November 2002 - Haskell

RE: Module re-exportation weekend puzzler
by Simon Peyton-Jones 06 Nov '02

06 Nov '02

Folks Another minor H98 glitch. Consider this: | > > module D (module Char) where | > > { import qualified Char; import List as Char } | > | > Everything in List, nothing from Char. | | Interesting... what happens when List and Char overlap here? Suppose | there exists entities List.f and Char.f, then it would be an error to | refer to Char.f in the body of the module. On export lists, the report | says: | | The form "module M" names the set of all entities whose | unqualified name, e, is in scope, and for which the qualified | name M.e is also in scope and refers to the same entity as e. | | Perhaps this could be clarified by insertion of the word "unambiguously" | before "refers to the same entity as e". It's not essential, but it | would make the expected behaviour in this case clearer. I agree with this. (Actually GHC gets it wrong right now.) Another way to say it is this: The export item 'module M' exports all entities e such that a) The qualified name M.e is unambiguous and refers to that entity b) The unqualified name e is in scope, perhaps ambiguously, and at least one of its bindings refers to that entity I'll make the one-word change in the Report that Simon suggests, though. Simon

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RE: getting the right types
by Simon Peyton-Jones 05 Nov '02

05 Nov '02

Interesting. You want to control a data type used *inside* an algorithm from outside. Here's a smaller version: foo :: String -> String foo s = show (read s) This is ambiguous; what type should 'read' return? Your idea: pass in that type via a proxy value: foo :: (Read a, Show a) => a -> String -> String foo p s = show (read s `asTypeOf` p) Now you can say foo (undefined :: Int) "34" and it'll work. A neater way to do this with GHC is to use scoped type variables: foo :: (Read a, Show a) => a -> String -> String foo (p::a) s = show (read s :: a) One reason this is neater is that it scales up better when you want to pass a type constructor instead of a type. First define a data type with no constructors, and a phantom type arg data Proxy (a :: * -> *) Now you can write a function like this f :: (MArray a ix e) => Proxy a -> .... f (p :: Proxy a) ... = do { (arr :: a ix e) <- newArray ... The type variable 'a' is bound by the (Proxy a) pattern, and scopes over the body. The type variables 'ix' and 'e' in the do-binding are bound right there (since they aren't already in scope). Another use for phantom types! Simon | -----Original Message----- | From: Hal Daume III [mailto:hdaume@ISI.EDU] | Sent: 03 November 2002 19:31 | To: Haskell Mailing List | Subject: getting the right types | | Hi all, | | I have a function which essentially looks like this: | | f my_data = do | a1 <- newArray ... | ... | a2 <- newArray ... | g my_data a1 a2 | | where f is a monadic operation essentially of type 'a -> m a'. The | problem is that when this function isn't given a type signature, you get | something like: | | f :: (MArray a1 p e, MArray a2 p e) => t | | where a1 and a2 aren't bound in t. Now, I could provide a type signature | on the array expressions, something like: | | ... (a1 :: IOArray Int Int) <- newArray ... | | but i would like to be able to use unboxed arrays when possible, and i | don't want to bind the funtion to be in IO. My current solution is to | define: | | data ArrayType arr prob = forall ix . ArrayType (arr ix prob) | asArray :: arr ix prob -> ArrayType arr prob -> arr ix prob | a `asArray` _ = a | | Sort of like asTypeOf. Then, I change f to: | | f :: (MArray arr p e) => ArrayType arr p -> t -> m t | f arr_type ... = ... | | And inside f I have a function: | | newArray_arr bnds init = | do a <- newArray bnds init | return (a `asArray` arr_type) | | This enables me to create arrays of arbitrary representation with the same | values but different indices (which is important). | | However, this strikes me as horribly hackish. Is there some better way to | do this? | | - Hal | | -- | Hal Daume III | | "Computer science is no more about computers | hdaume(a)isi.edu | than astronomy is about telescopes." -Dijkstra | www.isi.edu/~hdaume | | _______________________________________________ | Haskell mailing list | Haskell(a)haskell.org | http://www.haskell.org/mailman/listinfo/haskell

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RE: problems with ghc ffi
by Simon Peyton-Jones 04 Nov '02

04 Nov '02

GHC questions to ghc-users please, not the main Haskell list. You need the -ffi flag to use the FFI. S -----Original Message----- From: David Abbs [mailto:u0da2@dcs.shef.ac.uk] Sent: 04 November 2002 14:38 To: haskell(a)haskell.org Subject: problems with ghc ffi I am having problems with the GHC FFI, I am using GHC version 5.04.1 and am trying to compile the sample code given on the web site _______________________________________ module Foo where foreign export ccall foo :: Int -> IO Int foo :: Int -> IO Int foo n = return (length (f n)) f :: Int -> [Int] f 0 = [] f n = n:(f (n-1)) _____________________________________ when I enter c:/ghc M.hs to compile the code I get the following error M.hs:5: Type signature given for an expression I have tried compiling the code using GHC 5.04.1 on windows 98, XP and on Linux any help on would be greatly appreciated. _____________________________________________ David Abbs 3rd year Undergraduate in Computer Science at the University Of Sheffield _____________________________________________ u0da2(a)dcs.shef.ac.uk Have a very nice day !!

