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Question about scope of 'let' and 'where'
by Graham Klyne 18 Mar '03

18 Mar '03

In the function body (rhs): let { a = (e1) } in (e2) where { b = f a } Does the Haskell specification indicate that the definition of 'a' is in-scope for the definition of 'b'? Practical experience using HUGS suggests the answer is no, but my intuition is that the answer should be yes. I was unable to find anything in either the report or the "gentle introduction" that made the correct answer clear to me (which is not to say it's not there, just that I didn't find it). I think the tutorial might benefit from a discussion of what is in-scope for where clauses. <comment> FWIW, my intuition was that e where defs was a form of expression (like let ... in), in which some sub-expressions were factored out as subsidiary definitions; i.e. that I'd expect to be able to replace each occurrence of a name defined by 'where' with the body of the corresponding definition. Hence I'd expect the let definitions to be in-scope. I now see that use of 'where' is restricted to specific contexts. I wonder if such restriction is needed? The differences between let and where in Haskell are something I find to be confusing. </comment> #g ------------------- Graham Klyne <GK(a)NineByNine.org> PGP: 0FAA 69FF C083 000B A2E9 A131 01B9 1C7A DBCA CB5E

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Haskell History
by Steffen Mazanek 17 Mar '03

17 Mar '03

Hello, I want to create a source of historic information to delight the Haskell community and therefore I need a lot of material relating the following topics: - from lambda calculus to functional programming - other roots of Haskell (e.g. Gofer, ...) - genesis of the well known and beloved standard Haskell98 This website should act as an archive of old releases of popular Haskell interpreters and compilers, too (seemingly there is nothing online at present). Sometimes you need an old release of a particular software, e.g. for comparisons and you become really bored with following quit a lot of dead links in the internet, wasting time and staying without results. Help me to close this existing gap. All suggestions are welcome. Steffen Mazanek

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EACL2003 Workshop Programme, April 13-14
by Steven Krauwer 17 Mar '03

