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Re: diff in Haskell?
by Lloyd Allison 21 Nov '02

21 Nov '02

It is not quite "diff" but there is an "edit distance" in Haskell here http://www.csse.monash.edu.au/~lloyd/tildeFP/Haskell/1998/Edit01/ it might provide a starting point. (Diff treats a line as a "character" and, I think, uses an algorithm that's fast for small numbers of changes.) Lloyd -- Lloyd ALLISON, CSSE, Monash University, Victoria, Australia 3168. web: http://www.csse.monash.edu.au/~lloyd/ tel: +61 3 9905 5205 use: http://www.linux.org/ OpenOffice: http://www.openoffice.org/

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Re: diff in Haskell?
by Ashley Yakeley 21 Nov '02

21 Nov '02

At 2002-11-21 08:37, George Russell wrote: >Does anyone happen to have implemented diff in Haskell? Anyone else and I'd think this was a homework question... -- Ashley Yakeley, Seattle WA

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diff in Haskell?
by George Russell 21 Nov '02

21 Nov '02

Does anyone happen to have implemented diff in Haskell? Something like diff :: Ord a -> [a] -> [a] -> [DiffElement a] data DiffElement a = InBoth a | InFirst a | InSecond a So for example diff [1,2,3,4,5] [2,3,6,7,4] might return [InFirst 1,InBoth 2,InBoth 3,InSecond 6,InSecond 7,InBoth 4,InFirst 5] It would try to make the output list as short as possible, while still maintaining that the subsequence of InFirst and InBoth a's is the same as its first argument, while the subsequence of InSecond and Both a's is the same as its second argument. However it doesn't have to return the shortest possible output list; it may be that it can compute one which is close to optimal much faster. Also if you'd rather have a hash function than Ord I can manage that. Thanks if anyone can help, and save me a bit of work ... George Russell

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Call for Participation: PADL 2003
by Logic Programming Rsrch Association 21 Nov '02

21 Nov '02

[Apologies for multiple messages.] CALL FOR PARTICIPATION Fifth International Symposium on Practical Aspects of Declarative Languages http://www.research.avayalabs.com/user/wadler/padl03/ (PADL '03) New Orleans, LA, USA Jan 13-14, 2003 You are cordially invited to the Fifth International Symposium on Practical Aspects of Declarative Languages that will be held on Jan 13-14, 2003 right before ACM POPL. PADL received a record number of submissions (57) this year, out of which 23 papers were selected for presentation at the conference. Accepted papers also include "declarative pearls" and "Application Letters." The program includes invited talks by three distinguished speakers: Gerard Huet (INRIA, France), Shriram Krishnamurthi (Brown University) and David Page (U. of Wisconsin, USA). Registration rates ($175 regular and $125 student) have been kept very low to make the event affordable. If you are attending ACM POPL, we encourage you to stay for a whole week in New Orleans and attend PADL as well. More details can be found at: http://www.research.avayalabs.com/user/wadler/padl03/ -------------------------------------------------------------------- Invited Talks: o Gerard Huet, Zen and the Art of Symbolic Computing: Light and Fast Applicative Algorithms for Computational Linguistics. o David Page: The Role of Declarative Languages in Mining Biological Databases. o Shriram Krishnamurthi: The Continue Server (or, How I Administered PADL 2002 and 2003) List of Accepted Papers: o Non-monotonic Reasoning on Beowulf Platforms. E. Pontelli, M. Balduccini, F. Bermudez o Multi-Agent Reactive Systems. Prahladavaradan Sampath o Web Programming with SMLserver Martin Elsman and Niels Hallenberg o Reconstructing the Evolutionary History of Indo-European Languages using Answer Set Programming., Esra Erdem, Vladimir Lifschitz, Luay Nakhleh, and Donald Ringe o Logic Programs for Querying Inconsistent Databases Pablo Barcelo and Leopoldo Bertossi o Data mining the yeast genome in a lazy functional language Amanda Clare and Ross D. King o WAM Local Analysis Michel Ferreira, Luis Damas o Logic Programs as Compact Denotations Patricia M. Hill and Fausto Spoto o Sequence Quantification Peter Schachte o Garbage Collection Algorithms for Java--Based Prolog Engines Qinan Zhou, Paul Tarau o An Integrated Information System powered by Prolog Antonio Porto o Functional Hybrid Modelling Henrik Nilsson, John Peterson, Paul Hudak o A Logical Framework for Modelling eMAS Pierangelo Dell'Acqua and Luis Moniz Pereira o A Strafunski Application Letter Ralf Laemmel and Joost Visser o Roll: A language for specifying die-rolls Torben Mogensen o Solving Combinatorial Problems with a Constraint Functional Logic Language, Antonio J. Fernandez, Teresa Hortala-Gonzalez and Fernando Saenz-Perez o ACTILOG: An Agent Activation Language Jacinto A. Davila o Type-based XML Processing in Logic Programming Jorge Coelho and Mario Florido o Datalog with Constraints: A Foundation for Trust Management Languages Ninghui Li, John C. Mitchell o SXSLT: Manipulation Language for XML Oleg Kiselyov, Shriram Krishnamurthi o JMatch: Iterable Abstract Pattern Matching for Java Jed Liu, Andrew C. Myers o Lambda Goes to Hollywood Victor M. Gulias, Juan J. Sanchez, Carlos Abalde o A CLP-Based Tool for Computer Aided Generation and Solving of Maths Exercises, Ana Paula Tomas, Jose Paulo Leal