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problems with ghc ffi
by David Abbs 04 Nov '02

04 Nov '02

I am having problems with the GHC FFI, I am using GHC version 5.04.1 and am trying to compile the sample code given on the web site _______________________________________ module Foo where foreign export ccall foo :: Int -> IO Int foo :: Int -> IO Int foo n = return (length (f n)) f :: Int -> [Int] f 0 = [] f n = n:(f (n-1)) _____________________________________ when I enter c:/ghc M.hs to compile the code I get the following error M.hs:5: Type signature given for an expression I have tried compiling the code using GHC 5.04.1 on windows 98, XP and on Linux any help on would be greatly appreciated. _____________________________________________David Abbs 3rd year Undergraduate in Computer Science at the University Of Sheffield_____________________________________________u0da2(a)dcs.shef.ac.uk Have a very nice day !!

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getting the right types
by Hal Daume III 03 Nov '02

03 Nov '02

Hi all, I have a function which essentially looks like this: f my_data = do a1 <- newArray ... ... a2 <- newArray ... g my_data a1 a2 where f is a monadic operation essentially of type 'a -> m a'. The problem is that when this function isn't given a type signature, you get something like: f :: (MArray a1 p e, MArray a2 p e) => t where a1 and a2 aren't bound in t. Now, I could provide a type signature on the array expressions, something like: ... (a1 :: IOArray Int Int) <- newArray ... but i would like to be able to use unboxed arrays when possible, and i don't want to bind the funtion to be in IO. My current solution is to define: data ArrayType arr prob = forall ix . ArrayType (arr ix prob) asArray :: arr ix prob -> ArrayType arr prob -> arr ix prob a `asArray` _ = a Sort of like asTypeOf. Then, I change f to: f :: (MArray arr p e) => ArrayType arr p -> t -> m t f arr_type ... = ... And inside f I have a function: newArray_arr bnds init = do a <- newArray bnds init return (a `asArray` arr_type) This enables me to create arrays of arbitrary representation with the same values but different indices (which is important). However, this strikes me as horribly hackish. Is there some better way to do this? - Hal -- Hal Daume III "Computer science is no more about computers | hdaume(a)isi.edu than astronomy is about telescopes." -Dijkstra | www.isi.edu/~hdaume

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EACL2003 Workshop CfP: 9th European Workshop on Natural Language Generation
by steven.krauwer＠elsnet.org 02 Nov '02

