November 2003 - Haskell

MBR04 call for papers
by Lorenzo Magnani 16 Nov '03

16 Nov '03

****************************************************************** MODEL-BASED REASONING IN SCIENCE AND ENGINEERING ABDUCTION, VISUALIZATION, AND SIMULATION MBR'04 Pavia, Italy, December 16-18, 2004 Chairs: Lorenzo Magnani and Nancy J. Nersessian ****************************************************************** Up-to date information on the conference will be found at http://www.unipv.it/webphilos_lab/courses/progra1.html ****************************************************************** Paper Submission Deadline May 1st, 2004 GENERAL INFORMATION From Thursday 16 to Saturday 18 December 2004 (three days) the International Conference "MODEL-BASED REASONING IN SCIENCE AND ENGINEERING: ABDUCTION, VISUALIZATION, AND SIMULATION" will be held at the University of Pavia (near Milan, Italy). The conference continues the theme of the Conferences "Model-Based Reasoning in Scientific Discovery" MBR'98 and "Model-Based Reasoning: Scientific Discovery, Technological Innovation, and Values" MBR'01 The previous volumes derived from those conferences are: L. Magnani and N. J. Nersessian (eds.) (2002), Model-Based Reasoning. Science, Technology, Values, Kluwer Academic/Plenum Publishers, New York. http://www.wkap.nl/prod/b/0-306-47244-9 L. Magnani, N. J. Nersessian, and C. Pizzi (eds.) (2002), Logical and Computational Aspects of Model-Based Reasoning, Kluwer Academic, Dordrecht. http://www.wkap.nl/prod/b/1-4020-0791-4 L. Magnani, N. J. Nersessian, and P. Thagard (eds.) (1999), Model-Based Reasoning in Scientific Discovery, Kluwer Academic/Plenum Publishers, New York. http://www.wkap.nl/prod/b/0-306-46292-3 (Chinese edition, translated and edited by Q. Yu and T. Wang, China Science and Technology Press, Beijing, 2000). PROGRAM The conference will deal with the logical, epistemological, and cognitive aspects of modeling practices employed in science and engineering, including computational models of such practices. We solicit papers that examine the role of abduction, visualization, and simulation in model-based reasoning from philosophical, historical, sociological, psychological, or computational perspectives. RELEVANT RESEARCH AREAS We call for papers that cover topics pertaining to model-based reasoning in science and engineering from the following list: - abduction - visual, spatial, imagistic modeling and reasoning - simulative modeling - the role of diagrammatic representations - computational models of visual and simulative reasoning - causal and counterfactual reasoning in model construction - visual analogy - thought experimenting - logical analyses related to model-based reasoning - manipulative reasoning - distributed model-based reasoning - embodiment in model-based reasoning - model-based reasoning and technological innovation INVITED SPEAKERS The list of the invited speakers who already accepted to give e presentation at MBR04 is available in the Conference WEB SITE http://www.unipv.it/webphilos_lab/courses/progra1.html SUBMISSIONS OF PAPERS All submitted papers will be carefully refereed. The precise formatof the conference will be fixed after we have an idea of the number ofaccepted papers. We expect approximately 40 contributed presentations some of 40 and others of 20 minutes. There will be several invited papers of 1 hour. A selected subset will be invited for inclusion (subject to additional refereeing) in a book which will constitute an advanced handbook for researchers in this area. The book will