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[CFP] Continuation Workshop 2011
by oleg＠okmij.org 05 Feb '11

05 Feb '11

ACM SIGPLAN Continuation Workshop 2011 http://logic.cs.tsukuba.ac.jp/cw2011/ co-located with ICFP 2011, Tokyo, Japan Saturday, September 24, 2011 Call for Contributions Continuations have been discovered many times, which highlights their many applications in programming language semantics and program analysis, linguistics, logic, parallel processing, compilation and web programming. Recently, there has been a surge of interest specifically in delimited continuations: new implementations (in Scala, Ruby, OCaml, Haskell), new applications (to probabilistic programming, event-driven distributed processing), substructural and constructive logics, natural language semantics. The goal of the Continuation Workshop is to make continuations more accessible and useful -- to practitioners and to researchers in various areas of computer science and outside computer science. We wish to promote communication among the implementors and users in many fields. We would like to publicize the applications of continuations in academic (logic, linguistics) and practical fields and various programming languages (OCaml, Haskell, Scala, Ruby, Scheme, etc). Continuation Workshop 2011 will be informal. We aim at accessible presentations of exciting if not fully polished research, and of interesting academic, industrial and open-source applications that are new or unfamiliar. The workshop will have no published proceedings; submissions of short abstracts are preferred. We intend to organize a tutorial session on delimited continuations and their main applications, in the evening before the workshop, on Friday, September 23, 2011. Important dates --------------- Submission: June 25, 2011 Notification: August 8, 2011 Tutorials: September 23, 2011 Workshop: September 24, 2011 Format ------ The workshop will consist of presentations by the participants, selected from submitted abstracts. Participants are invited to submit working drafts, source code, and/or extended abstracts for distribution on the workshop homepage and to the attendees, but as the workshop will have no formal proceedings, any contributions may be submitted for publication to other venues. (See the SIGPLAN republication policy for more details.) Scope ----- We seek several types of presentations on topics related to continuations. We especially encourage presentations that describe work in progress, outline a future research agenda, or encourage lively discussion. Research presentations on: - implementations of continuations - semantics - type systems and logics - meta-theory and its mechanization - code generation with continuations or effects - distributed programming - systems programming and security - pearls Research presentations must be broadly accessible and should describe new ideas, experimental results, significant advances in the theory or application of continuations, or informed positions regarding new control operators. Application presentations, or status reports These broadly accessible presentations should describe interesting applications of continuations in research, industry or open source. We encourage presentations of applications from areas outside of programming language research -- such as linguistics, logics, AI, computer graphics, operating systems, etc. These presentations need not present original research, but should deliver information that is new or that is unfamiliar to the general ICFP audience. (A broadly accessible version of research presented elsewhere, with the most recent results and more discussion of future work may be acceptable as a CW 2011 status report.) The abstract submission should justify, to a general reader, why an application is interesting. Demos and work-in-progress reports Live demonstrations or presentations of preliminary results are intended to show new developments, interesting prototypes, or work in progress. In the abstract submission (which need only be about half a page), describe the demo and its technical content, and be sure to include the demo's title, authors, collaborators, references, and acknowledgments. A demonstration should take 10-15 minutes, and a work-in-progress report should take about 5 minutes. The exact time per demo will be decided based on the number of accepted submissions. (Presenters will have to bring all the software and hardware for their demonstration; the workshop organizers are only able to provide a projector.) Submission Guidelines and Instructions -------------------------------------- Unlike the previous Continuation Workshops, we do not require the submission of complete research papers. We will select presentations based on submitted abstracts, up to 2 (A4 or US letter) pages long in the PDF format (with the optional supplementary material, up to 8 PDF pages). Persons for whom this poses a hardship should contact the program chair. Submissions longer than a half a page should include a paragraph synopsis suitable for inclusion in the workshop program. Email submissions to cw2011-submit(a)logic.cs.tsukuba.ac.jp Organizers ---------- Yukiyoshi Kameyama, University of Tsukuba http://logic.cs.tsukuba.ac.jp/~kam/ Chung-chieh Shan, Rutgers University http://www.cs.rutgers.edu/~ccshan/ Oleg Kiselyov http://okmij.org/ftp/ Program Committee ----------------- Kenichi Asai, Ochanomizu University, Japan http://pllab.is.ocha.ac.jp/~asai/ Malgorzata Biernacka, University of Wroclaw, Poland http://www.ii.uni.wroc.pl/~mabi/ Hugo Herbelin, PPS - pi.r2, INRIA, France http://pauillac.inria.fr/~herbelin/index-eng.html Oleg Kiselyov http://okmij.org/ftp/ Julia Lawall, University of Copenhagen, Denmark http://www.diku.dk/~julia Tiark Rompf, EPFL, Switzerland Chung-chieh Shan, Rutgers University (Chair) http://www.cs.rutgers.edu/~ccshan/ Hayo Thielecke, University of Birmingham, UK http://www.cs.bham.ac.uk/~hxt

