- Haskell - Haskell.org

Haskell Weekly News: Issue 251
by Daniel Santa Cruz 22 Nov '12

22 Nov '12

Welcome to issue 251 of the HWN, an issue covering crowd-sourced bits of information about Haskell from around the web. This issue covers the week of November 4 to 17, 2012. Quotes of the Week * Ralith: [why some people don't use conduits/pipes] also, I think at least some people are waiting for edwardk to write his version. * edwardk: f -| g means that f a -> b is isomorphic to a -> g b (for arrows in the appropriate categories) * edwardk: @type (^.) lambdabot: s -> Getting a s t a b -> a byorgey: I would not like to be getting a stab, thank you * edwardk: I mean we're so oop even our member accessors have diagrams explaining their member accessors. * shapr: hylo! That's the category theorist greeting. * shachaf: type AbstractAlgebra a = Abstract a -> a * nicoo: Yet many Writers concern themselves with issues of State, imaginary or real * rwbarton: when you learn C, watch out for the keyword "return", it doesn't do what you'd expect * Oleg: We show how to program with the law of excluded middle. We specifically avoid call/cc, which is overrated. Top Reddit Stories * Haskell Platform 2012.4.0.0 is out Domain: self.haskell, Score: 89, Comments: 21 On Reddit: [1] http://goo.gl/BPno4 Original: [2] http://goo.gl/BPno4 * A Khan Academy style tutorial on generalized algebraic data types Domain: apfelmus.nfshost.com, Score: 56, Comments: 7 On Reddit: [3] http://goo.gl/kXQ0a Original: [4] http://goo.gl/NWn3B * Cartesian Closed Comic #17: Typing Domain: ro-che.info, Score: 53, Comments: 24 On Reddit: [5] http://goo.gl/6c4Uy Original: [6] http://goo.gl/dZeDx * Cartesian Closed Comic #18: Equality Domain: ro-che.info, Score: 53, Comments: 8 On Reddit: [7] http://goo.gl/8Qf9d Original: [8] http://goo.gl/XCyuB * Natural Language Processing for the Working Programmer (in Haskell!) Domain: nlpwp.org, Score: 50, Comments: 17 On Reddit: [9] http://goo.gl/3yLTZ Original: [10] http://goo.gl/BleWX * Waiting for garbage collection can kill parallelism? Domain: ics.p.lodz.pl, Score: 50, Comments: 7 On Reddit: [11] http://goo.gl/iUPlD Original: [12] http://goo.gl/N0kiV * foldr is made of monoids Domain: byorgey.wordpress.com, Score: 47, Comments: 12 On Reddit: [13] http://goo.gl/Y0mz5 Original: [14] http://goo.gl/IxKov * Solving Cabal Hell: vetted packages, multiple hackages Domain: yesodweb.com, Score: 46, Comments: 67 On Reddit: [15] http://goo.gl/dkzMz Original: [16] http://goo.gl/lDjuj * Parallel falling sand game with Repa Domain: github.com, Score: 45, Comments: 16 On Reddit: [17] http://goo.gl/G6MGG Original: [18] http://goo.gl/cP1zH * Agda, Epigram or Idris. Which one to learn Domain: self.haskell, Score: 38, Comments: 61 On Reddit: [19] http://goo.gl/3PGVo Original: [20] http://goo.gl/3PGVo * Fun with Fay - A ring oscillator Domain: skybluetrades.net, Score: 38, Comments: 6 On Reddit: [21] http://goo.gl/mGvcZ Original: [22] http://goo.gl/bJxCI * Introduction to Category Theory 1: Course Overview Domain: youtube.com, Score: 37, Comments: 6 On Reddit: [23] http://goo.gl/fbfYR Original: [24] http://goo.gl/Nx5SH * HALO: Haskell to Logic through Denotational Semantics [PDF] Domain: research.microsoft.com, Score: 35, Comments: 6 On Reddit: [25] http://goo.gl/V0RWs Original: [26] http://goo.gl/oCzUw * How to write Python in Haskell: State and Either Domain: stackoverflow.com, Score: 34, Comments: 25 On Reddit: [27] http://goo.gl/Z80yb Original: [28] http://goo.gl/W933i * What is foldr made of? Domain: web.jaguarpaw.co.uk, Score: 30, Comments: 22 On Reddit: [29] http://goo.gl/LdS9X Original: [30] http://goo.gl/I2uzX * How to shoot yourself in the foot with Haskell Domain: ics.p.lodz.pl, Score: 29, Comments: 34 On Reddit: [31] http://goo.gl/CcvZB Original: [32] http://goo.gl/SJYvd * Happstack, Fay, & Acid-State: Shared Datatypes are Awesome Domain: happstack.com, Score: 29, Comments: 8 On Reddit: [33] http://goo.gl/AUtj6 Original: [34] http://goo.gl/cYQr1 * ANN: OpenGL packages update Domain: haskell.org, Score: 28, Comments: 7 On Reddit: [35] http://goo.gl/0SN7O Original: [36] http://goo.gl/PbtlT * How can I cleanly/consistently work with 3 different Exception-raising schemes? Domain: self.haskell, Score: 28, Comments: 22 On Reddit: [37] http://goo.gl/Xf4sq Original: [38] http://goo.gl/Xf4sq Top StackOverflow Questions * What are paramorphisms? votes: 39, answers: 1 Read on SO: [39] http://goo.gl/V6rXq * In pure functional languages, is there an algorithm to get the inverse function? votes: 35, answers: 9 Read on SO: [40] http://goo.gl/wBtqv * What are free monads? votes: 26, answers: 5 Read on SO: [41] http://goo.gl/NAx8n * What's the status of current Functional Reactive Programming implementations? votes: 23, answers: 3 Read on SO: [42] http://goo.gl/FmRYF * What does the “world” mean in functional programming world? votes: 22, answers: 7 Read on SO: [43] http://goo.gl/dyM8c * Type-safe difference lists votes: 20, answers: 1 Read on SO: [44] http://goo.gl/TlvF4 * Is it possible to annotate a function's special properties (e.g. surjectivity)? votes: 12, answers: 3 Read on SO: [45] http://goo.gl/uzanF * Under what circumstances are monadic computations tail-recursive? votes: 12, answers: 2 Read on SO: [46] http://goo.gl/lPJef * Should I use new Haskell language extensions in favour of the old ones? votes: 12, answers: 2 Read on SO: [47] http://goo.gl/xkc78 Until next time, Daniel Santa Cruz References 1. http://www.reddit.com/r/haskell/comments/12pxiq/haskell_platform_2012400_is… 2. http://www.reddit.com/r/haskell/comments/12pxiq/haskell_platform_2012400_is… 3. http://apfelmus.nfshost.com/blog/2010/06/01-gadts-video.html 4. http://www.reddit.com/r/haskell/comments/12ou1p/a_khan_academy_style_tutori… 5. http://ro-che.info/ccc/17.html 6. http://www.reddit.com/r/haskell/comments/12nm3w/cartesian_closed_comic_17_t… 7. http://ro-che.info/ccc/18.html 8. http://www.reddit.com/r/haskell/comments/138crz/cartesian_closed_comic_18_e… 9. http://nlpwp.org/book/ 10. http://www.reddit.com/r/haskell/comments/13a0ut/natural_language_processing… 11. http://ics.p.lodz.pl/~stolarek/blog/2012/11/waiting-for-garbage-collection-… 12. http://www.reddit.com/r/haskell/comments/13cpm3/waiting_for_garbage_collect… 13. http://byorgey.wordpress.com/2012/11/05/foldr-is-made-of-monoids/ 14. http://www.reddit.com/r/haskell/comments/12prpr/foldr_is_made_of_monoids/ 15. http://www.yesodweb.com/blog/2012/11/solving-cabal-hell 16. http://www.reddit.com/r/haskell/comments/1306wn/solving_cabal_hell_vetted_p… 17. https://github.com/tranma/falling-turnip 18. http://www.reddit.com/r/haskell/comments/133nja/parallel_falling_sand_game_… 19. http://www.reddit.com/r/haskell/comments/132kg0/agda_epigram_or_idris_which… 20. http://www.reddit.com/r/haskell/comments/132kg0/agda_epigram_or_idris_which… 21. http://www.skybluetrades.net/blog/posts/2012/11/13/fay-ring-oscillator/inde… 22. http://www.reddit.com/r/haskell/comments/134tr6/fun_with_fay_a_ring_oscilla… 23. http://www.youtube.com/watch?v=eu0rj5C2Otg 24. http://www.reddit.com/r/haskell/comments/12vvn2/introduction_to_category_th… 25. http://research.microsoft.com/en-us/people/dimitris/hcc-popl.pdf 26. http://www.reddit.com/r/haskell/comments/12wovt/halo_haskell_to_logic_throu… 27. http://stackoverflow.com/a/13432926/208257 28. http://www.reddit.com/r/haskell/comments/13cz6b/how_to_write_python_in_hask… 29. http://web.jaguarpaw.co.uk/~tom/blog/posts/2012-11-04-what-is-foldr-made-of… 30. http://www.reddit.com/r/haskell/comments/12mnhu/what_is_foldr_made_of/ 31. http://ics.p.lodz.pl/~stolarek/blog/2012/11/how-to-shoot-yourself-in-the-fo… 32. http://www.reddit.com/r/haskell/comments/12rlgt/how_to_shoot_yourself_in_th… 33. http://www.happstack.com/c/view-page-slug/15/happstack-fay-acid-state-share… 34. http://www.reddit.com/r/haskell/comments/1375q0/happstack_fay_acidstate_sha… 35. http://www.haskell.org/pipermail/haskell-cafe/2012-November/104329.html 36. http://www.reddit.com/r/haskell/comments/12mk7h/ann_opengl_packages_update/ 37. http://www.reddit.com/r/haskell/comments/12relk/how_can_i_cleanlyconsistent… 38. http://www.reddit.com/r/haskell/comments/12relk/how_can_i_cleanlyconsistent… 39. http://stackoverflow.com/questions/13317242/what-are-paramorphisms 40. http://stackoverflow.com/questions/13404208/in-pure-functional-languages-is… 41. http://stackoverflow.com/questions/13352205/what-are-free-monads 42. http://stackoverflow.com/questions/13341937/whats-the-status-of-current-fun… 43. http://stackoverflow.com/questions/13340458/what-does-the-world-mean-in-fun… 44. http://stackoverflow.com/questions/13346200/type-safe-difference-lists 45. http://stackoverflow.com/questions/13281316/is-it-possible-to-annotate-a-fu… 46. http://stackoverflow.com/questions/13379060/under-what-circumstances-are-mo… 47. http://stackoverflow.com/questions/13422610/should-i-use-new-haskell-langua…

