RailsConf 2017

It's my keynote from RailsConf 2017

Transcript

1. View Slide

2. Hello ICON!
   

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3. Hello RailsConf!
   

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4. View Slide

5. Hi, I’m @tenderlove
   

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6. View Slide

7. h
   GitHub
   

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8. Le Git
   

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9. Le Gîte Hub
   

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10. Rails Core Team
    

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11. Ruby Core Team
    

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15. I have stickers!
    

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16. View Slide

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19. View Slide

20. "Why Slack is inappropriate for
    open source communications"
    

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21. "We are, temporarily, in a kind
    of dark ages of end-user open
    source software."
    

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22. Oops, I died of plague
    This is a rat
    

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23. Electron is flash for the
    desktop
    

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24. "slack often idles at 5% CPU
    usage"
    

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25. CPU
    Slack
    

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26. "Buy a bigger CPU, ya dummy"
    

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27. Alan Turning
    

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28. HN on Language Features
    

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29. "No generics and no sum types?
    Those are no longer groundbreaking,
    they're the bare minimum.*"
    *Emphasis not mine
    

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30. No generics means your
    language is a failure
    

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31. Insurance companies only
    cover Generics
    

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32. Sorry, your
    language has been
    denied
    L'Hôpital
    

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33. View Slide

34. View Slide

35. #supportlocal
    

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36. Local Coffee!
    

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37. Local Tea!
    

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38. Trolling DHH:
    An Annual Tradition
    

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41. Faith Based Programmer
    

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42. "Pleaseworkpleaseworkpleas
    eworkpleaseworkpleasework"
    The Programmer’s Prayer
    

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43. View Slide

44. View Slide

45. 24 bit audio
    

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46. 10+ Years of Rails
    

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47. It was the year 2003
    

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48. View Slide

49. What should I do with all this
    free time?
    

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50. "We’ve tried to charge your
    card hundreds of times"
    

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51. Technical Debt
    

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52. Developers want to pay off
    technical debt
    

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53. Managers do not want to
    pay off technical debt
    (if they can help it)
    

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54. Tech Debt
    Gem Gem
    Gem
    Gem
    Gem
    Meta Gem
    

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55. Tech Debt
    Gem Gem
    Gem
    Gem
    Gem
    "Bond"
    "Tranche"
    

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56. Tech Debt
    Gem Gem
    Gem
    Webpack
    Gem
    Rails
    

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57. Blood of
    young people
    

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58. Concatenating a bunch of
    strings
    

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59. View Slide

60. View Slide

61. View Slide

62. Not a Joke
    

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63. View Slide

64. View Slide

65. $5
    

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66. View Slide

67. 5.1
    

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68. Rails 5.1 is out!
    
    

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69. Thanks @rafaelfranca!!!
    ❤
    

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70. I don’t have time for this
    Things I don’t have time for but would like to do
    

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71. Non-committal
    

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72. Humorous use of common
    phrase
    

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73. "No Pressure"
    

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74. ALL OF THE
    PRESSURE
    

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75. Searls - Briggs
    

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76. STRESS
    

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77. Fear & Self Doubt
    

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78. 5 things I don’t have time
    to do
    but you should do them for me
    

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79. What if I don’t have time to
    present 5 things??
    

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80. What if I want to talk about
    things I do have time for?
    

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81. Some things I don’t have
    time to do
    but you should do them for me
    Maybe like 3 things?
    

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82. Probably Important
    Definitely Not Important
    

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83. HTTP/2 + Rack
    A thing that I do have time for
    

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84. What is HTTP/2?
    

