December 2003 - Libraries

Subprocesses (was: [ANNOUNCE] shell-haskell 1.0.0)
by Simon Marlow 08 Jul '04

08 Jul '04

Libraries people, There are currently two ways to create and communicate with external processes: - System.Cmd.system (very basic, doesn't give you access to the process's output but you can use shell primitives to redirect its input/output). - Posix.runProcess (can specify Handles for the process's input/output, but it doesn't create pipes so you can't actually communicate with the subprocess using these Handles.). - POpen.popen (can specify an input String, and gives you lazy output Strings. No interactive communication is possible.) Ok, *three* ways. System.Cmd.system, Posix.runProcess, POpen.popen, and shell-haskell. Er. *Four* ways. David Sankel's shell-haskell creates pipes for stdin/stdout/stderr, and lets you communicate interactively with the sub-process via Handles. It could do with a way to specify the environment and working directory of the sub-process (ala POpen and runProcess), but apart from that it seems to be the most flexible of the four. It could be simplified slightly by using one Handle rather than two for stdin/stdout. We should think about what functionality we want to provide in the core libraries. My preference would be to go for a full version with three pipes (like shell-haskell) and perhaps one or two more specialised versions covering common cases (I don't know what these should be, though). What do people think? Cheers, Simon -----Original Message----- From: haskell-admin(a)haskell.org [mailto:haskell-admin@haskell.org] On Behalf Of David Sankel Sent: 06 May 2003 03:06 To: haskell(a)haskell.org Subject: [ANNOUNCE] shell-haskell 1.0.0 =================== shell-haskell 1.0.0 =================== shell-haskell provides utilities to communicate with other process's via Haskell code. This library can be used for something as simple as getting the output of another program or as complex as interacting with an interpreter. see http://www.electronconsulting.com/shell-haskell for details. David J. Sankel _______________________________________________ Haskell mailing list Haskell(a)haskell.org http://www.haskell.org/mailman/listinfo/haskell

5 10

Your Trip To Las Vegas!
by GoldenStar 31 Dec '03

31 Dec '03

1 0

Bindings for libao
by Daniel Brown 24 Dec '03

24 Dec '03

Anyone ever heard of libao bindings for Haskell? I think I'm going to research and try to write some, but I figured that I would probe the community before getting to involved. danb -- Daniel Brown www.cs.utexas.edu www.utacm.org

1 0

Startpagina nieuws flits!
by Websitemaker.nl 18 Dec '03

18 Dec '03

Geachte heer/mevrouw, Is uw Startpagina aan vernieuwing toe? Bent u het zat om telkens tegen gebroken linken aan te lopen? Neem dan eens een kijkje op onze Startpagina! Op onze Startpagina vind u alles wat u zoekt op het Internet, wij beschikken over diverse zoekmachines die u nog beter van dienst kunnen zijn! Op onze Subpagina vind u al onze portalen, indien u het dan nog niet kunt vinden dan heeft u bij ons de keuze om op andere Nederlandse en Internationale Startpagina's te kijken! Op deze site vind u meer dan 400 Startpagina's, keuze genoeg dus. Omdat wij met diverse andere Startpagina's samen werken blijven de sites up to date! Wat zijn de gemakken van onze startpagina waar u gratis gebruik van kunt maken, wij beschikken over een Faxservice pagina waar u gratis een Fax met bevestiging kunt vesturen, een mailservice pagina hier kunt u gratis een mailtje online versturen naar wie u maar wilt, dan hebben wij nog de aanmeldservice, deze kunt u gebruiken voor uw eigen website! U meld uw website in enkele seconden aan bij 31 belangrijke Internationale zoekmachines, en dat alles kost u helemaal niets! U ziet de makers van de Websitemaker.nl Startpagina voor jong en oud, hebben overal aan gedacht juist om een ieder tevreden te stellen en het gemak van Internetten zo aangenaam mogelijk te maken. Wij hopen dat u blij bent met deze nieuwsbrief indien u deze nieuwsbrief niet meer wenst te ontvangen, dan hoefd u maar met 1 druk op de knop zich af te melden. Wij wensen u prettige feestdagen en een gelukkig nieuwjaar. _________________________________________________________________________ If you do not wish to be contacted by email in the future, reply with "remove" in the subject and your email address in the message text.