17 Mar '03

EACL 2003 in Budapest, April 12-17, 2003 Workshop Programme and Call for Participation Important dates: ---------------- Workshop dates: Apr 13-14, 2003 Conference dates: Apr 12-17, 2003 Important URLs: --------------- Registration: http://www.conferences.hu/EACL03/Registration.html Main conference: http://www.conferences.hu/EACL03/ Workshops: http://www.elsnet.org/workshops Workshop overview: ------------------ Workshop 01: "MT and other language technology tools; Improving MT through other language technology tools; Resources and tools for building MT" URL: http://www.elsnet.org/workshops/progw01.html Organizer(s): Bente Maegaard Email: bente(a)cst.dk Date: April 13, 2003 ___________________________________________________________________ Workshop 02: "9th European Workshop on Natural Language Generation" URL: http://www.ags.uni-sb.de/~horacek/EACL-EWNLG03.html Organizer(s): Ehud Reiter Email: ereiter(a)csd.abdn.ac.uk Date: April 13+14, 2003 ___________________________________________________________________ Workshop 03 [supported b y ELSNET]: "4th International Workshop on Linguistically Interpreted Corpora (LINC-03)" URL: http://www.coli.uni-sb.de/linc03 Organizer(s): Silvia Hansen Email: hansen(a)CoLi.Uni-SB.DE Date: April 13+14, 2003 ___________________________________________________________________ Workshop 04: "Language Modeling for Text Entry Methods" URL: http://www.uni-koblenz.de/~compling/eaclws2003/ Organizer(s): Michael Kuhn Email: kuehn(a)uni-koblenz.de Date: April 14, 2003 ___________________________________________________________________ Workshop 05: "The Computational Treatment of Anaphora" URL: http://www.clt.mq.edu.au/eacl03ana.html Organizer(s): Rob Dale Email: rdale(a)ics.mq.edu.au Date: April 14, 2003 (morning) ___________________________________________________________________ Workshop 06: "Dialogue Systems: interaction, adaptation and styles of management" URL: http://www.dcs.shef.ac.uk/~roberta/eacl-w06.html Organizer(s): Kristiina Jokinen and Roberta Catizone Email: kjokinen@uiah.fi,R.Catizone@dcs.shef.ac.uk Date: April 13+14, 2003 ___________________________________________________________________ Workshop 07 [supported by ELSNET]: "Evaluation Initiatives in Natural Language Processing: are evaluation methods, metrics and resources reusable?" URL: http://www.dcs.shef.ac.uk/~katerina/EACL03-eval Organizer(s): Katerina Pastra Email: e.pastra(a)dcs.shef.ac.uk Date: April 14, 2003 ___________________________________________________________________ Workshop 08: "Computational Linguistics for South Asian Languages -- Expanding Synergies with Europe" URL: http://computing.open.ac.uk/Sites/EACLSouthAsia Organizer(s): Durgesh Rao and Pat Hall Email: drsystems@vsnl.net,p.a.v.hall@open.ac.uk Date: April 14, 2003 ___________________________________________________________________ Workshop 09: "Workshop on Finite State Methods in Natural Language Processing" URL: http://www-igm.univ-mlv.fr/~laporte/fsw-cfp.htm Organizer(s): Eric Laporte and Ken Beesley Email: eric.laporte@univ-mlv.fr,Ken.Beesley@xrce.xerox.com Date: April 13+14, 2003 ___________________________________________________________________ Workshop 10: "Language Technology and the Semantic Web: 3rd Workshop on NLP and XML (NLPXML-2003)" URL: http://www.cs.vassar.edu/~ide/events/NLPXML3.html Organizer(s): Nancy Ide and Graham Wilcock Email: ide@cs.vassar.edu,graham.wilcock@helsinki.fi Date: April 13, 2003 ___________________________________________________________________ Workshop 11: "Natural Language Processing (NLP) for Question-Answering" URL: http://www.science.uva.nl/~mdr/NLP4QA/ Organizer(s): Bonnie Webber and Maarten de Rijke Email: bonnie@inf.ed.ac.uk,mdr@science.uva.nl Date: April 14, 2003 (afternoon) ___________________________________________________________________ Workshop 12: "Morphological Processing of Slavic Languages" URL: http://nl.ijs.si/mpsl03/ Organizer(s): Tomaz Erjavec and Dusko Vitas Email: Tomaz.Erjavec@ijs.si,vitas@matf.bg.ac.yu Date: April 13, 2003 ___________________________________________________________________ Contact info: - for the workshops in general: steven.krauwer(a)elsnet.org - for individual workshops: workshop organizers - for the main conference: kindl(a)sztaki.hu - for registration: kindl(a)sztaki.hu _______________________________________________________________

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ESS2003: Language and Speech Technology for Language Learning
by Steven Krauwer 17 Mar '03