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85. 1 better than HTTP/1
    

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86. 0.9 better than HTTP/1.1
    

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87. HTTP/2 (really)
    • Binary protocol
    • Multiplexes (multiple requests on the same socket)
    • Secure (only works over SSL*)
    • Push responses
    

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88. Push Response Flow
    

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89. HTTP 1.1
    Time
    index.html
    jquery.js
    gorby.css
    Client Server
    

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90. HTTP 2
    Time
    index.html
    jquery.js
    gorby.css
    Client Server
    

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91. Save Time by Pushing
    "Needed" Resources
    

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92. H2 Problems
    

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93. H2 is still stateless
    

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94. HTTP 2
    Time
    index.html
    jquery.js
    gorby.css
    Client Server
    

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95. Double Assets
    • Client can cancel (requires round trip)
    • Resend assets (extra bandwidth)
    

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96. Solution: H2O + SALT
    Get it, "solution"????
    

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97. Solution: H2O + Cookies
    

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98. What is H2O?
    https://h2o.examp1e.net
    

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99. Server (Unicorn)
    Proxy (h2o)
    Client
    HTTP/2 HTTP/1.1
    

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100. H2 Pushes with HTTP/1.1
     

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101. Link Header
     200 OK
     Content-Length: 1024
     Content-Type: text/html
     Link: ; rel=preload
     Link: ; rel=preload
     response body
     

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102. Server (Unicorn)
     Proxy (h2o)
     Client
     HTTP/2 HTTP/1.1
     200 OK
     Content-Length: 1024
     Content-Type: text/html
     Link: ; rel=preload
     Link: ; rel=preload
     response body
     

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103. No state tracking in the app
     

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104. Link Header Problem
     200 OK
     Content-Length: 1024
     Content-Type: text/html
     Link: ; rel=preload
     Link: ; rel=preload
     response body
     

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105. 103 Early Hints
     

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106. 103 Early Response
     103 Early Hints
     Link: ; rel=preload
     Link: ; rel=preload
     200 OK
     Content-Length: 1024
     Content-Type: text/html
     response body
     

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107. Rack Support
     Rack 3.0
     

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108. New ENV hash key! ("yay")
     env['rack.push'].call(103, [
     ['Link', '/gorby.css']
     ], [])
     

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109. Backwards Compatibility
     

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110. Graceful Upgrade
     

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111. Rack 3.0
     

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112. This is a talk about code
     smells
     

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113. Data I acquired (crap data)
     -100
     925
     1950
     2975
     4000
     Time
     2017-01-23
     15:53:51
     2017-01-23
     15:53:56
     2017-01-23
     15:54:01
     2017-01-23
     15:54:06
     2017-01-23
     15:54:11
     2017-01-23
     15:54:16
     2017-01-23
     15:54:21
     2017-01-23
     15:54:26
     2017-01-23
     15:54:31
     2017-01-23
     15:54:37
     2017-01-23
     15:54:42
     2017-01-23
     15:54:47
     2017-01-23
     15:54:52
     2017-01-23
     15:54:57
     2017-01-23
     15:55:02
     2017-01-23
     15:55:07
     2017-01-23
     15:55:12
     2017-01-23
     15:55:17
     2017-01-23
     15:55:22
     2017-01-23
     15:55:27
     2017-01-23
     15:55:32
     

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114. Ruby VM Tricks
     

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115. How a VM works
     

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116. VM
     [push, 4]
     [push, 3]
     [add]
     PC
     Program Stack
     4
     3
     7
     

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117. Implementation
     instructions = [
     [:push, 3],
     [:push, 7],
     [:add],
     ]
     pc = 0
     loop do
     instruction = instructions[pc]
     pc += 1
     send function_table[instruction.first]
     end
     

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118. Generate the VM
     

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119. Loop Elimination
     instructions = [ [:push, 3], [:push, 7], [:add], ]
     def push_op pc, val, instructions
     # code to push on the stack
     # ....
     next_instruction = instructions[pc]
     send(function_table[next_instruction.first]
     pc + 1,
     next_instruction,
     instructions)
     end
     def add pc, val, instructions
     # code to add
     # ....
     next_instruction = instructions[pc]
     send(function_table[next_instruction.first]
     pc + 1,
     next_instruction,
     instructions)
     end
     # start of VM
     pc = 0
     instruction = instructions[pc]
     pc += 1
     send function_table[instruction.first]
     Generated
     