1 0

RE: docon 2.06 triggers compiler bug
by Simon Peyton-Jones 17 Dec '03

17 Dec '03

I assume that by "standard" library you mean "distributed with GHC and Hugs". The trouble with this approach is that it ties the package to the GHC/Hugs release schedules, bloats the release size, and it seriously increases our test burden before a release. Our general plan is instead to try to make it much, much easier for people to distribute packages for GHC, Hugs etc, which download and install trivially easily. It's possible today, but requires a lot of work. That is exactly what the library infrastructure project is doing -- Isaac Jones is leading it, but I'm sure he could do with help. Isaac, how's it going? Simon | -----Original Message----- | From: cvs-all-bounces(a)haskell.org [mailto:cvs-all-bounces@haskell.org] On Behalf Of Peter Simons | Sent: 16 December 2003 20:15 | To: cvs-ghc(a)haskell.org | Subject: Re: docon 2.06 triggers compiler bug | | Donald Bruce Stewart writes: | | > Conclusion: this program should go in the test suite! | | Personally, I'd like to take it one step further: docon | should go into the standard library. :-) | | Not only to test ghc, but because it's really good software. | IMHO, Haskell would benefit greatly from the algebraic class | model docon provides. Not to mention the sophisticated tools | for solving all kind of algebraic problems. Using docon, I | find my programs become almost indistinguishable from formal | correctness proofs of the algorithm. It would be nice if | this "look and feel" could be extended into general | programs, which are not math related, and docon adds a lot | of expressivity to the language to do just that. | | Peter | _______________________________________________ | Cvs-ghc mailing list | Cvs-ghc(a)haskell.org | http://www.haskell.org/mailman/listinfo/cvs-ghc

2 1

FW: [Caml-list] Data structures and algorithms in Caml programs
by Simon Peyton-Jones 15 Dec '03

15 Dec '03

Dear Haskell library folk Here's an interesting survey about data structure libraries. It's Caml oriented, but very relevant to Haskell too. Simon -----Original Message----- From: owner-caml-list(a)pauillac.inria.fr [mailto:owner-caml-list@pauillac.inria.fr] On Behalf Of Diego Olivier Fernandez Pons Sent: 10 December 2003 14:43 To: caml-list(a)inria.fr Subject: [Caml-list] Data structures and algorithms in Caml programs Bonjour, I have reviewed 20 programs I think representative of Caml, trying to investigate the usages and needs in data structures and algorithms. http://www.edite-de-paris.com.fr/~fpons/Caml/Ressources/dsInCaml.html The purpose is to have a more precise idea of what is really giving trouble and help library designers to provide solutions that are closely related to the programmers needs. All comments are welcome including corrections and programmers feedback on code design, etc. Reviewed programs Caml (21) (data) aifad, ibal (bioinformatics) biocaml (compilation) ccured, dml, fftw, flowcaml, mojave (constraint solving) cime, facile, wallace (parsing) cil, cfg, sister-head (text) cduce, galax, hevea, regex, timbuk (theorem proving) coq, harrison, link Standard ML (1) (compilation) mlrisc Haskell (4) (parsing) alex, happy, parsec (text) regexplib

1 0

Small SMTP client library
by Massimo Zaniboni 15 Dec '03

15 Dec '03

Sorry for my bad english. If you find this limited module useful then you can insert in your project. It is very limited but it could be useful to send email message using insecure plain/login authentication. I have no time to extend it. Regards, Massimo Zaniboni.