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Feature Structures
by Markus.Schnell＠infineon.com 20 Nov '02

20 Nov '02

Has anybody tried to implement (typed) feature structures in Haskell with unification? I'm trying to build my own library, but if there is already support for it, I would consider using this alternative. Thanks, Markus -- Markus Schnell Speech Interface Group, Infineon Technologies AG Tel +49 (89) 234-20875, Fax +49 (89) 234-21670

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RE: ANNOUNCE: Hugs98 November 2002 release
by i 20 Nov '02

20 Nov '02

[mybox] gunzip hugs98-Nov2002.tar.gz [mybox] tar xvf hugs98-Nov2002.tar ................................... x hugs98-Nov2002/fptools/libraries/base/Text/ParserCombinators/Parsec/examples/Mondrian/Pretty.hs, 2918 bytes, 6 tape blocks tar: directory checksum error [mybox] :( -- http://www.kuro5hin.org/users/i --- On Wed 11/20, Sigbjorn Finne wrote: > We are pleased to announce a new release of Hugs98, an interpreter > and programming environment for developing Haskell programs. _______________________________________________ No banners. No pop-ups. No kidding. Introducing My Way - http://www.myway.com

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Why no findM ? simple Cat revisited
by Ahn Ki-yung 20 Nov '02

20 Nov '02

Simple Cat (revisitied) \begin{code} import IO findM f [] = return Nothing findM f (x:xs) = do { v <- x; if f v then return (Just v) else findM f xs } isLeft (Left _) = True isLeft _ = False main = findM (isLeft) (hCat stdin) where hCat h = try (hGetLine h) : hCat h \end{code} This is my answer for the question of my own, which is posted a couple There are mapM, filterM in the Haskell 98 Standard Library. But why no findM there ? As you can see from simple cat, it seems quite useful. I think fildM should be added to the module Monad. -- Ahn Ki-yung

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Re: Functional dependencies and Constructor Classes
by Yoann Padioleau 20 Nov '02