1 0

[ANN] gtk2hs-0.12.4
by wagnerdm＠seas.upenn.edu 21 Nov '12

21 Nov '12

Today, we welcome into the world version 0.12.4 of Gtk2Hs[1], a set of Haskell bindings to many of the libraries included in the Gtk+/Gnome platform. Gtk+ is an extensive and mature multi-platform toolkit for creating graphical user interfaces. GUIs written using Gtk2Hs use themes to resemble the native look on Windows. Gtk is the toolkit used by Gnome, one of the two major GUI toolkits on Linux. On Mac OS programs written using Gtk2Hs are run by Apple's X11 server but may also be linked against a native Aqua implementation of Gtk. This release is primarily a GHC-7.6 compatibility release, thanks in large part to John Lato. In addition to releases of the core packages, this release includes point updates to gconf and gstreamer. The release has been tested on Linux and Windows with a variety of combinations of Gtk+ and GHC versions. Installation ------------ Assuming you have the necessary Gtk+ base libraries already installed, you can get the basic set of Haskell bindings with these two commands: cabal install gtk2hs-buildtools cabal install gtk Other available packages include gconf, glade, gnomevfs, gstreamer, gtkglext, gtksourceview2, soegtk, svgcairo, vte, and webkit. There are longer-winded instructions that include pointers on getting the Gtk+ base libraries installed on the website [2]. Features -------- * Automatic memory management (unlike some other C/C++ GUI libraries, Gtk+ provides proper support for garbage-collected languages) * Unicode support * High quality vector graphics using Cairo * Extensive reference documentation * An implementation of the ``Haskell School of Expression'' graphics API Community --------- You can keep up with the latest developments on the mailing lists: * gtk2hs-users [3]: discussions about writing code that uses Gtk2Hs * gtk2hs-devel [4]: discussions about modifying the Gtk2Hs bindings * gtk2hs-commit [5]: a read-only mailing list with announcements of every patch to hit the darcs repository Check out the latest code via darcs: darcs get http://code.haskell.org/gtk2hs/ Or complain on the bug tracker [6]. This code was brought to you by: Duncan Coutts Axel Simon Andy Stewart Peter Gavin Jens Petersen John Obbele Hans van Thiel Daniel Wagner Bertram Felgenhauer John Lato ...and many, many more [1] http://projects.haskell.org/gtk2hs/ [2] http://code.haskell.org/gtk2hs/INSTALL [3] https://lists.sourceforge.net/lists/listinfo/gtk2hs-users [4] https://lists.sourceforge.net/lists/listinfo/gtk2hs-devel [5] https://lists.sourceforge.net/lists/listinfo/gtk2hs-commit [6] http://hackage.haskell.org/trac/gtk2hs/