17 Mar '03

FIRST ANNOUNCEMENT and CALL for PARTICIPATION The 11th ELSNET Summer School on Language and Speech Communication Topic: Language and Speech Technology in Language Learning Lille (France), Monday July 7 - Friday July 18, 2003 Organized by the University of Lille 3 We are happy to announce that registration for the 11th ELSNET Summer School is now open. For this school we have chosen a topic of great relevance to researchers and developers in Europe and in other multilingual environments: the use of language and speech technology in language learning, both of spoken and of written language. The goal of this workshop is to get young researchers on a track that will eventually contribute to an important application area. The underlying vision (or dream) is The automatic animated language tutor. + Audience and aims: We see the school as mainly research and development oriented, and hence the primary audience are researchers, developers and integrators who will make our vision happen (rather than teachers who would use it). Both technological and pedagogical aspects will be taken into consideration The aims are: * to make the students familiar with the main principles and problems of language learning/teaching * to make them familiar with current best practice in computer assisted language learning * to make them familiar with the main challenges in computer assisted language learning Participants are expected to have a general computational background and some familiarity with language or speech research and/or processing. After completion of the summer school participants should be able to function in teams aimed at designing or implementing tools, environments or courses for Computer Assisted Language Learning (abbreviated CALL). + Course programme: The provisonal programme is available at http://www.elsnet.org/ess2003/schedule.html The 2-weeks programme comprises the following courses: * Introduction to CALL (Teacher: Jozef Colpaert, [Univ of Antwerp]) * Introduction to natural language processing for CALL (Teacher: Wolfgang Menzel [Univ of Hamburg], to be confirmed) * Introduction to speech processing for CALL (Teacher: Philippe Delcloque [MSEC Manchester]) * Using NLP tools in CALL (hands-on) (Teacher: Wolfgang Menzel [Univ of Hamburg], to be confirmed) * Using Speech tools in CALL (hands-on) (Teacher: Michael McTear [Univ of Ulster]) * CALL design and interfaces (Teacher: Philippe Delcloque [MSEC Manchester]) * Grammatical and morphological error diagnosis (Teacher: Lars Borin [Univ of Gothenburg]) * Systems for pronunciation training (Teacher: Anne-Marie Oster [KTH Stockholm]) * Building a grammatical CALL system (hands-on) (Teacher: Lars Borin [Univ of Gothenburg]) * Building a speech CALL system (hands-on) (Teacher: Michael McTear [Univ of Ulster]) All students attend the same full programme, except for the hands-on sessions, where students can sign up for either NLP or Speech oriented streams. In special student sessions students can present their own work. The presentations will be published on the ELSNET website. Please note that the number of places for this summer school is limited and that early registration is recommended. The working language of the Summer School will be English. + Fees: Category Registration fee (euro) Students 125 Academic staff 250 Commercial organisations 500 ELSNET members are entitled to a 20% discount + Food and accommodation: The cost of accommodation (on campus) will be 30 euro per night. Meals will be free. Registration, grants and other information: For detailed information about registration procedures and deadlines, fees, accommodation, grant possibilities, venue, course and social programme, etc visit the ESS2003 website at http://www.univ-lille3.fr/ESS2003 [to be opened soon] or send an email to the local organizers at elsnetadmin(a)univ-lille3.fr A limited number of grants (covering the cost of accommodation) may be available for citizens of EU and associated countries. Details and application forms will be published on the website. For information about the programme visit the provisional ESS2003 website at http://www.elsnet.org/ess2003 or contact the chair of the programme committee, Steven Krauwer (steven.krauwer(a)elsnet.org)

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Class or parameterized type?
by Graham Klyne 17 Mar '03

17 Mar '03

I'm trying to figure how to use parameterized types and/or classes. Example: I wish to define a structured container type, let's call it a "RatsNest", that is type-variable in two ways: (a) it is parameterized by a type of some class, let's call it "RatsTail", such that a RatsNest is a structure of things that have common properties. Certain operations between RatsNest values (e.g. a merge) are valid only if they are containers for the same kind of RatsTail. Such operations would not be different operations due to variation of thye contained type. (b) it can be implemented in various ways; e.g. a simple version is an in-memory data structure, while another may be implemented in database storage. This corresponds to the Haskell idea of overloading, or classes. This seems to call for a type-parameterized class specification, e.g. [[ class (Eq n, RatsTail t) => (RatsNest t) n where merge :: ( (RatsNest t1) n1, (RatsNest t1) l2) => n1 -> n2 -> n2 ]] But this, as far as I can tell, is not valid Haskell. Is there a way to achieve this effect? What I can't figure out is a way to impose that the merge operation is not valid between *any* instances of RatsNest, but only those that are based on the same member element type, but *can* be used between different implementations (e.g. disk-based and memory-based). #g ------------------- Graham Klyne <GK(a)NineByNine.org> PGP: 0FAA 69FF C083 000B A2E9 A131 01B9 1C7A DBCA CB5E