1 0

Abstract Data Structures
by Robert Will 10 Dec '03

10 Dec '03

hi, Abstract Data Types plus Data Structures gives Abstract Data Structures. Divide by Conquer is a technique that every Computer Science Undergraduate learns: to sort a listm sort each of its halves then merge. This is what I call "Computational Divide and Conquer" and it is an important algorithm design strategy. Algorithm Design and Programming were once considerd the same and they were the heart of Computer Science. Nowadays, we get our algorithms from libraries and are instead faced with the complexity of programming applications. It is essential that we divide our programs into smaller parts and specify the contracts between those parts. This is what I call "Informational Divide and Conquer". (The words "informational" vs "calculational" go back to Dijkstra who said that a refinement step is good if it makes either "computational or informational progress". The former meaning decrease a loop or recursion variant, the latter meaning to get simpler assertions. I believe that the Art or Science or whatnot of Programming will make a leap forward, when it learns to profit from Dijkstras heritage.) -- Abstraction in Programming firmly rests on the separation -- of Specification and Implementation. Implementations in functional -- languages have always been on a "higher level", many of them -- serving as their own specifications. (Just take a look into -- Haskell's Prelude and try to specify one of the functions.) Due to -- take higher-level of built-in abstraction, they have resisted for a -- long time the use of programmer-defined abstraction, that is, the -- separation of Specification and Implementation. (Which is by the -- way also the basis of well-used polymorphism.) The main data -- structure of the Haskell programmer is still the same as the one -- from the first functional language in 1958. This file might -- convince the reader that a good functional language should have -- more to offer. http://www.stud.tu-ilmenau.de/~robertw/dessy/fun/AlgebraBasic.hs I have always considered it an advantage that almost all of the Prelude functions are there own specifications. If you had a question, just go ask the code. This approach, however, doesn't scale. If we want to include other data structures than functional stacks into a library (or how did you call that structure with the basic axioms head (x : xs) = x tail (x : xs) = xs ?) we must also include abstraction. I don't know why I write such philosphical stuff, actually I only wanted to annouce my little project and ask for comments: http://www.stud.tu-ilmenau.de/~robertw/dessy/fun/ Anyway, it doesn't hurt to remind every now and then. I would especially like interested people to have a look at AlgebraBasic.hs which I think is quite evolved and even already contains the words "standard proposal". Robert

1 0

"Time Warp"
by Graham Klyne 05 Dec '03

05 Dec '03

I spotted this and thought of some recent(ish) discussions... [[ # "Time Warp" New Scientist (11/22/03) Vol. 180, No. 2422, P. 30; Battersby, Stephen An unusual practice of modern timekeeping is the insertion of a "leap second" into the calendar, which occurs less than once a year on average; this is done to make up for the discrepancy between international atomic time and solar time, which is changing as the Earth's rate of rotation gradually slows. Since the inception of leap seconds 30 years ago, coordinated universal time has lagged in fits and starts behind universal atomic time, and the situation has been complicated by the rollout of various technologies that have their own internal time frames. "With [these technologies] becoming more interactive, they need to be synchronized," states the Naval Research Laboratory's Ron Beard. Technologies ranging from GPS to air traffic control systems to the Internet to military systems are not designed with leap seconds in mind, which makes leap second insertion the responsibility of software engineers. This task is difficult enough, but complicating matters is the unpredictable nature of the Earth's slowing spin, a phenomenon attributed to as-yet-indeterminate internal forces; in fact, the planet's rotation has recently sped up, the result being no leap seconds for the last five years. Affected by this is Motorola's Oncore GPS receiver, which will add an extra day to the calendar just after midnight on the morning of Nov. 28, 2003. This extra day will only last for a second, but Motorola GPS product manager Dave Huntingford is worried that this could affect Nov. 28 cell phone bills and lead to lost revenues; Global Timing Services consultant William Klepczynski is even more concerned that such glitches, when combined with worker stress, could lead to disastrous errors in air traffic control. Beard and others think leap seconds should be jettisoned in favor of a continuous timekeeping system called international time, although astronomers fervently oppose this because of their high reliance on software that automates the alignment of their telescopes. ]] -- http://www.acm.org/technews/articles/2003-5/1203w.html#item17 ------------ Graham Klyne For email: http://www.ninebynine.org/#Contact

2 1

"(±¤°í)±â°¡¸·Èù ºÎ¾÷Á¤º¸-½ºÆÄÀÌ´õ(ÀÏ¸í:µ·°Å¹Ì)¹«·áºÐ¾ç@"
by ��з�� 05 Dec '03

05 Dec '03

1 0