1 0

Tech Mesh alternative programming - London
by Andra Dinu 20 Nov '12

20 Nov '12

Check out the Tech Mesh alternative programming event- London 4th - 6th December: Topics include: · Haskell: practical as well as cool - Co-inventors of Haskell Simon Peyton Jones, Philip Wadler and John Hughes will do a joint keynote about three distinctive aspects of Haskell that might make it worth the bother. · 183 Years of Programming - Co-inventors of Erlang Joe Armstrong, Robert Virding and Mike Williams will be sharing their experience in a joint keynote · The Database as a Value: Rethinking fundamentals of database architecture, in light of the principles of functional programming - Rich Hickey is the author of the Clojure programming language and designer of the Datomic database system · Implementing Riak in Erlang Benefits and Challenges - The choice of using Erlang has resulted in both benefits and challenges to the Basho team and Riak community. Basho Technologies architect Steve Vinoski will tell you all about the process Over 50 speakers will be giving talks on Haskell, Erlang, OTP, Scala, Akka, Raspberry Pi, F#, Go, OCaml and much more. We also have tutorials on Erlang, Scala , Akka and OTP. See the full schedule here: http://techmeshconf.com/techmesh-london-2012/schedule/index.jsp You can get a ticket for Tech Mesh at a 20% discount. All you need to do is register through our website and enter the promotion code TECHMESH_FRIEND. Register here: https://secure.trifork.com/techmesh-london-2012/registration/registration.j… -- Andra Dinu Marketing executive ERLANG SOLUTIONS LTD New Loom House 101 Back Church Lane London, E1 1LU United Kingdom Tel +44(0)2076550344 Mob +44(0)7983484387 www.erlang-solutions.com

1 0

ANNOUNCE: Haskell Communities and Activities Report (23rd ed., November 2012)
by Janis Voigtländer 17 Nov '12

17 Nov '12

On behalf of all the contributors, I am pleased to announce that the Haskell Communities and Activities Report (23rd edition, November 2012) is now available in PDF and HTML formats: http://haskell.org/communities/11-2012/report.pdf http://haskell.org/communities/11-2012/html/report.html Many thanks go to all the people that contributed to this report, both directly, by sending in descriptions, and indirectly, by doing all the interesting things that are reported. I hope you will find it as interesting a read as I did. If you have not encountered the Haskell Communities and Activities Reports before, you may like to know that the first of these reports was published in November 2001. Their goal is to improve the communication between the increasingly diverse groups, projects, and individuals working on, with, or inspired by Haskell. The idea behind these reports is simple: Every six months, a call goes out to all of you enjoying Haskell to contribute brief summaries of your own area of work. Many of you respond (eagerly, unprompted, and sometimes in time for the actual deadline) to the call. The editor collects all the contributions into a single report and feeds that back to the community. When I try for the next update, six months from now, you might want to report on your own work, project, research area or group as well. So, please put the following into your diaries now: ======================================== End of April 2013: target deadline for contributions to the May 2013 edition of the HC&A Report ======================================== Unfortunately, many Haskellers working on interesting projects are so busy with their work that they seem to have lost the time to follow the Haskell related mailing lists and newsgroups, and have trouble even finding time to report on their work. If you are a member, user or friend of a project so burdened, please find someone willing to make time to report and ask them to "register" with the editor for a simple e-mail reminder in April (you could point me to them as well, and I can then politely ask if they want to contribute, but it might work better if you do the initial asking). Of course, they will still have to find the ten to fifteen minutes to draw up their report, but maybe we can increase our coverage of all that is going on in the community. Feel free to circulate this announcement further in order to reach people who might otherwise not see it. Enjoy! Janis Voigtlaender <hcar at haskell.org>

