February 2005 - Haskell

Haskell-mode 2.0
by Stefan Monnier 02 Feb '09

02 Feb '09

I have recently taken over maintainership of Haskell-mode, and after making a bunch of changes, I figured it would be a good idea to make a new release. You can find this new release at: http://www-perso.iro.umontreal.ca/~monnier/elisp/ If you think it should also be found at http://www.haskell.org/haskell-mode/, then please tell John Peterson to get back to me (my email to him seem to go straight to the bitbucket. John?). This release has several changes that have all been only lightly tested, especially w.r.t compatibility with various Emacsen. See appended the NEWS file that describes some of the notewirthy changes. Stefan Changes since 1.45: * keybindings C-c <char> have been replaced by C-c C-<char> so as not to collide with minor modes. * The following modules are now automatically activated without having to add anything to haskell-mode-hook: haskell-font-lock (just turn on global-font-lock-mode). haskell-decl-scan (just bind `imenu' to some key). * In recent Emacsen, haskell-doc hooks into eldoc-mode. * haskell-hugs and haskell-ghci are superceded by inf-haskell. * Indentation rules have been improved when using layout inside parens/braces. * Symbols like -> and \ can be displayed as actual arrows and lambdas. See haskell-font-lock-symbols. * Tweaks to the font-lock settings. Among other things paren-matching with things like \(x,y) should work correctly now. * New maintainer <monnier(a)gnu.org>.

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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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SOS 2005: Call for Papers
by sos2005＠mcs.le.ac.uk 22 Jun '05

22 Jun '05

First Call for Papers: Structural Operational Semantics 2005 A Satellite Workshop of ICALP 2005 July 10, 2005, Lisbon, Portugal http://www.cs.le.ac.uk/events/SOS2005 Aim: Structural operational semantics (SOS) provides a framework for giving operational semantics to programming and specification languages. A growing number of programming languages from commercial and academic spheres have been given usable semantic descriptions by means of structural operational semantics. Because of its intuitive appeal and flexibility, structural operational semantics has found considerable application in the study of the semantics of concurrent processes. Moreover, it is becoming a viable alternative to denotational semantics in the static analysis of programs, and in proving compiler correctness. Recently, structural operational semantics has been successfully applied as a formal tool to establish results that hold for classes of process description languages. This has allowed for the generalization of well-known results in the field of process algebra, and for the development of a meta-theory for process calculi based on the realization that many of the results in this field only depend upon general semantic properties of language constructs. This workshop aims at being a forum for researchers, students and practitioners interested in new developments, and directions for future investigation, in the field of structural operational semantics. One of the specific goals of the workshop is to establish synergies between the concurrency and programming language communities working on the theory and practice of SOS. Moreover, it aims at widening the knowledge of SOS among postgraduate students and young researchers from the U.K. and abroad. Specific topics of interest include (but are not limited to): * programming languages * process algebras * higher-order formalisms * rule formats for operational specifications * meaning of operational specifications * comparisons between denotational, axiomatic and SOS * compositionality of modal logics with respect to operational specifications * congruence with respect to behavioural equivalences * conservative extensions * derivation of proof rules from operational specifications * software tools that automate, or are based on, SOS. Papers reporting on applications of SOS to software engineering and other areas of computer science are welcome. History: The first SOS Workshop took place on 30th of August 2004 in London as one of the satellite workshops of CONCUR 2004. Over 30 participants attended the workshop. PAPER SUBMISSION: We solicit unpublished papers reporting on original research on the general theme of SOS. Prospective authors are invited to submit their work in two stages: Firstly, the title and abstract of the paper, together with the details of the author(s), should be emailed to sos2005 AT mcs.le.ac.uk by: Friday, 13 May 2005. Secondly, a pdf file with their full paper, whose length normally should not exceed 15 pages, should be sent by email to sos2005 AT mcs.le.ac.uk by: Monday, 23 May 2005. The email message with the full paper should also include, in plain text, contact information for the author(s), the title and abstract of the submission. Authors will be notified of acceptance by Monday, 13 June 2005. Submissions from the PC members are allowed. Proceedings: Preliminary proceedings containing the abstracts of the talks will be published as a Technical Report of the Department of Computer Science of Leicester University, and will be available at the meeting. The final proceedings of the workshop will appear as a volume in the ENTCS series. If the quality and quantity of the papers accepted for the workshop warrant it, submissions will be invited for a special issue of an archival journal devoted to full versions of selected papers. IMPORTANT DATES: * Submission of abstract: Friday, 13 May 2005 * Submission of full paper: Monday, 23 May 2005 * Notification: Monday, 13 June 2005 * Final version: Friday, 24 June 2005 * Workshop: Sunday, 10 July 2005. PROGRAMME COMMITTEE: Luca Aceto (BRICS, Aalborg, DK) Wan Fokkink (Amsterdam, NL) Rob van Glabbeek (NICTA, AU) Matthew Hennessy (Sussex, UK) Ralf Laemmel (CWI, NL) Peter Mosses (Swansea, UK, co-chair) David Sands (Chalmers, SE) Alex Simpson (Edinburgh, UK) Simone Tini (Insubria, I) Irek Ulidowski (Leicester, UK, co-chair) Erik de Vink (Eindhoven, NL) INVITED SPEAKERS: Jan Friso Groote Jose Meseguer CONTACT: sos2005 AT mcs.le.ac.uk WORKSHOP ORGANISERS: Peter D. Mosses Department of Computer Science University of Wales Swansea Singleton Park Swansea, SA2 8PP United Kingdom Irek Ulidowski Department of Computer Science University of Leicester University Road Leicester, LE1 7RH United Kingdom