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120. Threaded VM
     

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121. Function call elimination
     

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122. Function Name Lookup Table
     instructions = [ [:push, 3], [:push, 7], [:add], ]
     function_table = {
     :push => :push_op,
     :add => :add_op,
     }
     def push_op pc, val, instructions
     # code to push on the stack
     # ....
     next_instruction = instructions[pc]
     send(function_table[next_instruction.first]
     pc + 1,
     next_instruction,
     instructions)
     end
     

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123. JUMP
     instructions = [ [:push, 3], [:push, 7], [:add], ]
     function_table = {
     :push => ADDRESS_OF(:push_op),
     :add => ADDRESS_OF(:add_op),
     }
     label: :add_op
     # code to add
     # ...
     next_instruction = instructions[pc]
     val = next_instruction.drop(1)
     address = function_table[next_instruction.first]
     pc += 1
     GOTO(address)
     label: :push_op
     # code to push on the stack
     # ....
     next_instruction = instructions[pc]
     val = next_instruction.drop(1)
     address = function_table[next_instruction.first]
     pc += 1
     GOTO(address)
     Generated
     

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124. Lookup Table Elimination
     

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125. Addresses in Byte Code
     instructions = [
     [ADDRESS_OF(:push_op), 3],
     [ADDRESS_OF(:push_op), 7],
     [ADDRESS_OF(:add)],
     ]
     label: :add_op
     # code to add
     # ...
     next_instruction = instructions[pc]
     val = next_instruction.drop(1)
     address = next_instruction.first
     pc += 1
     GOTO(address)
     label: :push_op
     # code to push on the stack
     # ....
     next_instruction = instructions[pc]
     val = next_instruction.drop(1)
     address = next_instruction.first
     pc += 1
     GOTO(address)
     

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126. Direct Threaded VM
     

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127. Addresses are just integers
     

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128. MRI’s VM is Direct Threaded
     

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129. Create custom instructions built
     from machine code
     at runtime
     

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130. Extremely Simple Code
     require 'lolvm'
     class MyRuby
     attr_reader :rb_path2class, :rb_define_method, :mod
     def initialize ctx
     @mod = ctx.create_module 'ruby'
     @ctx = ctx
     init_functions
     end
     private
     def init_functions
     @rb_path2class = make_func('rb_path2class', @ctx.int8.pointer, [@ctx.int8.pointer])
     @rb_define_method = make_func('rb_define_method', @ctx.int8.pointer, [@ctx.int8.pointer, @ctx.int8.pointer, @ctx.int8.pointer, @ctx.int32])
     end
     def make_func name, ret, args
     func_type = LOLVM::Types::Function.new(ret, args, false)
     @mod.add_function name, func_type
     end
     end
     context = LOLVM::Context.instance
     builder = context.create_builder
     ruby = MyRuby.new context
     mod = context.create_module 'anon mod'
     func_type = LOLVM::Types::Function.new(context.double, [], false)
     testing = mod.add_function "testing", LOLVM::Types::Function.new(context.int64, [context.int8.pointer], false)
     testing.param(0).name = "foo"
     bb = context.append_basic_block testing, "entry"
     x = mod.add_global context.int64, 'rb_cObject'
     x.linkage = LOLVM::Linkages::External
     builder.position_at_end_of bb
     builder.ret builder.load x, "obj"
     func = mod.add_function "__anon", func_type
     bb = context.append_basic_block func, "entry"
     builder.position_at_end_of bb
     str = builder.global_string "MyRuby", 'string'
     func_name = builder.global_string "testing", 'func_name'
     my_ruby = builder.call testing, [str], 'rb_str'
     builder.ret my_ruby
     ee = mod.execution_engine
     ee.add_module ruby.mod
     p :GOT => ee.run("__anon")
     Assembles machine code
     at run time using LLVM
     

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131. Idea 1: Custom Instructions
     at Runtime
     

