Fibers

Transcript

1. Fibers
   DENIS DEFREYNE / RUG::B / MARCH 2ND, 2017
   

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2. Basics
   2
   

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3. 3
   f = lambda do
   puts "hi"
   end
   f.call
   

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4. 3
   f = lambda do
   puts "hi"
   end
   f.call
   hi
   

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5. 4
   f = Fiber.new do
   puts "hi"
   end
   f.resume
   

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6. 4
   f = Fiber.new do
   puts "hi"
   end
   f.resume
   hi
   

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7. 5
   f = lambda do
   puts "hi"
   end
   f.call
   hi
   

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8. 6
   f = lambda do
   puts "hi"
   return
   puts "bye"
   end
   f.call
   

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9. 6
   f = lambda do
   puts "hi"
   return
   puts "bye"
   end
   f.call
   hi
   

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10. 7
    f = Fiber.new do
    puts "hi"
    return
    puts "bye"
    end
    f.resume
    

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11. 7
    f = Fiber.new do
    puts "hi"
    return
    puts "bye"
    end
    f.resume
    hi
    

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12. 7
    f = Fiber.new do
    puts "hi"
    return
    puts "bye"
    end
    f.resume
    hi
    sample.rb:3:

    in`block in ':

    unexpected return

    (LocalJumpError)
    

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13. 8
    f = Fiber.new do
    puts "hi"
    Fiber.yield
    puts "bye"
    end
    f.resume
    

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14. 8
    f = Fiber.new do
    puts "hi"
    Fiber.yield
    puts "bye"
    end
    f.resume
    hi
    

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15. 9
    f = lambda do
    puts "hi"
    end
    f.call

    hi
    

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16. 10
    f = lambda do
    puts "hi"
    end
    f.call
    f.call
    

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17. 10
    f = lambda do
    puts "hi"
    end
    f.call
    f.call
    hi
    hi
    

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18. 11
    f = Fiber.new do
    puts "hi"
    end
    f.resume
    f.resume
    

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19. 11
    f = Fiber.new do
    puts "hi"
    end
    f.resume
    f.resume
    hi
    

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20. 11
    f = Fiber.new do
    puts "hi"
    end
    f.resume
    f.resume
    hi
    a.rb:6:

    in `resume':

    dead fiber called

    (FiberError)
    

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21. 12
    f = lambda do
    puts "hi"
    return
    puts "bye"
    end
    f.call

    hi

    

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22. 13
    f = lambda do
    puts "hi"
    return
    puts "bye"
    end
    f.call
    f.call
    

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23. 13
    f = lambda do
    puts "hi"
    return
    puts "bye"
    end
    f.call
    f.call
    hi
    hi
    

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24. 14
    f = Fiber.new do
    puts "hi"
    Fiber.yield
    puts "bye"
    end
    f.resume
    f.resume
    

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25. 14
    f = Fiber.new do
    puts "hi"
    Fiber.yield
    puts "bye"
    end
    f.resume
    f.resume
    hi
    bye
    

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26. 15
    Create a fiber Fiber.new { … }
    Start running a fiber f.resume
    Resume an running fiber f.resume
    Return from a fiber Fiber.yield
    

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27. 16
    f = Fiber.new do
    puts 'hi'
    end
    f.resume
    hi
    

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28. 17
    f = Fiber.new do |a|
    puts a
    end
    f.resume('hi')
    

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29. 17
    f = Fiber.new do |a|
    puts a
    end
    f.resume('hi')
    hi
    

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30. 18
    f = Fiber.new do |a|
    puts a

    

    end
    f.resume('hi')

    hi
    

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31. 19
    f = Fiber.new do |a|
    puts a
    Fiber.yield
    puts 'bye'
    end
    f.resume('hi')
    f.resume
    hi

    bye
    

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32. 20
    f = Fiber.new do |a|
    puts a
    b = Fiber.yield
    puts b
    end
    f.resume('hi')
    f.resume('bye')
    

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33. 20
    f = Fiber.new do |a|
    puts a
    b = Fiber.yield
    puts b
    end
    f.resume('hi')
    f.resume('bye')
    hi
    bye
    

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34. 21
    f = Fiber.new do
    puts 'hi'
    end
    f.resume
    hi
    

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35. 22
    f = Fiber.new do
    'hi'
    end
    puts f.resume
    

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36. 22
    f = Fiber.new do
    'hi'
    end
    puts f.resume
    hi
    

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37. 23
    f = Fiber.new do
    puts 'hi'
    end
    f.resume
    hi

    

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38. 24
    f = Fiber.new do
    puts 'hi'
    Fiber.yield
    'bye'
    end
    f.resume
    puts f.resume
    hi

    bye
    

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39. 25
    f = Fiber.new do

    Fiber.yield('hi')

    'bye'
    end
    puts f.resume
    puts f.resume
    

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40. 25
    f = Fiber.new do

    Fiber.yield('hi')

    'bye'
    end
    puts f.resume
    puts f.resume
    hi
    bye
    

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41. 26
    Create a fiber Fiber.new { … }
    Start running a fiber f.resume(…)
    Resume an running fiber f.resume(…)
    Return from a fiber Fiber.yield(…)
    

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42. Five
    (Practical)
    Applications
    27
    

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43. 0.
    Async, non-blocking IO

    and maybe reactive things
    28
    

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44. (Use your imagination here)
    29
    

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45. 1.
    Infinite lists
    30
    