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PPDP 2005 Submission Deadline Extended to February 22
by Amy Felty 18 May '05

18 May '05

Call for Papers: PPDP 2005 Seventh ACM-SIGPLAN International Symposium on Principles and Practice of Declarative Programming Lisboa, Portugal, 11-13 July 2005 IMPORTANT DATES Submission 22 February 2005 **** NEW **** Notification 1 April 2005 Final Version 1 May 2005 INVITED SPEAKERS: Joint ICALP/PPDP Giuseppe Castagna (ENS Paris) John Mitchell (Stanford University) PPDP Manuel Hermenegildo (Technical University of Madrid, University of New Mexico) WEB SITES: PPDP 2005: http://centria.di.fct.unl.pt/conferences/ppdp05/ PPDP 2005 CFP: http://www.site.uottawa.ca/~afelty/ppdp05/ PPDP: http://pauillac.inria.fr/~fages/PPDP/ SCOPE OF THE CONFERENCE: PPDP 2005 aims to provide a forum that brings together those in the declarative programming communities, including those working in the logic, constraint and functional programming paradigms. The goal is to stimulate research in the use of logical formalisms and methods for specifying, performing, and analyzing computations, and to stimulate cross-fertilization by including work from one community that could be of particular interest and relevance to the others. Topics of more specific interest are enhancements to such formalisms with mechanisms for mobility, modularity, concurrency, object-orientation, and static analysis, as well as the fuller exploitation of the programming-as-proof-search framework through new designs and improved implementation methods. At the level of methodology, the use of logic-based principles in the design of tools for program development, analysis, and verification relative to all declarative paradigms is of interest. Papers related to the use of declarative paradigms and tools in industry and education are especially solicited. This list is not exhaustive: submissions related to new and interesting ideas relating broadly to declarative programming are encouraged. Prospective authors are encouraged to communicate with the Program Chair about the suitability of a specific topic. TOPICS (Not exhaustive): Logic, Constraint, and Functional Programming; Applications of Declarative Programming; Methodologies for Program Design and Development; Declarative Aspects of Object-Oriented Programming; Concurrent Extensions to Declarative Languages; Declarative Mobile Computing; Integration of Paradigms; Proof Theoretic and Semantic Foundations; Type and Module Systems; Program Analysis and Verification; Program Transformation; Abstract Machines and Compilation; Programming Environments PAPER SUBMISSIONS: Papers should be submitted electronically by 22 FEBRUARY 2005 via the symposium's web page. Acceptable formats are PostScript or PDF, viewable by gv. Submissions should not exceed 12 pages (including bibliography and appendices) in standard ACM conference format (see URL below). They must be written in English, must have a cover page with an abstract of up to 200 words, keywords, postal and electronic mailing addresses, and phone and fax numbers of the corresponding author. EVALUATION OF SUBMISSIONS: Submitted papers will be judged on the basis of significance, relevance, correctness, originality, and clarity. They should include a clear identification of what has been accomplished and why it is significant. They must describe original, previously unpublished work that has not been simultaneously submitted for publication elsewhere. Authors who wish to provide additional material to the reviewers beyond the 12-page limit can do so in clearly marked appendices: reviewers are not required to read such appendices. Submissions that do not meet these guidelines may not be considered. PROCEEDINGS: Proceedings will be published by ACM Press. ACM formatting guidelines are available online, along with formatting templates or style files for LaTeX, Word Perfect, and Word: http://www.acm.org/sigs/pubs/proceed/template.html. Authors of accepted papers will be required to sign the ACM copyright form. RELATED EVENTS: PPDP 2005 will be co-located with the 32nd International Colloquium on Automata, Languages and Programming (ICALP 2005), which will take place 11-15 July 2005. See http://icalp05.di.fct.unl.pt for more information. CONFERENCE CHAIR: Pedro Barahona, Universidade Nova de Lisboa, web: http://centria.di.fct.unl.pt/~pb, email: pb(a)di.fct.unl.pt PROGRAM CHAIR: Amy Felty, University of Ottawa, web: http://www.site.uottawa.ca/~afelty, email: afelty(a)site.uottawa.ca PROGRAM COMMITTEE: Pedro Barahona (Univ. Nova de Lisboa, Portugal) Gopal Gupta (Univ. Texas at Dallas, USA) Michael Hanus (Univ. Kiel, Germany) Kohei Honda (Queen Mary & Westfield Coll., UK) Michael Maher (National ICT, Australia) Maria Chiara Meo (Univ. G. D'annunzio, Italy) Gopalan Nadathur (Univ. Minnesota, USA) Atsushi Ohori (JAIST, Japan) Carsten Schuermann (Yale Univ., USA) German Vidal (Technical Univ. Valencia, Spain) Joe Wells (Heriot-Watt Univ., UK) Elena Zucca (Univ. Genova, Italy) PREVIOUS PPDP CONFERENCES: Paris (1999), Montreal (2000), Firenze (2001), Pittsburgh (2002), Uppsala (2003), Verona (2004).

