- Haskell - Haskell.org

Linking Multiple Versions of the Same Package
by Ashley Yakeley 01 Sep '08

01 Sep '08

I tried doing this out of curiosity. Package B links to version 0.1 of open-witness, while package C links to B and version 0.1.1 of open-witness. Cabal stopped me when doing "cabal configure" in C: $ cabal configure Configuring C-0.1... Warning: This package indirectly depends on multiple versions of the same package. This is highly likely to cause a compile failure. package B-0.1 requires open-witness-0.1 package C-0.1 requires open-witness-0.1.1 It appears the issue is that package versions are not recorded in External Core names. Thus

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The initial view on typed sprintf and sscanf
by oleg＠okmij.org 01 Sep '08

01 Sep '08

We demonstrate typed sprintf and typed sscanf sharing the same formatting specification. Our solution is surprisingly trivial: it defines a simple embedded domain-specific language of formatting patterns. The functions sprintf and sscanf are two interpreters of the language, to build or parse a string according to the given pattern. Our solution relies only on GADTs. We demonstrate that lambda-abstractions at the type level are expressible already in the Hindley-Milner type system; GADT with the included polymorphic recursion help us use the abstractions. The typed sprintf takes the formatting specification and several arguments and returns the formatted string. The types and the number of arguments depend on the formatting specification. Conversely, the typed sscanf parses a string according to the formatting specification, passing parsed data to a consumer function. Again, the number and the types of the arguments to the consumer depend on the formatting specification. The typed sprintf problem has been investigated extensively: the first solution was shown by Danvy; more solutions were proposed by Hinze and Asai. The typed scanf problem received significantly less attention, if any. It seems that the implementation of the typed sprintf and sscanf sharing the same formatting specification has not been known. Here are a few examples of the typed sprintf and sscanf > tp1 = sprintf $ lit "Hello world" > -- "Hello world" > ts1 = sscanf "Hello world" (lit "Hello world") () > -- Just () > tp2 = sprintf (lit "Hello " ^ lit "world" ^ char) '!' > -- "Hello world!" > ts2 = sscanf "Hello world!" (lit "Hello " ^ lit "world" ^ char) id > -- Just '!' > fmt3 = lit "The value of " ^ char ^ lit " is " ^ int > tp3 = sprintf fmt3 'x' 3 > -- "The value of x is 3" > ts3 = sscanf "The value of x is 3" fmt3 (\c i -> (c,i)) > -- Just ('x',3) A formatting specification is built by connecting primitive specifications (such as lit "string", int, char) with (^). We observe that whereas sprintf $ lit "Hello world" has the type String, sprintf $ lit "The value of " ^ char ^ lit " is " ^ int has the type Char -> Int -> String. Likewise, the type of the consumer of the values parsed by sscanf varies with the formatting specification. The example of tp3 and ts3 demonstrates that sprintf and sscanf can indeed use exactly the same formatting specification, which is a first-class value. Printf and scanf are present in many languages (e.g., C and Haskell); in most of the cases, they are not type-safe: the type checker does not stop the programmer from passing to printf more or fewer arguments than required by the formatting string. OCaml supports typed sprintf and sscanf, which relies on a particular weird typing of these functions, resulting in formatting specifications being not first class. Our sscanf has exactly the same interface as that in OCaml, modulo weird typing. The complete code of the typed sprintf and sscanf with more examples is available at http://okmij.org/ftp/Haskell/PrintScan.hs It can be used in Haskell programs as it is; it is trivial to arrange it in a Haskell library or Hackage package. Our implementation is based on the observation of Hinze (Ralf Hinze. Functional Pearl: Formatting: a class act. JFP, 13(5):935-944, September 2003) that the formatting specification is a `type transformer', a functor. For example, the formatting specification 'int' is associated with a functor transforming a type 't' to a type 'Int -> t'. Hinze represented functors in Curry style; the functor associated with 'int' is then (Int ->). However, a more direct, Church-style representation is also possible. Let us consider a type "F a b" where "F" is a binary type constructor, "a" is a type variable, and "b" is a type that may include one or more occurrences of "a". That type is essentially a type abstraction, the type-level lambda-function. To apply the function to an argument, we unify "a" with the argument; the second parameter of "F" is the result of the application. This is the standard emulation of lambda-calculus in Prolog. Based on this observation, we define the language of formatting specifications as follows: > data F a b where > FLit :: String -> F a a > FInt :: F a (Int -> a) > FChr :: F a (Char -> a) > (:^) :: F b c -> F a b -> F a c > (^) = (:^) > lit = FLit > int = FInt The type of (:^) expresses the inverse functional composition of two type-level lambdas; one may read "F" as `big lambda'. The formatting specification can be interpreted in two different ways, for printing and for parsing. The types of the interpreters are pleasingly symmetric: > intp :: F a b -> (String -> a) -> b > intp (FLit str) k = k str > intp FChr k = \x -> k [x] > intp (a :^ b) k = intp a (\sa -> intp b (\sb -> k (sa ++ sb))) > ints :: F a b -> String -> b -> Maybe (a,String) > ints (FLit str) inp x = maybe Nothing (\inp' -> Just (x,inp')) $ > prefix str inp > ints FChr (c:inp) f = Just (f c,inp) > ints FChr "" f = Nothing > ints (a :^ b) inp f = maybe Nothing (\(vb,inp') -> ints b inp' vb) $ > ints a inp f The printing interpretation implements Asai's accumulator-less alternative to Danvy's functional unparsing: http://pllab.is.ocha.ac.jp/~asai/papers/tr07-1.ps.gz The printing interpretation of (a :^ b) is string concatenation in CPS form. The sprintf and sscanf are then simple wrappers: > sprintf :: F String b -> b > sprintf fmt = intp fmt id > sscanf :: String -> F a b -> b -> Maybe a > sscanf inp fmt f = maybe Nothing (Just . fst) $ ints fmt inp f The problem of the typed printf and scanf over the same formatting specification has been posed by Chung-chieh Shan in a discussion with Kenichi Asai and Yukiyoshi Kameyama. I'm grateful to them for inspiration.