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46. 31
    

    f = Fiber.new do
    Fiber.yield(0)
    Fiber.yield(1)
    Fiber.yield(2)
    …
    end
    puts f.resume
    puts f.resume
    puts f.resume
    0
    1
    2
    

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47. 32
    f = Fiber.new do
    v = 0
    loop do
    Fiber.yield(v)
    v += 1
    end
    end
    puts f.resume
    puts f.resume
    puts f.resume
    0
    1
    2
    

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48. 33
    class Ints
    def initialize
    @f = Fiber.new { … }
    end
    def each
    loop do
    yield(@f.resume)
    end
    end
    end
    

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49. 34
    Ints.new.each do |i|
    puts i
    end
    

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50. 34
    Ints.new.each do |i|
    puts i
    end
    0
    1
    2
    3
    4
    5
    6
    7
    8
    9
    10
    11
    12
    13
    

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51. 35
    Ints =
    Enumerator.new do |y|
    v = 0
    loop do
    y << v
    v += 1
    end
    end
    

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52. (You don’t need fibers for this.)
    36
    

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53. 2.
    Wizards
    37
    

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54. 38
    What is your first name?
    > Denis
    Hi, Denis.
    What is your last name?
    > Defreyne
    Got it — Defreyne!
    Thanks for your help, Denis Defreyne!
    Bye-bye for now!
    

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55. 39
    first_name = ask "What is your first name?"
    say "Hi, #{first_name}."
    last_name = ask "What is your last name?"
    say "Got it -- #{last_name}!"
    say "Thanks for your help, #{first_name}!"
    say "Bye-bye for now!"
    stop
    

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56. 40
    def ask(s)
    puts s
    print '> '
    gets.chomp
    end
    def say(s)
    puts s
    end
    def stop
    end
    

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57. 41
    first_name = ask "What is your first name?"
    say "Hi, #{first_name}."
    last_name = ask "What is your last name?"
    say "Got it -- #{last_name}!"
    say "Thanks for your help, #{first_name}!"
    say "Bye-bye for now!"
    stop
    

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58. 42
    wizard = Fiber.new do
    first_name = ask "What is your first name?"
    say "Hi, #{first_name}."
    last_name = ask "What is your last name?"
    say "Got it -- #{last_name}!"
    say "Thanks for your help, #{first_name}!"
    say "Bye-bye for now!"
    stop
    end
    

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59. 43
    def ask(s)
    Fiber.yield(Question.new(s))
    end
    def say(s)
    Fiber.yield(Statement.new(s))
    end
    def stop
    Fiber.yield(Stop.new)
    end
    

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60. 44
    answer = nil
    loop do
    instruction = wizard.resume(answer)
    case instruction
    when Question
    when Statement
    when Stop
    end
    end
    

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61. 45
    answer = nil
    loop do
    instruction = wizard.resume(answer)
    case instruction
    when Question
    puts instruction.text
    print '> '
    answer = gets.chomp
    when Statement
    when Stop
    end
    end
    

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62. 46
    answer = nil
    loop do
    instruction = wizard.resume(answer)
    case instruction
    when Question
    puts instruction.text
    print '> '
    answer = gets.chomp
    when Statement
    puts instruction.text
    when Stop
    end
    end
    

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63. 47
    answer = nil
    loop do
    instruction = wizard.resume(answer)
    case instruction
    when Question
    puts instruction.text
    print '> '
    answer = gets.chomp
    when Statement
    puts instruction.text
    when Stop
    break
    end
    end
    

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64. We’ve separated what to do (wizard)
    
    from how to do it (CLI, GUI, …)
    48
    

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65. 49
    pieces = []
    answer = nil
    loop do
    instruction = wizard.resume(answer)
    case instruction
    when Question
    when Statement
    when Stop
    end
    end
    

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66. 50
    when Question
    pieces << instruction.text
    pieces << ''
    pieces << ''
    pieces << ''
    pieces << ''
    return pieces.join(' ')
    

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67. 51
    when Statement
    pieces << instruction.text
    

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68. 52
    when Stop
    return pieces.join(' ')
    

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69. 3.
    Resumable exceptions
    53
    

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70. 54
    handle_exception do
    puts 'before'
    puts Boom.new.throw
    puts 'after'
    end.…
    

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71. 55
    handle_exception do
    puts 'before'
    puts Boom.new.throw
    puts 'after'
    end.on(Boom) do |e|
    e.resume('exceptional')
    end.…
    

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72. 56
    handle_exception do
    puts 'before'
    puts Boom.new.throw
    puts 'after'
    end.on(Boom) do |e|
    e.resume('exceptional')
    end.run
    

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73. 57
    handle_exception do
    puts 'before'
    puts Boom.new.throw
    puts 'after'
    end.on(Boom) do |e|
    e.resume('exceptional')
    end.run
    before
    exceptional
    after
    

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74. 58
    handle_exception do
    puts 'before'
    puts Boom.new.throw
    puts 'after'
    end.run
    before
    sample.rb:31:

    in `block in run':
    ohnoes kaboom

    (Boom)
    

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75. 4.
    Run-time dependencies
    59
    

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76. 60
    http://nanoc.ws
    Nanoc
    

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77. 61
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89. 62
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90. 63
    Create a fiber Fiber.new { … }
    Start running a fiber f.resume(…)
    Resume an running fiber f.resume(…)
    Return from a fiber Fiber.yield(…)
    

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91. 64
    Q&A
    Find me at @ddfreyne on Twitter, or denis@stoneship.org.
    

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