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ICALP'05: Call for Papers
by Luis Caires 13 May '05

13 May '05

___________________________________________________________________ CALL FOR PAPERS - ICALP'05 32nd International Colloquium on Automata, Languages and Programming July 11-15, 2005, Lisboa, Portugal http://icalp05.di.fct.unl.pt/ ___________________________________________________________________ The 32nd International Colloquium on Automata, Languages and Programming, the main conference and annual meeting of the European Association for Theoretical Computer Science EATCS will take place from the 11th to the 15th of July 2005 in Lisboa, Portugal. As a complement to the established Tracks on Algorithms, Automata, Complexity and Games (A), and on Logic, Semantics, and Theory of Programming (B), corresponding to the two main streams of the journal Theoretical Computer Science, ICALP'05 innovates on the structure of its traditional scientific program with the inauguration of a new special Track (C). The aim of Track C is to allow a deeper coverage of a particular topic, to be specifically selected for each year's edition of ICALP on the basis of its timeliness and relevance for the theoretical computer science community. Papers presenting original research on all aspects of theoretical computer science are sought. Typical but not exclusive topics of interest are: Track A (Algorithms, Automata, Complexity and Games): Giuseppe F. Italiano Università di Roma "Tor Vergata", Italy (PC Chair) * Algorithmic Aspects of Networks * Algorithms and Data Structures * Automata Theory and Formal Languages * Combinatorics in Computer Science * Computational Biology * Computational Complexity * Computational Geometry * Internet Algorithmics * Machine Learning * Parallel and Distributed Computing * Quantum Computing Track B (Logic, Semantics, and Theory of Programming): Catuscia Palamidessi INRIA Futurs and LIX, France (PC Chair) * Algebraic and Categorical Models * Databases, Semi-Structured Data and Finite Model Theory * Principles of Programming Languages * Logics, Formal Methods and Model Checking * Models of Concurrent, Distributed, and Mobile Systems * Models of Reactive, Hybrid and Stochastic Systems * Program Analysis and Transformation * Specification, Refinement and Verification * Type Systems and Typed Calculi Track C (Security and Cryptography Foundations): Moti Yung Columbia University, USA (PC Chair) * Cryptographic Notions, Mechanisms, Systems and Protocols * Cryptographic Proof Techniques, Lower bounds, Impossibilities * Foundations of Secure Systems and Architectures * Logic and Semantics of Security Protocols * Number Theory and Algebraic Algorithms in Cryptography * Pseudorandomness, Randomness, and Complexity Issues * Secure Data Structures, Storage, Databases and Content * Security Modeling: Combinatorics, Graphs, Games, Economics * Specifications, Verifications and Secure Programming * Theory of Privacy and Anonymity * Theory of Security in Networks and Distributed Computing * Quantum Cryptography and Information Theory SUBMISSIONS: ************ Authors are invited to submit an extended abstract of no more than 12 pages in LNCS style presenting original research on the theory of Computer Science. Submissions should indicate to which track (A, B, or C) the paper is submitted. No simultaneous submission to other publication outlets (either a