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132. Data I acquired (crap data)
     -100
     925
     1950
     2975
     4000
     Time
     2017-01-23
     15:53:51
     2017-01-23
     15:53:56
     2017-01-23
     15:54:01
     2017-01-23
     15:54:06
     2017-01-23
     15:54:11
     2017-01-23
     15:54:16
     2017-01-23
     15:54:21
     2017-01-23
     15:54:26
     2017-01-23
     15:54:31
     2017-01-23
     15:54:37
     2017-01-23
     15:54:42
     2017-01-23
     15:54:47
     2017-01-23
     15:54:52
     2017-01-23
     15:54:57
     2017-01-23
     15:55:02
     2017-01-23
     15:55:07
     2017-01-23
     15:55:12
     2017-01-23
     15:55:17
     2017-01-23
     15:55:22
     2017-01-23
     15:55:27
     2017-01-23
     15:55:32
     

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133. Build a Police Scanner
     

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134. View Slide

135. Software Defined Radio
     

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136. View Slide

137. FM Band
     

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138. Narrow FM
     Digital Trunking
     signal
     Audio
     

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139. Digital Signal Processing
     

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140. Continuous / Discrete
     Very Discrete
     tenderlove
     

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141. Discrete signals are just a list
     of points
     

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142. Discrete Signal (crap data)
     -100
     925
     1950
     2975
     4000
     Time
     2017-01-23
     15:53:51
     2017-01-23
     15:53:56
     2017-01-23
     15:54:01
     2017-01-23
     15:54:06
     2017-01-23
     15:54:11
     2017-01-23
     15:54:16
     2017-01-23
     15:54:21
     2017-01-23
     15:54:26
     2017-01-23
     15:54:31
     2017-01-23
     15:54:37
     2017-01-23
     15:54:42
     2017-01-23
     15:54:47
     2017-01-23
     15:54:52
     2017-01-23
     15:54:57
     2017-01-23
     15:55:02
     2017-01-23
     15:55:07
     2017-01-23
     15:55:12
     2017-01-23
     15:55:17
     2017-01-23
     15:55:22
     2017-01-23
     15:55:27
     2017-01-23
     15:55:32
     

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143. Convolution
     

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144. Signal Convolution
     -100
     925
     1950
     2975
     4000
     Time
     2017-01-23
     15:53:51
     2017-01-23
     15:54:01
     2017-01-23
     15:54:11
     2017-01-23
     15:54:21
     2017-01-23
     15:54:31
     2017-01-23
     15:54:42
     2017-01-23
     15:54:52
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     15:55:02
     2017-01-23
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     2017-01-23
     15:55:22
     2017-01-23
     15:55:32
     0
     0.25
     0.5
     0.75
     1
     0 1 2 3 4 5 6 7
     * =?
     

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145. Formal Definition
     

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146. X
     -1.5
     -0.5
     0.5
     1.5
     0 1 2 3 4 5 6 7 8
     H
     -0.5
     0
     0.5
     1
     3 2 1 0
     Y
     -1.5
     0
     1.5
     3
     0 1 2 3 4 5 6 7 8 9 10 11
     

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147. Convolution Code
     def convolve x, h
     Array.new(x.length + h.length - 1) do |i|
     h.map.with_index { |h_j, j|
     if i - j < 0 || i - j > x.length - 1
     0
     else
     h_j * x[i - j]
     end
     }.inject(:+)
     end
     end
     

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148. Convolved Signal Length:
     x.length + h.length - 1
     

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149. X
     -1.5
     -0.5
     0.5
     1.5
     0 1 2 3 4 5 6 7 8
     H
     -0.5
     0
     0.5
     1
     3 2 1 0
     x
     + y[i] value
     

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150. Low Pass Filters
     

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151. Identity Signal
     X
     -1.5
     -0.5
     0.5
     1.5
     0 1 2 3 4 5 6 7 8
     H
     0
     0.25
     0.5
     0.75
     1
     0 1 2 3
     * =
     Y
     -1.5
     -0.5
     0.5
     1.5
     0 1 2 3 4 5 6 7 8 9 10 11
     