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TLDI 2009 Call for Papers
by Amal Ahmed 01 Sep '08

01 Sep '08

********************************************************************* CALL FOR PAPERS TLDI 2009 ACM SIGPLAN Workshop on Types in Language Design and Implementation 24 January 2009 Savannah, Georgia, USA To be held in conjunction with POPL 2009 http://ttic.uchicago.edu/~amal/tldi2009/ ********************************************************************* IMPORTANT DATES Submission: 8 Oct 2008, 5PM EDT (Wed) Notification: 8 Nov 2008 (Sat) Camera ready: 19 Nov 2008 (Wed) TLDI'09: 24 January 2009 (Sat) SCOPE The role of types and proofs in all aspects of language design, compiler construction, and software development has expanded greatly in recent years. Type systems, type analyses, and formal deduction have led to new concepts in compilation techniques for modern programming languages, verification of safety and security properties of programs, program transformation and optimization, and many other areas. In light of this expanding role of types, the ACM SIGPLAN Workshop on Types in Language Design and Implementation (TLDI'09) follows six previous International Workshops on types in compilation and language design (TIC'97, TIC'98, TIC'00, TLDI'03, TLDI'05, and TLDI'07), with the hope of bringing together researchers to share new ideas and results in this area. Submissions for this event are invited on all interactions of types with language design, implementation, and programming methodology. This includes both practical applications and theoretical aspects. TLDI'09 specifically encourages papers from a broad field of programming language and compiler researchers, including those working in object-oriented, dynamically-typed, late-binding, systems programming, and mobile-code paradigms, as well as traditional fully-static type systems. Topics of interest include: - Typed intermediate languages and type-directed compilation - Type-based language support for safety and security - Types for interoperability - Type systems for system programming languages - Type-based program analysis, transformation, and optimization - Dependent types and type-based proof assistants - Types for security protocols, concurrency, and distributed computing - Type inference and type reconstruction - Type-based specifications of data structures and program invariants - Type-based memory management - Proof-carrying code and certifying compilation This is not meant to be an exhaustive list; papers on novel utilizations of type information are welcome. Authors concerned about the suitability of a topic are encouraged to inquire via electronic mail to the program chair prior to submission. SUBMISSION GUIDELINES Authors should submit a full paper of no more than 12 pages (including bibliography and appendices) by Wednesday, October 8, 2008 5PM Eastern Daylight Savings Time. The submission deadline and length limitations are firm. Submissions that do not meet these guidelines will not be considered. All submissions should be in standard ACM SIGPLAN conference format: two columns, nine-point font on a ten-point baseline. Detailed formatting guidelines are available on the SIGPLAN Author Information page, along with a LaTeX class file and template: http://www.sigplan.org/authorInformation.htm Papers must be submitted in Adobe Portable Document Format (PDF) and must be formatted for US Letter size (8.5"x11") paper. Authors for whom this is a hardship should contact the program chair before the deadline. Submitted papers must adhere to the SIGPLAN Republication Policy: http://www.sigplan.org/republicationpolicy.htm Submissions should contain original research not published or submitted for publication elsewhere. The URL for submission will be announced closer to the deadline. GENERAL CHAIR Andrew Kennedy Microsoft Research, Cambridge PROGRAM CHAIR Amal Ahmed Toyota Technological Institute, Chicago PROGRAM COMMITTEE Amal Ahmed Toyota Technological Institute, Chicago (Chair) Juan Chen Microsoft Research Peter Dybjer Chalmers University of Technology Jeff Foster University of Maryland, College Park Neal Glew Intel Robert Harper Carnegie Mellon University Andrew Myers Cornell University Atsushi Ohori Tohoku University Matthew Parkinson University of Cambridge Didier Remy INRIA Paris-Rocquencourt Andreas Rossberg Max Planck Institute for Software Systems STEERING COMMITTEE Craig Chambers University of Washington Robert Harper Carnegie Mellon University (Chair) Xavier Leroy INRIA Paris-Rocquencourt Greg Morrisett Harvard University George Necula Rinera Networks and UC Berkeley Atsushi Ohori Tohoku University Francois Pottier INRIA Paris-Rocquencourt Zhong Shao Yale University