conference or a journal) is allowed. The proceedings will be published in the Lecture Notes in Computer Science Series by Springer-Verlag. IMPORTANT DATES: **************** Workshop proposals due: November 28, 2004 Submissions: February 13, 2005 Notification: April 8, 2005 Final version due: April 30, 2005 PROGRAM COMMITTEE: ****************** Track A (Algorithms, Automata, Complexity and Games) * Lars Arge, Duke University, USA * Giorgio Ausiello, University of Rome "La Sapienza", Italy * Surender Baswana, Max-Planck-Institut fur Informatik, Saarbrucken, Germany * Hans Bodlaender, University of Utrecht, The Netherlands * Véronique Bruyère, University of Mons-Hainaut, Belgium * Adam Buchsbaum, AT&T Labs - Research, USA * Josep Diaz, Universitat Politecnica de Catalunya, Spain * David Eppstein, University of Irvine, USA * Andrew Goldberg, Microsoft, USA * Monika Henzinger, ETH Lausanne, Switzerland * Giuseppe F. Italiano, University of Rome "Tor Vergata", Italy (Chair) * Marios Mavronicolas, University of Cyprus, Cyprus * Peter Bro Miltersen, University of Aarhus, Denmark * Mike Paterson, University of Warwick, United Kingdom * Dominique Perrin, Université de Marne la Vallée, France * Seth Pettie, Max-Planck-Institut fur Informatik, Saarbrucken, Germany * Yuval Rabani, Technion, Israel * Antonio Restivo, University of Palermo, Italy * José Rolim, University of Geneva, Switzerland * Dorothea Wagner, University Karlsruhe, Germany * Tandy Warnow, University of Texas at Austin, USA * Christos Zaroliagis, CTI and University of Patras, Greece Track B (Logic, Semantics, and Theory of Programming) * Kenichi Asai, University of Ochanomizu, Japan * Joos Baeten, University of Eindhoven, NL * Peter Buneman, University of Edinburgh, UK * Zoltan Esik, University of Szeged, Hungary * Javier Esparza, University of Stuttgart, Germany * Marcelo Fiore, Christ's College and University of Cambridge, UK * Manuel Hermenegildo, Universidade de Madrid, Spain * Delia Kesner, Universite Paris VII, France * Kim Guldstrand Larsen, University of Aalborg , Denmark * Gopalan Nadathur, University of Minnesota, USA * Uwe Nestmann, EPFL, Switzerland * Catuscia Palamidessi, INRIA, France (Chair) * Amr Sabry, University of Indiana, USA * Davide Sangiorgi, Universita di Bologna, Italy * Roberto Segala, Universita di Verona, Italy * Harald Sondergaard, University of Melbourne, Australia Track C (Security and Cryptography Foundations) * David Basin, ETH Zurich, Switzerland * Christian Cachin, IBM Research, Switzerland * Alfredo De Santis, Universita di Salerno, Italy * Cynthia Dwork, Microsoft Research, USA * Matt Franklin, U.C. Davis, USA * Michael Goodrich, U.C. Irvine, USA * Andrew D. Gordon, Microsoft Research, UK * Roberto Gorrieri, Universita di Bologna, Italy * Yuval Ishai, Technion, Israel * Phil McKenzie, DoCoMo Labs., USA * Tatsuaki Okamoto, NTT Labs., Japan * David Pointcheval, ENS Paris, France * Tal Rabin, IBM Research, USA * Omer Reingold, IAS Princeton, USA * Adi Rosen, Technion, Israel * Amit Sahai, UCLA, USA * Andre Scedrov, University of Pennsylvania, USA * Igor Shparlinsky, Macquarie University, Australia * Nigel Smart, University of Bristol, UK * Moti Yung, Columbia University, USA (Chair) ORGANIZING COMMITTEE: ********************* Luis Monteiro Luis Caires Antonio Ravara Vasco Vasconcelos CONTACT ADDRESSES: ****************** For further information see: http://icalp05.di.fct.unl.pt/