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a quick question
by Navin Rustagi 04 Feb '11

04 Feb '11

Hi all, I am stuck at a piece of code and am not able to figure out the error. uptable::[[Char]]->[([Char],Int,Int,Int,Int)]->[([Char],Int,Int,Int,Int)] uptable (xf:xs) main_array = map (\(x,y,z,r,t)-> do if x==xf then tupup x y z r t second xs ) main_array here tupup and second are functions which are working . When compiling this it gives the error Syntax error in expression (unexpected `)') I am not able to figure out where I could have gone wrong. I have tried all bracketing combinations and nothing works. Navin

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Haskell Functions Help
by Manolache Andrei-Ionut 03 Feb '11

03 Feb '11

I need help with two functions....first this is the curent code :http://pastebin.com/UPATJ0r ->Function 1)removeTautologies :: Formula->Formula If in a clause, a literal and its negation are found, it means that the clause will be true, regardless of the value finally assigned to that propositional variable. Consider the following example: (A v B v -A) ^ (B v C v A) The first clause contains the literals A and -A. This means that the clause will always be true, in which case it can be simplify the whole set to simply (B v C v A) . I was tinking of using something like removeTautologies (f:fs)=filter rTf:removeTautologies fs where rT-is supposed to take the firs Literal from the clasue and search for a similar one,if one si found we compare the values if not the we go to the second literal. ->Function 2)pureLiteralDeletion :: Formula->Formula This is a little bit complicate but from What I get this function is suppose to implement a simplification step that assumes as true any atom in a formula that appears exclusively in a positive or negative form (not both). Consider the formula: (P v Q v R) ^ (P v Q v -R) ^ (-Q v R) Note that in this formula P is present but -P is not. Using Pure Literal Deletion it can be assumed that the value of P will be True thus simplifying the formula to (-Q v R). If the literal were false then the literal would simply be deleted from the clauses it appears in. In that case any satisfying model for the resulting formula would also be a satisfying model for the formula when we assume that the literal is true.

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ANNOUNCE: Database Supported Haskell (DSH)
by George Giorgidze 03 Feb '11

03 Feb '11

I am pleased to announce that Database Supported Haskell (DSH) has been released on Hackage [1]. DSH is a Haskell library for database-supported program execution. Using this library a relational database management system (RDBMS) can be used as a coprocessor for the Haskell programming language, especially for those program fragments that carry out data-intensive and data-parallel computation. Database executable program fragments can be written using the list comprehension notation (with modest syntax changes due to quasiquoting) and list processing combinators from the Haskell list prelude. Note that rather than embedding a relational language into Haskell, we turn idiomatic Haskell programs into SQL queries. DSH faithfully represents list order and nesting, and compiles the list processing combinators into relational queries. The implementation avoids unnecessary data transfer and context switching between the database coprocessor and the Haskell runtime by ensuring that the number of generated relational queries is only determined by the program fragment's type and not by the database size. DSH can be used to allow existing Haskell programs to operate on large scale data (e.g., larger than the available heap) or query existing database resident data with Haskell. Note that this package is flagged experimental and therefore not suited for production use. This is a proof of concept implementation only. To learn more about DSH, our paper entitled as "Haskell boards the Ferry: Database-supported program execution for Haskell" is a recommended reading [2]. The package includes a couple of examples that demonstrate how to use DSH. [1] http://hackage.haskell.org/package/DSH [2] http://www-db.informatik.uni-tuebingen.de/files/publications/ferryhaskell.p…

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ANNOUNCE: time-1.2.0.4
by Ashley Yakeley 03 Feb '11

