April 2006 - Haskell - Haskell.org

Deadline Extension: Mathematically Structured Functional Programming
by Conor McBride 11 Apr '06

11 Apr '06

+*->+*->+*->+*->+*->+*->+*->+*->+*->+*->+*->+*->+*->+*->+*->+*->+*->+*->+*-> DEADLINE-EXTENSION-DEADLINE-EXTENSION-DEADLINE-EXTENSION-DEADLINE-EXTENSION Workshop on Mathematically Structured Functional Programming http://cs.ioc.ee/mpc-amast06/msfp/ New deadlines: 17 April (abstracts); 21 April (papers) DEADLINE-EXTENSION-DEADLINE-EXTENSION-DEADLINE-EXTENSION-DEADLINE-EXTENSION +*->+*->+*->+*->+*->+*->+*->+*->+*->+*->+*->+*->+*->+*->+*->+*->+*->+*->+*-> We're delighted to be able to extend the deadline for MSFP 2006. The Workshop on Mathematically Structured Functional Programming will be held in Kuressaare, Estonia, on 2 July 2006, with invited speakers Andrzej Filinski and John Power. MSFP 2006 is a satellite workshop of MPC 2006 and a "small workshop" of the TYPES project. MSFP is about organizing functional programs more effectively with the aid of mathematical structures from semantics and elsewhere. The proceedings of MSFP 2006 will be published in the Electronic Workshops in Computing (eWiC) series of the British Computer Society. After the workshop, the authors of the best papers will be invited to submit revised and expanded versions to a special issue of the Journal of Functional Programming from Cambridge University Press. We look forward to hearing from you Conor McBride Tarmo Uustalu

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ANNOUNCE: DrIFT-2.2.0
by John Meacham 10 Apr '06

10 Apr '06

DrIFT 2.2.0 has been released. you can learn about and download it here http://repetae.net/john/computer/haskell/DrIFT/ a summary of changes since the last resease follows DrIFT-2.2.0: Mon Apr 10 00:39:24 PDT 2006 John Meacham <john(a)repetae.net> * add note about reconf script * make the parser handle newtype deriving without bailing out * fix bug in Ord deriving rule Wed Jan 18 03:59:21 PST 2006 David Roundy <droundy(a)darcs.net> * fix typo in src/Makefile.am Sun Nov 27 02:59:14 PST 2005 Malcolm.Wallace(a)cs.york.ac.uk * Change rule for Haskell2XmlNew into XmlContent, add Parse rule. The Haskell2XmlNew class was a temporary staging post on the way to developing a new XmlContent class, available in HaXml-1.14 onwards. This patch updates the name, and the rule, to match the latest developments. It also adds support for the textual (non-XML) Parse class, which is an experimental replacement for the Read class, using monadic parser combinators. This is also currently defined in HaXml-1.14. * docs should refer to StandardRules.hs, not .lhs * fix docs for Hugs usage * keep docs of --list option up-to-date Tue Nov 15 18:09:40 PST 2005 Einar Karttunen <ekarttun(a)cs.helsinki.fi> * Hook Arbitrary into DrIFT proper * Add UserRuleArbitrary Thu Nov 3 02:52:38 PST 2005 John Meacham <john(a)repetae.net> * fix data derving for new versions of ghc -- John Meacham - ⑆repetae.net⑆john⑈

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Haskell Weekly News: April 10, 2006
by dons＠cse.unsw.edu.au 10 Apr '06