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Compiler Construction course using Haskell?
by Johannes Waldmann 31 Aug '08

31 Aug '08

Hello. I plan to give a course in compiler construction, using Haskell as the implementation language (not as source or target language). Something along these lines: 1. combinator parsers (Parsec), 2. simple interpreter (arithmetical expressions) 3. add algebraic data types, functions 4. type checker 5. code generator. Ideally, 2..5 would be using the very same tree traversal code and just change the monad for evaluation. Any comments appreciated. Have you given such a course? Taken? If I really decide to do it, then slides (in German) will be made available. Best regards, J.W.

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Haskell Weekly News: Issue 83 - August 30, 2008
by Brent Yorgey 30 Aug '08

30 Aug '08

--------------------------------------------------------------------------- Haskell Weekly News http://sequence.complete.org/hwn/20080830 Issue 83 - August 30, 2008 --------------------------------------------------------------------------- Welcome to issue 83 of HWN, a newsletter covering developments in the [1]Haskell community. This is the "better late than never" edition. As an excuse I could tell you that my home internet service has been horrible (now fixed) and I was away from home for a few days with my wife celebrating our third wedding anniversary. But instead, I give you a link to the [2]Uncyclopedia entry on Haskell. If you haven't already seen it, you should give it a read, being sure not to drink any milk at the same time, or at least pointing your nose away from the keyboard if you insist on drinking milk. Community News If Dell sends John Goerzen (CosmicRay) one more catalog, it will [3]actually be a federal crime. Announcements LogFloat 0.9. wren ng thornton [4]announced a new official release of the [5]logfloat package for manipulating log-domain floating numbers. This release is mainly for those who are playing with Transfinite rather than LogFloat, but the interface changes warrant a minor version change. validating xml lib - need some guidance. Marc Weber [6]asked for help developing an xml generating library validating the result against a given DTD. gsl-random 0.1 and monte-carlo-0.1. Patrick Perry [7]announced that he has started on [8]bindings for the random number generators and random distributions provided by the gsl. He has also written a [9]monad and transformer for doing monte carlo computations that uses gsl-random internally. For a quick tutorial in the latter package, see [10]his blog. Wired 0.1.1. Emil Axelsson [11]announced the first release of the hardware description library [12]Wired. Wired can be seen as an extension to Lava that targets (not exclusively) semi-custom VLSI design. A particular aim of Wired is to give the designer more control over the routing wires' effects on performance. darcs weekly news #1. Eric Kow [13]sent out the first edition of the new Darcs Weekly News! zip-archive 0.0. John MacFarlane [14]announced the release of the [15]zip-archive library for dealing with zip archives. The Monad.Reader - Issue 11. Wouter Swierstra [16]announced a new issue of [17]The Monad.Reader, with articles by David Place, Kenn Knowles, and Doug Auclair. First Monad Tutorial of the Season. Hans van Thiel [18]announced a new monad tutorial, [19]The Greenhorn's Guide to becoming a Monad Cowboy. "Real World Haskell" hits a milestone. Bryan O'Sullivan [20]proudly announced that the draft manuscript of Real World Haskell is [21]complete! It is now available online in its entirety. The authors expect the final book to be published around the beginning of November, and to weigh in at about 700 pages. Mueval 0.5.1, 0.6, 0.6.1, 0.6.2, 0.6.3, 0.6.4. Gwern Branwen [22]announced a number of new releases of [23]Mueval. Lambdabot now uses mueval for all its dynamic Haskell evaluation needs. Hoogle Database Generation. Neil Mitchell (ndm) [24]announced that a new release of the [25]Hoogle command line is out, including bug fixes and additional features. Upgrading is recommended.Two interesting features of Hoogle 4 are working with multiple function databases (from multiple