2 1

ANN: hledger-web 0.19
by Simon Michael 17 Nov '12

17 Nov '12

I'm pleased to announce hledger-web 0.19, compatible with the latest hledger and Yesod. Release notes: * web: builds with yesod 1.1.3 * web: obeys command-line query options at startup again * the autogenerated session file is now a dot file (.hledger-web_client_session.aes) hledger is a command-line tool and haskell library for tracking financial transactions, which are stored in a human-readable plain text format. In addition to reporting, it can also help you record new transactions, or convert CSV data from your bank. Add-on packages include hledger-web, a web interface. hledger is inspired by and compatible with John Wiegley's Ledger. For more, see http://hledger.org . Install it: cabal update; cabal install hledger-web For more installation help, see http://hledger.org/MANUAL.html#installing . Or, sponsor a ready-to-run binary for your platform: http://hledger.org/DOWNLOAD.html .

1 0

Announce: Agda 2.3.2
by Andreas Abel 13 Nov '12

13 Nov '12

I am pleased to announce the source release of Agda 2.3.2! http://wiki.portal.chalmers.se/agda/pmwiki.php?n=Main.Download If you have a recent Haskell Platform installed, you can get it with cabal update cabal install Agda agda-mode setup agda-mode compile (The last step is optional.) Highlights from the release-notes: http://wiki.portal.chalmers.se/agda/uploads/Main.Download/release-notes-2-3… * A new backend that produces highlighted LaTeX from a literate agda file. * Improved Emacs interaction mode: - No longer depends on GHCi. - Syntax highlighting is updated while buffer is type-checked. - You can case split on several variables simultaneously. * Syntax extensions: - Pattern synonyms. - Qualified mixfix operators. - Sections and instantiated module imports. * Enhancements of the type checker: - Improved coverage checking. - Improved constraint solving and instance search. Enjoy, Andreas (for the Agda team) -- Andreas Abel <>< Du bist der geliebte Mensch. Theoretical Computer Science, University of Munich Oettingenstr. 67, D-80538 Munich, GERMANY andreas.abel(a)ifi.lmu.de http://www2.tcs.ifi.lmu.de/~abel/

1 0

Call for Papers: PLACES'13 -- Programming Language Approaches to Concurrency and Communication-cEntric Software
by Wim Vanderbauwhede 12 Nov '12

