September 2013 - Haskell-Cafe

Haskell Weekly News: Issue 281
by Daniel Santa Cruz 26 Sep '13

26 Sep '13

Welcome to issue 281 of the HWN, an issue covering crowd-sourced bits of information about Haskell from around the web. This issue covers the week of September 15 to 21, 2013. Quotes of the Week * jmcarthur: weak algebraic structures? ha! i prefer my algebraic structures to put up more of a fight. * newsham: teach a man to pred and he will pred to zero. teach a man to succ and he will succ forever Top Reddit Stories * Edward C++Hands Domain: bartoszmilewski.com, Score: 83, Comments: 102 On Reddit: [1] http://goo.gl/64LLo4 Original: [2] http://goo.gl/0H0yr7 * Perfect streaming using `pipes-bytestring` Domain: haskellforall.com, Score: 59, Comments: 45 On Reddit: [3] http://goo.gl/oSlzZP Original: [4] http://goo.gl/8xwZjc * Adding safe coercions to Haskell Domain: joachim-breitner.de, Score: 58, Comments: 23 On Reddit: [5] http://goo.gl/2vs5M9 Original: [6] http://goo.gl/n0RYA3 * Which programming languages do you like besides Haskell, and why? Domain: self.haskell, Score: 55, Comments: 104 On Reddit: [7] http://goo.gl/nzgwJQ Original: [8] http://goo.gl/nzgwJQ * GHC HEAD: merged checkable "minimal complete definitions" (#7633) Domain: ghc.haskell.org, Score: 48, Comments: 36 On Reddit: [9] http://goo.gl/VoZVYL Original: [10] http://goo.gl/5F61AX * Do companies ever hire someone who has no Haskell experience to be a Haskell programmer? If I pursue such a job, how important would a Domain: self.haskell, Score: 44, Comments: 50 On Reddit: [11] http://goo.gl/KA998k Original: [12] http://goo.gl/KA998k * [Haskell-cafe] PSA: do not install xcode 5 if you are using ghc 7.6 Domain: haskell.org, Score: 43, Comments: 4 On Reddit: [13] http://goo.gl/ut6k6p Original: [14] http://goo.gl/1G8Syo * Model Analysis - The New York Times’ Erik Hinton breaks down a Fashion Week special Domain: source.mozillaopennews.org, Score: 40, Comments: 4 On Reddit: [15] http://goo.gl/NdVw6l Original: [16] http://goo.gl/bYB8JS * Programming reactively with both barrels (experiences of Haskell/FRP for mobile games) Domain: blog.reactiveprogramming.org, Score: 39, Comments: 7 On Reddit: [17] http://goo.gl/QXacUo Original: [18] http://goo.gl/wLJwt6 * Why monads have not taken the Common Lisp world by storm [r/lisp] Domain: reddit.com, Score: 33, Comments: 14 On Reddit: [19] http://goo.gl/tZUVWx Original: [20] http://goo.gl/w5KHqc * 13,000 readers Domain: self.haskell, Score: 28, Comments: 11 On Reddit: [21] http://goo.gl/lTys0R Original: [22] http://goo.gl/lTys0R * A type for IO actions that do not throw exceptions Domain: self.haskell, Score: 25, Comments: 49 On Reddit: [23] http://goo.gl/Ao8HyB Original: [24] http://goo.gl/Ao8HyB * ANN: Scotty 0.5.0 Released Domain: github.com, Score: 24, Comments: 