10 Apr '06

Haskell Weekly News: April 10, 2006 Greetings, and thanks for reading issue 32 of HWN, a weekly newsletter covering developments in the Haskell community. Each Monday, new editions are posted to [1]the Haskell mailing list and to [2]The Haskell Sequence. [3]RSS is also available. Headlines also go to [4]haskell.org. 1. http://www.haskell.org/mailman/listinfo/haskell 2. http://sequence.complete.org/ 3. http://sequence.complete.org/node/feed 4. http://haskell.org/ Announcements hImerge: a graphical user interface for emerge. Luis Araujo released [5]hImerge, a graphical user interface for emerge, (Gentoo's Portage system) written in Haskell using gtk2hs. [6]Here's a jpg. The main idea is to simplify browsing the entire portage tree as well as of running the most basic and common options from the emerge command. hImerge also offers several handy tools, like global and local use flags browsers, and a minimal web browser. 5. http://haskell.org/~luisfaraujo/himerge/ 6. http://haskell.org/~luisfaraujo/rhimerge.jpeg MissingH 0.14.0. John Goerzen [7]announced MissingH 0.14.0, a library of "missing" functions. MissingH is available [8]here. 7. http://article.gmane.org/gmane.comp.lang.haskell.general/13531 8. http://quux.org/devel/missingh/ Haskell mailing list archives. Don Stewart [9]converted the Haskell mailing list archives from 1990-2000, into html format. The archive is available to view [10]here. 9. http://article.gmane.org/gmane.comp.lang.haskell.general/13521 10. http://www.cse.unsw.edu.au/~dons/haskell-1990-2000/threads.html Chapter 4 of Hitchhikers Guide to the Haskell. Dmitry Astapov [11]announced that the 4th chapter of the Hitchhikers Guide to Haskell is now [12]available. 11. http://article.gmane.org/gmane.comp.lang.haskell.cafe/12338 12. http://www.haskell.org/haskellwiki/Hitchhikers_Guide_to_the_Haskell Edison 1.2 rc3. Robert Dockins [13]announced that the 3rd release candidate for Edison 1.2 is now avaliable. 13. http://article.gmane.org/gmane.comp.lang.haskell.libraries/4508 Haskell' This section covers activity on [14]Haskell' standardisation process. * [15]State threads * [16]Terminating instances * [17]deriving Tree * [18]deriving Typeable * [19]deriving for newtypes * [20]deepSeq * [21]Asynchronous exceptions * [22]Exceptions 14. http://hackage.haskell.org/trac/haskell-prime 15. http://article.gmane.org/gmane.comp.lang.haskell.prime/1197 16. http://article.gmane.org/gmane.comp.lang.haskell.prime/1203 17. http://thread.gmane.org/gmane.comp.lang.haskell.prime/1218/focus=1218 18. http://article.gmane.org/gmane.comp.lang.haskell.prime/1243 19. http://thread.gmane.org/gmane.comp.lang.haskell.prime/1219/focus=1219 20. http://article.gmane.org/gmane.comp.lang.haskell.prime/1266 21. http://thread.gmane.org/gmane.comp.lang.haskell.prime/1222/focus=1222 22. http://thread.gmane.org/gmane.comp.lang.haskell.prime/1282/focus=1282 Code watch Wed Apr 5 06:33:44 PDT 2006 Simon Marlow * add support for x86_64; foreign import is now supported in GHCi on x86_64 Thu Apr 6 10:57:53 PDT 2006 Lemmih * GHC.Base.breakpoint isn't vaporware anymore. -fignore-breakpoints can be used to ignore breakpoints. Thu Apr 6 19:05:11 PDT 2006 Simon Marlow * Reorganisation of the source tree Most of the other users of the fptools build system have migrated to Cabal, and with the move to darcs we can now flatten the source tree without losing history, so here goes. The main change is that the ghc/ subdir is gone, and most of what it contained is now at the top level. The build system now makes no pretense at being multi-project, it is just the GHC build system. Quotes of the Week JaffaCake :: gcc is getting smarter, so we need to hit it with a bigger stick ihope :: Oops, I forgot that Djinn doesn't do GADT's. malig :: quantum mechanics actually strikes me as less weird than lazy evaluation sometimes. at least it disallows time travel Contributing to HWN Thanks to Luis Araujo for help preparing this issue. You can help us create new editions of this newsletter. Please see the [23]contributing information, send stories to dons -at- cse.unsw.edu.au. The darcs repository is available at darcs get http://www.cse.unsw.edu.au/~dons/code/hwn 23. http://haskell.org/haskellwiki/HWN

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Ignoring input
by UnfitElf 10 Apr '06

10 Apr '06

Hi everyone, Im new to haskell and finding it quite hard to pickup as im a C/C++ programmer however, im sticking with it as i think its a good thing to know. I have a problem were i have the user input a string, i then want to disregard the punctuation marks and spaces and change the case of the string to lower case. I was thinking that with the case i could work out the difference of the capital 'A' and the small 'a' and then change them somehow? As for ignoring punctuation marks and spaces im clueless. Thanks for any help Daniel -- View this message in context: http://www.nabble.com/Ignoring-input-t1422239.html#a3833983 Sent from the Haskell - Haskell forum at Nabble.com.