be published by an international publishing house. Moreover another selected subset will be invited for inclusion (subject to additional refereeing) in special issues of suitable international journals. Authors must submit an electronic version - formatted in Microsoft Word or RTF,PS or PDF ( in this last case two cases please include source - DOC, TEX, etc., file) - of an extended abstract (total word count aproximately 1000-1200).The file must also contain a 300 WORD abstract that will be used for the conference web site/booklet. Not later than May 1, 2004 Please send electronically the extended abstract to the Prof. Magnani at the address lmagnani(a)cc.gatech.edu (if the previous address does not work please use lorenzo.magnani(a)unipv.it) A RIGID LAW ON PRIVACY IN ITALY DOES NOT FAVOR MORE COMFORTABLE COMPUTATIONAL METHODS OF PAYMENTS (CONFERENCE AND ACCOMMODATION FEES), SORRY. PLEASE FOLLOW THE INSTRUCTIONS INDICATED BELOW. REGISTRATION AND FURTHER INFORMATION PLEASE REGISTER by email lmagnani(a)cc.gatech.edu (or lorenzo.magnani(a)unipv.it) fax or air mail by sending the PROGRAM CHAIR Lorenzo Magnani first and last name, function, institution, full address, phone, fax and email. For information about paper submission and the program that is not available on the web site, please contact the program chair. Registration Fees: Before October 15, 2004: Standard: Euro 180,00 (to participate in all the activities of the Conference Social Dinner included) Phd Students: Euro 120,00 Students (Undergraduates): Free After October 15, 2004: Standard: Euro 240,00 (to participate in all the activities of the Conference Social Dinner Included) Phd Students: Euro 160,00 Students (Undergraduates): Free One day only: Euro 100,00 No refunds will be granted after November 1st Terms & Conditions: an administration fee of Euro 75,00 will be charged for cancellations confirmed in writing by December 1st. We regret that no refund can be made after that date, for whatever reason,although substitutions will be acceptable if notified in writing before the event. METHOD OF PAYMENT: SWIFT TRANSFER Bank (Swift) Transfer to BANCA REGIONALE EUROPEA S.p.A BRANCH PAVIA - Sede SWIFT BREUITM2 301 Bank Code 06906.11301 Acc. n. 42113 COMITATO CONVEGNI E. W. I. C. IBAN: IT32O0690611301000000042113 (attention: the fifth symbol is the letter O and not zero). Please indicate CONVEGNO INTERNAZIONALE MBR04. Please ask your BANK to clearly indicate in the order of payment your first and last NAME. In case of problems please contact Elena Gandini Local Organizer elena(a)acrossevents.com) If you prefer, you can mail an international check to CONVEGNO INTERNAZIONALE MBR04, Dipartimento di Filosofia, Piazza Botta 6, 27100 Pavia, Italy. ACCOMMODATION To book a reservation please fill and fax to +39-0382-23215 the ACCOMMODATION FORM you will find in the Conference Web Site http://www.unipv.it/webphilos_lab/courses/progra1.html (to dr. Elena Gandini Local Organizer). POSSIBLY BEFORE NOVEMBER 10, 2003. For information please email Elena Gandini, Local Organizer elena(a)acrossevents.com. Please do not send email messages containing your credit card data. All accommodation is hotel-based with en-suite facilities (the prices are per room per day). Hotel Moderno ****Euro 103,00 (single b&b) Euro138,00 (double b&b) Hotel Ariston *** Euro 80,00(single) Euro 110,00 (double), Breakfast Euro 10,00 Hotel Excelsior *** Euro 50,00(single) Euro 73,00(double) Euro 62,00(D/S) breakfast Euro 6,00 Hotel Ritz*** Euro 65,00 (single b&b) Euro 87,00 (double