20 Nov '02

Martin Sulzmann <sulzmann(a)comp.nus.edu.sg> writes: > Hi, > > I was wondering whether other people made similiar observations. > Functional dependencies seem to be expressiveness enough to encode > some of the kinding rules required for Constructor Classes. read this page: http://cvs.haskell.org/Hugs/pages/hugsman/exts.html I think that the designer of constructor class and functionnal depedencies is the same person si it makes sense that one generalise the other. nevertheless i found constructor class more elegant for many problems. Your solution is less elegant that the one using constructor classes. I found too that type error messages of class using functionnal depedencies are not easy to read. There is often ambiguity in code that are not easy to solver. this problem does not appear with constructor classes. > > Take a look at the Haskell code below > (runs under hugs -98 or ghci -fglasgow-exts-fallow-undecidable-instances) > > Martin > > > > -- An alternative to constructor classes > > module Fmap where > > {- Instead of > class Functor f where fmap :: (a->b)->(f a->f b) > > use > -} > > class Fmap a b fa fb | a fb -> b fa, > b fa -> a fb, > fa fb -> a b > where fmap2 :: (a->b)->(fa -> fb) > > {- We require: > > (1) fmap2 transforms a function into another function, > i.e. fmap2's type should always be of shape (a->b)->(fa->fb) > > (2) b, fa uniquely determine a and fb > > (3) a, fb " b and fa > > (4) fa, fb " a and b > > Note that (1) is enforced by the class definition. (2)-(4) are enforced by FDs. > > My guess/conjecture is that the above axiomatization of functors is equivalent to the > one found in Haskell98. > -} > > -- some Examples > > {- The following is a variation of an example taken from Mark Jones original paper > "A System of Constructor Classes: Overloading and Implicit Higher-Order Polymorphism". > He used this example to motivate the introduction of constructor classes. The example > is type correct using the alternative formulation of functors. > -} > > cmap :: (Fmap a b fb1 fb, Fmap a1 b1 fa fb1) => > (a1 -> b1) -> (a -> b) -> fa -> fb > cmap f g = (fmap2 g) . (fmap2 f) > > > -- identity functor > instance Fmap a a a a where fmap2 h = h > > -- functor composition > -- Instance is not allowed, cause leads to undecidable type inference > > {- > instance (Fmap a b c d, Fmap e f a b) => Fmap e f c d > where fmap2 h = fmap2 (fmap2 h) > -} > > comp :: (Fmap fa1 fb1 fa fb, Fmap a b fa1 fb1) => > (a -> b) -> fa -> fb > comp h = fmap2 (fmap2 h) > > > > _______________________________________________ > Haskell mailing list > Haskell(a)haskell.org > http://www.haskell.org/mailman/listinfo/haskell > -- Yoann Padioleau, INSA de Rennes, France, Opinions expressed here are only mine. Je n'écris qu'à titre personnel. **____ Get Free. Be Smart. Simply use Linux and Free Software. ____**

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ANNOUNCE: Hugs98 November 2002 release
by Sigbjorn Finne 20 Nov '02

20 Nov '02

We are pleased to announce a new release of Hugs98, an interpreter and programming environment for developing Haskell programs. Sources and binaries are freely available on the World-Wide Web. Feature highlights of this new release are: - Much improved FFI support (contributed by Alastair Reid), bringing Hugs really very close to the Haskell FFI specification. - Adoption of a significant subset of GHC's hierarchical libraries (contributed by Ross Paterson). - An (allegedly) complete implementation of the Haskell98 module system (Sigbjorn Finne). - Numerous bug fixes since the previous major release in Dec 2001. The home page for Hugs is at http://haskell.org/hugs. Send email to hugs-users-request(a)haskell.org to join the hugs-users mailing list. Bug reports should be sent to hugs-bugs(a)haskell.org. Send email to hugs-bugs-request(a)haskell.org to subscribe to the hugs-bugs list. Enjoy! ---------------------------------------------------------------------------- -- The Hugs 98 system is Copyright (c) Mark P Jones, Alastair Reid, the Yale Haskell Group, and the OGI School of Science & Engineering at OHSU, 1994-2002, All rights reserved. It is distributed as free software under the license in the file "License", which is included in the distribution. ---------------------------------------------------------------------------- --

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MD5 in Haskell
by Peter Thiemann 20 Nov '02

20 Nov '02

Folks, there used to be a Haskell implementation of MD5 and other cryptographic hashes available on http://c93.keble.ox.ac.uk/~ian/haskell/ Unfortunately, this URL seems to be obsolete (I cannot access it and it does not come up in Google anymore). If anybody out there still holds on to a copy of this, please send it to me! -Peter

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