwv09 PUBLICATION Accepted papers will be published in a preliminary proceedings volume, which will be available during the workshop. After the workshop, a special issue of the Journal of Symbolic Computation on the topic of the WWV workshop is planned. PROGRAM CO-CHAIRS Demis Ballis University of Udine, Italy Temur Kutsia Johannes Kepler University Linz, Austria WORKSHOP CO-CHAIRS Temur Kutsia Johannes Kepler University Linz, Austria Wolfgang Schreiner Johannes Kepler University Linz, Austria INVITED SPEAKERS François Bry Ludwig Maximilian University of Munich, Germany Axel Polleres National University of Ireland, Galway, Ireland PROGRAM COMMITTEE Maria Alpuente Technical University of Valencia, Spain Demis Ballis University of Udine, Italy Wlodzimierz Drabent Linköping University, Sweden, and Institute Of Computer Science, Polish Academy of Sciences, Poland Santiago Escobar Technical University of Valencia, Spain Moreno Falaschi University of Siena, Italy Mário Florido University of Porto, Portugal Temur Kutsia Johannes Kepler University Linz, Austria Massimo Marchiori University of Padova, Italy Mircea Marin University of Tsukuba, Japan Catherine Meadows Naval Research Laboratory, USA Rosario Pugliese University of Florence, Italy I.V. Ramakrishnan Stony Brook University, USA Antonio Vallecillo University of Malaga, Spain

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Call for papers TAP 2009
by Koen Claessen 26 Nov '08

26 Nov '08

[Apologize if you receive multiple copies] Call for Papers TAP: Tests And Proofs 2009 The Third International Conference on Tests And Proofs (TAP) will be held at ETH Zurich, Switzerland on 2 and 3 July 2009. It will be co-located with TOOLS Europe 2009. The TAP conference is devoted to the convergence of proofs and tests. It combines ideas from both sides for the advancement of software quality. Purpose and Scope ----------------- To prove the correctness of a program is to demonstrate, through impeccable mathematical techniques, that it has no bugs; to test a program is to run it with the expectation of discovering bugs. The two techniques seem contradictory: if you have proved your program, it's fruitless to comb it for bugs; and if you are testing it, that is surely a sign that you have given up on any hope to prove its correctness. Accordingly, proofs and tests have, since the onset of software engineering research, been pursued by distinct communities using rather different techniques and tools. And yet the development of both approaches leads to the discovery of common issues and to the realization that each may need the other. The emergence of model checking has been one of the first signs that contradiction may yield to complementarity, but in the past few years an increasing number of research efforts have encountered the need for combining proofs and tests, dropping earlier dogmatic views of incompatibility and taking instead the best of what each of these software engineering domains has to offer. The conference will include a mix of invited and submitted presentation, and a generous allocation of panels and informal discussions Topics ------- Possible topics include (as an indicative rather than exhaustive list): - Generation of test data, oracles, or preambles by deductive techniques such as o theorem proving, o model checking, o symbolic execution, o constraint logic programming, etc. - Generation of specifications by deduction - Verification techniques combining proofs and tests - Program proving with the aid of testing techniques - Transfer of concepts from testing to proving (e.g., coverage criteria) - Automatic bug finding - Formal frameworks - Tool descriptions and experience reports - Case studies Invited speakers ---------------- Boutheina CHETALI Security Labs, Technology & Innovation Gemalto - France Sriram K. Rajamani Microsoft Research India Contributions ------------- Two kinds of contributions are expected: - Research papers: full papers of not more than 14 pages in LNCS format, which have to be original, unpublished and not submitted elsewhere. The research papers proceedings will be published in Springer's LNCS series. - Short presentations of work in progress, industrial experience reports and tool demonstrations. An extended abstract of not more than 3 pages is expected and will be reviewed. The accepted extended abstracts will be made available in supplementary proceedings. They will be presented during the cnference days. Important dates ---------------- * Submission deadline: 15 February 2009 * Notification of acceptance: 22 March 2009 * Submission of final camera-ready version: 15 April 2009 The dates are firm; no extension will be granted. Web site --------- http://tap.ethz.ch/2009