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old hugs versions?
by Steffen Mazanek 17 Mar '03

17 Mar '03

Hello, are there any valid links in the whole internet pointing to old versions of hugs? Concretely I need hugs-1.3b and all hints how to find it would be very appreciated. One may ask what the hell I want to do with this old stuff :-). My intention is to compare its parser.y file with the one of Johan Nordlanders ohugs (http://www.cs.chalmers.se/~nordland/ohugs/) Thanks in advance, Steffen Mazanek

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redefining methods in a subCLASS
by Oleg 14 Mar '03

14 Mar '03

Hi (Posted this to Haskell-Cafe 12 hours ago with no replies) Is it possible to redefine methods in a subclass (not an instance)? E.g. I get errors in class (Show a) => Employee a where speak :: a -> [Char] speak x = "Employee: " ++ (show x) class (Employee a) => Manager a where speak x = "Manager: " ++ (show x) Thanks Oleg

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RE: big lambda in class declarations
by Simon Peyton-Jones 14 Mar '03

14 Mar '03

Big lambda is in terms. You mean a "lambda at the type level", which is usually written as a small lambda. Confusing, I know. There's an ICFP02 paper on the subject, by Thiemann et al. Worth a read. Problem with inference is that the type checker can't guess lambdas. Suppose we need to unify m Int with ST Int Int One possibility is m = ST Another is m = \t. ST t Int Another is m = \t. ST Int t One solution is to restrict what lambdas are allowable, and that is what Thiemann et al do. Another is to declare the typechecker should never guess a lambda; instead the programmer has to specify what lambda to use whenever there is doubt. That is the approach that we're ruminating on here. Stay tuned, but don't hold your breath. Simon | -----Original Message----- | From: Hal Daume III [mailto:hdaume@ISI.EDU] | Sent: 04 March 2003 16:34 | To: Haskell Mailing List | Subject: big lambda in class declarations | | So the word on the street is that allowing big lambda makes type inference | undecidable. This makes sense to me since allowing big lambda essentially | allows you to program at the type level and thus of course you'll get | undecidability. | | However, I'm having difficulty understanding where the undecidability | sneaks in if you allow big lambda in class declarations. I suppose the | cannonical example is when you want to write something like: | | > class Set s where { ... } | > instance Set (/\ a. FiniteMap a ()) where { ... } | | but now you have to write: | | > data FMSet a = FMSet (FiniteMap a ()) | > instance Set FMSet where { ... } | | The big lambda is of course equivalent to not applying type synonyms | completely, somethign like: | | > type FM a = FiniteMap a () | > instance Set FM where { ... } | | will of course also be rejected (since this would give us a way to do big | lambda). | | Could some one help my intuition a bit here and explain to me how you | could use big lambdas in class declarations to write programs? | | Thanks! | | - Hal | | -- | Hal Daume III | hdaume(a)isi.edu | "Arrest this man, he talks in maths." | www.isi.edu/~hdaume | | _______________________________________________ | Haskell mailing list | Haskell(a)haskell.org | http://www.haskell.org/mailman/listinfo/haskell

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Re: Recursion with do??
by Alexandre Weffort Thenorio 14 Mar '03