12 Nov '12

CALL FOR PAPERS PLACES'13 Programming Language Approaches to Concurrency and Communication-cEntric Software 23rd March 2013, Rome, Italy (affiliated with ETAPS 2013) http://places13.di.fc.ul.pt/ Applications today are built using numerous interacting services; soon off-the-shelf CPUs will host thousands of cores, and sensor networks will be composed from a large number of processing units. Many applications need to make effective use of thousands of computing nodes. At some level of granularity, computation in such systems is inherently concurrent and communication-centred. To exploit and harness the richness of this computing environment, designers and programmers will utilise a rich variety of programming paradigms, depending on the shape of the data and control flow. Plausible candidates for such paradigms include structured imperative concurrent programming, stream-based programming, concurrent functions with asynchronous message passing, higher-order types for events, and the use of types for communications and data structures (such as session types and linear types), to name but a few. Combinations of these abstractions will be used even in a single application, and the runtime environment needs to ensure seamless execution without relying on differences in available resources such as the number of cores. The development of effective programming methodologies for the coming computing paradigm demands exploration and understanding of a wide variety of ideas and techniques. This workshop aims to offer a forum where researchers from different fields exchange new ideas on one of the central challenges for programming in the near future, the development of programming methodologies and infrastructures where concurrency and distribution are the norm rather than a marginal concern. ** Topics of Interest ** Submissions are invited in the general area of foundations of programming languages for concurrency, communication and distribution. Specific topics include: * language design and implementations for communications and/or concurrency, * session types, * concurrent data types, * concurrent objects and actors, * multicore programming, * use of message passing in systems software, * interface languages for communication and distribution, * program analysis, * web services, * novel programming methodologies for sensor networks, * integration of sequential and concurrent programming, * high-level programming abstractions for security concerns in concurrent, distributed programming, * runtime architectures for concurrency, * scalability and/or resource allocations. Papers are welcome which present novel and valuable ideas as well as experiences. ** Submission Guidelines ** Authors should submit a title and an abstract by Wednesday 14th December 2012. Papers of up to *five pages* in length should be submitted in PDF format by Wednesday 21st December 2012 using the EasyChair proceedings template available at: http://www.easychair.org/easychair.zip Abstracts and papers should be submitted using EasyChair: http://www.easychair.org/conferences/?conf=places2013 Preliminary proceedings will be available at the workshop. The post proceeding will be published as an EPTCS volume. Note that, as we accept short papers, extended versions of the accepted works could be also submitted elsewhere. Enquiries can be sent to the PC co-chairs. ** Important Dates ** Abstract (title & abstract): 14th December 2012 Paper Submission (up to 5 pages): 21st December 2012 Paper Notification: 23rd January 2012 Final versions of papers: 4th February 2012 ** Program Committee ** Alastair Beresford, University of Cambridge, UK Viviana Bono, Universita di Torino, Italy Alastair Donaldson, Imperial College London, UK Dan Ghica, University of Birmingham, UK Joshua Guttman, Worcester Polytechnic Institute, MA, US Thomas Hildebrandt, University of Copenhagen, Denmark Paul Keir, Codeplay Ltd, UK Hans-Wolfgang Loidl, Heriot-Watt University, UK Conor McBride, University of Strathclyde, UK Jeremy Singer, University of Glasgow, UK Sven-Bodo Scholz, Heriot-Watt University, UK Nikhil Swamy, Microsoft Research, US Wim Vanderbauwhede (co-chair), University of Glasgow, UK Hugo Torres Vieira, Universidade de Lisboa, Portugal Nobuko Yoshida (co-chair), Imperial College London, UK ** Organizing Committee ** Alastair Beresford, University of Cambridge, UK Kohei Honda, Queen Mary, University of London, UK Simon Gay, University of Glasgow, UK Alan Mycroft, University of Cambridge, UK Vasco Vasconcelos, University of Lisbon, Portugal Nobuko Yoshida, Imperial College London, UK

1 0

HaXml
by Michael Mossey 11 Nov '12

11 Nov '12

I'm fairly beginnerish. I'm trying to use HaXml with MusicXML. I got a hold of the MusicXML DTD and ran DtdToHaskell. It generated a file which I then attempted to import to a test program. I got a few compiler errors about duplicate definitions and ambiguous definitions. It seemed pretty clear that these resulted from names in the DTD clashing with each other or with existing names, and I just tweaked some of those. Those compile errors went away. However, I have a new set of compiler errors. I'm getting a similar error hundreds of times, namely "Couldn't match expected type Text.XML.HaXml.Types.QName with actual type "String". Poking around, I found this webpage describing an issue with a change to HaXml that happened after version 1.20.2: < http://stackoverflow.com/questions/7501037/how-to-make-haxml-and-drift-work… > This web page suggests that I need to install HaXml-1.20.2 to use it with the current version of the DtdToHaskell utility. Note that I already have the latest version of HaXml installed, so I would need to replace it with an older version. I tried running cabal install HaXml-1.20.2 but got "Ambiguous model name 'Prelude': it was found in multiple packages: base haskel98-2.0.0.1" This sounds like something fundamental about the Haskell packages but I don't know enough to know what to do. Mike

3 2

haskell.org committee: Call for nominations
by Jason Dagit 09 Nov '12

09 Nov '12

Dear Haskellers, The second year of the haskell.org committee is drawing to a close and it is therefore time to seek replacements for those members whose term is expiring. This year one member has a term ending, Ganesh Sittampalam. Ganesh has been an excellent contributor and the rest of the committee would like to thank him for his excellent service. To nominate yourself, please send an e-mail to committee at haskell.org by 30 November 2012. As usual, retiring members are eligible to re-nominate themselves. Please feel free to include any information about yourself that you think will help us to make a decision. Being a member of the committee does not require a significant amount of time, but committee members should aim to be responsive during discussions when the committee is called upon to make a decision. More details about the committee's roles and responsibilities are on http://www.haskell.org/haskellwiki/Haskell.org_committee If you have any questions about the process, please feel free to e-mail us at committee at haskell.org or to contact one of us individually. Regards, Jason On behalf of the haskell.org committee

