- Haskell - Haskell.org

library Directory.hs
by Nicole Gabler 19 Jun '01

19 Jun '01

Hi all, I have a problem: I need the library Directory.hs. But there is no directory.hs in {Hugs}/lib/ !! All standard libraries are there expect of this one. I downloaded Hugs from http://www.haskell.org/hugs/. Is there any alternative?? Or did I understand something wrong?? I hope you can help me! Best regards, Nicole ______________________________________________________________________________ Sie surfen im Internet statt im Meer? Selbst schuld! Auf zum Strand: http://lastminute.de/?PP=1-0-100-105-1

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RE: Haskell report typo (bad law for readsPrec)
by Simon Peyton-Jones 19 Jun '01

19 Jun '01

| Another simple alternative is to weaken the the equation by | replacing the variable r by the empty string: [Alternative B:] | | ... | should be the case that | | fst (head (readsPrec d (showsPrec d x ""))) == x Yes, I like this alternative too. I'll implement it. Thank you for spotting it. Simon

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Re: GHC version 5.00.2 is available
by Juan Carlos Arevalo Baeza 18 Jun '01

18 Jun '01

At 07:46 AM 6/18/2001 -0700, Julian Seward (Intl Vendor) wrote: >The (Interactive) Glasgow Haskell Compiler -- version 5.00.2 > >[...] > >Pre-built >packages for Linux, FreeBSD, and Solaris(sparc) are also available. > >[...] > > What's new in 5.00.1 >====================== > >[...] > >At the moment there is no Win32 build of 5.00 or 5.00.1 available. We >decided to push Win32 support to the 5.02 release, so as not to delay >5.00.1 any further. So, what's up? I've been completely unable to build it (the previous version) on my own... It says it requires Happy, and no matter what I do (Happy build just fine), it doesn't see it. No hurry, but still, I'd like to play with this new version. Salutaciones, JCAB --------------------------------------------------------------------- Juan Carlos "JCAB" Arevalo Baeza | http://www.roningames.com Senior Technology Engineer | mailto:jcab@roningames.com Ronin Entertainment | ICQ: 10913692 (my opinions are only mine) JCAB's Rumblings is so off-line O:-(

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Ray Tracing
by Heron 18 Jun '01

18 Jun '01

Hello Haskell & GHC people, I need the source code of a Ray Tracing written in Haskell. This code was used for parallelization using Caliban and Eden. Can you help me on how or where I can obtain it ? Heron de Carvalho, Msc.

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3 Lectureships at St Andrews
by Kevin Hammond 18 Jun '01

18 Jun '01

St Andrews University has three lectureships available in Computer Science. We are looking for good researchers, with an emphasis on practical skills: functional programmers would obviously be very good from my perspective! The deadline is the 22nd of June, but a late application may be acceptable if there is a good reason. Further details are available at. http://www.dcs.st-and.ac.uk/jobs/#lec or send me email if you'd like to discuss it. The salary is on the standard UK Lecturer scale: currently UK pounds 18,731 to 30,967 Best Wishes, Kevin

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Working Conference on Generic Programming: first call for papers
by Johan Jeuring 18 Jun '01

