Elixir in Elixir

Transcript

1. Elixir Elixir In

2. How much?

3. It depends

4. What is “Elixir”?

5. Basics + STDLIB

6. of Elixir is written in Elixir 78%

7. Compare to Ruby’s 44%

8. Numbers? Meh

9. if

10. def

11. |>

12. Metaprogramming

13. Code generation

14. +BZ
    )BZFT IUUQTJBNWFSZDPN
    n
    !JBNWFSZ

15. None
16. None

17. 8F
    EFWFMPQ

18. 8F
    UFBDI

19. 8F
    XSJUF

20. “I’m speaking at ElixirConf!”

21. “That’s nice. Where is it?”

22. “Orlando.”

23. “DISNEY IS THERE!!! CAN WE GO?!”

24. “Ya, actually it’s at Disney.”

25. “OMG!!! YOU’RE SPEAKING AT DISNEY?!!”

26. “Haha, sort of” *interrupted*

27. *on phone* “YA! He’s speaking at Disney!! We’re GOING!!!” *squeal*

28. None
29. None

30. Metaprogramming

31. None

32. programming Meta

33. Working on Data

34. data quantities on which operations are performed — Dictionary.app

35. 4 + 2 data

36. +(4, 2) data

37. Kernel.+(4, 2)

38. The program is data

39. Macros

40. Macros are everywhere

41. good macros are invisible

42. defmodule ItTest do use ExUnit.Case test “works” do assert It.works?

    end end macros

43. Where is the data? Program

44. defmodule ItTest do use ExUnit.Case test “works” do assert It.works?

    end end

45. defmodule ItTest do use ExUnit.Case test “works” do assert It.works?

    end end

46. defmodule ItTest do use ExUnit.Case test “works” do assert It.works?

    end end

47. defmodule ItTest do use ExUnit.Case test “works” do assert It.works?

    end end

48. Expression macro Expression ✨ ✨

49. Expression?

50. “Quoted” Elixir code

51. {func, …, args}

52. Abstract Syntax Tree

53. + 1 - 2 3

54. + 1 - 2 3 ( ( )) func Args

55. 1 + ( 2 - 3 )

56. Args are quoted

57. Expression.match?(:lol > :wat) # => false Expression.match?(:lol = :wat) #

    => true

58. defmacro match?({:=, _, _}) do true end defmacro match?(_expr) do

    false end

59. Expression.match?(:lol > :wat) # => false Expression.match?(:lol = :wat) #

    => true

60. false # => false true # => true

61. Must return quoted

62. defmacro badmatch do {:=, [], [:lol, :wat]} end

63. defmacro badmatch do quote do :lol = :wat end end

64. Expression.badmatch # (MatchError)

65. :lol = :wat # (MatchError)

66. Quote

67. {func, meta, args}

68. {:=, [], [:lol, :wat]}

69. quote do :lol = :wat end

70. Sort of like strings…

71. “1+1”

72. quote(do: 1+1)

73. quote do 1+1 end

74. Return AST of Expression

75. 2 - 3 quote do end

76. - 2 3 {: , […], [ , ]} (-

    2 3)

77. quote do 1 + (2 - 3) end

78. {: , […], [ , {: , […], [ ,

    ]}]} + 1 - 2 3 (+ 1 (- 2 3))

79. Easier to grok

80. {:+, […], [1, {:-, […], [2, 3]}]} quote do 1

    + (2 - 3) end

81. Quoted Literals

82. quote do: “foo” # “foo” quote do: :foo # :foo

    quote do: 1 # 1 quote do: [1] # [1] quote do: {1,2} # {1,2} quote do: [a: 1] # [a: 1]

83. Unquote

84. “Inject value in quote”

85. Like string interpolation

86. “Inject value into quoted string”

87. name = “Sue” “hi name” # => “hi name”

88. name = “Sue” “hi #{name}” # => “hi Sue”

89. “Inject value into quoted Expression”

90. num = 42 # => 42 quote do: 1 +

    num # => {:+, [], [1, {:num, [], :Elixir}]}

91. num = 42 # => 42 quote do: 1 +

    unquote(num) # => {:+, [], [1, 42]}

92. name = “Sue” “hi #{name}” # => “hi Sue”

93. if

94. if foo > 0 do IO.puts(“Pass!”) else IO.puts(“Fail.”) end

95. if(…, do: …, else: …)

96. if(…, [do: …, else: …]) cases cond

97. Truthy & Falsey

98. false || nil Falsey

99. anything else Truthy

100. case … do x when x in [false, nil] ->

     … _ -> … end cond cases

101. defmacro if(c, do: tc, else: fc) do quote do case

     unquote(c) do x when x in [false, nil] -> unquote(fc) _ -> unquote(tc) end end end cond cases cond cases

102. if do else end foo > 0 IO.puts(“Pass!”) IO.puts(“Fail.”)