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reading binary files
by minh thu 07 Apr '06

07 Apr '06

hi all, two things: 1/ i do something and i'd like to know if it is correct 2/ i propose something about 1/ 1/ i want to read some binary file (e.g. targa file format : *.tga). i do this : -- first way : via IOUArray showInfoHeader1 handle = do a <- newArray_ (1,8) :: IO (IOUArray Int Word8) hGetArray handle a 8 idLength <- readArray a 1 -- or getElems... putStrLn ("id length : " ++ show idLength) return () -- second way : via c-like array showInfoHeader2 handle = do b <- mallocArray 8 :: IO (Ptr Word8) hGetBuf handle b 8 [idLength] <- peekArray 1 b -- or peakArray 8 b putStrLn ("id length : " ++ show idLength) free b return () so, briefly, i have to read some content into some kind of buffer (IOUArray Int Word8 or Ptr Word8), then get one (or more) elements from the buffor into a standard haskell variable (is it the correct word ?) (or list). in the second case, i also have to free the buffer. in some case, when the data is more than one Word8 long, i have to 'reconstruct' it, i.e.: [x1,x2] <- getElems a let x = fromIntegral x1 + fromIntegral x2 * 256 :: Int is it the correct way to read binary files ? ------- 2/ haskell is (i heard that once ... :-) a high level language, so it has (must have) good support for abstraction... but in 1/, i have to choose between different kind of array representation (and i dont know which one is better) and it seems to me that the resulting code (compiled) would have to be the same. the thing i want to say here is : what i want to do is pretty obvious (in both code) but could be expressed more succintly and with only one possible syntax: for example, the couples (hGet*,peek/readArray) could be written in one line; also, one line for the reading/reconstructing more-than-one-Word8 value. is it already possible ? would it be interesting to add such capabilities to haskell ? (i think so) i can try to add it but i need some pointers about how to do it. thx a lot, vo minh thu

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AOSD 2007
by Oege de Moor 07 Apr '06

07 Apr '06

*** apologies for multiple copies *** AOSD 2007 CALL FOR RESEARCH PAPERS 6th International Conference on Aspect-Oriented Software Development http://www.aosd.net/2007/cfc/research.php AOSD is the premier conference on software modularity that crosscuts traditional abstraction boundaries. It welcomes papers on this topic from all relevant communities, including software engineering, programming languages, type systems, formal methods, as well as applications and experience reports.

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CHR 2006: 2nd Call for Papers
by Tom Schrijvers 07 Apr '06

07 Apr '06

---------------------------------------- Apologies if you receive multiple copies ________________________________________ Second Call for Papers ------------------------------------------------------------ Third Workshop on Constraint Handling Rules CHR 2006 July 9, 2006 S. Servolo, Venice, Italy Co-located with the International Colloquium on Automata, Languages and Programming (ICALP 2006) ------------------------------------------------------------ http://www.cs.kuleuven.be/~toms/CHR2006/ Introduction ------------ The Constraint Handling Rules (CHR) language has become a major declarative specification and implementation language for constraint reasoning algorithms and applications. Algorithms are often specified using inference rules, rewrite rules, sequents, proof rules or logical axioms that can be directly written in CHR. Its clean semantics facilitates program design, analysis and transformation. See the CHR website (http://www.cs.kuleuven.be/~dtai/projects/CHR/) for more information. Previous Workshops on Constraint Handling Rules were organized in May 2004 in Ulm (Germany) and in October 2005 in Sitges (Spain). Topics of Interest ------------------ The workshop calls for full papers and short papers describing ongoing work, on all aspects of CHR, including topics such as: - (Logical) Algorithms - Applications - Comparisons with Related Approaches - Constraint Solvers - Critical Assessment - Expressivity and Complexity - Implementations and Optimization - Language Extensions (Types, Modules) - Program Analysis - Program Transformation and Generation - Programming Environments (Debugging) - Programming Pearls - Retractable Constraints - Semantics Awards ------ The best paper receives the CHR Best Paper Award. It is chosen among all submissions for its outstanding quality in both presentation and scientific contribution and for its impact on the field of CHR. Submission Information ---------------------- All papers must be written in English and not exceed 15 pages in Springer LNCS format. The authors are encouraged, although not obliged, to submit their papers already in Springer LNCS format. General information about the Springer LNCS series and the LNCS authors' instructions are available at the Springer LNCS/LNAI home page. Submissions should be sent to chrworkshop(a)gmail.com and mention 'CHR 2006 Submission' in the subject. Every submission should include the names and e-mail addresses of the authors (with the corresponding author indicated), the paper abstract in ASCII format and the actual paper in postscript or PDF format. The submission should also indicate whether it is a full paper or a short paper. Accepted papers will be published in a technical report. Important dates --------------- * submission: May 7, 2006 * notification of acceptance: June 9, 2006 * final version due: June 23, 2006 * workshop date: July 9, 2006 Organization ------------ Program Committee: * Alessandra Raffaeta, Universita Ca' Foscari di Venezia * François Fages, INRIA Rocquencourt * Gregory Duck, NICTA Victoria Laboratory * Henning Christiansen, Roskilde University * Jacques Robin, Universidade Federal de Pernambuco * Martin Sulzmann, National University of Singapore * Maurizio Gabbrielli, Universita di Bologna * Thom Fruehwirth, Universitaet Ulm * Tom Schrijvers, Katholieke Universiteit Leuven Workshop Coordinators: chrworkshop(a)gmail.com Tom Schrijvers (contact person) Department of Computer Science K.U.Leuven http://www.cs.kuleuven.be/~toms/ Thom Fruehwirth Fakultaet fuer Informatik Universitaet Ulm http://www.informatik.uni-ulm.de/pm/fileadmin/pm/home/fruehwirth/

