Presentation from DC |> Elixir, March 19, 2019. Covered transitioning from Ruby on Rails to Elixir and Phoenix, and why developers want to make that transition, and why management should be supportive of that transition.

1. Going off the Rails into
Elixir
Dan Ivovich
DC |> Elixir
March 19, 2019

2. Why the dev team wants to
❗
AND
Why they should

3. Who Am I?

4. Who Am I?
• Software Developer

5. Who Am I?
• Software Developer
• Director of Development at SmartLogic

6. Who Am I?
• Software Developer
• Director of Development at SmartLogic
• Rails developer for 12 years

7. Who Am I?
• Software Developer
• Director of Development at SmartLogic
• Rails developer for 12 years
• Elixir convert since Summer 2016

8. Who Am I?
• Software Developer
• Director of Development at SmartLogic
• Rails developer for 12 years
• Elixir convert since Summer 2016
• Organizer of the Baltimore Elixir and Erlang
Meetup

9. Why Devs Love
Elixir
https://unsplash.com/photos/FoKO4DpXamQ

10. New!
https://unsplash.com/photos/CqKNkmNNLnI

11. Shiny!
https://unsplash.com/photos/nmUwlzQeQ

12. Fun!
https://unsplash.com/photos/TVfVo1pga9s

13. Compiled
https://xkcd.com/303/

14. But More Seriously
https://unsplash.com/photos/heyiNKAAJWc

15. Pattern Matching
https://unsplash.com/photos/vdbG0z6YDwM

16. Pattern Matching
> [1, b, 4] = [1, 5, 4]
[1, 5, 4]
> b
5
> [head | tail] = [1, 2, 3]
[1, 2, 3]
> head
1
> tail
[2, 3]

17. Pattern Matching
> [1, b, 4] = [1, 5, 4]
[1, 5, 4]
> b
5
> [head | tail] = [1, 2, 3]
[1, 2, 3]
> head
1
> tail
[2, 3]

18. Pattern Matching
> [1, b, 4] = [1, 5, 4]
[1, 5, 4]
> b
5
> [head | tail] = [1, 2, 3]
[1, 2, 3]
> head
1
> tail
[2, 3]

19. Pattern Matching
> [1, b, 4] = [1, 5, 4]
[1, 5, 4]
> b
5
> [head | tail] = [1, 2, 3]
[1, 2, 3]
> head
1
> tail
[2, 3]

20. Pattern Matching
> [1, b, 4] = [1, 5, 4]
[1, 5, 4]
> b
5
> [head | tail] = [1, 2, 3]
[1, 2, 3]
> head
1
> tail
[2, 3]

21. Pattern Matching
def execute({:ok, value}) do
IO.puts "Execute: #{value}"
end
def execute({:error, reason}) do
IO.puts "Error: #{reason}"
end
> execute({:ok, "Well Done!"})
Execute: Well Done!
> execute({:error, "Fail!"})
Error: Fail!

22. Pattern Matching
def execute({:ok, value}) do
IO.puts "Execute: #{value}"
end
def execute({:error, reason}) do
IO.puts "Error: #{reason}"
end
> execute({:ok, "Well Done!"})
Execute: Well Done!
> execute({:error, "Fail!"})
Error: Fail!

23. Pattern Matching
def execute({:ok, value}) do
IO.puts "Execute: #{value}"
end
def execute({:error, reason}) do
IO.puts "Error: #{reason}"
end
> execute({:ok, "Well Done!"})
Execute: Well Done!
> execute({:error, "Fail!"})
Error: Fail!

24. Pattern Matching
def execute({:ok, value}) do
IO.puts "Execute: #{value}"
end
def execute({:error, reason}) do
IO.puts "Error: #{reason}"
end
> execute({:ok, "Well Done!"})
Execute: Well Done!
> execute({:error, "Fail!"})
Error: Fail!

