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Type Inference for Overloading without Restrictions
by Peter Verswyvelen 17 Jan '10

17 Jan '10

A while ago, someone provided me a link to the paper "Type Inference for Overloading without Restrictions" http://www.dcc.ufmg.br/~camarao/ct-flops99.ps.gz Although I don't understand everything in this paper, I wander what people's opinions are about this regarding a future Haskell language revision or extension? Would a feature like this be preferable over typeclasses? Would it be practical to implement? Are people working on this? Thanks, Peter Verswyvelen

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ANN: afv-0.0.2
by Tom Hawkins 17 Jan '10

17 Jan '10

AFV is an infinite state model checker for simple, iterative C programs. This release adds some new name checks, a few minor bug fixes, basic support for functions, and a little stronger type checking. Though most of the C language is still not supported, it can verify a lot of interesting behavior -- including one of my bugs that pulverized about $40K of hydraulics hardware last year. :-) http://hackage.haskell.org/package/afv/

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cabal install vacuum-cairo
by Ozgur Akgun 17 Jan '10

17 Jan '10

Cafe, I've been trying to install vacuum-cairo using cabal but I couldn't have it installed because of the missing packages cairo, svg and gtkcairo. What should I do to install vacuum-cairo? Thanks for any help in advance, -- Ozgur Akgun

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Dependency trickery
by Andrew Coppin 17 Jan '10

17 Jan '10

Suppose I write some code that can work with Gtk2hs or wxHaskell. How do I go about making that into a package? Specifically, how do I make it so that you don't have to install Gtk2hs *and* wxHaskell to build it? Do I have to actually make it into two seperate packages to do that? Also, supposing we have another package which requires the first, but doesn't care whether it's using Gtk2hs or wxHaskell. How do I do that? Obviously the answer depends on what happens in the previous step. If I make two seperate packages, for example, and they both export the same module, can I just add optional dependancies on both? Does Cabal support that? Not that I'm attempting to *do* this, you understand. I'd just like to know if it's possible...

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AlternativePrelude extension
by Sjur Gjøstein Karevoll 17 Jan '10

17 Jan '10

Here's an idea I'd like to air: A new extension called AlternativePrelude. Like the NoImplicitPrelude extension we have already, this would disable implicitly importing the Prelude in every other module, but would also implicitly import a substitute. The purpose is to make it easier to play around with alternative preludes. Today we have to specify NoImplicitPrelude, but also explicitly import our alternative everywhere, making the transition between the different preludes that much more painful. With this new extension, the alternative prelude can be specified in the cabal file, or on the command line when building. This will hopefully make the alternative prelude efforts a little bit more mainstream, giving us more data we can use to consider modifications to the current standard prelude. I'm thinking the syntax would be something like AlternativePrelude="MyPrelude". This is new among the extensions in that it requires a parameter. An alternative is an ImplicitImport extension that doesn't disable the implicit importing of the Prelude, but while this does serve the same purpose as the AlternativePrelude proposal, I think it might be easier to use it for nefarious purposes. -- Sjur Gjøstein Karevoll

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ANN: amqp-0.1
by Holger Reinhardt 17 Jan '10

17 Jan '10

Hi, I've built an AMQP library. It currently only works with RabbitMQ and supports most of the 0-8 spec. If you don't know that AMQP is, this is a good introduction: http://blogs.digitar.com/jjww/2009/01/rabbits-and-warrens/ I have not done much testing, so this should be regarded as alpha quality. Get it here: http://hackage.haskell.org/package/amqp For some reason it doesn't compile on Hackage. It says "At least the following dependencies are missing: network-bytestring >=0.1.2". Is there a way to solve this? Regards, Holger

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Language simplicity
by Andrew Coppin 17 Jan '10

17 Jan '10

OK people, it's random statistics time! Haskell '98 apparently features 25 reserved words. (Not counting "forall" and "mdo" and so on, which AFAIK are not in Haskell '98.) So how does that compare to other languages? C: 32 C++: 62 Borland Turbo Pascal: ~50 [without the OOP extensions added later] Eiffel: 59 VB: The source I checked listed in excess of 120 reserved words, but I'm dubious as to how "reserved" they really are. (Is CInt really reserved? I doubt it!) It also depends wildly on which of the bazillion VB dialects you mean. Java: 50 JavaScript: 36 Smalltalk: 0 Lisp: AFAIK, there are no truly reserved words in Lisp, only predefined functions. (??) Python: 31 Ruby: 38 Tcl: Same analysis as for Lisp I believe. As you can see, this conclusively proves... something. Hmm, I wonder if there's some way to compare the size of the language specification documents? :-} PS. It comes as absolutely no surprise to me that C++ has the most keywords. But then, if I were to add AMOS Professional, that had well over 800 keywords at the last count...