b&b) Hotel Excelsior (from the station walk east) Hotel Moderno (from the station walk north) Hotel Ritz (San Genesio-PV); an Hotel bus service is available. To reach Hotel Ariston take the bus n. 3 or taxi. If the Hotels above will be completely booked other Hotels are available, in this last case please email dr. Elena Gandini Local Organizer e-mail: elena(a)acrossevents.com PENALTY In case of no show the Hotels will charged you their own penalty. For further information, please contact our local organiser Elena Gandini elena(a)acrossevents.com. IMPORTANT DATES Submission deadline.....................May 1, 2004 Notification of acceptance..............Aug 30, 2004 Conference............................. Dec 16-18, 2004 Final papers......................due.. February 15, 2005 PROGRAM CHAIR Lorenzo MAGNANI Department of Philosophy and Computational Philosophy Laboratory University of Pavia, Piazza Botta 6, 27100 Pavia, Italy Office: +39-0382-506283, Home: +39-0383-371067 Fax: +39-0382-23215 & Weissman Distinguished Visiting Professor Department of Philosophy, Baruch College, 1 Bernard Baruch Way, New York , NY 10010 Office: +646-312-4367, Fax: +646- 312-4361, Home: 646-432-9309 Email: lmagnani(a)unipv.it, lmagnani(a)cc.gatech.edu PROGRAM CO-CHAIR Nancy J. NERSESSIAN (Program Co- Chair) Professor of Cognitive Science Program in Cognitive Science College of Computing Georgia Institute of Technology Atlanta, GA 30332-0280 Phone: 404-894-1232 FAX: 404-894-2970 Email: nancyn(a)cc.gatech.edu PROGRAM COMMITTEE - Atocha Aliseda, Instituto de Investigaciones Filosoficas Universidad Nacional Autonoma de Mexico (UNAM), Mexico City, MEXICO - Diderik Batens, Centre for Logic and Philosophy of Science, Universiteit Gent, Ghent, Belgium - Walter Carnielli,Centre for Logic, Epistemology and the History of Science - CLEHC State University of Campinas - UNICAMP, Campinas, SP, Brazil - Simon Colton, Department of Computing, Imperial College London 180 Queens Gate, London SW7 2BZ, United Kingdom - Roberto Cordeschi, Department of Communication Sciences, University of Salerno, Salerno , ITALY - Kenneth D. Forbus, Walter P. Murphy Professor of Computer Science and Education, Northwestern University, 1890 Maple Avenue, Evanston, IL, 60201, USA - Ronald N. Giere, Department of Philosophy, 831 Heller Hall University of Minnesota, Minneapolis, MN USA 55455 - David Gooding, Science Studies Centre, Department of Psychology University of Bath, Bath BA2 7AY, UK - Elke Kurz-Milcke, College of Computing, Georgia Institute of Technology 801 Atlantic Dr. NW, Atlanta, GA 30332-0280, USA - Michael Leyton, Center for Discrete Mathematics & Theoretical Computer Science (DIMACS), Busch Campus, Rutgers University, New Brunswick, NJ 08854. USA - Lorenzo Magnani, Department of Philosophy, University of Pavia, Pavia, ITALY and Baruch College, The City University of New York, New York, USA - Nancy J. Nersessian, College of Computing, Georgia Institute of Technology, Atlanta, GA, USA - Wendy C. Newstetter, Director of Learning Sciences Research Wallace H. Coulter Dept. of Biomedical Engineering, Georgia Institute of Technology/Emory University school of Medicine, Atlanta, GA, USA - Claudio Pizzi, Department of Philosophy and Social Sciences, University of Siena, Siena, ITALY -.Stefanelli Mario, Dipartimento di Informatica e Sistemistica, Università di Pavia, Pavia, ITALY - Ryan D. Tweney, Professor of Psychology, Bowling Green State University Bowling Green, OH 43403, USA - Riccardo Viale, Fondazione Rosselli,Via San Quintino, 18/c, 10121 