July 2004 - Haskell - Haskell.org

Mixing monadic and non-monadic functions
by Sean E. Russell 17 Sep '05

17 Sep '05

Hello, I posted this question to comp.lang.functional, and someone suggested that I try this group instead. I'm struggling with monads. Well, not monads themselves, but mixing them with non-monadic functions. Here's my base case: someFunc :: String -> IO [a] ... ax <- someFunc a bx <- someFunc b assertBool "fail" $ length ax == length bx I don't like the assignments; the typing is redundant, if I have a lot of asserts like this, and the "variables" are temporary. What I'd much rather have is: ... assertBool "fail" $ (length $ someFunc a) == (length $ someFunc b) which is more readable, to my eye. The only solution which has been suggested that may work is liberal use of the liftM variants, but this gets *really* tedious and obtuse. Is there an elegant way to do what I want to do, or am I stuck with procedural-style assignments and bunches of temp vars? Thanks! -- ### SER ### Deutsch|Esperanto|Francaise|Linux|XML|Java|Ruby|Aikido ### http://www.germane-software.com/~ser jabber.com:ser ICQ:83578737 ### GPG: http://www.germane-software.com/~ser/Security/ser_public.gpg

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WS-FM 2004 Call For Participation
by Mario Bravetti 20 Jul '05

20 Jul '05

---------------------------------------------------------------------- We apologize if you receive multiple copies of this announcement. ---------------------------------------------------------------------- ====================================================================== 1st International Workshop on Web Services and Formal Methods (WS-FM 2004) February 23-24, 2004, Pisa, Italy Workshop affiliated to COORDINATION 2004, February 24-27, 2004 WS-FM 2004 homepage: http://www.cs.unibo.it/~lucchi/ws-fm04/ ====================================================================== - The technical program is available at: http://www.cs.unibo.it/~lucchi/ws-fm04/ - Information about registration, travel and accomodation can be found at the COORDINATION 2004 web site: http://www.di.unipi.it/Coordination2004/ If you intend to participate, we recommend you to register and book the hotel as soon as possible. The Coordination 2004 Organizing Committee informed us that hotels are going to be fully booked in short time.

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RE: [Haskell] confusing language in report and a bug in (ghc|hugs)
by Simon Peyton-Jones 02 Aug '04

02 Aug '04

I'm inclined to think John is right, thought the Report could be clearer. I'll open a GHC sourceforge bug for this. Simon | -----Original Message----- | From: haskell-bounces(a)haskell.org [mailto:haskell-bounces@haskell.org] On Behalf Of John Peterson | Sent: 29 July 2004 03:36 | To: haskell(a)haskell.org | Subject: Re: [Haskell] confusing language in report and a bug in (ghc|hugs) | | The intention in the report was to match in the order listed in the | pattern - you need not consult the data declaration to understand the | ordering. I think the report is clear enough - it's just a bug in | ghc. | | John | _______________________________________________ | Haskell mailing list | Haskell(a)haskell.org | http://www.haskell.org/mailman/listinfo/haskell

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Invitation to write book reviews
by S.J.Thompson 30 Jul '04

30 Jul '04

The journal of functional programming publishes reviews of books on functional programming an related subjects. A list of currently available titles is always at http://www.cs.kent.ac.uk/people/staff/sjt/JFP/available.html and currently it lists Inductive Synthesis of Functional Programs Ute Schmid Verification of Reactive Systems: Formal Methods and Algorithms Klaus Schneider Duration Calculus: A Formal Approach to Real-Time Systems Zhou Chaochen, Michael R. Hansen Concepts, Techniques and Models of Computer Programming Peter van Roy and Seif Haridi Programming Languages and Operational Semantics Maribel Fernandez The Haskell Road to Logic, Maths and Programming Kees Doets and Jan van Eijck If you are interested in reviewing any of these titles, or if you would like to suggest any other books for review, please mail me. If you are interested, but not sure what writing a review involves, there are review guidelines at http://uk.cambridge.org/journals/functionalprogramming/reviews.htm Regards Simon Thompson