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Presentation about ICFP'09 programming contest
by Janis Voigtländer 17 Jan '10

17 Jan '10

Hi Haskell folk, If you are in Madrid tomorrow (Monday), you will likely not want to miss the video presentation by Andy Gill and his group about the techniques behind their running the ICFP'09 programming contest: http://www.program-transformation.org/PEPM10/SpecialFeature The presentation is scheduled to start 17:15, in the PEPM workshop room. Ciao, Janis. -- Jun.-Prof. Dr. Janis Voigtländer http://www.iai.uni-bonn.de/~jv/ mailto:jv@iai.uni-bonn.de

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Haskell Weekly News: Issue 146 - January 17, 2010
by jfredett＠gmail.com 17 Jan '10

17 Jan '10

--------------------------------------------------------------------------- Haskell Weekly News http://sequence.complete.org/hwn/20100117 Issue 146 - January 17, 2010 --------------------------------------------------------------------------- Welcome to issue 146 of HWN, a newsletter covering developments in the [1]Haskell community. This has been a pretty light week in terms of discussion and announcments, but even in this comparative news lull we have the release of several new versions of packages. Inlcluding the start of a new IDE, some new job and graduate program openings, and some really excellent blog noise. Until next week, Haskellers, your Haskell Weekly News. Announcements haskell-src-exts 1.7.0. Niklas Broberg [2]announced a new release of haskell-src-exts Lite Haskell IDE. Mambo Banda [3]announced a new Haskell IDE, as part of his effort to learn Haskell. Functional Programming Bibliography. James Russell [4]announced the Functional Programming Bibliography, a new resource for the FP community. It, though in it's early stages, contains oer 1500 references (most of which are Haskell-related) to resources within the Functional Programming World. hakyll-1.0. Jasper Van der Jeugt [5]announced the release of version 1.0 of his static site generation tool, hakyll. From all (one) of us at the HWN, contragulations on the big 1.0! afv-0.0.0. Tom Hawkins [6]announced the initial release of 'Atom's Formal Verifier', a tool for verifying C code generated by Atom chp-2.0.0, chp-plus-1.0.0. Neil Brown [7]announced released new versions of his Comminicating Haskell Processes (CHP) packages. CHP is a message-passing concurrency library for Haskell. The major change in this version is a split of CHP into two packages, one containing core functionality, and one containing additional capabilities. Update for type-level library (0.2.4). Seyed Hosein Attarzadeh Niaki [8]announced a new version of his type-level library for type-level programming. This is a minor update to fix compatibility issues with dependencies. Two PhD positions in theoretical computer science. Alexandra Silva [9]announced vacancies for PhD positions in theoretical computer science at Leiden University. HaXml-1.20.1. Malcolm Wallace [10]announced a new, stable release of HaXml AST 2010 reminder--call for papers and presentations. John Hughes [11]reminded us of the AST 2010 call for papers and presentations. The submission deadline is only one week away. Job at Mylife. Julien Verlaguet [12]announced an availabiity for an OCaml developer at MyLife. Open Position (PhD student or Postdoc), U Tubingen, Germany. Torsten Grust [13]announced an open PhD/Postdoc position at the University of Tubingen in Germany. (ED: Apologies for the improper 'u' -- it should have an umlaut, but the compilation software is not cooperating) Palindromes 0.2. Johan Jeuring [14]announced a new release of the Palindromes package, including many new features and upgrades. Discussion From records to a type class. Taru Karttunen [15]asked about turning records into type classes, in an effort to make his bindings for Fuse more elegant. AlternativePrelude extension. Sjur Gjostein Karevoll [16]suggested a language pragma for alternative preludes. (ED: Again, apologies for the look-alike, but improper character). Blog noise [17]Haskell news from the [18]blogosphere. Blog posts from people new to the Haskell community are marked with >>>, be sure to welcome them! * Holumbus: [19]Linking Hayoo! Search Results. * Jeff Heard: [20]SPDE, Semi-functional programming for Processing. * Neil Mitchell: [21]Using .ghci files to run