Torino, Italy - Andrea Woody, Department of Philosophy, University of Washington Box 353350, 345 Savery Hall, University of Washington, Seattle, WA 98195 - Xiang Chen, Department of Philosophy, California Lutheran University Thousand Oaks, CA 91360 LOCAL ORGANIZER dr. Elena Gandini Across Events s.r.l. Via A. Moro, 12 27021 Bereguardo (PV) Italy mobile +39 349 55 41 915 e-mail: elena(a)acrossevents.com www.acrossevents.com LOCAL ORGANIZING COMMITTEE Elena Gandini (elena(a)acrossevents.com) Riccardo Dossena (riki.dox(a)libero.it) Lorenzo Magnani (lmagnani(a)cc.gatech.edu) (Department of Philosophy, University of Pavia, Pavia, Italy) Stefanelli Mario (mstefa(a)aim.unipv.it) Matteo Piazza (pimat(a)yahoo.com) (Dipartimento di Informatica e Sistemistica, Università di Pavia, Pavia, Italy) CONFERENCE SITE: Collegio Ghislieri, Piazza Ghislieri, 27100 PAVIA, Italy, phone +39 0382 37861. http://www.ghislieri.it/ The Conference is sponsored by UNIVERSITY OF PAVIA, ITALY UNIVERSITY OF SIENA, ITALY MIUR (Ministero dell'Università e della Ricerca Scientifica e Tecnologica), ITALY CARIPLO (Cassa di Risparmio delle Provincie Lombarde) HOW TO REACH PAVIA LINATE Airport: www.sea-aeroportimilano.it/linate People arriving by plane at LINATE should take the bus to the CENTRAL STATION of Milan (cf. below from this Station to Pavia). In LINATE it could be convenient to take a Taxi because the airport is close to the center of Milan. Moreover,the bus company SILA ( www.sila.it ) offers six runs from LINATE to Pavia at 9.00, 10.00, 12.00 AM and 2.00, 5.00, 8.30 PM. The last stop is Pavia, near the station (see again our updated web page for possible alterations of this time-table) (from Pavia to LINATE six runs at 5.00, 7.30, 10.00 AM, 1.00, 4.00, 6.00 PM) (one hour trip; _13,00 return ticket, _8,00 one way ticket). In Pavia there is only one station. The easiest way to reach the center of the town is to get off at the station and than take the bus n. 3. MALPENSA 2000 and OLD MALPENSA Airports: www.sea-aeroportimilano.it/malpensa (usually people arrive to Malpensa 2000 and not to OLD MALPENSA): People arriving by plane at MALPENSA 2000 (also called MALPENSA 2000 Terminal 1) or at "old" MALPENSA (now called MALPENSA NORTH but also called Malpensa 2000 Terminal 2) should take the bus to the CENTRAL STATION of Milan. There is also a bus AND A shuttle TRAIN (Malpensa Express) from Malpensa 2000 to the NORTH STATION (Piazzale Cadorna) of Milan, in this case from NORTH Station you will have to take the underground MM2 (green line) to the Central Raylway Station: trains to Pavia leave from Central station. Moreover, the bus company SILA offers various runs from MALPENSA 2000 to Pavia at 9.00, 11:00 AM, 1:30 3:00, 5:00, 7:00, 9:30, PM (from Pavia to MALPENSA 2000 and to OLD MALPENSA various runs at 7.00, 9:00, 11:00 AM, 1:00, 3:15, 5:00, 7:00 PM) (one hour and half trip; _18,00 retourn ticket, _12,00 one way ticket). The last stop is Pavia, near the rail station. In Pavia there is only one rail station. The easiest way to reach the center of the town is to get off at the station and than take the bus n. 3. There are trains from MILAN (Central Raylway Station) to PAVIA and vice versa about every an hour www.trenitalia.it (routes: MILAN-GENOVA; MILAN-VENTIMIGLIA; MILAN-LA SPEZIA; MILAN-SAVONA; MILAN-SESTRI LEVANTE; MILAN-IMPERIA; MILAN-ALBENGA; Pavia is the first stop only if the train is not slow, that is, if it is not, in ITALIAN, "L", locale). (see again our updated web page for possible alterations of this time-table)