packages), and running your own web server. Blog noise [26]Haskell news from the [27]blogosphere. * Real-World Haskell: [28]Source handed over to production. * Douglas M. Auclair (geophf): [29]Earning \bot-Trophies. * Douglas M. Auclair (geophf): [30]Scanner-parsers II: State Monad Transformers. * Douglas M. Auclair (geophf): [31]Scanner-parsers I: lifting functions. * >>> software engineering radio: [32]Episode 108: Simon Peyton Jones on Functional Programming and Haskell. A podcast interview with Simon Peyton Jones. * Neil Mitchell: [33]Running your own Hoogle on a Web Server. * Braden Shepherdson: [34]Announcing xmonad-light. Braden is rolling out a new configuration framework for xmonad, providing an easier learning curve for those not wanting to learn Haskell right away, and an easy transition to a more powerful Haskell configuration when they want it. * Gabor Grief: [35]Category. Gabor is excited that base-3.0 will include Control.Category. * Douglas M. Auclair (geophf): [36]Ten = 1+2+3+4. Solving an arithmetic puzzle with Haskell, Prolog-style. * Paul R Brown: [37]perpubplat now on github. * Douglas M. Auclair (geophf): [38]"Lucky you!"?. Doug shares some secrets of his success in getting Haskell/Dylan/Mercury/Prolog jobs. * Neil Mitchell: [39]Hoogle Database Generation. Neil releases a new command-line version of Hoogle, including bug fixes and additional features -- multiple function databases and the ability to run your own Hoogle server. * Patrick Perry: [40]A Monte Carlo Monad for Haskell. * Mads Lindstroem: [41]Proposal: Adding composability to WxHaskell. * Tom Moertel: [42]PXSL Tools now on Hackage and GitHub. * Gabor Greif: [43]Uploaded. Gabor uploads his first contribution to Hackage, [44]thrist-0.1. * Muad`Dib (vixey): [45]Tail Call Optimization doesn't exist in Haskell. * >>> Hans van Thiel: [46]The Greenhorn's Guide to becoming a Monad Cowboy. YAMT * Dan Piponi (sigfpe): [47]Untangling with Continued Fractions: Part 2. Dan continues his excellent series on rational tangles, this time showing the connection between tangles and rational numbers. * >>> Praki Prakash: [48]Learning Haskell Redux. * Gabor Greif: [49]Ca(ni)balized. Gabor creates his first cabal package! * Real-World Haskell: [50]Our writing is now complete!. * Tom Moertel: [51]Thinking algebraically: a functional-programming dividend that pays during your imperative-programming day job. * Jason Dagit: [52]Darcs 2 Real-World Push Performance Evaluation. * Well-Typed.Com: [53]What's wrong with make?. A lot, apparently: it's too static, and makes it easy to write incorrect rules. Duncan (dcoutts) provides an analysis. * Dougal Stanton: [54]Lord of the Flies as a window onto monadic IO. * Real-World Haskell: [55]A tighter page count estimate. Real World Haskell is going to be about 700 pages!? * Real-World Haskell: [56]Real World Haskell tutorial next month at DEFUN 2008. Quotes of the Week * shepheb: #haskell isn't so much on-topic when discussing Haskell, but off-off-topic. * chrisdone: it's neat how you learn haskell because you are drawn in by the purely functional paradigm, and then you find loads more things like algebraic data types, monad abstractions, arrows and applicative, lack of objects... so that when people say "well, it's not haskell, but at least X is functional", it's just not the same at all * lambdabot: [tristes_tigres] @vixen unsafe [lambdabot] you're turning me on :) * b\6: sometimes i make variables f and ck and find some reason to multiply them like f*ck if i'm having a bad day. * waynemokane: wow... thanks everyone - it looks like I have a full day of reading type signatures ahead of me. * mauke: call/cthulhu * seydar: monads are just like saran wrap. * b\6: keep this info private, but you can actually overclock your brain. the technique i use is to loop mplayer playing oggs but increase the speed like -speed 1.25 for 125% normal. your brain's speed increases accordingly, allowing you to solve problems much more easily. About the Haskell Weekly News New editions are posted to [57]the Haskell mailing list as well as to [58]the Haskell Sequence and [59]Planet Haskell. [60]RSS is also available, and headlines appear on [61]haskell.org. To help create new editions of this newsletter, please see the information on [62]how to contribute. Send stories to byorgey at cis dot upenn dot edu. The darcs repository is available at darcs get [63]http://code.haskell.org/~byorgey/code/hwn/ . References 1. http://haskell.org/ 2. http://uncyclopedia.org/wiki/Haskell 3. http://changelog.complete.org/posts/741-From-Dell,-a-Uniquely-Terrible-Expe… 4. http://article.gmane.org/gmane.comp.lang.haskell.cafe/43829 5. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/logfloat 6. http://article.gmane.org/gmane.comp.lang.haskell.cafe/43825 7. http://article.gmane.org/gmane.comp.lang.haskell.cafe/43764 8. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/gsl-random 9. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/monte-carlo 10. http://quantile95.com/2008/08/27/a-monte-carlo-monad-for-haskell/ 11. http://article.gmane.org/gmane.comp.lang.haskell.cafe/43658 12. http://www.cs.chalmers.se/~emax/wired/index.html 13. http://article.gmane.org/gmane.comp.lang.haskell.cafe/43626 14. http://article.gmane.org/gmane.comp.lang.haskell.cafe/43539 15. http://johnmacfarlane.net/zip-archive/ 16. http://article.gmane.org/gmane.comp.lang.haskell.cafe/43491 17. http://www.haskell.org/haskellwiki/The_Monad.Reader 18. http://article.gmane.org/gmane.comp.lang.haskell.cafe/43403 19. http://www.muitovar.com/monad/moncow.xhtml 20. http://article.gmane.org/gmane.comp.lang.haskell.cafe/43401 21. http://www.realworldhaskell.org/blog/2008/08/22/our-writing-is-now-complete/ 22. http://article.gmane.org/gmane.comp.lang.haskell.cafe/43372 23. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/mueval 24. http://neilmitchell.blogspot.com/2008/08/hoogle-database-generation.html 25. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hoogle 26. http://planet.haskell.org/ 27. http://haskell.org/haskellwiki/Blog_articles 28. http://www.realworldhaskell.org/blog/2008/08/30/source-handed-over-to-produ… 29. http://logicaltypes.blogspot.com/2008/08/earning.html 30. http://logicaltypes.blogspot.com/2008/08/scanner-parsers-ii-state-monad.html 31. http://logicaltypes.blogspot.com/2008/08/scanner-parsers-i-lifting-function… 32. http://www.se-radio.net/podcast/2008-08/episode-108-simon-peyton-jones-func… 33. http://neilmitchell.blogspot.com/2008/08/running-your-own-hoogle-on-web-ser… 34. http://braincrater.wordpress.com/2008/08/28/announcing-xmonad-light/ 35. http://heisenbug.blogspot.com/2008/08/category.html 36. http://logicaltypes.blogspot.com/2008/08/ten-1234.html 37. http://mult.ifario.us/p/perpubplat-now-on-github 38. http://logicaltypes.blogspot.com/2008/08/lucky-you.html 39. http://neilmitchell.blogspot.com/2008/08/hoogle-database-generation.html 40. http://quantile95.com/2008/08/27/a-monte-carlo-monad-for-haskell/ 41. http://lindstroem.wordpress.com/2008/03/16/proposal-adding-composability-to… 42. http://blog.moertel.com/articles/2008/08/24/pxsl-tools-now-on-hackage-and-g… 43. http://heisenbug.blogspot.com/2008/08/uploaded.html 44. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/thrist 45. http://muaddibspace.blogspot.com/2008/08/tail-call-optimization-doesnt-exis… 46. http://www.muitovar.com/monad/moncow.xhtml 47. http://sigfpe.blogspot.com/2008/08/untangling-with-continued-fractions_23.h… 48. http://monadict.blogspot.com/2008/08/learning-haskell-redux-when-you-are.ht… 49. http://heisenbug.blogspot.com/2008/08/canibalized.html 50. http://www.realworldhaskell.org/blog/2008/08/22/our-writing-is-now-complete/ 51. http://blog.moertel.com/articles/2008/08/20/thinking-algebraically-a-functi… 52. http://blog.codersbase.com/2008/08/21/darcs-2-real-world-push-performance-e… 53. http://blog.well-typed.com/2008/08/whats-wrong-with-make/ 54. http://www.dougalstanton.net/blog/index.php/2008/08/21/lord-of-the-flies-as… 55. http://www.realworldhaskell.org/blog/2008/08/20/a-tighter-page-count-estima… 56. http://www.realworldhaskell.org/blog/2008/08/20/real-world-haskell-tutorial… 57. http://www.haskell.org/mailman/listinfo/haskell 58. http://sequence.complete.org/ 59. http://planet.haskell.org/ 60. http://sequence.complete.org/node/feed 61. http://haskell.org/ 62. http://haskell.org/haskellwiki/HWN 63. http://code.haskell.org/~byorgey/code/hwn/