25. Pattern Matching
def execute({:ok, value}) do
IO.puts "Execute: #{value}"
end
def execute({:error, reason}) do
IO.puts "Error: #{reason}"
end
> execute({:ok, "Well Done!"})
Execute: Well Done!
> execute({:error, "Fail!"})
Error: Fail!

26. Pattern Matching
case HTTP.get(url) do
{:ok, %HTTP.Resp{status: 200, body: body}} ->
IO.puts body
{:ok, %HTTP.Resp{status: 404}} ->
IO.puts "Not found!"
{:ok, %HTTP.Resp{status: status}} ->
IO.puts "HTTP Status: #{status}"
{:error, %HTTP.Error{reason: reason}} ->
IO.inspect reason
_ ->
IO.puts "Some other error"
end

27. Pattern Matching
case HTTP.get(url) do
{:ok, %HTTP.Resp{status: 200, body: body}} ->
IO.puts body
{:ok, %HTTP.Resp{status: 404}} ->
IO.puts "Not found!"
{:ok, %HTTP.Resp{status: status}} ->
IO.puts "HTTP Status: #{status}"
{:error, %HTTP.Error{reason: reason}} ->
IO.inspect reason
_ ->
IO.puts "Some other error"
end

28. Pattern Matching
case HTTP.get(url) do
{:ok, %HTTP.Resp{status: 200, body: body}} ->
IO.puts body
{:ok, %HTTP.Resp{status: 404}} ->
IO.puts "Not found!"
{:ok, %HTTP.Resp{status: status}} ->
IO.puts "HTTP Status: #{status}"
{:error, %HTTP.Error{reason: reason}} ->
IO.inspect reason
_ ->
IO.puts "Some other error"
end

29. Pattern Matching
case HTTP.get(url) do
{:ok, %HTTP.Resp{status: 200, body: body}} ->
IO.puts body
{:ok, %HTTP.Resp{status: 404}} ->
IO.puts "Not found!"
{:ok, %HTTP.Resp{status: status}} ->
IO.puts "HTTP Status: #{status}"
{:error, %HTTP.Error{reason: reason}} ->
IO.inspect reason
_ ->
IO.puts "Some other error"
end

30. Pattern Matching
case HTTP.get(url) do
{:ok, %HTTP.Resp{status: 200, body: body}} ->
IO.puts body
{:ok, %HTTP.Resp{status: 404}} ->
IO.puts "Not found!"
{:ok, %HTTP.Resp{status: status}} ->
IO.puts "HTTP Status: #{status}"
{:error, %HTTP.Error{reason: reason}} ->
IO.inspect reason
_ ->
IO.puts "Some other error"
end

31. Pattern Matching
case HTTP.get(url) do
{:ok, %HTTP.Resp{status: 200, body: body}} ->
IO.puts body
{:ok, %HTTP.Resp{status: 404}} ->
IO.puts "Not found!"
{:ok, %HTTP.Resp{status: status}} ->
IO.puts "HTTP Status: #{status}"
{:error, %HTTP.Error{reason: reason}} ->
IO.inspect reason
_ ->
IO.puts "Some other error"
end

32. Pattern Matching
case HTTP.get(url) do
{:ok, %HTTP.Resp{status: 200, body: body}} ->
IO.puts body
{:ok, %HTTP.Resp{status: 404}} ->
IO.puts "Not found!"
{:ok, %HTTP.Resp{status: status}} ->
IO.puts "HTTP Status: #{status}"
{:error, %HTTP.Error{reason: reason}} ->
IO.inspect reason
_ ->
IO.puts "Some other error"
end

33. Pipe Operator
three = add(1, 2)
six = add(three, 3)
ten = add(six, 4)
ten = add(add(add(1, 2), 3), 4)
ten =
1
|> add(2)
|> add(3)
|> add(4)

34. Pipe Operator
three = add(1, 2)
six = add(three, 3)
ten = add(six, 4)
ten = add(add(add(1, 2), 3), 4)
ten =
1
|> add(2)
|> add(3)
|> add(4)