15 On Reddit: [25] http://goo.gl/jgGJhO Original: [26] http://goo.gl/BejPTF * Haskell version freezing Domain: blog.docmunch.com, Score: 23, Comments: 8 On Reddit: [27] http://goo.gl/9LJSjY Original: [28] http://goo.gl/Ikd86k * PHOAS For Free by Edward Kmett Domain: fpcomplete.com, Score: 21, Comments: 8 On Reddit: [29] http://goo.gl/RDt1BV Original: [30] http://goo.gl/o0phN7 * Cellular Automata, Part III by Edward Kmett Domain: fpcomplete.com, Score: 20, Comments: 0 On Reddit: [31] http://goo.gl/AKCfGw Original: [32] http://goo.gl/x7GtH1 * Translating Haskell programs to Coq [/Gallina] programs Domain: github.com, Score: 20, Comments: 2 On Reddit: [33] http://goo.gl/IQAp3K Original: [34] http://goo.gl/qcib77 * ANN: pipes-csv: a fast, streaming csv parser based on cassava and pipes Domain: github.com, Score: 20, Comments: 9 On Reddit: [35] http://goo.gl/aITtGX Original: [36] http://goo.gl/yrzZ7n Top StackOverflow Questions * What does the “Just” syntax mean in Haskell? votes: 12, answers: 4 Read on SO: [37] http://goo.gl/f17UEP * How can I understand “:t ((==) <*>)” in haskell? votes: 10, answers: 1 Read on SO: [38] http://goo.gl/CwyBn4 * why polymorphism is so costly in haskell(GHC)? votes: 10, answers: 3 Read on SO: [39] http://goo.gl/4MjcbH * Break and continue in GHCi debugger without use of breakpoints votes: 9, answers: 0 Read on SO: [40] http://goo.gl/HrtcXZ * Why is there no `-XDeriveApplicative` extension? votes: 8, answers: 1 Read on SO: [41] http://goo.gl/4dcRF1 * Downsides to ScopedTypeVariables votes: 7, answers: 2 Read on SO: [42] http://goo.gl/UjBcsg * Haskell design encompassing several monads votes: 7, answers: 1 Read on SO: [43] http://goo.gl/EwWd5d * How to correct my OOP tendencies when programming in Haksell votes: 7, answers: 3 Read on SO: [44] http://goo.gl/9JVqh7 * composing functions with higher arity votes: 7, answers: 5 Read on SO: [45] http://goo.gl/jQjNJW * Why are Haskell Maps implemented as balanced binary trees instead of traditional hashtables? votes: 7, answers: 3 Read on SO: [46] http://goo.gl/nZaLGV Until next time, [47]+Daniel Santa Cruz References 1. http://bartoszmilewski.com/2013/09/19/edward-chands/ 2. http://www.reddit.com/r/haskell/comments/1mqni1/edward_chands/ 3. http://www.haskellforall.com/2013/09/perfect-streaming-using-pipes-bytestri… 4. http://www.reddit.com/r/haskell/comments/1msinm/perfect_streaming_using_pip… 5. http://www.joachim-breitner.de/blog/archives/610-Adding-safe-coercions-to-H… 6. http://www.reddit.com/r/haskell/comments/1mfz8z/adding_safe_coercions_to_ha… 7. http://www.reddit.com/r/haskell/comments/1mvb2e/which_programming_languages… 8. http://www.reddit.com/r/haskell/comments/1mvb2e/which_programming_languages… 9. http://ghc.haskell.org/trac/ghc/ticket/7633#comment:28 