- Haskell - Haskell.org

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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RE: [Haskell] haskell-in-a-box?
by Assini, Pasqualino 05 Apr '06

05 Apr '06

Many thanks for the links. Has anyone tried to squeeze House in a VMWare or XEN virtual machine? Best, titto ------------------------- Pasqualino "Titto" Assini E-mail: titto(a)quicquid.org Skype: tittoassini MSN : titto(a)kamus.it > -----Original Message----- > From: Jared Updike [mailto:jupdike@gmail.com] > Sent: 05 April 2006 16:23 > To: Assini, Pasqualino > Cc: haskell(a)haskell.org > Subject: Re: [Haskell] haskell-in-a-box? > > > And: has anyone already built a 'haskell-in-a-box' virtual machine? > > Some are working on an all-Haskell-boots-from-scratch OS: > House (Haskell User's Operating System and Environment): > > http://www.cse.ogi.edu/~hallgren/House/ > > From the page: "House is a demo of software written in Haskell, > running in a standalone environment. It is a system than can serve as > a platform for exploring various ideas relating to low-level and > system-level programming in a high-level functional language. More > details are available in our ICFP 2005 paper: A Principled Approach to > Operating System Construction in Haskell." > > Also, YHC is (in development) a new Haskell compiler based on nhc98 > that aims to produce highly portable bytecode which can then be ported > to JVM, .NET, etc. and of course a C virtual machine: > > http://www-users.cs.york.ac.uk/~ndm/yhc/ > > Jared. > > -- > http://www.updike.org/~jared/ > reverse ")-:"

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RE: [Haskell] haskell-in-a-box?
by Assini, Pasqualino 05 Apr '06

05 Apr '06

Very cool. Has anyone experience of using House? If it is reliable and it supports enough of the GHC libraries to run the Haskell Web Server (http://www.informatik.uni-freiburg.de/~thiemann/haskell/WASH/#wsp) we are in business :-) titto ------------------------- Pasqualino "Titto" Assini E-mail: titto(a)quicquid.org Skype: tittoassini MSN : titto(a)kamus.it > -----Original Message----- > From: Greg Buchholz [mailto:haskell@sleepingsquirrel.org] > Sent: 05 April 2006 16:15 > To: Assini, Pasqualino > Subject: Re: [Haskell] haskell-in-a-box? > > Assini, Pasqualino wrote: > > Since the question: what is the smallest X86 OS core on top of which one > > might compile Haskell (and I am mainly thinking of GHC Haskell here) > > programs? > > > > And: has anyone already built a 'haskell-in-a-box' virtual machine? > > You might be interested in "House"... > > http://www.cse.ogi.edu/~hallgren/House/ > > Greg Buchholz

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haskell-in-a-box?
by Assini, Pasqualino 05 Apr '06

05 Apr '06

Hello, you are probably all aware of the recent brouhaha relative to virtualisation, that is to say the possibility of running multiple operating systems in parallel on the same PC (see http://en.wikipedia.org/wiki/Virtualisation) This opens all kind of interesting possibilities, in particular for software distribution. Rather then having to worry about creating and maintaining different versions of a program for Windows + the infinite variations of Linux/Unix one could simply distribute a stand-alone virtual machine including the kernel of the OS of choice plus the application (this naturally only applies to applications with a network interface, e.g. web-based applications). This would have significant advantages in terms of ease of installation, safety, manageability and possibly also efficiency of execution as the underlying OS could be fine-tuned to support the application in an optimal way. This new trend might also be good news for Haskell as, coupled with a free OS with a small footprint, it might be used to create network applications that are both powerful and easy-to-install and manage. Since the question: what is the smallest X86 OS core on top of which one might compile Haskell (and I am mainly thinking of GHC Haskell here) programs? And: has anyone already built a 'haskell-in-a-box' virtual machine? Regards, titto ------------------------- Pasqualino "Titto" Assini E-mail: titto(a)quicquid.org Skype: tittoassini MSN : titto(a)kamus.it

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haskell@ archives, 1990-2000
by dons＠cse.unsw.edu.au 03 Apr '06

03 Apr '06

I managed, with the help of some custom hacks, to convert Simon's tarball of the haskell@ archives from 1990-2000 into html. I've hosted the lot here: http://www.cse.unsw.edu.au/~dons/haskell-1990-2000/threads.html I'm not sure these archives are available anywhere else, other than the tarball on SPJs page, here http://research.microsoft.com/~simonpj/haskell/haskell-email-11Sep1990-27Oc… Enjoy reading about the problems of n+k and why Haskell needs a binary IO class, way back in 1990 :) -- Don P.S. if you find oddities in the conversion, let me know.

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