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152. Amplifier
     X
     -1.5
     -0.5
     0.5
     1.5
     0 1 2 3 4 5 6 7 8
     H
     0
     0.5
     1
     1.5
     2
     0 1 2 3
     * =
     Y
     -3
     -1
     1
     3
     0 2 4 6 8 10
     

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153. Shift
     X
     -1.5
     -0.5
     0.5
     1.5
     0 1 2 3 4 5 6 7 8
     H
     0
     0.25
     0.5
     0.75
     1
     0 1 2 3
     * =
     Y
     -1.5
     -0.5
     0.5
     1.5
     0 1 2 3 4 5 6 7 8 9 10 11
     

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154. Echo
     X
     -1.5
     -0.5
     0.5
     1.5
     0 1 2 3 4 5 6 7 8
     H
     0
     0.5
     1
     1.5
     2
     0 1 2 3
     * =
     Y
     -3.75
     -1.25
     1.25
     3.75
     0 1 2 3 4 5 6 7 8 9 10 11
     

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155. Average
     X
     -1.5
     -0.5
     0.5
     1.5
     0 1 2 3 4 5 6 7 8
     H
     0
     0.25
     0.5
     0.75
     1
     0 1 2 3
     * H
     0
     0.125
     0.25
     0.375
     0.5
     0 1 2 3
     *
     

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156. Radar
     

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157. Radar
     Transmission
     0
     25
     50
     75
     100
     Reception
     -25
     0
     25
     50
     75
     100
     

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158. Does one signal contain the
     other?
     

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159. received * transmitted
     Detection
     -10000
     0
     10000
     20000
     30000
     40000
     

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160. Gaussian Distribution
     

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161. Self Convolution
     signal = 100.times.map { rand }
     3.times do
     signal = convolve signal, signal
     end
     

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162. Self Convolution
     Gaussian Distribution
     0
     75000000000
     150000000000
     225000000000
     300000000000
     Neat!
     tenderlove
     

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163. Convolution Code
     def convolve x, h
     Array.new(x.length + h.length - 1) do |i|
     h.map.with_index { |h_j, j|
     if i - j < 0 || i - j > x.length - 1
     0
     else
     h_j * x[i - j]
     end
     }.inject(:+)
     end
     end
     

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164. My Signal
     

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165. R, the hard way
     

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166. Arrays are 1 based
     > data > data[0]
     numeric(0)
     > data[0] + 1
     numeric(0)
     >
     

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167. There must be an
     easier way!
     tenderlove
     

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168. Data I acquired (crap data)
     -100
     925
     1950
     2975
     4000
     Time
     2017-01-23
     15:53:51
     2017-01-23
     15:53:56
     2017-01-23
     15:54:01
     2017-01-23
     15:54:06
     2017-01-23
     15:54:11
     2017-01-23
     15:54:16
     2017-01-23
     15:54:21
     2017-01-23
     15:54:26
     2017-01-23
     15:54:31
     2017-01-23
     15:54:37
     2017-01-23
     15:54:42
     2017-01-23
     15:54:47
     2017-01-23
     15:54:52
     2017-01-23
     15:54:57
     2017-01-23
     15:55:02
     2017-01-23
     15:55:07
     2017-01-23
     15:55:12
     2017-01-23
     15:55:17
     2017-01-23
     15:55:22
     2017-01-23
     15:55:27
     2017-01-23
     15:55:32
     

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169. Implementing cons, car,
     and cdr in many languages
     (using only lambdas)
     

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170. Why?
     

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171. I like learning new languages
     

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172. But I don’t have much time
     

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173. Bare minimum to get
     endorsed on Linked In
     Do people still use Klout?
     

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174. What are cons, car, and cdr?
     

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175. cons forms a cell
     L R
     

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176. car returns the left side
     L R
     

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177. cdr returns the right side
     L R
     

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178. Only Lambdas?
     