10. http://www.reddit.com/r/haskell/comments/1mp434/ghc_head_merged_checkable_m… 11. http://www.reddit.com/r/haskell/comments/1mtcox/do_companies_ever_hire_some… 12. http://www.reddit.com/r/haskell/comments/1mtcox/do_companies_ever_hire_some… 13. http://www.haskell.org/pipermail/haskell-cafe/2013-September/108902.html 14. http://www.reddit.com/r/haskell/comments/1ml97r/haskellcafe_psa_do_not_inst… 15. http://source.mozillaopennews.org/en-US/learning/model-analysis/ 16. http://www.reddit.com/r/haskell/comments/1mlgwd/model_analysis_the_new_york… 17. http://blog.reactiveprogramming.org/?p=107 18. http://www.reddit.com/r/haskell/comments/1moob5/programming_reactively_with… 19. http://www.reddit.com/r/lisp/comments/1mkqvj/why_monads_have_not_taken_the_… 20. http://www.reddit.com/r/haskell/comments/1mn6vb/why_monads_have_not_taken_t… 21. http://www.reddit.com/r/haskell/comments/1modra/13000_readers/ 22. http://www.reddit.com/r/haskell/comments/1modra/13000_readers/ 23. http://www.reddit.com/r/haskell/comments/1mpsvj/a_type_for_io_actions_that_… 24. http://www.reddit.com/r/haskell/comments/1mpsvj/a_type_for_io_actions_that_… 25. https://github.com/xich/scotty/blob/master/ReleaseNotes.md 26. http://www.reddit.com/r/haskell/comments/1mr9hf/ann_scotty_050_released/ 27. http://blog.docmunch.com/blog/2013/haskell-version-freezing 28. http://www.reddit.com/r/haskell/comments/1mjldi/haskell_version_freezing/ 29. https://www.fpcomplete.com/user/edwardk/phoas 30. http://www.reddit.com/r/haskell/comments/1mo59h/phoas_for_free_by_edward_km… 31. https://www.fpcomplete.com/user/edwardk/cellular-automata/part-3 32. http://www.reddit.com/r/haskell/comments/1mfaqx/cellular_automata_part_iii_… 33. https://github.com/gdijkstra/hs-to-gallina/blob/master/docs/report/report.p… 34. http://www.reddit.com/r/haskell/comments/1miawm/translating_haskell_program… 35. https://github.com/jb55/pipes-csv 36. http://www.reddit.com/r/haskell/comments/1mvbk7/ann_pipescsv_a_fast_streami… 37. http://stackoverflow.com/questions/18808258/what-does-the-just-syntax-mean-… 38. http://stackoverflow.com/questions/18813431/how-can-i-understand-t-in-haske… 39. http://stackoverflow.com/questions/18854866/why-polymorphism-is-so-costly-i… 40. http://stackoverflow.com/questions/18876128/break-and-continue-in-ghci-debu… 41. http://stackoverflow.com/questions/18861231/why-is-there-no-xderiveapplicat… 42. http://stackoverflow.com/questions/18852341/downsides-to-scopedtypevariables 43. http://stackoverflow.com/questions/18866558/haskell-design-encompassing-sev… 44. http://stackoverflow.com/questions/18867620/how-to-correct-my-oop-tendencie… 45. http://stackoverflow.com/questions/18905867/composing-functions-with-higher… 46. http://stackoverflow.com/questions/18908639/why-are-haskell-maps-implemente… 47. https://plus.google.com/105107667630152149014/about