35. Pipe Operator
three = add(1, 2)
six = add(three, 3)
ten = add(six, 4)
ten = add(add(add(1, 2), 3), 4)
ten =
1
|> add(2)
|> add(3)
|> add(4)

36. Pipe Operator
three = add(1, 2)
six = add(three, 3)
ten = add(six, 4)
ten = add(add(add(1, 2), 3), 4)
ten =
1
|> add(2)
|> add(3)
|> add(4)

37. Ecto
Changesets

38. Ecto
Changesets
• Ever try and run just some ActiveRecord
validations depending on the current user?

39. Ecto
Changesets
• Ever try and run just some ActiveRecord
validations depending on the current user?
• Ever have a set of validations dependent on
data state?

40. Ecto
Changesets
def edit_self_changeset(user, params %{}) do
user
|> cast(params, [:name, :age])
|> validate_required([:name])
|> validate_inclusion(:age, 18..100)
end
def admin_edit_changeset(user, params %{}) do
user
|> cast(params, [:name, :email, :age])
|> validate_required([:name, :email])
|> validate_format(:email, ~r/@/)
|> validate_inclusion(:age, 18..100)
|> unique_constraint(:email)
end

41. Ecto
Changesets
def edit_self_changeset(user, params %{}) do
user
|> cast(params, [:name, :age])
|> validate_required([:name])
|> validate_inclusion(:age, 18..100)
end
def admin_edit_changeset(user, params %{}) do
user
|> cast(params, [:name, :email, :age])
|> validate_required([:name, :email])
|> validate_format(:email, ~r/@/)
|> validate_inclusion(:age, 18..100)
|> unique_constraint(:email)
end

42. Ecto
Changesets
def edit_self_changeset(user, params %{}) do
user
|> cast(params, [:name, :age])
|> validate_required([:name])
|> validate_inclusion(:age, 18..100)
end
def admin_edit_changeset(user, params %{}) do
user
|> cast(params, [:name, :email, :age])
|> validate_required([:name, :email])
|> validate_format(:email, ~r/@/)
|> validate_inclusion(:age, 18..100)
|> unique_constraint(:email)
end

43. Ecto
Changesets
def edit_self_changeset(user, params %{}) do
user
|> cast(params, [:name, :age])
|> validate_required([:name])
|> validate_inclusion(:age, 18..100)
end
def admin_edit_changeset(user, params %{}) do
user
|> cast(params, [:name, :email, :age])
|> validate_required([:name, :email])
|> validate_format(:email, ~r/@/)
|> validate_inclusion(:age, 18..100)
|> unique_constraint(:email)
end

44. Phoenix
Param Matching
def show(conn, %{"user_params" => user_params} = params) do
end
def show(conn, %{"admin_params" => admin_params} = params) do
end

45. Phoenix
View Code

46. Phoenix
View Code
• Not a pile of global namespace helpers

47. Phoenix
View Code
• Not a pile of global namespace helpers
• Good encapsulation of presentation logic

48. Gen Server
No need for external workers
GenServer.cast(MyWorker, {:process, this_thing})
def handle_cast({:process, this_thing}, state) do
# do work
{:noreply, state}
end

49. Gen Server
No need for external workers
GenServer.cast(MyWorker, {:process, this_thing})
def handle_cast({:process, this_thing}, state) do
# do work
{:noreply, state}
end

50. Gen Server
No need for external workers
GenServer.cast(MyWorker, {:process, this_thing})
def handle_cast({:process, this_thing}, state) do
# do work
{:noreply, state}
end

51. Management should support
Elixir
https://unsplash.com/photos/FoKO4DpXamQ

52. All that cool tech didn't
convince you!?!
https://unsplash.com/photos/FO7JIlwjOtU

53. What does Elixir bring?

54. What does Elixir bring?
• Ruby-inspired syntax

55. What does Elixir bring?
• Ruby-inspired syntax
• Meta programming

56. What does Elixir bring?
• Ruby-inspired syntax
• Meta programming
• Polymorphism via protocols

57. What does Elixir bring?
• Ruby-inspired syntax
• Meta programming
• Polymorphism via protocols
• Great tooling

58. What does Elixir bring?
• Ruby-inspired syntax
• Meta programming
• Polymorphism via protocols
• Great tooling
• Better code organization facilities than Erlang