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announce: wxhaskell 0.9
by Daan Leijen 16 Mar '05

16 Mar '05

Announcement: wxHaskell version 0.9 ---------------------------------------------------------------------- <http://wxhaskell.sourceforge.net> I am pleased to announce a new release of wxHaskell. This new release has support for the printing and much improved support for processes and the grid control. Binary installers are provided for MacOS X, Linux (RPM), and Windows, for use with ghc 6.2.2. Have fun, Daan Leijen. ---------------------------------------------------------------------- wxHaskell is a portable GUI library for Haskell. The goal of the project is to provide an industrial strength portable GUI library, but without the burden of developing (and maintaining) one ourselves. wxHaskell is therefore build on top of wxWidgets -- a comprehensive C++ library that is portable across all major GUI platforms; including GTK, Windows, X11, and MacOS X. Furthermore, it is a mature library (in development since 1992) that supports a wide range of widgets with native look-and-feel, and it has a very active community (ranked among the top 25 most active projects on sourceforge). Since most of the interface is automatically generated from the wxEiffel binding, the current release of wxHaskell already supports about 75% of the wxWindows functionality -- about 2900 methods in 500 classes with 1400 constant definitions. wxHaskell has been build with GHC 6.x on Windows, MacOS X and Unix systems with GTK. A binary distribution is available for Windows, Linux (RPM) and MacOS X. And even if you don't intend to write GUI's yourself, it will be fun to check out the screenshots at <http://wxhaskell.sourceforge.net>. ---------------------------------------------------------------------- Version 0.9 ------------- Non backward compatible changes: - Changed "image" attribute to "picture" Backward compatible additions: - Added Multiple OpenGL Canvas example and fixed old example. - Much improved process support in WXCore.Process. Use "processExecAsyncTimed" instead of "processExecASync". - Full printing support in WXCore.Print - Added SpintControl events. - Fixed bug in MultiListBoxes where selections would only be added. - Added "pixelBufferGetPixels" and "pixelBufferSetPixels" and according functions for images. - Added "image" and made it an instance of the "Sized" class exported "imageCreateFromPixels" and "imageCreateFromPixelArray" - Added "drawImage" - Removed dependency on "readline" package in ghc 6.2.2 - Added "--cache" argument to configure script Bug fixes: - fixed "on command" event handlers in submenus.

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Compiling GHC on Panther using darwin ports
by Chris Brown 08 Mar '05

08 Mar '05

Hi, I am trying to install GHC on Mac OS X (Panther) using Darwin Ports. When i run sudo port install ghc I get the following error message shortly into the compilation: ------------------------------------------------------------------------ ==fptools== make boot - --no-print-directory -r; in /Users/chrisbrown/darwinports/dports/lang/ghc/work/ghc-6.2.2/ghc/utils/ hasktags ------------------------------------------------------------------------ /Users/chrisbrown/darwinports/dports/lang/ghc/work/ghc-bootstrap/bin/ ghc -M -optdep-f -optdep.depend -osuf o -H16m -O -I/opt/local/include -L/opt/local/lib HaskTags.hs dyld: /Users/chrisbrown/darwinports/dports/lang/ghc/work/ghc-bootstrap/lib/ ghc-6.2.2/ghc-6.2.2 can't open library: /opt/local/lib/libdl.1.dylib (No such file or directory, errno = 2) make[3]: *** [depend] Trace/BPT trap make[2]: *** [boot] Error 1 make[1]: *** [boot] Error 1 make: *** [build] Error 1 I remember on Tiger this was because the portfile which tells darwin ports what to do has a condition in it to compile the bootstrap differently for panther or jaguar (and obviously not tiger). Could anyone please help me to fix this compilation error? Thanks, Chris Brown.