03 Feb '11

A small update, time-1.2.0.4 fixes a bug in parseTime reported to me by Michael Gurlitz: > import Data.Time > import Data.Time.Clock > import System.Locale > > main = print (parseTime defaultTimeLocale "%e %B %Y" "April 2000" :: > Maybe Day) > -- Just *** Exception: Prelude.read: no parse Specifically: > parseTime defaultTimeLocale "%e" "" :: Maybe Day > -- Just *** Exception: Prelude.read: no parse In time-1.2.0.4, they now correctly evaluate to Nothing. I've updated the unit tests to catch this too. -- Ashley Yakeley

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Haskell Weekly News: Issue 167 - February 02, 2011
by Daniel Santa Cruz 03 Feb '11

03 Feb '11

Welcome to issue 167 of the HWN, a newsletter covering developments in the [1]Haskell community. This release covers the week of January 23 to 29, 2011. This week I've added a section which compiles a list of the top answers given in StackOverflow during the week. These seem to be of more interest to more experienced Haskell users than the newbie questions usually posted on the site. See what you think. Announcements R. Emre Basar [2]annouced the release of follower, a tool that allows you to follow people's tweets without having an account with Twitter. Alberto Ruiz [3]announced hmatrix version 0.11, a package for numerical computation based on LAPACK and SGL. Michael Snoyman [4]made some point updates for WAI and Warp. "They fix some documentation issues, add some status aliases, make it possible to handle exceptions more easily, and make things more responsive on Windows." Antoine Latter [5]announced a minor point release for Parsec 3.1.0. John Meacham [6]announced version 0.7.7 of jhc is out! "This release fixes a large number of bugs that cropped up when compiling haskell out in the wild as well as adds some more features. A major one being the garbage collector is enabled by default." Quotes of the Week * Twey: Maybe Bool: the Haskell equivalent to True/False/FileNotFound * elliott: Only two things in the universe are certain: Death, and two of the libraries you've decided to use taking different types of ByteString. * shapr: my personal heuristics judge Haskell as totally practical, perhaps too practical. * monochrom: the guys that I see when I look into the irc window believe that I'm just a bunch of text. * bernardh: Refactoring: spend a week to get where you were * Question: How do I use "fix", and how does it work? Answer (by TomMD): The prank answer is "fix has no real use, it's just there so you can type 'fix error' in ghci and feel good about yourself." Top Reddit Stories * Haskell at Bump Domain: devblog.bu.mp, Score: 44, Comments: 9 On Reddit: http://www.reddit.com/r/haskell/comments/f8cr8/haskell_at_bump/ Original: http://devblog.bu.mp/haskell-at-bump * How to write a simple TCP Server in Haskell Domain: catonmat.net, Score: 35, Comments: 5 On Reddit: http://www.reddit.com/r/haskell/comments/faa80/how_to_write_a_simple_tcp_se… Original: http://catonmat.net/blog/simple-haskell-tcp-server * Snap Framework article in IEEE Internet Computing Domain: steve.vinoski.net, Score: 32, Comments: 1 On Reddit: http://www.reddit.com/r/haskell/comments/fa0e0/snap_framework_article_in_ie… Original: http://steve.vinoski.net/blog/2011/01/21/column-on-the-snap-framework/ * My Dream GHCi Session, Take 2 Domain: cdsmith.wordpress.com, Score: 23, Comments: 5 On Reddit: http://www.reddit.com/r/haskell/comments/f8im5/my_dream_ghci_session_take_2/ Original: http://cdsmith.wordpress.com/2011/01/24/my-dream-ghci-session-take-2/ * Text: a visual programming language based on Haskell, demo Domain: vimeo.com, Score: 20, Comments: 3 On Reddit: http://www.reddit.com/r/haskell/comments/fbgxd/text_a_visual_programming_la… Original: http://vimeo.com/19273744 * Hoogle Embed Domain: neilmitchell.blogspot.com, Score: 16, Comments: 3 On Reddit: http://www.reddit.com/r/haskell/comments/f7iqa/hoogle_embed/ Original: http://neilmitchell.blogspot.com/2011/01/hoogle-embed.html * What does this mean for Haskell on Android? Domain: reddit.com, Score: 15, Comments: 12 On Reddit: http://www.reddit.com/r/haskell/comments/f9o67/what_does_this_mean_for_hask… Original: http://www.reddit.com/r/Android/comments/f97zh/google_not_happy_with_number… * Evolving a computer with Genprog (exercises from the TECS book) Domain: jpmoresmau.blogspot.com, Score: 13, Comments: On Reddit: http://www.reddit.com/r/haskell/comments/f7y6a/evolving_a_computer_with_gen… Original: http://jpmoresmau.blogspot.com/2011/01/evolving-computer-with-tecs-and-genp… * All about MVars : Inside T5 Domain: blog.ezyang.com, Score: 13, Comments: 4 On Reddit: http://www.reddit.com/r/haskell/comments/fduxb/all_about_mvars_inside_t5/ Original: http://blog.ezyang.com/2011/02/all-about-mvars/ * What textbooks would be useful to start approaching the low-hanging fruit on the ghc project? Domain: self.haskell, Score: 12, Comments: 8 On Reddit: http://www.reddit.com/r/haskell/comments/f8dm5/what_textbooks_would_be_usef… Original: /r/haskell/comments/f8dm5/what_textbooks_would_be_useful_to_start/ Top StackOverflow Answers * What is an idiomatic way to add lists in Haskell? Votes: 14 Read on SO: http://stackoverflow.com/questions/4776750/what-is-an-idiomatic-way-to-add-… There is a zipWith library function that combines two lists by using a supplied function. It does exactly what you want here and you get: addLists = zipWith (+) This uses (+) to combine the elements of lists given as further arguments. * Why don't the Haskell standard libraries make more use of polymorphism? Votes: 15 Read on SO: http://stackoverflow.com/questions/4779028/why-dont-the-haskell-standard-li… There is a very good pragmatic reason that "standard" Haskell (Prelude + base + maybe some more) doesn't use more polymorphism: Designing general-use type classes is hard. Good designs for classes that abstract over container types like lists, arrays and "bytestrings" (personally I don't really consider Bytestring a container) aren't floating round waiting … * How do I use fix, and how does it work? Votes: 17 Read on SO: http://stackoverflow.com/questions/4787421/how-do-i-use-fix-and-how-does-it… You are doing nothing wrong. fix id is an infinite loop. When we say that fix returns the least fixed point of a function, we mean that in the domain theory sense. So fix (\x -> 2*x-1) is not going to return 1, because although 1 is a fixed point of that function, it is not the least one in the domain ordering. I can't describe the domain ordering in … Top StackOverflow Questions * Why don't the Haskell standard libraries make more use of polymorphism? votes: 20, answers: 4 Read on SO: http://stackoverflow.com/questions/4779028/why-dont-the-haskell-standard-li… * How do I use fix, and how does it work? votes: 11, answers: 3 Read on SO: http://stackoverflow.com/questions/4787421/how-do-i-use-fix-and-how-does-it… * Why wrapping the Data.Binary.Put monad creates a memory leak? votes: 11, answers: 2 Read on SO: http://stackoverflow.com/questions/4828902/why-wrapping-the-data-binary-put… * Is there any kind of statistical natural language processing library for Haskell? votes: 9, answers: 1 Read on SO: http://stackoverflow.com/questions/4808702/is-there-any-kind-of-statistical… * How do you structure a stateful module in Haskell? votes: 8, answers: 2 Read on SO: http://stackoverflow.com/questions/4785379/how-do-you-structure-a-stateful-… About the Haskell Weekly News You can find an html version of this newsletter at my blog: http://contemplatecode.blogspot.com/2011/02/haskell-weekly-news-issue-167.h… Special thanks to Jean-Philippe Gariepy for sending in a quote for this week's quotes! We need more eyes! To help create new editions of this newsletter, please send stories to dstcruz(a)gmail.com. I'm in dire need of finding good "quotes of the week". If you happen to come across any, please don't hesitate to send it along. Until next time, Daniel Santa Cruz References 1. http://haskell.org/ 2. http://permalink.gmane.org/gmane.comp.lang.haskell.cafe/85566 3. http://permalink.gmane.org/gmane.comp.lang.haskell.cafe/85648 4. https://groups.google.com/d/topic/haskell-cafe/Yd2ADZzonSI/discussion 5. http://permalink.gmane.org/gmane.comp.lang.haskell.cafe/85761 6. https://groups.google.com/d/topic/fa.haskell/T6EM4jbhj8w/discussion

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PhD studentships in Nottingham
by Graham Hutton 31 Jan '11