02 Nov '02

[ NB: the message you just received on the same subject contained the general CfP rather than the one for this workshop -- we apologize! ] Call for Papers 9th EUROPEAN WORKSHOP ON NATURAL LANGUAGE GENERATION (in conjunction with EACL2003) 13-14 April 2003 Budapest, Hungary (http://www.ags.uni-sb.de/~horacek/EACL-EWNLG03.html) Natural language generation (NLG) is a subfield of natural language processing that focuses on the generation of written texts in English or other human languages, generally from some non-linguistic data or knowledge. Accomplishing this goal may be envisioned for a number of different purposes, including standardized and/or multi-lingual reports, summaries, machine translation, dialog applications, and embedding in multi-media and hypertext environments. Consequently, the automated production of language is associated with a large number of highly diverse tasks whose appropriate orchestration in high quality poses a variety of theoretical and practical problems. Relevant issues include content selection, text organization, the production of referring expressions, aggregation, lexicalization, and surface realization, as well as coordination with other media. This workshop is part of a biennial series of workshops about natural language generation that has been running since 1987. Previous European workshops have been held at Royaumont, Edinburgh, Judenstein, Pisa, Leiden, Duisburg, and Toulouse. The goal of the workshop is to be an informal meeting which facilitates the dissemination of knowledge and expertise in the field. A substantial amount of time will be devoted to discussions, either in sequence or in parallel, depending on the number of participants. The workshop will focus on the following topics: - Formal semantics and NLG In several subareas of NLG (generation of referring expressions, lexicalization, among others) methods of formal semantics have already been used successfully. By focusing on this topic, we hope to strengthen the theoretical basis of NLG, complementing the application-oriented emphasis that has become dominant recently. - Evaluation of NLG systems Evaluation is an important factor for all NL systems, which is notoriously underrepresented in the generation field. By focusing on this topic, we hope to strengthen the empirical basis of NLG, preparing the ground for dedicated activities on this topic. We are considering organizing an invited talk on the first and a panel on the second topic. Substantial and original submissions on all subfields of NLG, especially on the two special topics, are welcome. Accepted papers will be scheduled for presentation. Since this is a workshop, we encourage papers that describe speculative ideas, work in progress, and discussions of important issues. WORKSHOP CHAIRS Ehud Reiter, Univ. of Aberdeen Helmut Horacek, Univ. of the Saarland Kees van Deemter, Univ. of Brighton PROGRAMME COMMITTEE John Bateman, Univ. of Bremen, Germany Nadjet Bouayad-Agha, Univ. Pompeu Fabra, Spain Stephan Busemann, DFKI, Germany Jo Calder, Fourth Person LtD, UK Charles Callaway, IRST, Italy John Carroll, Univ. of Sussex, UK Robert Dale, Macquarie University, Australia Claire Gardent, CNRS Nancy, France Pamela Jordan, Univ. of Pittsburgh, USA Rodger Kibble, Univ. of London, UK Emiel Krahmer, Univ. of Tilburg, The Netherlands Chris Mellish, Univ. of Edinburgh, UK Owen Rambow, Columbia Univ., USA Leo Wanner, Univ. of Stuttgart, Germany SUBMISSIONS Papers describing original work in all areas of NLG, in particular related to the workshop focus topics above, should be submitted electronically. Papers should be 4-8 pages long in PDF format following the guidelines at the EACL site (http://ufal.ms.mff.cuni.cz/~hajic/eacl03/submission.html) Send your submission to Ehud Reiter (ereiter(a)csd.abdn.ac.uk) IMPORTANT DATES Paper submissions: 7 January 2003 Notification of acceptance: 28 January 2003 Camera-ready copies due: 13 February 2003 Registration deadline: as ACL Workshop dates: 13-14 April 2003 REGISTRATION The registration fees include attendance of the workshop and a copy of workshop proceedings. Follow the registration instructions at the EACL site (http://www.conferences.hu/EACL03) and indicate that you would like to attend the NLG workshop. PARTICIPATION WITHOUT SUBMISSION People wishing to attend the workshop but not submitting papers should send a notification of attendance: a 1-2 page stating interest to participate, work done in NLG so far, and potential contributions / material for discussions about one of the topics. This information will help with the organisation of discussions and allow for an informal and highly interactive workshop. CONTACT INFO Notifications of attendance should be sent to Ehud Reiter (ereiter(a)csd.abdn.ac.uk)

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EACL2003 Workshop CfP: 9th European Workshop on Natural Language Generation
by steven.krauwer＠elsnet.org 02 Nov '02

02 Nov '02

EACL 2003 in Budapest, April 12-17, 2003 Workshop Programme and Call for Workshop Papers Important dates for all workshops: ---------------------------------- Submission deadline: Jan 07, 2003 Notification: Jan 28, 2003 Deadline for final papers: Feb 13, 2003 Workshop dates: Apr 13/14, 2003 Conference dates: Apr 12-17, 2003 Important URLs: --------------- Main conference: http://www.conferences.hu/EACL03/ Workshops: http://www.elsnet.org/workshops Workshop overview: ------------------ Workshop w01: "MT and other language technology tools; Improving MT through other language technology tools; Resources and tools for building MT" URL: not available Organizer(s): Bente Maegaard Email: bente(a)cst.dk 1st CfP: http://www.elsnet.org/workshops/w01.doc Date: April 13, 2003 ___________________________________________________________________ Workshop w02: "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 1st CfP: http://www.elsnet.org/workshops/w02.txt Date: April 13+14, 2003 ___________________________________________________________________ Workshop w03: "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 1st CfP: http://www.elsnet.org/workshops/w03.txt Date: April 14, 2003 ___________________________________________________________________ Workshop w04: "Language Modeling for Text Entry Methods" URL: http://www.uni-koblenz.de/~compling/eaclws2003/ Organizer(s): Michael Kuhn Email: kuehn(a)uni-koblenz.de 1st CfP: http://www.elsnet.org/workshops/w04.txt Date: April 13, 2003 ___________________________________________________________________ Workshop w05: "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 1st CfP: http://www.elsnet.org/workshops/w05.txt Date: April 14, 2003 ___________________________________________________________________ Workshop w06: "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 1st CfP: http://www.elsnet.org/workshops/w06.txt Date: April 13+14, 2003 ___________________________________________________________________ Workshop w07: "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 1st CfP: http://www.elsnet.org/workshops/w07.txt Date: April 13, 2003 ___________________________________________________________________ Workshop w08: "Computational Linguistics for South Asian Languages -- Expanding Synergies with Europe" URL: not available Organizer(s): Durgesh Rao and Pat Hall Email: durgesh@saathi.ncst.ernet.in,p.a.v.hall@open.ac.uk 1st CfP: http://www.elsnet.org/workshops/w08.txt Date: April 14, 2003 ___________________________________________________________________ Workshop w09: "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 1st CfP: http://www.elsnet.org/workshops/w09.txt Date: April 13+14, 2003 ___________________________________________________________________ Workshop w10: "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 1st CfP: http://www.elsnet.org/workshops/w10.txt Date: April 14, 2003 ___________________________________________________________________ Workshop w11: "Natural Language Processing (NLP) for Question-Answering" URL: not available Organizer(s): Bonnie Webber and Maarten de Rijke Email: bonnie@inf.ed.ac.uk,mdr@science.uva.nl 1st CfP: http://www.elsnet.org/workshops/w11.txt Date: April 13, 2003 ___________________________________________________________________ Workshop w12: "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 1st CfP: http://www.elsnet.org/workshops/w12.txt 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 _______________________________________________________________