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ANNOUNCE: Wired 0.1.1
by Emil Axelsson 27 Aug '08

27 Aug '08

Hello, This is to announce the first release of the hardware description library Wired. Wired can be seen as an extension to Lava that targets (not exclusively) semi-custom VLSI design. A particular aim of Wired is to give the designer more control over the routing wires' effects on performance. The only working backends in this version are simulation and verification (through Lava), and generation of postscript layouts. Soon, there will also be static timing analysis and DEF file generation. The DEF format is accepted by most tools for physical design. Wired is available from Hackage: http://hackage.haskell.org/cgi-bin/hackage-scripts/package/Wired or using Darcs: darcs get http://www.cs.chalmers.se/~emax/darcs/Wired/ There is also a homepage at: http://www.cs.chalmers.se/~emax/wired/index.html Comments, questions, patches are welcome. Cheers, / Emil

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Final CFP and extended deadline IFL 2008
by Sven-Bodo Scholz 26 Aug '08

26 Aug '08

******************************************************************************** * * FINAL CALL FOR PAPERS -- EXTENDED DEADLINE!! * CALL FOR PARTICIPATION * * 20th International Symposium on the * Implementation and Application of Functional Languages * IFL 2008 * 10-12.Sept 2008, Hatfield UK * * http://events.sac-home.org/ifl2008/ * ******************************************************************************** UPDATED DEADLINES: * Submission for draft proceedings: NOW 1. Sept * Early Registration: NOW 2. Sept Please note, that the draft proceedings do NOT require full papers; extended abstracts will be considered too. ******************************************************************************** The aim of the IFL symposia is to bring together researchers actively engaged in the implementation and application of functional and function-based programming languages. They provide an open forum for researchers who wish to present and discuss new ideas and concepts, work in progress, preliminary results, etc. related primarily but not exclusively to the implementation and application of functional languages. Formal proceedings are produced after the symposium, so that authors can incorporate the feedback from discussions at the symposium in their published papers. Topics ====== Topics of interest include, but are not limited to: * language concepts * type checking * compilation techniques * (abstract) interpretation * generic programming techniques * automatic program generation * array processing * concurrent/parallel programming * concurrent/parallel program execution * functional programming on embedded systems * functional programming on multi-cores/ many-cores * heap management * runtime profiling * performance measurements * debugging and tracing * (abstract) machine architectures * verification * formal aspects * tools and programming techniques Papers on applications or tools demonstrating the suitability of novel ideas in any of the above areas and contributions on related theoretical work are also welcomed. The change of the symposium name adding the term application, introduced in 2004, is to reflect the broader scope IFL has gained over the years. Paper Submissions ================= Prospective authors are encouraged to submit papers to be published in the draft proceedings and to present them at the symposium. All contributions must be written in English, conform to the Springer-Verlag LNCS series format and not exceed 16 pages. The draft proceedings will appear as a Technical Report of the School of Computer Science of the University of Hertfordshire. Attendees of IFL 2008 will have the opportunity to submit a revised version of their paper for post-symposium reviewing. As in previous years, we hope that selected papers will be published by Springer Verlag in the Lecture Notes in Computer Science (LNCS) Series. The Peter Landin Prize ====================== Since 2002 every year the Peter Landin Prize of 150 GBP is awarded to the best paper presented at the symposium, as selected by the program committee. Important Dates =============== * Submission for draft proceedings: NOW 1. Sept. * Early Registration: NOW 2. Sept. * Symposium: 10-12. September * Submission for post-refereeing: 14. November * Notification of acceptance / rejection: 23. January 2009 * Submission of a camera ready version: 20. February 2009 Contact ======= For further details see <http://events.sac-home.org/ifl2008/> or contact us by email: events <at> sac-home.org