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Re: [Haskell] What's up with this Haskell runtime error message:
by Garrett Mitchener 06 Apr '06

06 Apr '06

I came up with a system of coloring -- you'll have to view this message as html to see it. You start with the input parameters -- those are green. Anything defined in terms of green is blue. Anything defined in terms of green & blue is purple. Anything defined in terms of green, blue, and purple is orange, etc. Then you can see the problem. So in foo, everything checks out, you get to orange and there's just a couple of expressions left and you can see that there's no loop. > ----------------------------------------------------------------------------------------------------------- > > foo (step,r0,mu0) = bar (step,r1,r0,mu1,mu0) > where > r1 = r0-step*rd > mu1 = mu0-step*mud > > rd = c*c*mu0 > mud = c*c/r0 - (foobar_r z)/c > c = baz(z) > z = 6.378388e6-r0 > > baz z | z<125 = -0.25*z+1537.5 > | otherwise = 0.0169*z+1504.1 > > foobar_r z | z<125 = 0.25 > > | otherwise = -0.0169 > > But when you try coloring bar, you get this far and then we're stuck. The problem is clear: r depends on rdc, which depends on rd0, which depends on c0, which depends on z0, which depends on r. So your definition for r includes a loop. bar (step,r2,r1,mu2,mu1) = (r,z0) : bar (step,r1,r,mu1,m) > where > r = r2+2*step*rdc > m = mu2+2*step*mudc > rdc = (rd2+rd1+rd0)/6 > mudc = (mud2+mud1+mud0)/6 > > rd2 = c2*c2*mu2 > mud2 = c2*c2/r2 - (foobar_r z2)/c2 > > rd1 = c1*c1*mu1 > mud1 = c1*c1/r1 - (foobar_r z1)/c1 > > rd0 = c0*c0*m > mud0 = c0*c0/r - (foobar_r z0)/c0 > > c2 = baz(z2) > > c1 = baz(z1) > c0 = baz(z0) > > z2 = 6.378388e6-r2 > z1 = 6.378388e6-r1 > z0 = 6.378388e6-r > > main :: IO () > main = do > print $ take 100 (foo (0.1, 6.378388e6,0)) > > > > > >

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ANN: MissingH 0.14.0
by John Goerzen 06 Apr '06

06 Apr '06

I am rewriting my Debian From Scratch (DFS/dfsbuild) system using Haskell. As part of this effort, I've been making improvements in MissingH, and have release 0.14.0. API changes include: * Logger handlers now are passed the calling logger name. * When a new logger must be spontaneously created, it uses the closest ancestor logger for its default priority, rather than using a compile-time default. Other changes: * New function splitWs, to split a string along common whitespace characters. * New log handler verboseStreamHandler, which adds the logger name and log priority to the front of each log message. * Syslog handler now also adds name & priority to each message. As usual, you may download this from http://quux.org/devel/missingh/ -- John Goerzen Author, Foundations of Python Network Programming http://www.amazon.com/exec/obidos/tg/detail/-/1590593715

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What's up with this Haskell runtime error message:
by Michael Goodrich 05 Apr '06

05 Apr '06

Greetings All: GHC gives: Fail: <<loop>> Hugs gives: [(ERROR - C stack overflow cheers, -Mike

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