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Haskell Weekly News: Issue 280
by Daniel Santa Cruz 25 Sep '13

25 Sep '13

Welcome to issue 280 of the HWN, an issue covering crowd-sourced bits of information about Haskell from around the web. This issue covers the week of September 8 to 14, 2013. Quotes of the Week * haasn: edwardk uses things in anger. shachaf uses them with disappointment :( * shachaf: Are you reading Mac Lane now? Saizan: yeah, it's not so bad if you skip the examples Top Reddit Stories * For my 17th birthday, my best friend got me "The most obscure programming book I could find" as a joke. I know what language I am learning next! Domain: i.imgur.com, Score: 163, Comments: 67 On Reddit: [1] http://goo.gl/0SyN5l Original: [2] http://goo.gl/oqGBzL * pipes-4.0: Simpler types and API Domain: haskellforall.com, Score: 95, Comments: 36 On Reddit: [3] http://goo.gl/ciVnq5 Original: [4] http://goo.gl/g9oq3i * Hackage 2 now available for beta testing -- switchover in a few weeks Domain: beta.hackage.haskell.org, Score: 91, Comments: 17 On Reddit: [5] http://goo.gl/aIhL67 Original: [6] http://goo.gl/zfprr9 * Cartesian Closed Comic #22: Cabal 1.18 Domain: ro-che.info, Score: 90, Comments: 3 On Reddit: [7] http://goo.gl/tVUUFG Original: [8] http://goo.gl/O0BR6c * Parallel and Incremental CRCs by Edward Kmett Domain: fpcomplete.com, Score: 58, Comments: 7 On Reddit: [9] http://goo.gl/YAChJl Original: [10] http://goo.gl/WnMsbY * Conquering Folds by Edward Kmett Domain: fpcomplete.com, Score: 47, Comments: 42 On Reddit: [11] http://goo.gl/reAjgu Original: [12] http://goo.gl/kHsSye * Conal Elliot: From Haskell to hardware via cartesian closed categories Domain: conal.net, Score: 47, Comments: 3 On Reddit: [13] http://goo.gl/VCwp7Y Original: [14] http://goo.gl/NO1sbs * FP Complete to release a personal edition of their online IDE Domain: fpcomplete.com, Score: 39, Comments: 38 On Reddit: [15] http://goo.gl/QOMy5Y Original: [16] http://goo.gl/XBE7zT * Quark : A Web Browser with a Formally Verified Kernel Domain: goto.ucsd.edu, Score: 36, Comments: 6 On Reddit: [17] http://goo.gl/RDZMY0 Original: [18] http://goo.gl/rgBcki * My first Haskell program - FNIStash - a utility for Torchlight 2 using threepenny for the GUI Domain: fluffynukeit.com, Score: 36, Comments: 19 On Reddit: [19] http://goo.gl/cK2N8v Original: [20] http://goo.gl/XOMTgQ * Conal Elliott: Overloading lambda Domain: conal.net, Score: 34, Comments: 4 On Reddit: [21] http://goo.gl/fQTt1P Original: [22] http://goo.gl/oPSQ3R * Cost semantics for STG in modern GHC Domain: blog.ezyang.com, Score: 31, Comments: 5 On Reddit: [23] http://goo.gl/mIQQxm Original: [24] http://goo.gl/5Sa49T * 0install - Python vs. OCaml vs. Haskell Domain: roscidus.com, Score: 31, Comments: 23 On Reddit: [25] http://goo.gl/htCf1x Original: [26] http://goo.gl/zhrVp0 * LogicGrowsOnTrees: a parallel implementation of logic programming using distributed tree exploration Domain: github.com, Score: 31, Comments: 9 On Reddit: [27] http://goo.gl/zp5lou Original: [28] http://goo.gl/5BgYh2 * RSS reader made by Haskell running on mbed platform (RAM size 64kB, using Ajhc Haskell compiler). Domain: youtube.com, Score: 30, Comments: 5 On Reddit: [29] http://goo.gl/n0Gkan Original: [30] http://goo.gl/cwL4vP * Conal Elliott: Optimizing CCCs Domain: conal.net, Score: 30, Comments: 12 On Reddit: [31] http://goo.gl/HVv8dr Original: [32] http://goo.gl/MCn0sO * Snap (and Heist) 0.13 released Domain: snapframework.com, Score: 29, Comments: 7 On Reddit: [33] http://goo.gl/zW5Sdn Original: [34] http://goo.gl/1wSLeJ * ANN: threepenny-gui-0.3 – GUI framework that uses the web browser as a display – now with FRP built-in Domain: apfelmus.nfshost.com, Score: 28, Comments: 8 On Reddit: [35] http://goo.gl/RUDrKD Original: [36] http://goo.gl/WZMeZN Top StackOverflow Questions * In Haskell, where does the range ['a'..] stop? votes: 20, answers: 2 Read on SO: [37] http://goo.gl/Oms7lr * Why were Haskell 98's standard classes made inferior to Haskell 1.3's? votes: 18, answers: 1 Read on SO: [38] http://goo.gl/WxvdL2 * 27 different Bool to Bool values in Haskell votes: 14, answers: 1 Read on SO: [39] http://goo.gl/1PcD1g * How to reconstruct Haskell expression from type votes: 10, answers: 1 Read on SO: [40] http://goo.gl/Qx06kz * Can links to anchors in haddock be labeled? votes: 8, answers: 0 Read on SO: [41] http://goo.gl/5deOMM * How to convert between ByteString and Storable Vector? votes: 7, answers: 1 Read on SO: [42] http://goo.gl/zBVVzI * Why is not GHC optimizing for constants? votes: 7, answers: 2 Read on SO: [43] http://goo.gl/sfo64S * newtype around ST causes type error votes: 7, answers: 1 Read on SO: [44] http://goo.gl/CwXaJp * GHC does not generate a binary despite no errors shown votes: 6, answers: 1 Read on SO: [45] http://goo.gl/PAv1oQ Until next time, [46]+Daniel Santa Cruz References

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Mystery of an Eq instance
by damodar kulkarni 24 Sep '13