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CFP for LDTA 2004
by jas＠di.uminho.pt 14 Nov '03

14 Nov '03

Apologies if you receive multiple copies of this message. ********************************************************** *** Fourth Workshop on *** *** Language Descriptions, Tools and Applications *** *** LDTA 2004 *** *** *** *** APRIL, 3, 2004 *** *** BARCELONA, SPAIN *** *** *** *** http://www.di.uminho.pt/LDTA04 *** ********************************************************** The workshop will be held in conjunction with the 7th European Joint Conferences on Theory and Practice of Software (ETAPS), March 27 - April 4, 2004 - http://www.lsi.upc.es/etaps04 ----------------------------------------------------------------------- IMPORTANT DATES ----------------------------------------------------------------------- December 1st 2003 Submission of full paper January 5th 2004 Submission of a tool demo paper January 15th 2004 Notification February 15th 2004 Final version due April 3rd 2004 LDTA 2004 Invited Speaker: --------------- Jim Cordy, Professor and Director, School of Computing, Queen's University, Canada Scope: ------ The aim of this one day workshop is to bring together researchers from academia and industry interested in the field of formal language definitions and language technologies, with a special emphasis on tools developed for or with these language definitions. Some of the scientific areas that take advantage from these active research fields are: - Program analysis, transformation, generation - Formal analysis of language properties - Automatic generation of language processing tools For example, language definitions can be augmented in a manner so that not only compilers and interpreters can be automatically generated but also other tools such as syntax-directed editors, debuggers, partial evaluators, test generators, documentation generators, etc. These beneficial results are well known and we would like to make them widely exploited in current practice. Domains of applications that are of interest for this workshop are among others: - Language components, modeling languages - Re-engineering, re-factoring - Aspect-oriented programming, adaptive programming - Domain-specific languages - XML processing - Visualization and graph transformation The workshop welcomes contributions on all aspects of formal language definitions, with special emphasis on applications and tools developed for or with these language definitions. We also encourage contributions on the use of these methodologies in education. Tool demonstrations: -------------------- The one day LDTA 2004 workshop program will also include a session on tool demonstrations. Submission procedure and publication: ------------------------------------- Authors should submit a full paper (15-20 pages) to LDTA 2004 program committee chairs. Tool demo papers (2 pages) should also be submitted to the PC chairs. Further information will be available at the LDTA 2004 home page. Accepted papers will be published and available during the workshop. After revision, final copies of the accepted papers will be published in Electronic Notes in Theoretical Computer Science (ENTCS), Elsevier Science. Author's instructions are given here. The authors of the best papers will be invited to write a journal version of their paper which will be separately reviewed and after acceptance be published in a special issue devoted to LDTA 2004 of the journal Science of Computer Programming (Elsevier Science). Organizing Committee: --------------------- Isabelle Attali, INRIA Sophia Antipolis, France Thomas Noll, Aachen University of Technology, Germany Joao Saraiva, University of Minho, Portugal Program committee co-chairs: ---------------------------- Gorel Hedin, Lund Institute of Technology, Sweden Eric Van Wyk, University of Minnesota, USA Program Committee members: -------------------------- John Boyland, University of Wisconsin, USA Olivier Danvy, University of Aarhus, Denmark Jose Labra Gayo, Oviedo University, Spain Paul Klint, CWI, The Netherlands Jens Knoop, Vienna University of Technology, Austria Erik Meijer, Microsoft Research, USA Didier Parigot, INRIA, France Paul Roe, QUT, Australia Ganesh Sittampalam, Oxford University Computing Laboratory, England Anthony Sloane, Macquarie University, Australia Yannis Smaragdakis, Georgia Institute of Technology, USA Doaitse Swierstra, Utrecht University, The Netherlands Kris de Volder, University of British Columbia, Canada

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AW: Generic Haskell Diffs?
by Markus.Schnell＠infineon.com 14 Nov '03

14 Nov '03

Thank you, Ralf. Curiosity satisfied. :) Markus -- Markus Schnell > There is just one Generic Haskell project > even though the actual language extension is a moving target of course > because this is an active project. > > The boilerplate approach is about lightweight generic programming IN > Haskell. > The fact that the boilerplate approach is supported by GHC is > very, very > convenient, but in a sense optional: in principle, you could write > Typeable and Data > instances yourself, and you could still leverage generic > programming in > Haskell. Anyway, some more information can be found on the > boilerplate > page. > > Using both approaches together would be quite cool!?! > There is no technical reason why this would be impossible. > But it is certainly not the case that the two approaches are > complementary. > They overlap quite a bit. The boilerplate approach tries to > be easy in the > traversal arena. In the literature, there are some comments > on how these and > other approaches relate. I would still find it interesting to see a > survey that > works through some examples and compares the two approaches > and others. > > Ralf