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Top Level <-
by Ashley Yakeley 26 Aug '08

26 Aug '08

Is there any interest in implementing a top level "<-" to run monadic code? Currently this sort of thing is done with unsafePerformIO and switching off inlining with some pragma. Indeed, the 'atomically' haddock actually advises doing this to declare top-level TVars. The same trick is used in the source of Data.Unique and System.Random. This is bad Haskell. To avoid observation of effects, etc., we would need a new monad rather than IO. There would be equivalents of IO functions such as these: newIORef newMVar newTVarIO newUnique I can think of two uses: 1. Global mutable state. For instance, here's the count variable for Data.Unique rewritten: uniqSource :: MVar Integer uniqSource <- newMVarTL 0 Isn't that much nicer? <http://haskell.org/haskellwiki/Top_level_mutable_state> 2. Solving the expression problem using open witnesses, a recent hobby-horse of mine. For instance, here's a simple scheme for extensible exceptions using top-level "<-": -- declare exception carrying an Int myException :: Exn Int <- newExn -- throw with 5 foo = do ... throw myException 5 -- catch, print the Int bar = catch foo myException (\i -> putStrLn (show i)) I already have code for this, except with an unsafe hack to do the "<-" declaration: <http://hackage.haskell.org/packages/archive/open-witness/0.1.1/doc/html/Dat…> My open-witness package, which also shows how to do Typeable/Dynamic safely: <http://hackage.haskell.org/cgi-bin/hackage-scripts/package/open-witness> -- Ashley Yakeley Seattle, WA

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ANN: The Monad.Reader - Issue 11
by Wouter Swierstra 25 Aug '08

25 Aug '08

I am pleased to announce that a new issue of The Monad.Reader is now available: http://www.haskell.org/haskellwiki/The_Monad.Reader Issue 11 consists of the following three articles: * David F. Place How to Refold a Map * Kenneth Knowles First-Order Logic a la Carte * Douglas M. Auclair MonadPlus: What a Super Monad! The Monad.Reader is a quarterly magazine about functional programming. It is less formal than a journal, but a bit more enduring than a wiki page or blog post. If you'd like to write something for the next issue of The Monad.Reader, please get in touch. I haven't fixed the deadline for the next issue just yet. Expect a deadline early 2009. Wouter

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Another First course in Haskell
by ppk＠cse.iitk.ac.in 22 Aug '08

22 Aug '08

Hi, I am planing a haskell based functional programming course. It is supposed to be a first course and I intend to show how real world applications can be built quite easily in haskell. Goals: 1) Cover all the basics like recursion, interesting data structures like zippers, monads 2) Haskell programming environment: by this I mean things like ghci, hadock, cabal The students after the course should seriously consider Haskell as a programming language for implementing their final year projects. In this aspect if one can convince that things like web-programming cgi scripting, networking, compiler projects, which are the favorits for programming projects, are better done in Haskell than in traditional languages like C and Java that would be a success. The course will be taken by mostly Computer Science undergrads. Any feed back is really welcome. I have about 2-3 months to plan the course. Regards ppk

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