59. What does Elixir bring?
• Ruby-inspired syntax
• Meta programming
• Polymorphism via protocols
• Great tooling
• Better code organization facilities than Erlang
• Erlang functions can be called from Elixir

60. What does Elixir bring?

61. What does Elixir bring?
• Lightweight and isolated concurrency

62. What does Elixir bring?
• Lightweight and isolated concurrency
• Shared nothing concurrent programming

63. What does Elixir bring?
• Lightweight and isolated concurrency
• Shared nothing concurrent programming
• Lazy and async collections

64. What does Elixir bring?
• Lightweight and isolated concurrency
• Shared nothing concurrent programming
• Lazy and async collections
• Pattern matching

65. What does Elixir bring?
• Lightweight and isolated concurrency
• Shared nothing concurrent programming
• Lazy and async collections
• Pattern matching
• Unicode support and UTF-8 strings

66. Scaleable and Fault-tolerant

67. Scaleable and Fault-tolerant
• Isolation means each process is garbage
collected independently

68. Scaleable and Fault-tolerant
• Isolation means each process is garbage
collected independently
• This means less system wide pauses.

69. Scaleable and Fault-tolerant
• Isolation means each process is garbage
collected independently
• This means less system wide pauses.
• Things go wrong. Especially with network or
disk activity.

70. Scaleable and Fault-tolerant
• Isolation means each process is garbage
collected independently
• This means less system wide pauses.
• Things go wrong. Especially with network or
disk activity.
• Supervisor processes are instructed in how to
maintain your application

71. Stable and Extensible

72. Stable and Extensible
• Only 1 planned language deprecation for 2.0

73. Stable and Extensible
• Only 1 planned language deprecation for 2.0
• No planned timeline for 2.0

74. Stable and Extensible
• Only 1 planned language deprecation for 2.0
• No planned timeline for 2.0
• The core team believes all the right
fundamentals are in place

75. Speed (Throughput)

76. Speed (Throughput)
• Sure, it isn't C

77. Speed (Throughput)
• Sure, it isn't C
• For a Rails shop, that isn't the benchmark

78. Speed (Throughput)
• Sure, it isn't C
• For a Rails shop, that isn't the benchmark
• Multi-thread by default, no global lock

79. Speed (Throughput)
• Sure, it isn't C
• For a Rails shop, that isn't the benchmark
• Multi-thread by default, no global lock
• Fast garbage collection

80. Speed (Throughput)
• Sure, it isn't C
• For a Rails shop, that isn't the benchmark
• Multi-thread by default, no global lock
• Fast garbage collection
• All means high throughput web apps

81. Used by Big Names

82. Used by Big Names
• Discord

83. Used by Big Names
• Discord
• Pagerduty

84. Used by Big Names
• Discord
• Pagerduty
• Bleacher Report

85. Used by Big Names
• Discord
• Pagerduty
• Bleacher Report
• Square Enix

86. Used by Big Names
• Discord
• Pagerduty
• Bleacher Report
• Square Enix
• Motorola

87. Used by Big Names
• Discord
• Pagerduty
• Bleacher Report
• Square Enix
• Motorola
• https://elixir-companies.com/browse

88. Costs
All of the items we've discussed have a real impact on:

89. Costs
All of the items we've discussed have a real impact on:
• Development pace, build from pure functions

90. Costs
All of the items we've discussed have a real impact on:
• Development pace, build from pure functions
• Developer focus, cognitive load of functions over
objects

91. Costs
All of the items we've discussed have a real impact on:
• Development pace, build from pure functions
• Developer focus, cognitive load of functions over
objects
• Ease of implementing new features