24 Sep '13

Hello, There were some recent discussions on the floating point support in Haskell and some not-so-pleasant "surprises" people encountered. There is an Eq instance defined for these types! So I tried this: *Main> sqrt (10.0) ==3.1622776601683795 True *Main> sqrt (10.0) ==3.16227766016837956 True *Main> sqrt (10.0) ==3.1622776601683795643 True *Main> sqrt (10.0) ==3.16227766016837956435443343 True It seems strange. So my doubts are: 1. I wonder how the Eq instance is defined in case of floating point types in Haskell? 2. Can the Eq instance for floating point types be considered "meaningful"? If yes, how? In general, programmers are **advised** not to base conditional branching on tests for **equality** of two floating point values. 3. Is this particular behaviour GHC specific? (I am using GHC 6.12.1) If there are references on this please share. Thanks and regards, -Damodar Kulkarni

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Hackathon der Frankfurt-Haskell-User-Group
by Peter Althainz 24 Sep '13

24 Sep '13

the Frankfurt Haskell User Group announces its first Hackathon, if interested, see here: http://www.meetup.com/Frankfurt-Haskell-User-Group/events/138895112/ Peter Althainz

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Strange exit status behavior from the process package
by Michael Xavier 23 Sep '13

23 Sep '13

I've run into some strangeness with the process package. When you kill some processes on the command line you correctly get a non-zero exit status. However when using the process package's terminateProcess (which sends a SIGTERM), it returns an ExitSuccess: module Main (main) where import Control.Concurrent (threadDelay) import System.Process (createProcess, proc, getProcessExitCode, terminateProcess) main :: IO () main = do (_, _, _, ph) <- createProcess $ proc "/usr/bin/sleep" ["100"] terminateProcess ph threadDelay 1000000 print =<< getProcessExitCode ph -- prints Just ExitSuccess, should be Just (ExitFailure 143) term1: sleep 100 term2: pkill sleep term1: echo $? # 143 Anyone know what might be going on? -- Michael Xavier http://www.michaelxavier.net

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Creating a local Hoogle ...
by aditya siram 23 Sep '13

23 Sep '13

Hi all, I've installed Hoogle but am having issues creating the databases. I first did: `hoogle data all`, tried a search `hoogle "[a] -> a" and got: Could not find some databases: default Searching in: . ~/.cabal/share/hoogle-4.2.21/databases Either the package does not exist or has not been generated Found 4263 databases, including: abacate abcnotation abortt-monadstf abortt-mtl abortt-transformers So to create th default database I did: `hoogle combine *.hoo` and then got: Combining 4263 databases hoogle: embroidery.hoo: openFile: resource exhausted (Too many open files) Any help is appreciated. Thanks! -deech

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Embedding compiled Haskell Platform in custom application
by blackbox.dev.ml 23 Sep '13

23 Sep '13

Hi! I'm writing a tool that generates haskell code, build it with cabal and launch it. I want to deliver that tool to clients, but I don't want to force them, to install system wide any specific ghc or cabal version. How can I embed compiled ghc, cabal and selected libraries (for specific platform) in installer of my application?

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PSA: do not install xcode 5 if you are using ghc 7.6
by Carter Schonwald 23 Sep '13

23 Sep '13

Hey everyone, if you are actively using ghc 7.6 on your mac, for now please do not install xcode 5. It will break your ghc install, because 7.6 doesn't know how to correctly use Clang for the CPP work. (ghc head / and thus 7.8 will work fine with xcode 5, thanks to some outstanding work by Austin Seipp, 7.6 does not) if you do not need xcode 5, and you're actively using ghc 7.6, stay with xcode 4.6 for now. if you installed xcode 5 because its there, and now your ghc 7.6 is occasionally giving you strange errors involving CPP parse failures on fragments like "#-}", you should go to the apple developers website, download, and reinstall the xcode 4.6 CLI tools. if you need both xcode 5 and ghc in working order *right now, tomorrow*, either a) live on the wildside: test out using ghc head: also means you could play with ghc-ios too! b) if you need both in working order now, and stabilish, Darin Morrison has a set of mac-homebrew taps that should be you use https://github.com/darinmorrison/homebrew-haskell these taps should be regarded as more "official" and "canonical" than the formula's that brew provides (the normal brew ones recurrently have problems induced by folks who aren't haskell devs) c) wait a wee bit till 7.8 lands in all its glory, and have both the freshest of xcodes, and the newest of awesome ghcs tl;dr if you don't need xcode 5, having xcode 4.6 CLI tools installed will stand you in good stead. if you are on os x mavericks, or absolutely need xcode 5 installed, and you want a ghc thats already released, use darin's brew formulae https://github.com/darinmorrison/homebrew-haskell Darin and I plan to spend some time next month preparing an unofficial patched version of ghc 7.6 that should play nice with clang / xcode 5, though at such a time ghc 7.8 will be in RC status at the very least. cheers -Carter

