Introduction to Elixir

Slides for the "Introduction to Elixir" talk I gave at the first Elixir/Erlang meetup in Italy, set in Bologna (October 2015).

Transcript

1. introduction to
   Elixir
   

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2. Erlang
   compiles to
   bytecode
   

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3. Elixir is what would happen if Erlang, Clojure and
   Ruby somehow had a baby and it wasn't an
   accident
   Devin Torres
   

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4. Andrea Leopardi
   @whatyouhide
   

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5. metaprogramming
   tooling
   interop
   concurrency
   features
   

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6. features
   

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7. data structures
   

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8. 199
   "t-rex"
   :dr_manhattan
   [:red, :white, :blue]
   {:error, "nope"}
   %{hair: :red, weight: :high}
   

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9. immutability
   

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10. all data structures
    are immutable
    

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11. animals = ["lion", "table", "bear"]
    List.delete(animals, "table")
    animals
    #=> ["lion", "table", "bear"]
    

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12. data+functions
    

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13. data
    functions
    modules
    

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14. String.upcase("meh")
    m
    
    o
    
    d
    
    u
    
    l
    
    e
    f
    
    u
    
    n
    
    c
    
    t
    
    i
    
    o
    
    n
    d
    
    a
    
    t
    
    a
    

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15. defmodule String do
    def upcase(str) do
    # ...
    end
    end
    

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16. high-order functions
    

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17. doubler = fn(i) -> i * 2 end
    Enum.map([1, 2, 3], doubler)
    #=> [2, 4, 6]
    

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18. pattern matching
    

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19. = ≠ =
    

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20. match the structure of the data
    bind variables while doing that
    

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21. [first, second, third] = [
    :houston,
    :austin,
    :dallas,
    ] first
    #=> :houston
    second
    #=> :austin
    

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22. [first, second, _] = [
    :houston,
    :austin,
    :dallas,
    ] first
    #=> :houston
    second
    #=> :austin
    

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23. [first, second, _] = [
    :houston,
    :austin,
    :dallas,
    :seattle,
    ]
    ** (MatchError)
    

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24. protocols
    

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25. à la Clojure
    

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26. JSON.encode(thing)
    defines API
    

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27. defprotocol JSON do
    def encode(thing)
    end
    

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28. JSON.encode(thing)
    dispatches to implementation
    

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29. defimpl JSON, for: Integer do
    def encode(i), do: # ...
    end
    

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30. concurrency
    

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31. Any sufficiently complicated
    concurrent program in another
    language contains an ad hoc
    informally-specified bug-ridden
    slow implementation of half of
    Erlang. Robert Virding
    

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32. spawn fn ->
    IO.puts "from another process"
    end
    

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33. not OSprocesses
    

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34. lightweight
    isolation
    message passing
    

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35. for _ spawn(fn -> :ok end)
    end
    lightweight
    

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36. animals = [:dog, :cat]
    spawn fn ->
    animals # it's a copy
    end
    isolation
    

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37. isolation
    per-process garbage
    collection!!!
    

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38. message passing
    the only way
    processes can
    communicate
    

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39. pid = spawn fn ->
    # ...
    end
    send pid, "a message"
    message passing
    

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40. spawn fn ->
    receive do
    msg -> :ok
    end
    end
    message passing
    

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41. spawn_monitor fn ->
    raise "die!"
    end
    receive do m -> m end
    #=> {:DOWN, ...}
    message passing
    

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42. actor model
    

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43. def loop(state) do
    receive do
    {from, :get} ->
    send(from, state)
    loop(state)
    {from, :put, new_state} ->
    loop(new_state)
    end
    end
    

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44. def loop(state) do
    receive do
    {from, :get} ->
    send(from, state)
    loop(state)
    {from, :put, new_state} ->
    loop(new_state)
    end
    end
    

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45. def loop(state) do
    receive do
    {from, :get} ->
    send(from, state)
    loop(state)
    {from, :put, new_state} ->
    loop(new_state)
    end
    end
    

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46. def loop(state) do
    receive do
    {from, :get} ->
    send(from, state)
    loop(state)
    {from, :put, new_state} ->
    loop(new_state)
    end
    end
    

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47. def loop(state) do
    receive do
    {from, :get} ->
    send(from, state)
    loop(state)
    {from, :put, new_state} ->
    loop(new_state)
    end
    end
    

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48. def loop(state) do
    receive do
    {from, :get} ->
    send(from, state)
    loop(state)
    {from, :put, new_state} ->
    loop(new_state)
    end
    end
    

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49. def loop(state) do
    receive do
    {from, :get} ->
    send(from, state)
    loop(state)
    {from, :put, new_state} ->
    loop(new_state)
    end
    end
    

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50. def loop(state) do
    receive do
    {from, :get} ->
    send(from, state)
    loop(state)
    {from, :put, new_state} ->
    loop(new_state)
    end
    end
    

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51. def loop(state) do
    receive do
    {from, :get} ->
    send(from, state)
    loop(state)
    {from, :put, new_state} ->
    loop(new_state)
    end
    end spawn(&loop/0)
    

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52. Node.spawn(node, fun)
    

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53. interop
    

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54. Elixir data structures
    are
    Erlang data structures
    

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55. lists:map(fun(X) -> X * 2 end,
    [1, 2, 3]).
    :lists.map(fn(x) -> x * 2 end,
    [1, 2, 3])
    

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56. :queue.in("customer1",
    :queue.new())
    

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57. tooling
    

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58. iex> 8 * 2
    16
    IEx
    

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59. mix new my_app
    compile
    test
    deps.get
    Mix
    

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60. test "math works!" do
    assert 1 + 1
    end
    ExUnit
    

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61. Hey there, !
    EEx
    

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62. defp deps do
    [{:phoenix, "~> 1.0"},
    {:ecto, "~> 1.0"}]
    end
    Hex
    

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63. so
    

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64. lots of companies use Elixir in prod
    it's awesome to work with
    thriving ecosystem, smart devs
    phoenix
    metaprogramming
    

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65. @whatyouhide
    

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