1 1

Haskell Weekly News: Issue 250
by Daniel Santa Cruz 08 Nov '12

08 Nov '12

Welcome to issue 250 of the HWN, an issue covering crowd-sourced bits of information about Haskell from around the web. This issue covers the week of October 28 to November 3, 2012. Quotes of the Week * Cale: A list is a bit like a loop which hasn't happened yet. This operation is similar to "how do I make the 5th iteration of my loop do something different from the others?" * broombs: Why are there multiple packages for EitherT? broombs: edwardk: which is the better one? edwardk: broombs: either And today, we have our first quote submited via twitter! Thank you @gersei for sending this one in. If you'd like to submit quotes via twitter, add @HWNQuotes to your tweet. * @kmett:We now generate pretty core but have ugly code. Top Reddit Stories * Cartesian Closed Comic #15: Iteratees Domain: ro-che.info, Score: 75, Comments: 2 On Reddit: [1] http://goo.gl/9NpD2 Original: [2] http://goo.gl/SB7HZ * Are there any, or is there interest in starting, an online Haskell course like the Scala course on Coursera? Domain: class.coursera.org, Score: 69, Comments: 16 On Reddit: [3] http://goo.gl/UzBdF Original: [4] http://goo.gl/1Zzct * Why is this simple text processing program so much slower than in dynamic languages? Domain: honza.ca, Score: 65, Comments: 189 On Reddit: [5] http://goo.gl/jW5ow Original: [6] http://goo.gl/pPzIb * Fast Code Nation: The Bright Side of High-Level Languages Domain: bos.github.com, Score: 59, Comments: 11 On Reddit: [7] http://goo.gl/KmBRt Original: [8] http://goo.gl/jm9s7 * Fay slides Domain: fay-lang.org, Score: 56, Comments: 42 On Reddit: [9] http://goo.gl/0UM4T Original: [10] http://goo.gl/h8iZE * Data.Records: extensible records using the latest GHC features Domain: github.com, Score: 55, Comments: 44 On Reddit: [11] http://goo.gl/64wUj Original: [12] http://goo.gl/XVdB2 * Why Cabal Has Problems Domain: softwaresimply.blogspot.com, Score: 50, Comments: 41 On Reddit: [13] http://goo.gl/ZX1Ia Original: [14] http://goo.gl/TgnOG * The cabal/hackage situation, and what you can do about it Domain: alpmestan.com, Score: 49, Comments: 14 On Reddit: [15] http://goo.gl/jEGIj Original: [16] http://goo.gl/EK2DB * Brian O'Sullivan's favorite bug in GHC Domain: twitter.com, Score: 48, Comments: 12 On Reddit: [17] http://goo.gl/nMjeK Original: [18] http://goo.gl/odPH4 * Haskell for all: "Hello, core!" Domain: haskellforall.com, Score: 45, Comments: 6 On Reddit: [19] http://goo.gl/qXRd2 Original: [20] http://goo.gl/9cBeo * Michael Snoyman: Yesod, AngularJS and Fay Domain: yesodweb.com, Score: 43, Comments: 26 On Reddit: [21] http://goo.gl/8yfVd Original: [22] http://goo.gl/0xtPP * Cellular automata as comonads Domain: blog.sigfpe.com, Score: 41, Comments: 10 On Reddit: [23] http://goo.gl/73nr2 Original: [24] http://goo.gl/vH4TK * pipes-2.5: Faster and slimmer Domain: haskellforall.com, Score: 41, Comments: 56 On Reddit: [25] http://goo.gl/wtUZg Original: [26] http://goo.gl/rKR2D Top StackOverflow Questions * Writing cojoin or cobind for n-dimensional grid type votes: 41, answers: 3 Read on SO: [27] http://goo.gl/qbz7z * Why not be dependently typed? votes: 39, answers: 3 Read on SO: [28] http://goo.gl/1TSVh * Concrete example showing that monads are not closed under composition (with proof)? votes: 32, answers: 4 Read on SO: [29] http://goo.gl/sys7F * Monad Transformers vs Passing parameters to functions votes: 24, answers: 1 Read on SO: [30] http://goo.gl/UpU57 * Why is there no IO transformer in