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A thought on the LinkedIn spam and an "upstream spam filter"
by damodar kulkarni 23 Sep '13

23 Sep '13

Hello, Sorry for dwelling on a "spammy" topic. If you are NOT interested in this then please accept my regret and let me assure you that this is NOT to add to the existing spam. If you still are unconvinced, then the only thing I can tell you is "sorry, accept my apologies for wasting your time and please stop reading further." Okay, here is what I thought of it. Yesterday I sent a mail as a response to a spam from LinkedIn to the cafe. I don't know how, but part of my mail text was missing. (I must have pressed Ctrl-C instead of Ctrl-V to paste the text from another file.) I had thought of an idea which I call "upstream spam filter". Anyway here is the text: I thought, some people here on the list, who might have links with the higher-ups at linked-in might bring the issue to their notice and would make them *register* the Haskell-Cafe list on their server so that they never send a spam to the entire list. They should install such an "upstream spam filter". This "upstream spam filter" based solution would be more effective in culling spam as compared to solutions based on requesting/heckling individual linked-in subscribers to take some action at his/her end. Note that here the individual may or may not be doing intentional spamming BUT the linkedin is *hiding* behind the subscribers' ignorance. I propose that more *influential* people on the list demand that the linked-in company should provide a way to register some emails (e.g. mailing lists) which they SHOULD spare from their spamming machines. I have already tried communicating with them but was unsuccessful. Is there any DND like service, at least, to force these big companies (like linked-in), who are happily spamming the world, behave properly?[1] Please send such protest mails to the personal email ids of the linked-in (and other such companies) top brass or other linkedin top level technical staff, if you know them. If anybody on this list is working for linkedin, then this mail is for you too. [1] http://en.wikipedia.org/wiki/Do_Not_Disturb_%28telecommunications%29 Thanks and regards, -Damodar Kulkarni On Mon, Sep 23, 2013 at 12:43 AM, MigMit <miguelimo38(a)yandex.ru> wrote: > So, instead of emailing this guy and asking him to change the address in > his LinkedIn profile (which is simple, since he did write a lot to café), > you decided to continue spamming the mailing list. > > Nice > > Отправлено с iPad > > 22 сент. 2013 г., в 21:31, damodar kulkarni <kdamodar2000(a)gmail.com> > написал(а): > > What a surprise, I didn't know the real name of "Haskell Cafe" till date, > BUT today I came to know it: it is Minh Thu V. > > linked in sucks ... > > > Thanks and regards, > -Damodar Kulkarni > > > On Sun, Sep 22, 2013 at 2:53 PM, Kyle Hanson via LinkedIn < > member(a)linkedin.com> wrote: > >> >> [image: LinkedIn] >> <http://www.linkedin.com/e/uc6lxc-hlw276p4-5e/hom/?hs=false&tok=1F1OVFpS1PWl…> >> >> >> >> >> Hi Minh Thu, >> >> I'd like to connect with you on LinkedIn. >> >> Accept<http://www.linkedin.com/e/uc6lxc-hlw276p4-5e/XvIdBwmueHfd6vFMPXXdLaqreCbl5o…> >> >> View Profile<http://www.linkedin.com/e/uc6lxc-hlw276p4-5e/rso/60831967/_LLG/name/2272454…> >> >> >> >> >> <http://www.linkedin.com/e/uc6lxc-hlw276p4-5e/rso/60831967/_LLG/name/2272454…> >> >> Kyle Hanson<http://www.linkedin.com/e/uc6lxc-hlw276p4-5e/rso/60831967/_LLG/name/2272454…> >> >> Engineer at eShares, Inc. >> >> Greater Chicago Area >> >> >> >> You are receiving Invitation emails. Unsubscribe<https://www.linkedin.com/e/uc6lxc-hlw276p4-5e/XvIdBwmueHfd6vFMPXXdLaqreCbl5…>. >> >> >> This email was intended for Minh Thu Vo (Core/Server Lead Developer at >> OpenERP). Learn why we included this<http://www.linkedin.com/e/uc6lxc-hlw276p4-5e/plh/http%3A%2F%2Flinkedin%2Ecu…>. >> © 2013, LinkedIn Corporation. 2029 Stierlin Ct. Mountain View, CA 94043, >> USA >> >> >> _______________________________________________ >> Haskell-Cafe mailing list >> Haskell-Cafe(a)haskell.org >> http://www.haskell.org/mailman/listinfo/haskell-cafe >> >> > _______________________________________________ > Haskell-Cafe mailing list > Haskell-Cafe(a)haskell.org > http://www.haskell.org/mailman/listinfo/haskell-cafe > >