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ANNOUNCE: Chameleon version (04-07)
by Martin Sulzmann 30 Jul '04

30 Jul '04

We are pleased to announce Chameleon version 04-07. Latest version can be downloaded via http://www.comp.nus.edu.sg/~sulzmann/chameleon/ New features include: * Improved Type Inference and Lexically Scoped Annotations * Improving Type Error Diagnosis * Beyond Functional Dependencies. * Existentially Quantified Type Classes. (includes guarded recursive data types aka first-class phantom types etc) Martin Sulzmann (sulzmann at comp.nus.edu.sg) Jeremy Wazny (jeremyrw at students.cs.mu.OZ.AU)

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IFL'04, Luebeck: Hotel reservation deadline approaching
by Clemens Grelck 29 Jul '04

29 Jul '04

Please accept our apologies if you receive multiple copies of this mail. Sincerely, Clemens Grelck and Frank Huch IFL'04 ------------------------------------------------------------------------ Announcement, Call for Papers and Call for Participation for the 16th International Workshop on Implementation and Application of Functional Languages (IFL'04) September 8th -- 10th, 2004, Luebeck, Germany http://www.isp.uni-luebeck.de/ifl04/index.htm ------------------------------------------------------------------------ Important Dates --------------- Jul 15th, 2004 Hotel reservation deadline =========================================== Jul 31st, 2004 Registration deadline Aug 20th, 2004 Submission deadline for draft proceedings Sep 8th, 2004 Workshop starts in the morning Sep 9th, 2004 Excursion and banquet dinner Sep 10th, 2004 Workshop ends in the evening Sep 11th, 2004 Post-workshop excursion Oct 29th, 2004 Submission deadline for post-refereeing process Dec 10th, 2004 Notification of acceptance/rejection Jan 21st, 2005 Camera-ready papers due Scope and Topics ---------------- The IFL workshops form a tradition that has lasted for over a decade. The aim of these workshops is to bring together researchers actively engaged in the implementation and application of functional and function-based programming languages. They provide an open forum for researchers who wish to present and discuss new ideas and concepts, work in progress, preliminary results, etc. related primarily but not exclusively to the implementation and application of functional languages. Topics of interest include, but are not limited to - language concepts - type checking - compilation techniques - (abstract) interpretation - automatic program generation - (abstract) machine architectures - formal aspects - array processing - concurrent/parallel programming - concurrent/parallel program execution - heap management - runtime profiling - performance measurements - debugging and tracing - verification - tools and programming techniques Papers on applications demonstrating the suitability of novel ideas in any of the above areas and contributions on related theoretical work are also welcome. The change of the workshop name adding the term "application" is to reflect the broader scope IFL has gained over recent years. Contributions ------------- Prospective authors are encouraged to submit papers to be published in the draft proceedings (published as a technical report of the Institute of Computer Science and Applied Mathematics of the University of Kiel) and to give presentations at the workshop. All contributions must be written in English, conform to the Springer-Verlag LNCS series format (see: http://www.springer.de/comp/authors/index.html) and not exceed 16 pages. Papers must be submitted by August 20th as postscript or pdf files through the workshop web page at http://www.isp.uni-luebeck.de/ifl04/index.htm. Following the IFL tradition since 1996, a subset of high-quality contributions will be published by Springer-Verlag in the well-known Lecture Notes in Computer Science (LNCS) series. All participants who gave a presentation at the workshop are invited to submit a revised version of their paper for the post-workshop proceedings. They will be refereed by the program committee according to normal conference standards. Program Committee ----------------- Matthias Blume (Toyota Technological Institute, Chicago, USA) Andrew Butterfield (Trinity College Dublin, Ireland) Manuel Chakravarty (University of New South Wales,Sydney,Australia) Clemens Grelck (chair)(University of Luebeck, Germany) Frank Huch (chair) (University of Kiel, Germany) Hans-Wolfgang Loidl (Ludwig-Maximilians-University, Munich, Germany) Frederique Loulergue (University of Paris XII, France) Simon Marlow (Microsoft Research, Cambridge, UK) Greg Michaelson (Heriot-Watt University, Edinburgh, UK) Yolanda Ortega-Mallen (University Complutense of Madrid, Spain) Rinus Plasmeijer (University of Nijmegen, The Netherlands) Colin Runciman (University of York, UK) Peter Thiemann (University of Freiburg, Germany) Phil Trinder (Heriot-Watt University, Edinburgh, UK) German Vidal (Technical University of Valencia, Spain) Workshop Organization --------------------- Clemens Grelck Frank Huch Institute of Software Technology Institute of Computer Science and Programming Languages and Applied Mathematics University of Luebeck, Germany University of Kiel, Germany Further Information ------------------- Website: http://www.isp.uni-luebeck.de/ifl04/index.htm E-mail: ifl04(a)isp.uni-luebeck.de