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Generic Haskell Diffs?
by Markus.Schnell＠infineon.com 14 Nov '03

14 Nov '03

According to the communities report there are different generic haskell projects (Jeuring/Hinze and PJ/Lämmel) out there. But I don't understand their relation. Can you use both at the same time? Is one building on the other? Are there adressing different issues? A clarifying sentence or two would be heartily welcome. Cheers, Markus -- Markus Schnell

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Vital visual notations?
by George Russell 14 Nov '03

14 Nov '03

Martin Ewig wrote (snipped) > I think that some visual notations are more readable than text > (but not all). In particular, if you try to teach lambda calculus > or type inference to beginners, visual notations can be extremely > helpful. For some people, perhaps. I don't have a very good mind for visual things and I much prefer symbolic versions of lambda calculus. Perhaps beginners need to be shown it both ways.

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AW: Generic Haskell Diffs?
by Markus.Schnell＠infineon.com 14 Nov '03

14 Nov '03

let (Just mail) = lookup "Generic Haskell Diffs?" mailbox in replace "Are there" "Are they" mail > -----Ursprüngliche Nachricht----- > Von: haskell-bounces(a)haskell.org > [mailto:haskell-bounces@haskell.org] Im Auftrag von > Markus.Schnell(a)infineon.com > Gesendet: Freitag, 14. November 2003 10:49 > An: haskell(a)haskell.org > Betreff: Generic Haskell Diffs? > > > According to the communities report there are different > generic haskell projects (Jeuring/Hinze and PJ/Lämmel) out there. > But I don't understand their relation. > Can you use both at the same time? > Is one building on the other? > Are there adressing different issues? > > A clarifying sentence or two would be heartily welcome. > > Cheers, > Markus > > > -- > Markus Schnell > _______________________________________________ > Haskell mailing list > Haskell(a)haskell.org > http://www.haskell.org/mailman/listinfo/haskell >

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[rpms] updated greencard rpm package for ghc-6.0.1 available
by Jens Petersen 14 Nov '03

14 Nov '03

FYI a new greencard rpm package built with ghc-6.0.1 is now available from : http://haskell.org/~petersen/rpms/greencard/?C=M&O=D Cheers, Jens

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ANNOLUNCE: attribute 0.2
by Abraham Egnor 14 Nov '03

14 Nov '03

I apologize for the frequency, but based on initial feedback I made some interface-breaking changes and thought it wise to release. The major changes are: * use functions instead of a datatype for Property construction. From the user's point of view, this just means the colon goes at the end instead of the beginning, i.e. (=:) instead of (:=). * split non-haskell98 functions (MRef, attrMRef[T]) off into their own module - Data.Attribute.Util. Data.Attribute itself is now pure Haskell 98. * added an MRef instance for lazy STRefs. The new tarball is at "http://abe.egnor.name/attribute-0.2.tar.bz2". Abe

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StateT space leak
by Wojtek Moczydlowski 14 Nov '03

14 Nov '03

Consider the following program: module A where import Control.Monad.State f :: StateT Int IO () f = (sequence_ $ repeat $ return ()) t = runStateT f 0 When t is evaluated under ghci or hugs, the program quickly runs out of heap memory. What's going on here? Is this inherent in StateT monad? If so, then this is very surprising, I would expect f to run in constant space for any sensible monad. Wojtek

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ANNOUNCE: attribute 0.1
by Abraham Egnor 13 Nov '03