31 Jan '11

+------------------------------------------------------------------+ PhD Studentships in Functional Programming School of Computer Science University of Nottingham, UK The Functional Programming Lab (FP Lab) in the School of Computer Science at the University of Nottingham is seeking to appoint up to two new PhD students, starting on 1st October 2011. The topics for the studentships are open, but will be within the general area of functional programming. The studentships are for 3.5 years, include a maintenance grant of 13,590 UK pounds per year and UK/EU tuition fees, and are open to UK and EU applicants. Particularly strong candidates from outside the EU may also be considered, subject to additional funds being available. Applicants will require a first-class Honours degree (or equivalent) in Computer Science, Mathematics, and/or Physics, experience in functional programming, and an aptitude for mathematical subjects. A higher degree (e.g. Masters) would be desirable. Additionally, experience in one or more of the following will be particularly welcome: formal semantics, type theory, program verification, theorem provers, domain-specific languages, languages for physical modelling, programming language implementation and tools. Successful applicants will work under the supervision of Dr Graham Hutton or Dr Henrik Nilsson in the FP Lab in Nottingham, a leading centre for research on functional programming. The group currently comprises 5 academic staff, 1 research fellow, and 10 PhD students. In order to apply, please submit the following to Dr Graham Hutton (gmh(a)cs.nott.ac.uk) or Dr Henrik Nilsson (nhn(a)cs.nott.ac.uk) by 1st March 2011: an up-to-date copy of your CV (including the results of all your University examinations to date) along with a brief covering letter that describes your experience in functional programming, your reasons for wishing to pursue a PhD in this area, and any ideas you have regarding possible research directions. Note: applicants to the FP Lab should follow the procedure above, rather than applying directly to the School or University, e.g. in response to a general advert for PhD studentships. Closing date for applications: 1st March 2011. +------------------------------------------------------------------+

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Literate Haskell editing with Emacs and MMM: the $ operator
by Julian Gilbey 30 Jan '11

30 Jan '11

I've been editing literate (LaTeX-based) Haskell code using Emacs and MMM-mode, using the instructions posted in http://www.haskell.org/pipermail/haskell/2006-April/017855.html There's one annoyance, however: the $ operator in Haskell code ends up being interpreted as the beginning of math mode, completely messing up any font-lock colo(u)ring. Has anyone else found this, and has anyone come up with a good solution? Thanks, Julian

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ANNOUNCE: jhc 0.7.7 is out.
by John Meacham 30 Jan '11

30 Jan '11

Announcing jhc 0.7.7! This release fixes a large number of bugs that cropped up when compiling haskell out in the wild as well as adds some more features. A major one being the garbage collector is enabled by default. http://repetae.net/computer/jhc/ Changes: (including some changes from the unannounced 0.7.6 release) * The Garbage Collector is now enabled by default. * new standard libraries * transformers * parsec * QuickCheck * report proper errors with line numbers for various issues with compiled code. * New option '-C' that compiles to C code and stops, useful for targeting other platforms or building shared libraries. * Nintendo Wii added as target (thanks to Korcan Hussein) * Fix major performance bug that kept WRAPPERs from being inlined in certain places. * Typechecking speed greatly increased. * monomorphism-restriction flag is now respected * empty class contexts now work * unicode in haskell source supported now * Type Defaulting now works properly * RULES parse like ghc now for compatibility * 'do' 'where' on same indent now parses * Build system fixes and cleanups * irrefutable lambda pattern bindings desugar properly now. * GHC parsing regression tests have been ported to jhc, helped find and fix many bugs. * Certain optimizations would discard RULES, these have been fixed. * Removed quadratic behavior in optimizer, speeds things up noticibly. * Garbage collector improvements, caches are pre-initialized. * Fix shiftL/R implementations for built in types. * All Num, Real, and Integral magic removed from compiler. This is a very good thing. * improved help messages John

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Internships at MSR Cambridge, summer 2011 and later
by Simon Marlow 28 Jan '11

28 Jan '11

Hi folks, If you're a postgraduate and would like to spend 12 weeks in Cambridge working on a GHC or Haskell-related project, then apply for an internship: we have open slots starting in July this year and later. We've had many successful intern projects over the years. Lots more information here: http://hackage.haskell.org/trac/ghc/wiki/Internships The earliest available slot is the popular July-September summer slot, and for that you would need to have an application in by *Wednesday Feb 16*. However, we can also be flexible about start dates, and if you wanted to start later than July then you have more time to get an application in. By all means apply if you're interested in coming later in the year. Don't forget to email either Simon or myself if you intend to apply. This is very important: otherwise your application gets lost in the system. Cheers, Simon

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