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confusing language in report and a bug in (ghc|hugs)
by John Meacham 29 Jul '04

29 Jul '04

in section 3.17.2 case #6 of the haskell report There is some confusing language in the report. Furthermore there is either a bug in ghc, or hugs, depending on which way you interpret it. it says: # Matching against a constructor using labeled fields is the same as # matching ordinary constructor patterns except that the fields are # matched in the order they are named in the field list. All fields # listed must be declared by the constructor; fields may not be named # more than once. Fields not named by the pattern are ignored (matched # against _). If you interpret 'field list' to mean the order the fields appear in the pattern then given the code below "bar" should be printed, as the 'b' field is compared and fails so the a field is never matched against. If you interpret 'field list' to mean the order the fields were DECLARED in, then this should equal _|_ as the 'a' field is matched first and is undefined. ghc seems to follow the second interpretation, hugs the first. If the first is indeed the correct interpretation, (it is what I thought) I don't see a trivial translation to dispose of fields, as there is no easy way in Haskell98 to change the order of pattern matching without rewriting everything as a big mess of nested cases. (i mean, obviously it can be done, but the translation is harder than just placing the patterns in the right slots and dropping the field names) -- the code -- data Foo = Foo { a,b::Int } au = Foo { a = undefined, b = 0 } main = case au of Foo { b = 1, a = 0 } -> print "foo" _ -> print "bar" ghc => error: Prelue.undefined hugs => "bar" -- John Meacham - ⑆repetae.net⑆john⑈

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ICFP'04 Call for Participation
by Amr A Sabry 28 Jul '04

28 Jul '04

The 2004 International Conference on Functional Programming (ICFP) Snowbird, Utah September 19-22, 2004 Call for Participation ***************************************************** *** Early registration rates until 25 August 2004 *** ***************************************************** Registration, hotel information, conference program (accepted papers, poster session, and affiliated workshops on Erlang, Haskell, and Scheme) at the following web site: http://www.cs.indiana.edu/icfp04/

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Re: [Haskell] Memo function help
by MR K P SCHUPKE 28 Jul '04

28 Jul '04

>Note that it doesn't have to be lazy, Most traditional dynamic programming techniques use arrays to store intermediate values. Lazy techniques could use a prohibative amount of memory due to the size of the thunks. The best general technique I have found in Haskell is to use unboxed mutable arrays in the ST monad to compute the result eagerly. Even this can result in huge memory usage. The best lazy technique I have seen is this: http://www.csse.monash.edu.au/~lloyd/tildeStrings/Alignment/92.IPL.html (in tests this lazy method was more or less the same speed as the eager method, but it does take advantage of particular access patterns in the string edit distance algorithm). Keean.

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Memo function help
by Tom Hofte 28 Jul '04

28 Jul '04

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