103. case do x when x in [false, nil] -> _

     -> end foo > 0 IO.puts(“Fail.”) IO.puts(“Pass!”)

104. When to macro…

105. #1 Don’t

106. Write functions

107. defmacro add(a, b) do quote do unquote(a) + unquote(b) end

     end

108. def add(a, b) do a + b end

109. More direct

110. Less error-prone

111. #2 Constants

112. defmacro seconds_per_minute, do: 60 defmacro minutes_per_hour, do: 60

113. #3 DSL

114. html do body do div class: “content” do p “Engaging

     content.” end end end

115. #4 Hide details

116. test “works” do assert It.works? end

117. #5 Reduce boilerplate

118. Language extension

119. defmodule Lolwat do def lol do :wat end end

120. :elixir_module.compile(Lolwat, {:def, [context: Elixir, import: Kernel], [{:lol, [context: Elixir], Elixir},

     [do: :wat]]}, [], __ENV__)

121. :elixir_module.compile(Lolwat, {:def, [context: Elixir, import: Kernel], [{:lol, [context: Elixir], Elixir},

     [do: :wat]]}, [], %{__struct__: Macro.Env, aliases: [], context: nil, context_modules: [Mex], export_vars: nil, file: "iex", function: nil, functions: [Mex: [expand_all: 2], "IEx.Helpers": [c: 1, c: 2, cd: 1, clear: 0, flush: 0, h: 0, i: 1, l: 1, ls: 0, ls: 1, nl: 1, nl: 2, pid: 1, pid: 3, pwd: 0, r: 1, recompile: 0, respawn: 0, v: 0, v: 1], Kernel: [!=: 2, !==: 2, *: 2, +: 1, +: 2, ++: 2, -: 1, -: 2, --: 2, /: 2, <: 2, <=: 2, ==: 2, ===: 2, =~: 2, >: 2, >=: 2, abs: 1, apply: 2, apply: 3, binary_part: 3, bit_size: 1, byte_size: 1, div: 2, elem: 2, exit: 1, function_exported?: 3, get_and_update_in: 3, get_in: 2, hd: 1, inspect: 1, inspect: 2, is_atom: 1, is_binary: 1, is_bitstring: 1, is_boolean: 1, is_float: 1, is_function: 1, is_function: 2, is_integer: 1, is_list: 1, is_map: 1, is_number: 1, is_pid: 1, is_port: 1, is_reference: 1, is_tuple: 1, length: 1, macro_exported?: 3, make_ref: 0, map_size: 1, max: 2, min: 2, node: 0, node: 1, not: 1, pop_in: 2, put_elem: 3, put_in: 3, rem: 2, round: 1, self: 0, send: 2, spawn: 1, spawn: 3, spawn_link: 1, spawn_link: 3, spawn_monitor: 1, spawn_monitor: 3, struct: 1, struct: 2, struct!: 1, struct!: 2, throw: 1, tl: 1, trunc: 1, tuple_size: 1, update_in: 3]], lexical_tracker: nil, line: 2, macro_aliases: [], macros: [Mex: [mex: 1], "IEx.Helpers": [b: 1, h: 1, import_file: 1, import_file: 2, import_file_if_available: 1, import_if_available: 1, import_if_available: 2, s: 1, t: 1], Kernel: [!: 1, &&: 2, ..: 2, <>: 2, @: 1, alias!: 1, and: 2, binding: 0, binding: 1, def: 1, def: 2, defdelegate: 2, defexception: 1, defimpl: 2, defimpl: 3, defmacro: 1, defmacro: 2, defmacrop: 1, defmacrop: 2, defmodule: 2, defoverridable: 1, defp: 1, defp: 2, defprotocol: 2, defstruct: 1, destructure: 2, get_and_update_in: 2, if: 2, in: 2, is_nil: 1, match?: 2, or: 2, pop_in: 1, put_in: 2, raise: 1, raise: 2, reraise: 2, reraise: 3, sigil_C: 2, sigil_D: 2, sigil_N: 2, sigil_R: 2, sigil_S: 2, sigil_T: 2, sigil_W: 2, sigil_c: 2, sigil_r: 2, sigil_s: 2, sigil_w: 2, to_char_list: 1, to_charlist: 1, to_string: 1, unless: 2, update_in: 2, use: 1, use: 2, var!: 1, var!: 2, |>: 2, ||: 2]], module: nil, requires: [IEx.Helpers, Kernel, Kernel.Typespec, Mex], vars: []})

122. good macros are invisible

123. CJUMZ&MJYJS.FUB

124. !JBNWFSZ Questions?