projects. * Neil Mitchell: [22]Better .ghci files. * Neil Brown: [23]Darcs. * Neil Brown: [24]Splitting CHP. * Darcs: [25]darcs weekly news #50. * Bryan O'Sullivan: [26]Progress on GHC's I/O manager. * Michael Snoyman: [27]New blog address. * Conal Elliot: [28]Exact Numeric Integration. I had missed this one last week (amidst the myriad, I failed to see it), so it is presented in this week's edition. Quotes of the Week * Jafet: <gwern> closures are a poor man's object <ddarius> objects are a poor man's closure <Berengal> objects are a rich man's structs <Jafet> Poor programmers should start unions * monochrom: Time flies like an Arrow. Space leaks like a Monad. * monochrom: Haskell already has natural language support. Just switch your natural language to simple-typed lambda calculus. * edwardk: @remember Baugn @remember lambdabot fasta says: I think the @remember command is way overused. * Berengal: data Neither a b = Left | Right * Cale: Removing monad comprehensions was actually the snowball which caused the avalanche of fail in Haskell 98 About the Haskell Weekly News New editions are posted to [29]the Haskell mailing list as well as to [30]the Haskell Sequence and [31]Planet Haskell. [32]RSS is also available, and headlines appear on [33]haskell.org. To help create new editions of this newsletter, please see the information on [34]how to contribute. Send stories to jfredett . at . gmail . dot . com. The darcs repository is available at darcs get [35]http://patch-tag.com/r/jfredett/HWN2/pullrepo HWN2 . References 1. http://haskell.org/ 2. http://article.gmane.org/gmane.comp.lang.haskell.cafe/69197 3. http://article.gmane.org/gmane.comp.lang.haskell.cafe/69176 4. http://article.gmane.org/gmane.comp.lang.haskell.cafe/69153 5. http://article.gmane.org/gmane.comp.lang.haskell.cafe/69106 6. http://article.gmane.org/gmane.comp.lang.haskell.cafe/68995 7. http://article.gmane.org/gmane.comp.lang.haskell.cafe/68943 8. http://article.gmane.org/gmane.comp.lang.haskell.cafe/68940 9. http://article.gmane.org/gmane.comp.lang.haskell.general/17727 10. http://article.gmane.org/gmane.comp.lang.haskell.general/17725 11. http://article.gmane.org/gmane.comp.lang.haskell.general/17724 12. http://article.gmane.org/gmane.comp.lang.haskell.general/17723 13. http://article.gmane.org/gmane.comp.lang.haskell.general/17722 14. http://article.gmane.org/gmane.comp.lang.haskell.general/17721 15. http://thread.gmane.org/gmane.comp.lang.haskell.cafe/69207 16. http://thread.gmane.org/gmane.comp.lang.haskell.cafe/69194 17. http://planet.haskell.org/ 18. http://haskell.org/haskellwiki/Blog_articles 19. http://holumbus.fh-wedel.de/blog/?p=30 20. http://vis.renci.org/jeff/2010/01/15/spde-semi-functional-programming-for-p… 21. http://neilmitchell.blogspot.com/2010/01/using-ghci-files-to-run-projects.h… 22. http://neilmitchell.blogspot.com/2010/01/better-ghci-files.html 23. http://chplib.wordpress.com/2010/01/14/darcs/ 24. http://chplib.wordpress.com/2010/01/11/splitting-chp/ 25. http://blog.darcs.net/2010/01/darcs-weekly-news-50.html 26. http://www.serpentine.com/blog/2010/01/11/progress-on-ghcs-io-manager/ 27. http://snoyberg.wordpress.com/2010/01/10/new-blog-address/ 28. http://conal.net/blog/posts/exact-numeric-integration/ 29. http://www.haskell.org/mailman/listinfo/haskell 30. http://sequence.complete.org/ 31. http://planet.haskell.org/ 32. http://sequence.complete.org/node/feed 33. http://haskell.org/ 34. http://haskell.org/haskellwiki/HWN 35. http://patch-tag.com/r/jfredett/HWN2/pullrepo%20HWN2

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Data.Ring -- Pre-announce
by John Van Enk 17 Jan '10

17 Jan '10

Hi List, I recently needed a ring structure (circular list with bi-directional access) and didn't see anything obvious on Hackage. I threw something together fairly quickly and would like some feedback before tossing it on Hackage. I'd really appreciate if some one would: 1. make sure the code looks goodish (127 lines with full docs) 2. make sure my tests look saneish If I hear nothing, I'll assume wild support and push to Hackage. Code: http://github.com/sw17ch/data-ring/blob/master/src/Data/Ring.hs Tests: http://github.com/sw17ch/data-ring/blob/master/tests/quickcheck.hs Package Root: http://github.com/sw17ch/data-ring Thanks ahead of time, John Van Enk

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