18 Jun '01

WCGP '02 IFIP TC2 Working Conference on GENERIC PROGRAMMING http://www.generic-programming.nl/wcgp/cfp.html Organised in conjunction with MPC'02 July 8 - July 13, 2002 Dagstuhl, Germany CALL FOR PAPERS Generic programming is about making programs more adaptable by making them more general. Generic programs often embody non-traditional kinds of polymorphism; ordinary programs are obtained from them by suitably instantiating their parameters. In contrast with normal programs, the parameters of a generic programs are often quite rich in structure. For example they may be other programs, types or type constructors, class hierarchies, or even programming paradigms. Generic programming techniques have always been of interest, both to practitioners and to theoreticians, but only recently have generic programming techniques become a specific focus of research in the functional and object-oriented programming language communities. This working conference will bring together leading researchers in generic programming from around the world, and feature papers capturing the state of the art in this important emerging area. We welcome contributions on all aspects, theoretical as well as practical, of generic programming, aspect-oriented programming, polytypic programming, adaptive object-oriented programming, generic components, and so on. SUBMISSION Full papers should be submitted in Postscript or pdf format by e-mail to reach Jeremy.Gibbons(a)comlab.ox.ac.uk by February 16, 2002. The details of the submission procedure can be found at http://www.generic-programming.nl/wcgp/submit.html Although there is no page limit, submissions should strive for brevity and clarity. IMPORTANT DATES Submission February 16, 2002 Notification April 12, 2002 Final version due May 24, 2002 PROGRAMME COMMITTEE Matt Austern Eerke Boiten Ulrich Eisenecker Jeremy Gibbons (co-chair) Ralf Hinze Johan Jeuring (co-chair) Gary Leavens Karl Lieberherr Lambert Meertens Eugenio Moggi Bernhard Moeller Oege de Moor David Musser Martin Odersky Ross Paterson Simon Peyton Jones Colin Runciman Doaitse Swierstra Stephanie Weirich LOCAL ORGANISATION Jeremy Gibbons Johan Jeuring Bernhard Moeller CORRESPONDENCE Jeremy Gibbons (Jeremy.Gibbons(a)comlab.ox.ac.uk) Johan Jeuring (johan(a)jeuring.net)

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RE: Eq instance for (a,b,c,d,e) and upwards
by Simon Peyton-Jones 18 Jun '01

18 Jun '01

Folks It seems that people are happy with the draft Haskell report (I'm glad to say). There seem to be two outstanding issues: * Tuples. I've decided to specify that tuples up to size 15 exist, along with all their Eq, Ord, etc instances up to that size. * The Prelude types of deleteBy deleteFirstsBy intersectBy Although these could be given more general types, it's an unforced change, and Fergus points out that the more general types could change error messages for the worse. I'm going to let sleeping dogs lie and make no change here. [Recall that no-change is the *strong* default.] The final version of everything is at http://research.microsoft.com/~simonpj/haskell98-revised I'm ready to call it a day, but of course I may have made some stupid error. Take a look please and let me know. I have not yet made PDF; there are issues I don't understand about how to get PDF to look right. Help sought! Simon

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PLI 2001 in Firenze
by Rocco De Nicola 15 Jun '01

15 Jun '01

CALL FOR PARTICIPATION AND EARLY REGISTRATION PLI 2001 Principles, Logics, and Implementations of high-level programming languages Firenze, ITALY September 2 - 8, 2001 http://music.dsi.unifi.it/pli01/ The colloquium on Principles, Logics, and Implementations of high- level programming languages is a collection of events aimed at the advancement of high-level programming languages. PLI 2001 includes the following conferences and workshops: ACM Sponsored Conferences: ICFP (September 3-5) Int. Conf. on Functional Programming General chair: Benjamin Pierce (Univ. Pennsylvania) Program chair: Xavier Leroy (INRIA Rocquencourt) Invited speakers: To be announced PPDP (September 5-7) Int. Conf. on Principles and Practice of Declarative Programming Conference chair: Rocco De Nicola (Univ. Firenze) Program chair: Harald Søndergaard (Univ. Melbourne) Invited speakers: J. Esparza, A. Gordon, and D.A. Schmidt. ACM Sponsored Workshops: · BABEL (Multi-language Infrastructure and Interoperability) · HASKELL · QAPL (Quantitative Aspects of Programming Languages) · RULE (Rule-Based Programming) · SAIG (Semantics, Applications, and Implementation of Program Generation) · SCHEME (Scheme and Functional Programming) · VCL (Verification and Computational Logic) Co-located Workshops: · ERLANG · FICS (Fixed Points in Computer Science) A detailed presentation of PLI2001, including schedule of events, travel and tourist information, is available at the WEB page http://music.dsi.unifi.it/pli01/. Registration and accommodation information and forms are available at http://music.dsi.unifi.it/pli01/registration/ Early registration rates apply until July 25. For informations about hotels please contact (mentioning PLI 2001) Giubbi Jet di Volo Viaggi Piazza San Jacopino, 34/r - 50144 Firenze Telephone: +39 055 3249074 - +39 055 350577 Fax: +39 055 366807 E-mail: incoming(a)voloviaggi.com For all other informations mail to pli-org(a)gdn.dsi.unifi.it ------------------------------------------------------------------- Firenze is packed in September; do book accommodation as soon as possible. ------------------------------------------------------------------- -- <><><><><><><><><><><><><><><><><><><><><><><><><><> Prof. Rocco De Nicola Dip. Sistemi e Informatica Univ. di Firenze Via C. Lombroso 6/17 I-50134 FIRENZE (ITALY) tel. +39 055 4796733 fax +39 055 4796730 Web Page: http://www.dsi.unifi.it/~denicola/ <><><><><><><><><><><><><><><><><><><><><><><><><><>