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GSoC Result - Communicating with Mobile devices - Push Notifications
by Marcos Pividori 23 Sep '13

23 Sep '13

I am happy to announce the result of 3 months working on the GSoC project: "Communicating with mobile devices". After reading many documentation, looking for a good abstraction, learning about mobile apps and networks connections, and really valuable recommendations from my mentor, (I really want to thank Michael Snoyman for his availability and kindness) I succeeded in developing 3 libraries to make it easy to send push notifications to mobile devices. They are available on Hackage: ** push-notify-0.1.0.0 : *This library offers a simple API for sending notifications through APNS, GCM and MPNS. [1]<http://hackage.haskell.org/package/push-notify-0.1.0.0> ** push-notify-ccs-0.1.0.0 :* This library offers an API for sending/receiving notifications through CCS (XMPP - Google Cloud Messaging). [2] <http://hackage.haskell.org/package/push-notify-ccs-0.1.0.0> ** push-notify-general-0.1.0.0 : *This library offers a general API for sending/receiving notifications, and handling the registration of devices on the server. It provides a general abstraction which can be used to communicate through different services as APNS, GCM, MPNS, hiding as much as possible, the differences between them. [3]<http://hackage.haskell.org/package/push-notify-general> Now, it is easy to send/receive information with mobile devices, so you can develop server applications which interact with them. So, to clarify this, as part of this project, I developed many test examples, including Android/WPhone and Yesod apps. I really want to thank FPComplete for giving me the possibility of hosting the Yesod app. The code is available on GitHub: [4]<https://github.com/MarcosPividori/GSoC-Communicating-with-mobile-devices> and they are running online on: [5] <http://gsoc.marcospividori.com.ar/> , so can be downloaded and tested on mobile devices. (BackAndForth Messaging and Connect4 apps) ** BackAndForth Messaging:* In this example, I show how to use the push-general library to handle the registration/reception and sending of messages. From a Yesod app [5]<http://gsoc.marcospividori.com.ar/>, you can send notifications to devices registered and receive messages from them. It is avaliable for Android and WPhone on [6]<http://gsoc.marcospividori.com.ar/apps> . ** Connect 4:* I have been thinking of an app which lets me show how useful push notifications are. The advantage of this notifications is that you can receive information from server when it is available without needing to continually poll. So, I started to think about a multiplayers game. Every time a player does something, you let the rest know about the new movement. So, I ran into the board game: "Connect 4". Both, authenticated web players and users of the android app, can play one against each other. For actualizing the website [5] <http://gsoc.marcospividori.com.ar/> , I use long polling, while for the Android app, push notifications. The Android app is available on [6]<http://gsoc.marcospividori.com.ar/apps> . Every feedback is welcome! Thanks, Marcos [1] http://hackage.haskell.org/package/push-notify-0.1.0.0 [2] http://hackage.haskell.org/package/push-notify-ccs-0.1.0.0 [3] http://hackage.haskell.org/package/push-notify-general [4] https://github.com/MarcosPividori/GSoC-Communicating-with-mobile-devices [5] http://gsoc.marcospividori.com.ar [6] http://gsoc.marcospividori.com.ar/apps

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