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Not quite another Haskell tutorial, but ...
by Janis Voigtlaender 25 Nov '08

25 Nov '08

... I submitted my Habilitation thesis last week. The first few chapters of it try to give an introduction to Haskell with emphasis on types and reasoning principles. That might be an interesting read for some, so I made it accessible at http://wwwtcs.inf.tu-dresden.de/~voigt/habil.pdf. And yes, the November HCAR will also be coming. Rather soon now that this cause for delay is out of the way. Ciao, Janis. -- Dr. Janis Voigtlaender http://wwwtcs.inf.tu-dresden.de/~voigt/ mailto:voigt@tcs.inf.tu-dresden.de

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GHC 6.10 and OpenGL
by Paul L 24 Nov '08

24 Nov '08

Hi everyone, It's sad to see the OpenGL binding being dropped from GHC binary installers starting from 6.10. Though this issue has been brought up and discussed before, I'm sure a lot of people who based their work on OpenGL would share the same sympathy. I'm not here to argue whether this decision by GHC dev team is right or wrong, but what's really causing the pain is that the OpenGL binding doesn't have its own binary installer for Windows, and compilation from source on this platform is non-trivial. I wouldn't recommend doing it for ordinary users. So my question is, are we going to see a binary installer for OpenGL binding provided separately from either HOpenGL site, or Hackage? Or even the GHC installation page? -- Regards, Paul Liu Yale Haskell Group http://www.haskell.org/yale

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PhD Positions in Language-based Security at Chalmers
by Andrei Sabelfeld 24 Nov '08

24 Nov '08

------------------------------------------------------------------------ *PhD Student Positions in Programming Language-based Security* Dept. of Computer Science and Engineering Chalmers University of Technology, Sweden Application deadline: January 30, 2009 Full version of this announcement is at: http://www.chalmers.se/cse/EN/news/vacancies/positions/ph-d-positions-in ------------------------------------------------------------------------ *The Department* The department provides a strong, international, and dynamic research environment with about 75 faculty members. For more information, see http://www.chalmers.se/cse/EN/. ------------------------------------------------------------------------ *PhD Project* The PhD students will join a world-leading team of researchers on *programming language-based security*. Language-based security facilitates specifying and enforcing security policies at the level of programming languages early in the software design and construction phase. Drawing on the recent progress in this area, the goal of the positions is to pursue the following directions of work: * To design *rich security policies* for confidentiality and integrity, as demanded by practical applications (such as web applications). These security policies should be formal: they should operate at the level of programming-language semantics. * To develop *practical enforcement mechanisms* for these policies in expressive programming languages (such as web languages). These enforcement mechanisms may combine static (for example, type system-based) and dynamic (for example, execution monitoring-based) techniques. * To support the above with case studies in web-application security. In pursuing these goals, there are possibilities for collaboration with our high-profile academic and industrial partners. ------------------------------------------------------------------------ *Details about Employment* PhD student positions are limited to five years and will then normally include 20 per cent departmental work, mostly teaching duties. Salary for the position is as specified in Chalmers? general agreement for PhD student positions, currently around 23,000SEK a month before tax. The positions are intended to start in spring or fall 2009. ------------------------------------------------------------------------ *Suitable Background* Applicants must have a degree in Computing Science or in a related subject with a strong Computing Science component. They must also have a strong, documented interest in doing research. The ideal student for the project will have strong background in both programming languages and security. You may even apply if you have not yet completed your degree, but expect to do so before the position starts. In order to improve gender balance, Chalmers welcomes in particular applications from female candidates. ------------------------------------------------------------------------ *How to Apply* Application can be submitted electronically following the "Application details" and "Application procedure" guidelines at: http://www.chalmers.se/cse/EN/news/vacancies/positions/ph-d-positions-in

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