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EACL2003: Call for Workshop Papers
by steven.krauwer＠elsnet.org 01 Nov '02

01 Nov '02

Workshop Programme and Call for Workshop Papers Important dates for all workshops: ---------------------------------- Submission deadline: Jan 07, 2003 Notification: Jan 28, 2003 Deadline for final papers: Feb 13, 2003 Workshop dates: Apr 13/14, 2003 Conference dates: Apr 12-17, 2003 Important URLs: --------------- Main conference: http://www.conferences.hu/EACL03/ Workshops: http://www.elsnet.org/workshops Workshop overview: ------------------ Workshop w01: "MT and other language technology tools; Improving MT through other language technology tools; Resources and tools for building MT" URL: not available Organizer(s): Bente Maegaard Email: bente(a)cst.dk 1st CfP: http://www.elsnet.org/workshops/w01.doc Date: April 13, 2003 ___________________________________________________________________ Workshop w02: "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 1st CfP: http://www.elsnet.org/workshops/w02.txt Date: April 13+14, 2003 ___________________________________________________________________ Workshop w03: "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 1st CfP: http://www.elsnet.org/workshops/w03.txt Date: April 14, 2003 ___________________________________________________________________ Workshop w04: "Language Modeling for Text Entry Methods" URL: http://www.uni-koblenz.de/~compling/eaclws2003/ Organizer(s): Michael Kuhn Email: kuehn(a)uni-koblenz.de 1st CfP: http://www.elsnet.org/workshops/w04.txt Date: April 13, 2003 ___________________________________________________________________ Workshop w05: "The Computational Treatment of Anaphora" URL: not available Organizer(s): Rob Dale Email: rdale(a)ics.mq.edu.au 1st CfP: http://www.elsnet.org/workshops/w05.txt Date: April 14, 2003 ___________________________________________________________________ Workshop w06: "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 1st CfP: http://www.elsnet.org/workshops/w06.txt Date: April 13+14, 2003 ___________________________________________________________________ Workshop w07: "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 1st CfP: http://www.elsnet.org/workshops/w07.txt Date: April 13, 2003 ___________________________________________________________________ Workshop w08: "Computational Linguistics for South Asian Languages -- Expanding Synergies with Europe" URL: not available Organizer(s): Durgesh Rao and Pat Hall Email: durgesh@saathi.ncst.ernet.in,p.a.v.hall@open.ac.uk 1st CfP: http://www.elsnet.org/workshops/w08.txt Date: April 14, 2003 ___________________________________________________________________ Workshop w09: "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 1st CfP: http://www.elsnet.org/workshops/w09.txt Date: April 13+14, 2003 ___________________________________________________________________ Workshop w10: "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 1st CfP: http://www.elsnet.org/workshops/w10.txt Date: April 14, 2003 ___________________________________________________________________ Workshop w11: "Natural Language Processing (NLP) for Question-Answering" URL: not available Organizer(s): Bonnie Webber and Maarten de Rijke Email: bonnie@inf.ed.ac.uk,mdr@science.uva.nl 1st CfP: http://www.elsnet.org/workshops/w11.txt Date: April 13, 2003 ___________________________________________________________________ Workshop w12: "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 1st CfP: http://www.elsnet.org/workshops/w12.txt 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 _______________________________________________________________

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