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179. cons
     tenderlove.cons function(m) { m(x, y) }
     }
     R
     Node
     cons = ->(x, y) {
     ->(m) { m.(x, y) }
     }
     Ruby
     var cons = function(x, y) {
     return function(m) { return m(x, y); };
     }
     

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180. car
     tenderlove.car z(function(p, q) { p })
     }
     R
     var car = function(z) {
     return z(function(p, q) { return p; });
     }
     Node
     car = ->(z) {
     z.(->(p, q) { p })
     }
     Ruby
     

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181. Usage
     > tenderlove.cons(1, 2)
     function(m) { m(x, y) }
     
     > tenderlove.car
     function(z) { z(function(p, q) { p }) }
     > tenderlove.car(tenderlove.cons(1, 2))
     [1] 1
     >
     

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182. cdr
     tenderlove.cdr z(function(p, q) { q })
     }
     R
     var cdr = function(z) {
     return z(function(p, q) { return q; });
     }
     Node
     cdr = ->(z) {
     z.(->(p, q) { q })
     }
     Ruby
     

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183. Tree of Cells
     1
     2
     3 NUL
     

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184. each
     tenderlove.each if (!is.null(lst)) {
     element func(element)
     tenderlove.each(func, tenderlove.cdr(lst))
     }
     }
     R
     Node
     each = ->(func, list) {
     if list
     element = car.(list)
     func.(element)
     each.(func, cdr.(list))
     end
     }
     Ruby
     var each = function(func, list) {
     if(list) {
     element = car(list);
     func(element);
     each(func, cdr(list));
     }
     }
     

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185. Usage
     var each = function(func, list) {
     if(list) {
     element = car(list);
     func(element);
     each(func, cdr(list));
     }
     }
     each(console.log, cons(1, (cons(2, cons(3, null)))));
     [aaron@TC dsp (master)]$ node dsp.js
     1
     2
     3
     [aaron@TC dsp (master)]$
     

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186. Don’t need loops
     

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187. Don’t need arrays
     

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188. Don’t need hashes
     

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189. Numbers?
     

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190. Numbers
     tenderlove.zero function(x) { x }
     }
     tenderlove.one function(x) { f(x) }
     }
     tenderlove.two function(x) { f(f(x)) }
     }
     tenderlove.three function(x) { f(f(f(x))) }
     }
     print(tenderlove.three(function(x) { x + 1 })(0)) => 3
     

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191. Addition
     tenderlove.one function(x) { f(x) }
     }
     tenderlove.add function(f) { function(x) { a(f)(b(f)(x)) } }
     }
     tenderlove.two tenderlove.three print(tenderlove.three(function(x) { x + 1 })(0)) # => 3
     

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192. Church Encoding
     

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193. Don’t need Numbers
     

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194. Don’t need Mathematics
     

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195. Logic?
     

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196. true / false / if
     True = ->(x, y) { x }
     False = ->(x, y) { y }
     If = ->(cond, t, f) { cond.(t, f) }
     If.(True, ->() { :true }, ->() { :false }).call # => :true
     If.(False, ->() { :true }, ->() { :false }).call # => :false
     

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197. Don’t need booleans
     

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198. Don’t need conditionals
     

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199. My Signal (crap data)
     -100
     925
     1950
     2975
     4000
     Time
     2017-01-23
     15:53:51
     2017-01-23
     15:53:56
     2017-01-23
     15:54:01
     2017-01-23
     15:54:06
     2017-01-23
     15:54:11
     2017-01-23
     15:54:16
     2017-01-23
     15:54:21
     2017-01-23
     15:54:26
     2017-01-23
     15:54:31
     2017-01-23
     15:54:37
     2017-01-23
     15:54:42
     2017-01-23
     15:54:47
     2017-01-23
     15:54:52
     2017-01-23
     15:54:57
     2017-01-23
     15:55:02
     2017-01-23
     15:55:07
     2017-01-23
     15:55:12
     2017-01-23
     15:55:17
     2017-01-23
     15:55:22
     2017-01-23
     15:55:27
     2017-01-23
     15:55:32
     

