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_out/
   2. http://www.reddit.com/r/haskell/comments/12pxiq/haskell_platform_2012400_is_out/
   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_tutorial_on_generalized/
   5. http://ro-che.info/ccc/17.html
   6. http://www.reddit.com/r/haskell/comments/12nm3w/cartesian_closed_comic_17_typing/
   7. http://ro-che.info/ccc/18.html
   8. http://www.reddit.com/r/haskell/comments/138crz/cartesian_closed_comic_18_equality/
   9. http://nlpwp.org/book/
  10. http://www.reddit.com/r/haskell/comments/13a0ut/natural_language_processing_for_the_working/
  11. http://ics.p.lodz.pl/~stolarek/blog/2012/11/waiting-for-garbage-collection-can-kill-parallelism/
  12. http://www.reddit.com/r/haskell/comments/13cpm3/waiting_for_garbage_collection_can_kill/
  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_packages_multiple/
  17. https://github.com/tranma/falling-turnip
  18. http://www.reddit.com/r/haskell/comments/133nja/parallel_falling_sand_game_with_repa/
  19. http://www.reddit.com/r/haskell/comments/132kg0/agda_epigram_or_idris_which_one_to_learn/
  20. http://www.reddit.com/r/haskell/comments/132kg0/agda_epigram_or_idris_which_one_to_learn/
  21. http://www.skybluetrades.net/blog/posts/2012/11/13/fay-ring-oscillator/index.html
  22. http://www.reddit.com/r/haskell/comments/134tr6/fun_with_fay_a_ring_oscillator/
  23. http://www.youtube.com/watch?v=eu0rj5C2Otg
  24. http://www.reddit.com/r/haskell/comments/12vvn2/introduction_to_category_theory_1_course_overview/
  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_through_denotational/
  27. http://stackoverflow.com/a/13432926/208257
  28. http://www.reddit.com/r/haskell/comments/13cz6b/how_to_write_python_in_haskell_state_and_either/
  29. http://web.jaguarpaw.co.uk/~tom/blog/posts/2012-11-04-what-is-foldr-made-of.html
  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-foot-with-haskell/
  32. http://www.reddit.com/r/haskell/comments/12rlgt/how_to_shoot_yourself_in_the_foot_with_haskell/
  33. http://www.happstack.com/c/view-page-slug/15/happstack-fay-acid-state-shared-datatypes-are-awesome
  34. http://www.reddit.com/r/haskell/comments/1375q0/happstack_fay_acidstate_shared_datatypes_are/
  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_cleanlyconsistently_work_with_3/
  38. http://www.reddit.com/r/haskell/comments/12relk/how_can_i_cleanlyconsistently_work_with_3/
  39. http://stackoverflow.com/questions/13317242/what-are-paramorphisms
  40. http://stackoverflow.com/questions/13404208/in-pure-functional-languages-is-there-an-algorithm-to-get-the-inverse-function
  41. http://stackoverflow.com/questions/13352205/what-are-free-monads
  42. http://stackoverflow.com/questions/13341937/whats-the-status-of-current-functional-reactive-programming-implementations
  43. http://stackoverflow.com/questions/13340458/what-does-the-world-mean-in-functional-programming-world
  44. http://stackoverflow.com/questions/13346200/type-safe-difference-lists
  45. http://stackoverflow.com/questions/13281316/is-it-possible-to-annotate-a-functions-special-properties-e-g-surjectivity
  46. http://stackoverflow.com/questions/13379060/under-what-circumstances-are-monadic-computations-tail-recursive
  47. http://stackoverflow.com/questions/13422610/should-i-use-new-haskell-language-extensions-in-favour-of-the-old-ones