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Hierarchical module namespace extension not sufficiently flexible
by Duncan Coutts 07 Mar '05

07 Mar '05

All, So here's the problem: we have a binding to a large foreign library (GTK) which we are trying to fit nicely into hierarchical module name space. It would live under Graphics.UI.Gtk Graphics.UI.Gtk.Button Graphics.UI.Gtk.Frame ... etc Now there are over 100 modules directly under Graphics.UI.Gtk and you don't want to have to import each one of them separately. Of course you will not use all of them in one module but you might reasonably use 20+ of them. So it'd be nice to be able to say: > import Graphics.UI.Gtk or > import qualified Graphics.UI.Gtk as Gtk But now we have a problem. These import directives import a flat namespace, or a flat namespace qualified by a single module alias (ie Gtk in the second example). But the Gtk modules are deliberatly designed to have hierarchical names. You cannot simply combine them all together into a flat namespace without falling back to the trick of prefixing each function name with the module name. So while we would like to be able for users to do this: > import Graphics.UI.Gtk > > ... Button.setLabel ... They will instead have to say: > import Graphics.UI.Gtk > > ... buttonSetLabel ... Which is one of the things that the hierarchical module namespace extension was trying to get rid of! All the other language bindings for Gtk (apart from C) use the former import and useage style. It doesn't make us look good! :-) So my question is: have I overlooked something or is this really not possible at the moment. And secondly, if it is currently not possible is there a 'nice' extension that would allow this sort of thing. (Where nice probably means Haskell98 compatible / 'doesn't' break existing programs) How about: > module Graphics.UI.Gtk ( > > module qualified Graphics.UI.Gtk.Button as Button > ... > ) where > > import Graphics.UI.Gtk.Button or equivalently(?): > module Graphics.UI.Gtk ( > > module qualified Button > ... > ) where > > import Graphics.UI.Gtk.Button as Button Duncan Ps there's a oddity I found where if you say: > module Foo ( > module Bar > ) > > import qualified Bar then module Foo exports precisely nothing. But there's no error or warning.

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Proposal: Allow "\=" for field update in record update syntax
by S. Alexander Jacobson 05 Mar '05

05 Mar '05

I don't know what it takes to get this sort of change into circulation, but I assume it starts with a clear and specific description of the problem, exploration of alternatives, and a specific proposed solution. So here goes: ---------- Proposal: Allow "\=" for field update in record update syntax Specifically, intepret rec {field\=fn} as rec {field = fn (field rec)} Jusitification: It is extremely common when updating records to be updating a field value based on its prior value rather than simply assigning a new value from nothing. Unforunately the syntax supports the later clearly but makes the former awkward to read, understand, and debug: myFun db myType1 = db { tMyType1 = insert myType1 $ tMyType1 db nextId = 1 + (nextId db) } One solution to this problem that does not involve changing syntax is to generate field update functions for every field of a type e.g.: update_tMyType1 f s = s {tMyType1= f $ myType1 s} update_nextId f s = s {nextId = f $ nextId s} Once you have those functions, myFun looks much better: myFun db myType = update_nextId (+1) $ update_tMyType1 f db where f= insert myType1 But, generating the update_ functions is not programming; its just manual syntax generation. And, even if you have template haskell to do it, * it is annoying to have to find/write the TH code to implement * update_ is incredibly verbose * shortening it risks proliferation of psuedo-syntax: u_tMyType, u__tMyType, or utMyType? * it adds clutter to have to call the TH for each record type, and * it pollutes the name space/increases risk of name collision Rather than force the user to jump through these hoops, why not make the syntax flow naturally from the existing record update syntax? It makes sense to use \= for this task as it is the functional generalization of C or Java's += or *= . Then myFun would have the elegant and clear syntax: myFun db myType1 =db {tMyType1\=insert myType1, nextId\=(+1)} -Alex- ______________________________________________________________ S. Alexander Jacobson tel:917-770-6565 http://alexjacobson.com

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