92. Costs
All of the items we've discussed have a real impact on:
• Development pace, build from pure functions
• Developer focus, cognitive load of functions over
objects
• Ease of implementing new features
• Test quality and speed

93. Costs
All of the items we've discussed have a real impact on:
• Development pace, build from pure functions
• Developer focus, cognitive load of functions over
objects
• Ease of implementing new features
• Test quality and speed
• Bug rates

94. Costs
All of the items we've discussed have a real impact on:
• Development pace, build from pure functions
• Developer focus, cognitive load of functions over
objects
• Ease of implementing new features
• Test quality and speed
• Bug rates
• Maintainability

95. Staffing

96. Staffing
• Innovative tech attracts innovative developers

97. Staffing
• Innovative tech attracts innovative developers
• Syntax is approachable

98. Staffing
• Innovative tech attracts innovative developers
• Syntax is approachable
• Resources are plentiful

99. Staffing
• Innovative tech attracts innovative developers
• Syntax is approachable
• Resources are plentiful
• Training is easy, and fun

100. Paradigm Shift?
Functional Programming

101. Paradigm Shift?
Functional Programming
• Might take some adjustment

102. Paradigm Shift?
Functional Programming
• Might take some adjustment
• Fits your use case more than you expect, it is
about the data

103. Paradigm Shift?
Functional Programming
• Might take some adjustment
• Fits your use case more than you expect, it is
about the data
• Makes writing great tests easy

104. Paradigm Shift?
Functional Programming
• Might take some adjustment
• Fits your use case more than you expect, it is
about the data
• Makes writing great tests easy
• Makes writing fast tests easy

105. Ecosystem and Resources
https://unsplash.com/photos/FzrjgIId6NU

106. Mix and IEx
Mix - A great build tool for dependency
management and other tasks
IEx - An interactive shell

107. Docs, Tests, and DocTests
Documentation - a first class citizen in the
Elixir ecosystem
Tests - Testing libraries built into the language
with ExUnit
DocTests - A hybrid of testing and documentation

108. What is Next
https://unsplash.com/photos/FoKO4DpXamQ

109. Getting Started
See my other talks
https://www.danivovich.com/other

110. Resources - Books
Programming Elixir
https://pragprog.com/book/elixir16/programming-elixir-1-6
Programming Phoenix
https://pragprog.com/book/phoenix14/programming-phoenix-1-4
Metaprogramming Elixir
https://pragprog.com/book/cmelixir/metaprogramming-elixir
Functional Web Development with Elixir, OTP, and Phoenix
https://pragprog.com/book/lhelph/functional-web-development-with-
elixir-otp-and-phoenix

111. Resources - Newsletters
Elixir Radar
http://plataformatec.com.br/elixir-radar
Elixir Weekly
https://elixirweekly.net/
Elixir Digest
https://elixirdigest.net

112. Resources - Conferences
ElixirConf EU (April 8-10, Prague)
http://www.elixirconf.eu/
EMPEX NYC (May 18, NYC)
http://empex.co/nyc
ElixirConf (August, Colorado)
https://elixirconf.com/

113. Resources - Podcasts
Smart Software with SmartLogic (First Season on Elixir in
Production)
https://podcast.smartlogic.io/
Elixir Outlaws Podcast
https://elixiroutlaws.com/
ElixirTalk Podcast
http://elixirtalk.com/
Elixir Mix Podcast
https://devchat.tv/elixir-mix

114. Resources - Meetups
DC
https://www.meetup.com/DC-Elixir/
Baltimore
https://www.meetup.com/Baltimore-Elixir-and-
Erlang-Meetup/

115. Resources - Others
Elixir Status Twitter
https://twitter.com/elixirstatus
Elixir Slack
http://elixir-slackin.herokuapp.com/
Elixir Forum
https://elixirforum.com

116. ❤

117. We hope you will too

118. Questions? ❔