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Re: Why is there a space leak here?
by cwitty＠newtonlabs.com 11 Jun '01

11 Jun '01

"S. Alexander Jacobson" <alex(a)shop.com> writes: > On 6 Jun 2001, Carl R. Witty wrote: > > > "S. Alexander Jacobson" <alex(a)shop.com> writes: > > > > > For example w/ foldl: > > > > > > foldl + 0 [1..10000] > > > foldl (+) ((+) 0 1) [2..10000] > > > foldl (+) ((+) ((+) 0 1) 2) [3..10000] > > > > > > Can't the implementation notice that each iteration leads to a > > > larger closure and, if it is running out of space go ahead an just > > > evaluate (+) 0 1? > > > > It's complicated. You can't (in general) know whether application of > > a function will increase or decrease the space used. If you were > > running out of space, would you just search the whole unevaluated > > program graph for reductions which somehow seemed "likely" to reduce > > the space used? Would you add such reduction nodes to some global > > list at the time they were created? > > I'm not clear why you can't in general notice that you are using > more space after function application than before. I it hard to see why a > program couldn't do the analysis I just did on foldl. I wasn't worried about foldl; you assumed that (+) 0 1 got smaller if you carried out the application. Even for (+) on Integer, this is not guaranteed (for large integers, if something else happens to be holding on to the summands, evaluating the addition can increase total space usage). > You could accumulate statistics on funtions that increase/decrease space > used at runtime and evaluate those that do reduce space used... Right, that's the sort of thing I meant about "likely" above. But how do you find such function applications in the global program graph, if you seem to be running low on space? (And you also need to realize that some functions might usually have "small" outputs, and sometimes have "large" outputs.) > > One portable way to implement a memoizing function in Haskell (if the > > domain of the function is countable) is to lazily build a data > > structure that contains the results of the function on every possible > > argument. Then you evaluate the portions of the data structure that > > you need; the result on each argument is only evaluated once. This > > probably would count as a "growing expression", and it's certainly > > possible that the function on some arguments would be bottom. > > I don't think I understood this. Can you clarify? Let me know if JCAB's response wasn't enough here. Carl Witty

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Haskell 98 Report
by Simon Peyton-Jones 11 Jun '01

11 Jun '01

Folks I've finished what I hope is the final version of the Haskell 98 Language and Library Reports http://research.microsoft.com/~simonpj/haskell98-revised However, experience shows that bug fixes are often themselves buggy, so I urge you, once again, to take a look at your favourite passages and check they are correct. As ever, there's a complete list of changes at the above URL, with the ones I've made since the April release identified for your pleasure. Comments (hopefully vanishingly few) by 15 June please. Thanks very much Simon

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