14 Mar '03

Thanks it works but what exactly does this "in" before the last statement does?? I have never seen it before and the program gives me the parse error if I don't have it?? Best Regards NooK ----- Original Message ----- From: "Hal Daume III" <hdaume(a)ISI.EDU> To: "Alexandre Weffort Thenorio" <alethenorio(a)home.se> Sent: Friday, March 14, 2003 4:32 PM Subject: Re: Recursion with do?? > > fbk size new_str (x:xs) = do > > let first = findstr size new_str x > > let bksize = (Function that gives the size of the string to substitute in > > this line) > > let done = fbk bksize new_str xs > > return done > > There's no reason to use do notation here. This is a pure function. YOu > can write it as: > > > fbk size new_str (x:xs) = > > let first = ... > > bksize = ... > > in fbk bksize new_str xs > > I'm not sure why you would be getting a parse error though. > > > > ----- Original Message ----- > > From: "Hal Daume III" <hdaume(a)ISI.EDU> > > To: "Alexandre Weffort Thenorio" <alethenorio(a)home.se> > > Sent: Thursday, March 13, 2003 9:33 PM > > Subject: Re: How to search for a string sequence in a file a rewrite it??? > > > > > > > what is the type signature of write, and why are you using do > > > notation? might you want something like: > > > > > > fillIn lines = do > > > let bkfilled = findstr str str2 lines > > > write bkfilled > > > > > > or something like that? > > > > > > -- > > > Hal Daume III | hdaume(a)isi.edu > > > "Arrest this man, he talks in maths." | www.isi.edu/~hdaume > > > > > > On Thu, 13 Mar 2003, Alexandre Weffort Thenorio wrote: > > > > > > > Ooops a small error before but here is the right one. > > > > > > > > Great. I got almost everything. My problem now is: > > > > > > > > I got a function called findstr where > > > > > > > > findstr "aaaa" "zzzzz" ["xxxxaaaa","xxxaaaaxxx"] = > > > > ["xxxxzzzzz","xxxzzzzzxxx"] > > > > > > > > and then I try something like > > > > > > > > fillIn lines = do > > > > bkfilled <- (findstr str str2 lines) > > > > write bkfilled > > > > > > > > where write takes a [String] and concatenates it writing it to a file > > then. > > > > But I get this error saying: > > > > > > > > Expected Type: [String] > > > > Inferred Type: String > > > > In the first argument of 'write' namelly 'bkfilled' > > > > In a do expection pattern binding: write bkfilled > > > > > > > > Any idea?? I mean bkfilled is supposed to be [String] but it says it is > > a > > > > String, any idea why??? > > > > > > > > Best Regards > > > > > > > > Alex > > > > > > > > ----- Original Message ----- > > > > From: "Hal Daume III" <hdaume(a)ISI.EDU> > > > > To: "Alexandre Weffort Thenorio" <alethenorio(a)home.se> > > > > Cc: <haskell(a)haskell.org> > > > > Sent: Thursday, March 13, 2003 1:38 AM > > > > Subject: Re: How to search for a string sequence in a file a rewrite > > it??? > > > > > > > > > > > > > Right. *Recurse* down the list. Somethign like: > > > > > > > > > > foo orig_str new_str xl@(x:xs) > > > > > | orig_str `isPrefixOf` xl = <something> > > > > > | otherwise = x : <something> > > > > > > > > > > -- > > > > > Hal Daume III | hdaume(a)isi.edu > > > > > "Arrest this man, he talks in maths." | www.isi.edu/~hdaume > > > > > > > > > > On Thu, 13 Mar 2003, Alexandre Weffort Thenorio wrote: > > > > > > > > > > > Well the problem is that the string I want to replace will usually > > be in > > > > the > > > > > > middle of a line in the text file and then is PrefixOf of no use?? > > Any > > > > other > > > > > > suggestion?? > > > > > > > > > > > > Like the text file will be similar to > > > > > > > > > > > > abcdedjkfhlafl > > > > > > sajkhlabbbbsf > > > > > > akfhjklafjkhfk > > > > > > sdfasfsaasffaa > > > > > > > > > > > > So I want to replace this bbbb in the middle there with aaaa. I > > could > > > > run > > > > > > lines on the file but from there i have no idea. I have got an idea > > but > > > > for > > > > > > it to work I need to know if there is a function that I can replace > > a > > > > > > certain Char in a string by another Char by knowing the index of > > this > > > > char?? > > > > > > > > > > > > Best Regards > > > > > > > > > > > > NooK > > > > > > ----- Original Message ----- > > > > > > From: "Hal Daume III" <hdaume(a)ISI.EDU> > > > > > > To: "Alexandre Weffort Thenorio" <alethenorio(a)home.se> > > > > > > Cc: <haskell(a)haskell.org> > > > > > > Sent: Thursday, March 13, 2003 1:05 AM > > > > > > Subject: Re: How to search for a string sequence in a file a rewrite > > > > it??? > > > > > > > > > > > > > > > > > > > This is how I would do it: > > > > > > > > > > > > > > recurse down the input string. use isPrefixOf to check is the > > string > > > > youw > > > > > > > ant to replace is at the head of the string. if it is, 'drop' the > > > > > > > appropriate number of characters and stick the replacement string > > on > > > > the > > > > > > > front. then recurse. > > > > > > > > > > > > > > this should be about 3 lines of code. > > > > > > > > > > > > > > -- > > > > > > > Hal Daume III | hdaume(a)isi.edu > > > > > > > "Arrest this man, he talks in maths." | > > www.isi.edu/~hdaume > > > > > > > > > > > > > > On Thu, 13 Mar 2003, Alexandre Weffort Thenorio wrote: > > > > > > > > > > > > > > > OK Guys. First I would like to say thanks for all the help given > > > > before. > > > > > > As > > > > > > > > I said I am still learning Haskell. My problem is the following: > > > > > > > > > > > > > > > > I have a text file and somewhere in the file there is string > > (Let's > > > > say > > > > > > > > aaaa). So I need to find this exact string and overwrite with > > > > another > > > > > > string > > > > > > > > (Lets say bbbb). > > > > > > > > > > > > > > > > I have thought a bit and couldn't find any solution, and I > > believe > > > > it is > > > > > > a > > > > > > > > piece of cake for some of you. Is there a method already > > implemented > > > > in > > > > > > > > haskell to do that?? > > > > > > > > Anyway thanks in advance. > > > > > > > > > > > > > > > > Best Regards > > > > > > > > > > > > > > > > NooK > > > > > > > > > > > > > > > > ----- Original Message ----- > > > > > > > > From: "Arthur Baars" <arthurb(a)cs.uu.nl> > > > > > > > > To: <haskell(a)haskell.org> > > > > > > > > Cc: "Norman Ramsey" <nr(a)eecs.harvard.edu> > > > > > > > > Sent: Wednesday, March 12, 2003 1:06 AM > > > > > > > > Subject: Re: clueless GHCI user wishes to load QuickCheck > > > > > > > > > > > > > > > > > > > > > > > > > QuickCheck is in de "util" package. You can load a package > > with > > > > the > > > > > > > > > -package flag: > > > > > > > > > > > > > > > > > > $ ghci -package util > > > > > > > > > Prelude> :browse QuickCheck > > > > > > > > > class Arbitrary a where { > > > > > > > > > arbitrary :: Gen a; coarbitrary :: forall b. a -> Gen > > b -> > > > > Gen > > > > > > b; } > > > > > > > > > arbitrary :: forall a. (Arbitrary a) => Gen a > > > > > > > > > ... > > > > > > > > > Prelude>:module QuickCheck > > > > > > > > > > > > > > > > > > Prelude QuickCheck> :info trivial > > > > > > > > > -- trivial is a variable > > > > > > > > > trivial :: forall a. (Testable a) => Bool -> a -> Property > > > > > > > > > > > > > > > > > > Hope this helps. > > > > > > > > > > > > > > > > > > Cheers, > > > > > > > > > > > > > > > > > > Arthur > > > > > > > > > > > > > > > > > > On Tuesday, March 11, 2003, at 07:02 PM, Norman Ramsey wrote: > > > > > > > > > > > > > > > > > > > Can anyone help me figure out how to load QuickCheck into > > GHCI? > > > > > > > > > > QuickCheck is included in my Debian package, but my attempts > > > > > > > > > > at loading it are bootless: > > > > > > > > > > > > > > > > > > > > Prelude> :load QuickCheck > > > > > > > > > > can't find module `QuickCheck' > > > > > > > > > > Prelude> :load util/QuickCheck > > > > > > > > > > can't find module `util/QuickCheck' > > > > > > > > > > Prelude> :info > > > > > > > > > > syntax: `:i <thing-you-want-info-about>' > > > > > > > > > > Prelude> :load util/QuickCheck.hi > > > > > > > > > > can't find module `util/QuickCheck.hi' > > > > > > > > > > Prelude> :load > > /usr/lib/ghc-5.02.2/imports/util/QuickCheck.hi > > > > > > > > > > can't find module > > > > `/usr/lib/ghc-5.02.2/imports/util/QuickCheck.hi' > > > > > > > > > > Prelude> :load /usr/lib/ghc-5.02.2/imports/util/QuickCheck > > > > > > > > > > can't find module > > `/usr/lib/ghc-5.02.2/imports/util/QuickCheck' > > > > > > > > > > Prelude> > > > > > > > > > > > > > > > > > > > > Any advice, anyone? > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Norman > > > > > > > > > > _______________________________________________ > > > > > > > > > > Haskell mailing list > > > > > > > > > > Haskell(a)haskell.org > > > > > > > > > > http://www.haskell.org/mailman/listinfo/haskell > > > > > > > > > > > > > > > > > > > > > > > > > > > > _______________________________________________ > > > > > > > > > Haskell mailing list > > > > > > > > > Haskell(a)haskell.org > > > > > > > > > http://www.haskell.org/mailman/listinfo/haskell > > > > > > > > > > > > > > > > > > > > > > > > > _______________________________________________ > > > > > > > > Haskell mailing list > > > > > > > > Haskell(a)haskell.org > > > > > > > > http://www.haskell.org/mailman/listinfo/haskell > > > > > > > > > > > > > > > > > > > > > > _______________________________________________ > > > > > > > Haskell mailing list > > > > > > > Haskell(a)haskell.org > > > > > > > http://www.haskell.org/mailman/listinfo/haskell > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > >