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200. cons / car / cdr / each
     tenderlove.cons tenderlove.car tenderlove.cdr tenderlove.each if (!is.null(lst)) {
     element func(element)
     tenderlove.each(func, tenderlove.cdr(lst))
     }
     }
     tenderlove.each_with_index idx tenderlove.each(function(element) {
     func(idx, element)
     idx = idx + 1
     }, lst)
     }
     

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201. array indexing
     tenderlove.vec_at if(idx == 0) {
     tenderlove.car(lst)
     } else {
     tenderlove.vec_at(idx - 1, tenderlove.cdr(lst))
     }
     }
     

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202. Converting Vectors to cons
     tenderlove.c2cons foldl if(length(lst) == 0) {
     init
     } else {
     foldl(proc, proc(head(lst, 1), init), tail(lst, -1))
     }
     }
     foldl(tenderlove.cons, NULL, rev(cs))
     }
     

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203. Convolution in R
     tenderlove.conv x_list h_list indexes sapply(indexes, function(i) {
     sum(tenderlove.cons2c(tenderlove.map_with_index(function(j, h_j) {
     if (i - j < 0 || i - j > length(x) - 1) {
     0
     } else {
     h_j * tenderlove.vec_at(i - j, x_list)
     }
     }, h_list)))
     })
     }
     

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204. Feed in test data
     > data > plot(data)
     > filter > plot(filter)
     > plot(tenderlove.conv(data, filter))
     

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205. * =
     Nice.
     tenderlove
     

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206. Input Real Data
     > plot(tenderlove.conv(unlist(dat$V2), c(1)))
     Error: evaluation nested too deeply: infinite
     recursion / options(expressions=)?
     I f#$@*ing hate R.
     tenderlove
     

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207. Things I don’t have time for:
     Figuring out R.
     

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208. My Signal (crap data)
     -100
     925
     1950
     2975
     4000
     Time
     2017-01-23
     15:53:51
     2017-01-23
     15:53:56
     2017-01-23
     15:54:01
     2017-01-23
     15:54:06
     2017-01-23
     15:54:11
     2017-01-23
     15:54:16
     2017-01-23
     15:54:21
     2017-01-23
     15:54:26
     2017-01-23
     15:54:31
     2017-01-23
     15:54:37
     2017-01-23
     15:54:42
     2017-01-23
     15:54:47
     2017-01-23
     15:54:52
     2017-01-23
     15:54:57
     2017-01-23
     15:55:02
     2017-01-23
     15:55:07
     2017-01-23
     15:55:12
     2017-01-23
     15:55:17
     2017-01-23
     15:55:22
     2017-01-23
     15:55:27
     2017-01-23
     15:55:32
     

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209. Something I built
     

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210. View Slide

211. Bathroom Scale
     

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212. msp430
     

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213. Raspberry Pi + Motion Sensor
     

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214. Litter Box
     

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215. I made this
     Weight (g)
     -100
     925
     1950
     2975
     4000
     Time
     2017-01-23
     15:53:51
     2017-01-23
     15:53:56
     2017-01-23
     15:54:01
     2017-01-23
     15:54:06
     2017-01-23
     15:54:11
     2017-01-23
     15:54:16
     2017-01-23
     15:54:21
     2017-01-23
     15:54:26
     2017-01-23
     15:54:31
     2017-01-23
     15:54:37
     2017-01-23
     15:54:42
     2017-01-23
     15:54:47
     2017-01-23
     15:54:52
     2017-01-23
     15:54:57
     2017-01-23
     15:55:02
     2017-01-23
     15:55:07
     2017-01-23
     15:55:12
     2017-01-23
     15:55:17
     2017-01-23
     15:55:22
     2017-01-23
     15:55:27
     2017-01-23
     15:55:32
     Cat Enters Cat Leaves
     

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216. ~100g
     

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217. Wrap-Up
     

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218. It’s hard to make shit scale
     I told you those graphs were crap
     

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