Haskell? votes: 16, answers: 2 Read on SO: [31] http://goo.gl/04Xc7 * Is it possible to make GHC optimize (deforest) generic functions such as catamorphisms? votes: 16, answers: 1 Read on SO: [32] http://goo.gl/f4ZlU * Is it possible to use irrefutable tilde (`~`) patterns in lambda expressions? votes: 14, answers: 1 Read on SO: [33] http://goo.gl/BmGY0 * Can Scala's Cake Pattern be implemented in Haskell? votes: 13, answers: 2 Read on SO: [34] http://goo.gl/QiMfg * Confused by the meaning of the 'Alternative' type class and its relationship to other type classes votes: 13, answers: 5 Read on SO: [35] http://goo.gl/RXNuV * How to add fields that only cache something to ADT? votes: 13, answers: 0 Read on SO: [36] http://goo.gl/FjLlX * Type algebra and Knuth's up arrow notation votes: 13, answers: 1 Read on SO: [37] http://goo.gl/kyYIn Until next time, Daniel Santa Cruz References 1. http://ro-che.info/ccc/15.html 2. http://www.reddit.com/r/haskell/comments/11t7ru/cartesian_closed_comic_15_i… 3. https://class.coursera.org/course/progfun 4. http://www.reddit.com/r/haskell/comments/12865b/are_there_any_or_is_there_i… 5. http://honza.ca/2012/10/haskell-strings 6. http://www.reddit.com/r/haskell/comments/120h6i/why_is_this_simple_text_pro… 7. http://bos.github.com/reaktor-dev-day-2012/reaktor-talk-slides.html 8. http://www.reddit.com/r/haskell/comments/11sl47/fast_code_nation_the_bright… 9. http://fay-lang.org/fay-talk/ 10. http://www.reddit.com/r/haskell/comments/11yrpi/fay_slides/ 11. https://github.com/jonsterling/Data.Records 12. http://www.reddit.com/r/haskell/comments/12835b/datarecords_extensible_reco… 13. http://softwaresimply.blogspot.com/2012/11/why-cabal-has-problems.html 14. http://www.reddit.com/r/haskell/comments/12hbzb/why_cabal_has_problems/ 15. http://alpmestan.com/posts/2012-11-02-cabal-hackage-what-you-can-do-about-i… 16. http://www.reddit.com/r/haskell/comments/12ijs7/the_cabalhackage_situation_… 17. https://twitter.com/bos31337/status/116372971509121025 18. http://www.reddit.com/r/haskell/comments/127emo/brian_osullivans_favorite_b… 19. http://www.haskellforall.com/2012/10/hello-core.html 20. http://www.reddit.com/r/haskell/comments/11vuzz/haskell_for_all_hello_core/ 21. http://www.yesodweb.com/blog/2012/10/yesod-fay-js 22. http://www.reddit.com/r/haskell/comments/12ct6p/michael_snoyman_yesod_angul… 23. http://blog.sigfpe.com/2006/12/evaluating-cellular-automata-is.html 24. http://www.reddit.com/r/haskell/comments/11o6nu/cellular_automata_as_comona… 25. http://www.haskellforall.com/2012/10/pipes-25-faster-and-slimmer.html 26. http://www.reddit.com/r/haskell/comments/12gikh/pipes25_faster_and_slimmer/ 27. http://stackoverflow.com/questions/12963733/writing-cojoin-or-cobind-for-n-… 28. http://stackoverflow.com/questions/12961651/why-not-be-dependently-typed 29. http://stackoverflow.com/questions/13034229/concrete-example-showing-that-m… 30. http://stackoverflow.com/questions/12968351/monad-transformers-vs-passing-p… 31. http://stackoverflow.com/questions/13056663/why-is-there-no-io-transformer-… 32. http://stackoverflow.com/questions/13099203/is-it-possible-to-make-ghc-opti… 33. http://stackoverflow.com/questions/13185632/is-it-possible-to-use-irrefutab… 34. http://stackoverflow.com/questions/12947176/can-scalas-cake-pattern-be-impl… 35. http://stackoverflow.com/questions/13080606/confused-by-the-meaning-of-the-… 36. http://stackoverflow.com/questions/13098448/how-to-add-fields-that-only-cac… 37. http://stackoverflow.com/questions/13170803/type-algebra-and-knuths-up-arro…

1 0