Welcome to issue 266 of the HWN, an issue covering crowd-sourced bits of information about Haskell from around the web. This issue covers the week of April 7 to 27, 2013. Quotes of the Week * hpc: the dirty secret of haskell programmers is that their power does not come from their PhD, but their bowtie * tibbe: I think I have implemented a reverse state monad by mistake. The numbers suggest I'm getting the values tunneled back from the future. :/ * SaulGorn: A formalist is one who cannot understand a theory unless it is meaningless. * cmccann: laziness by default is a shortcoming. eagerness by default is a bigger shortcoming. * monochrom: #haskell-blah has brilliant people too. for example me. * limo: OK, guys was nice meeting you and now I'm a proud owner of a GHCi icon on my desktop * otters: lens law #1: the implementation must be shorter than the type * MartinDeMello: Any sufficiently well-commented Lisp program contains an ML program in its comments. * tgeeky: whatever man. Jesus only had twelve or so deciples, lens has 80! * SatnamSingh: I always thought that category theory was something that happened to other people. (#ICFP) * cmccann: see the thing is tabs are good for indentation. haskell doesn't use indentation, it uses alignment. it is not indenting. it is ASCII art. * JohnVonNeumann: In mathematics you don't understand things. You just get used to them. * edwardk: you can view Yoneda f as enforced fmap fusion and Codensity f as enforced bind fusion. Top Reddit Stories * Functors, applicatives, and monads in pictures Domain: adit.io, Score: 136, Comments: 67 On Reddit: [1] http://goo.gl/xRC6K Original: [2] http://goo.gl/QcfqM * What I Wish I Knew When Learning Haskell, Stephen Diehl [39 slides, Left/Rgt-arrow key to back/advance] Domain: dev.stephendiehl.com, Score: 119, Comments: 37 On Reddit: [3] http://goo.gl/T8uzi Original: [4] http://goo.gl/eZTA0 * git clone in Haskell from the bottom up Domain: stefan.saasen.me, Score: 86, Comments: 6 On Reddit: [5] http://goo.gl/Al86J Original: [6] http://goo.gl/nWSXV * Vinyl: Modern Records for Haskell Domain: jonmsterling.com, Score: 56, Comments: 27 On Reddit: [7] http://goo.gl/pSUph Original: [8] http://goo.gl/ra0Jb * Follow-up: Web Woes for Haskell Domain: self.haskell, Score: 49, Comments: 9 On Reddit: [9] http://goo.gl/PJZEA Original: [10] http://goo.gl/PJZEA * What does “coalgebra” mean in the context of programming? (StackOverflow) Domain: stackoverflow.com, Score: 45, Comments: 23 On Reddit: [11] http://goo.gl/nMqBF Original: [12] http://goo.gl/UH2Wl * The Mother of all Monads - School of Haskell Domain: self.haskell, Score: 42, Comments: 27 On Reddit: [13] http://goo.gl/XO7mQ Original: [14] http://goo.gl/XO7mQ * Why do all the Haskell Web Frameworks rely on Template Haskell? Domain: self.haskell, Score: 40, Comments: 59 On Reddit: [15] http://goo.gl/v5p6F Original: [16] http://goo.gl/v5p6F * Job opening for Haskell developer in Nijmegen (NL) Domain: self.haskell, Score: 39, Comments: 6 On Reddit: [17] http://goo.gl/Uzqs8 Original: [18] http://goo.gl/Uzqs8 * Tutorial: Building a Sample Application with Haskell Snap, PostgreSQL, and the PostgreSQL Simple Snaplet Domain: janrain.com, Score: 39, Comments: 17 On Reddit: [19] http://goo.gl/TAM6J Original: [20] http://goo.gl/37Nry * Haskell for all: Defaults Domain: haskellforall.com, Score: 38, Comments: 20 On Reddit: [21] http://goo.gl/7NYex Original: [22] http://goo.gl/FqiuW * Haskell for all: pipes-concurrency-1.0.0: Reactive programming Domain: haskellforall.com, Score: 38, Comments: 23 On Reddit: [23] http://goo.gl/DaSaZ Original: [24] http://goo.gl/eGw3F * Haskell in Ipython Domain: github.com, Score: 38, Comments: 7 On Reddit: [25] http://goo.gl/Y7DEP Original: [26] http://goo.gl/324JX * A taste of Curry (Wolfgang Jeltsch) Domain: jeltsch.wordpress.com, Score: 38, Comments: 0 On Reddit: [27] http://goo.gl/Ijh6Y Original: [28] http://goo.gl/17Ry1 * Complete and Easy Bidirectional Typechecking for Higher-Rank Polymorphism Domain: semantic-domain.blogspot.co.uk, Score: 37, Comments: 21 On Reddit: [29] http://goo.gl/Yv9RY Original: [30] http://goo.gl/qW1Qq * Template Haskell on impossible architectures (x-post from r/programming) Domain: joeyh.name, Score: 37, Comments: 14 On Reddit: [31] http://goo.gl/m1Jvp Original: [32] http://goo.gl/GqiAR * inefficient Ackermann implementation not obvious how to improve Domain: stackoverflow.com, Score: 37, Comments: 20 On Reddit: [33] http://goo.gl/CEaOT Original: [34] http://goo.gl/JploA * Haskell for all: pipes and io-streams Domain: haskellforall.com, Score: 37, Comments: 20 On Reddit: [35] http://goo.gl/fmLhr Original: [36] http://goo.gl/8BoLg * Build applications with Shake build system Domain: lethalman.blogspot.it, Score: 35, Comments: 5 On Reddit: [37] http://goo.gl/MZBLj Original: [38] http://goo.gl/bP7lK * What’s in a number? criterion edition Domain: serpentine.com, Score: 34, Comments: 6 On Reddit: [39] http://goo.gl/cfVMa Original: [40] http://goo.gl/hqBfW * Announcing postgresql-simple 0.3.1 Domain: blog.melding-monads.com, Score: 34, Comments: 5 On Reddit: [41] http://goo.gl/LEuEv Original: [42] http://goo.gl/jrn5v * LGtk: Lens-based Gtk Interface Domain: people.inf.elte.hu, Score: 32, Comments: 64 On Reddit: [43] http://goo.gl/SC7kn Original: [44] http://goo.gl/FfYeE * Introduction to QuickCheck testing (new FP complete SoH tutorial) Domain: fpcomplete.com, Score: 32, Comments: 7 On Reddit: [45] http://goo.gl/2BnS6 Original: [46] http://goo.gl/6DKRG * Introduction to Haskell, Lecture 12 is Live (Category Theory). This is the last lecture in this series. Thank you for your support! Domain: shuklan.com, Score: 31, Comments: 4 On Reddit: [47] http://goo.gl/to9jd Original: [48] http://goo.gl/JZYSv Top StackOverflow Questions * What does “coalgebra” mean in the context of programming? votes: 134, answers: 3 Read on SO: [49] http://goo.gl/UH2Wl * Ackermann very inefficient with Haskell/GHC votes: 39, answers: 7 Read on SO: [50] http://goo.gl/JploA * How to concisely express function iteration? votes: 21, answers: 3 Read on SO: [51] http://goo.gl/OknK3 * Does the GHC garbage collector have any special optimisations for large objects? votes: 16, answers: 1 Read on SO: [52] http://goo.gl/p1zvM * Parallel computations with fast randomness and purity? votes: 16, answers: 4 Read on SO: [53] http://goo.gl/O3FzX * Idiomatic Scala translation of Kiselyov's zippers? votes: 15, answers: 1 Read on SO: [54] http://goo.gl/TCBaL * Singleton types in Haskell votes: 14, answers: 1 Read on SO: [55] http://goo.gl/u3867 * Encoding correctness constraints directly into the Haskell type system? votes: 14, answers: 2 Read on SO: [56] http://goo.gl/in0xv * Monad transformers with identity monad votes: 12, answers: 2 Read on SO: [57] http://goo.gl/hx2Ic * Extensible Haskell Type Classes votes: 12, answers: 4 Read on SO: [58] http://goo.gl/zdYpL * GADT's failed exhaustiveness checking votes: 12, answers: 2 Read on SO: [59] http://goo.gl/GIFDu * QuickCheck: Arbitrary instances of nested data structures that generate balanced specimens votes: 11, answers: 1 Read on SO: [60] http://goo.gl/WH3FV * What is this special functor structure called? votes: 11, answers: 1 Read on SO: [61] http://goo.gl/cKt7o Until next time, [62]+Daniel Santa Cruz References 1. http://adit.io/posts/2013-04-17-functors,_applicatives,_and_monads_in_pictur... 2. http://www.reddit.com/r/haskell/comments/1co0s5/functors_applicatives_and_mo... 3. http://dev.stephendiehl.com/hask/ 4. http://www.reddit.com/r/haskell/comments/1cbjqm/what_i_wish_i_knew_when_lear... 5. http://stefan.saasen.me/articles/git-clone-in-haskell-from-the-bottom-up/ 6. http://www.reddit.com/r/haskell/comments/1ch3l2/git_clone_in_haskell_from_th... 7. http://www.jonmsterling.com/posts/2013-04-06-vinyl-modern-records-for-haskel... 8. http://www.reddit.com/r/haskell/comments/1buh5y/vinyl_modern_records_for_has... 9. http://www.reddit.com/r/haskell/comments/1cy58c/followup_web_woes_for_haskel... 10. http://www.reddit.com/r/haskell/comments/1cy58c/followup_web_woes_for_haskel... 11. http://stackoverflow.com/questions/16015020/what-does-coalgebra-mean-in-the-... 12. http://www.reddit.com/r/haskell/comments/1cht4v/what_does_coalgebra_mean_in_... 13. http://www.reddit.com/r/haskell/comments/1cyajx/the_mother_of_all_monads_sch... 14. http://www.reddit.com/r/haskell/comments/1cyajx/the_mother_of_all_monads_sch... 15. http://www.reddit.com/r/haskell/comments/1czxvj/why_do_all_the_haskell_web_f... 16. http://www.reddit.com/r/haskell/comments/1czxvj/why_do_all_the_haskell_web_f... 17. 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