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state of Standard
by Serge D. Mechveliani 14 Mar '03

14 Mar '03

Dear Haskellers, Could you, please, tell me what is the recent state of the Haskell Standard development? I have a wish for the Standard Library: FiniteMap, Set (of GHC library). And I have a question on the function name overloading, and on the record field name overloading. A language should support a natural naming of objects. For example: data Operator = Operator{opName :: String, opWeight :: Int, opSortage :: ([String],[String],String), opOrd :: Int, opPrecedences :: (Int, Int) } is not good -- due to `op' prefix. And many other data also have name, weight, ord, and so on. So, one may try to introduce class WithName a where name :: a -> String set_name :: a -> String -> a class WithWeight a where weight :: a -> Int set_weight :: a -> Int -> a ... trivialOperator = Operator{ ... some trivial setting ...} , to change the names like opName to opName__, opWeight__, ... to show that the latter are local and not for usage, to introduce instance WithName Operator where name = opName__ ... , and then, use all this, for example, as follows: let nm = name opr opr' = set_name "foo" $ set_weight 1 $ set_ord 2 $ opr in ... This leads to following complications. * Class declarations add. * The Standard does not allow to define the instances like type BN = (String, Bool) instance WithName BN where name = fst * There are many operations that should be synonymic but have different kind. For example, weight :: a -> Int weight :: Table -> a -> Int This leads to adventures with multiple parameter classes, and so on. Similar difficulties arise with the function names. Is Haskell all right at this point? Reply, please, to mechvel(a)botik.ru Thank you in advance for the explanation. ----------------- Serge Mechveliani mechvel(a)botik.ru

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