13 Nov '03

Attribute is a library for storing and retrieving named values from haskell datatypes in arbitrary monads. Many of the haskell GUI libraries have implemented something similar; in one of my current projects, I discovered that such a thing would be useful. However, I didn't want to tie it to my specific use, the result of which is this library. The README included with the source is hopefully enough documentation to get started, the text of which is included at the end of this email. A tarball is available at "http://abe.egnor.name/attribute-0.1.tar.bz2". Source can also be obtained via arch: tla register-archive http://ofb.net/~abe/archive/2003 tla get abe-tla@ofb.net--2003/attribute--main === README === This is attribute, monadic attributes for haskell datatypes. See COPYRIGHT for copying information. Building: edit the Makefile for the install path make make install (as root) The only dependency is a recent version of ghc (>=6). Use: Abstractly, an attribute represents a value that can be retrieved from or stored into a specific type in a specific monad; an attribute can either be readable, writable, or both, represented by the types Read, Write, and ReadWrite. A note on naming conventions: I've used general words (such as Read, Write, set, get, etc.) for most functions; this does not follow Haskell convention, but does follow the ideas at "http://haskell.org/hawiki/UsingQualifiedNames", which makes far more sense to me. If you can't live without prefixes, qualify the import. Example: "ReadWrite Int String IO" represents a String that can be both extracted from and stored into an Int in the IO monad (although such a property is unlikely to be useful). A more useful attribute might be something like: contents :: Read FilePath String IO which would represent the contents of a file, probably read in via getContents or some such. Attributes can be constructed directly from setter or getter functions: data (Monad m) => Read o d m = Read (o -> m d) data (Monad m) => Write o d m = Write (o -> d -> m ()) data (Monad m) => ReadWrite o d m = ReadWrite (o -> m d) (o -> d -> m ()) A few convenience functions are provided for constructing attributes: attrMRef :: (MRef r m) => (a -> b -> b) -> (b -> a) -> ReadWrite (r b) a m attrMRefT :: String -> ExpQ attrMRef takes a pure mutator and extractor, and creates an attribute that applies those functions to a monadic reference. Instances for MRef are provided for both IORef and STRef. attrMRefT simplifies a common case, where you have a pure datatype defined with named records and you'd like to make attributes for some of the records: data Foo = Foo { fooBar :: Int, fooBaz :: String } bar :: (MRef r m) => ReadWrite (r Foo) Int m bar = $(attrMRefT "Main:fooBar") baz :: (MRef r m) => ReadWrite (r Foo) String m baz = $(attrMRefT "Main:fooBaz") The String passed to attrMRefT is the name of one of the records; the current implementation of template haskell requires that it be prefixed with the name of the module in which it's defined. attributes are bound to values by creating a Property; the constructors for property are ":=", ":~", "::=", and "::~", which are pure set, pure mutate, monadic set, and monadic mutate respectively. To reuse the Foo example from above: test :: IO (Int, String) test = do ref <- newMRef $ Foo { fooBar = 3, fooBaz = "hello" } set ref [ bar := 5, baz :~ (++" world") ] bar' <- get ref bar baz' <- get ref baz return (bar', baz') will return (5, "hello world"). Note that because attributes created with attrMRef or attrMRefT are qualified by monad type, this example could be changed to use the ST monad simply by changing the type signature. Two functions are provided for manipulating attributes: "set" and "get". set :: (Monad m) => o -> [Property o m] -> m () get :: (Monad m, CanRead a) => o -> a o d m -> m d The "CanRead" class constraint simply enforces the readability of the particular attribute; both Read and ReadWrite are instances. There is a similarly used "CanWrite" class: class CanRead a where aGet :: (Monad m) => (a o d m) -> (o -> m d) class CanWrite a where aSet :: (Monad m) => (a o d m) -> (o -> d -> m ()) While you are certainly free to define new instances of the classes, I have yet to find a use case where the simple Read/Write/ReadWrite types do not suffice. See the files in src/test/ for examples. Have fun! Abe Egnor (abe-attribute(a)ofb.net)

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