Elixir - introduction - Speaker Deck

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Elixir - Introduction

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Karol Galanciak • Full-stack developer at • Twitter: @Azdaroth • blog: karolgalanciak.com, blog.ragnarson.com

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Programming should be about transforming data

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Programming should be about transforming data OOP:

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Programming should be about transforming data OOP: • classes

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Programming should be about transforming data OOP: • classes • objects

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Programming should be about transforming data OOP: • classes • objects • state

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Programming should be about transforming data OOP: • classes • objects • state • modelling real world with hierarchies

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Programming should be about transforming data Elixir:

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Programming should be about transforming data Elixir: getting things done

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Why Elixir?

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Why Elixir? • Functional

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Why Elixir? • Functional: • immutability

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Why Elixir? • Functional: • immutability • pattern matching

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Why Elixir? • Functional: • pattern matching • immutability • side-effects free

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Why Elixir? • Functional • Erlang VM

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Why Elixir? • Functional • Erlang VM • Concurrency

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Why Elixir? • Functional • Erlang VM • Concurrency • Syntax

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Why Elixir? • Functional • Erlang VM • Concurrency • Syntax • Erlang compatible

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Match operator • a = 1

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Match operator • a = 1=> 1

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Match operator • a = 1 => 1 • 1 = a

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Match operator • a = 1 => 1 • 1 = a => 1

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Match operator • a = 1 => 1 • 1 = a => 1 • 2 = a

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Match operator • a = 1 => 1 • 1 = a => 1 • 2 = a => (MatchError) no match of right hand side value: 1

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Match operator • a = 1 => 1 • 1 = a => 1 • 2 = a => (MatchError) no match of right hand side value: 1 • list = [1, 2, 3]

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Match operator • a = 1 => 1 • 1 = a => 1 • 2 = a => (MatchError) no match of right hand side value: 1 • list = [1, 2, 3] • [a, b, c] = list

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Match operator • a = 1 => 1 • 1 = a => 1 • 2 = a => (MatchError) no match of right hand side value: 1 • list = [1, 2, 3] • [a, b, c] = list • [1, b, 3] = list

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Match operator • a = 1 => 1 • 1 = a => 1 • 2 = a => (MatchError) no match of right hand side value: 1 • list = [1, 2, 3] • [a, b, c] = list • [1, b, 3] = list • [2, 2, 3] = list

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Match operator • a = 1 => 1 • 1 = a => 1 • 2 = a => (MatchError) no match of right hand side value: 1 • list = [1, 2, 3] • [a, b, c] = list • [1, b, 3] = list • [2, 2, 3] = list • [d, _, _] = list

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Match operator • a = 1 => 1 • 1 = a => 1 • 2 = a => (MatchError) no match of right hand side value: 1 • list = [1, 2, 3] • [a, b, c] = list • [1, b, 3] = list • [2, 2, 3] = list • [d, _, _] = list • { status, _ } = { :ok, ”content” }

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Types

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Types • Value Types:

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Types • Value Types: • Integers

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Types • Value Types: • Integers • Floats

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Types • Value Types: • Integers • Floats • Atoms (:like_ruby_symbol)

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Types • Value Types: • Integers • Floats • Atoms (:like_ruby_symbol) • Ranges (1..100)

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Types • Value Types: • Integers • Floats • Atoms (:like_ruby_symbol) • Ranges (1..100) • Regular expressions (%r{regexp})

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Tpes • System types:

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Types • System types: • PIDs

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Types • System types: • PIDs • Ports

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Types • System types: • PIDs • Ports • References

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Types • Collection types:

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Types • Collection types: • Tuples

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Types • Collection types: • Tuples • => {:ok, ”content”}

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Types • Collection types: • Tuples • => {:ok, ”content”} • => {:error, ”error message”}

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Types • Collection types: • Tuples • => {:ok, ”content”} • => {:error, ”error message”} • Lists

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Types • Collection types: • Tuples • => {:ok, ”content”} • => {:error, ”error message”} • Lists • => [1, 2, 3]

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Types • Collection types: • Tuples • => {:ok, ”content”} • => {:error, ”error message”} • Lists • => [1, 2, 3] • => [1, 2, 3] ++ [4]

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Types • Collection types: • Tuples • => {:ok, ”content”} • => {:error, ”error message”} • Lists • => [1, 2, 3] • => [1, 2, 3] ++ [4] • => [1, 2, 3] -- [1]

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Types • Collection types: • Tuples • => {:ok, ”content”} • => {:error, ”error message”} • Lists • => [1, 2, 3] • => [1, 2, 3] ++ [4] • => [1, 2, 3] -- [1] • => 1 in [1, 2, 3]

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Types • Collection types: • Keyword Lists

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Types • Collection types: • Keyword Lists • => [name: ”Elixir”, status: ”awesome”]

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Types • Collection types: • Keyword Lists • => [name: ”Elixir”, status: ”awesome”] • => [name: ”Elixir”, status: ”awesome”][:name]

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Types • Collection types: • Keyword Lists • => [name: ”Elixir”, status: ”awesome”] • => [name: ”Elixir”, status: ”awesome”][:name] • Maps

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Types • Collection types: • Keyword Lists • => [name: ”Elixir”, status: ”awesome”] • => [name: ”Elixir”, status: ”awesome”][:name] • Maps • %{”ruby” => ”oop”, :elixir => ”functional”}

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Functions

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Functions • add_one = fn n -> n + 1 end

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Functions • add_one = fn n -> n + 1 end • add_one.(1) => 2

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Functions • add_one = fn n -> n + 1 end • add_one.(1) => 2 • square = &(&1 * &1)

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Functions • add_one = fn n -> n + 1 end • add_one.(1) => 2 • square = &(&1 * &1) • => square.(3) => 9

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Functions • add_one = fn n -> n + 1 end • add_one.(1) => 2 • square = &(&1 * &1) • => square.(3) => 9 • len = &Enum.count/1

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Functions • add_one = fn n -> n + 1 end • add_one.(1) => 2 • square = &(&1 * &1) • => square.(3) => 9 • len = &Enum.count/1 • len.([1, 2, 3]) => 3

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Organizing code

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Organizing code defmodule SomeName do end

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Organizing code defmodule SomeName do def hello_world do IO.puts ”hello world” end end

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Organizing code defmodule SomeName do def hello_world do IO.puts ”hello world” end end SomeName.hello_world => ”hello world”

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Functions and Pattern Matching

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Functions and Pattern Matching defmodule MySum do end

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Functions and Pattern Matching defmodule MySum do def sum(array), do: _sum(0, array) end

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Functions and Pattern Matching defmodule MySum do def sum(array), do: _sum(0, array) defp _sum(total, []), do: total end

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Functions and Pattern Matching defmodule MySum do def sum(array), do: _sum(0, array) defp _sum(total, []), do: total defp _sum(total, [head | tail]), do: _sum(total + head, tail) end

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Functions and Pattern Matching defmodule MySum do def sum([head | tail]), do: _sum(head, tail) defp _sum(total, []), do: total defp _sum(total, [head | tail]), do: _sum(total + head, tail) end MySum.sum([1, 2, 3]) => 6

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Guard Clauses

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Guard Clauses defmodule NumberType do def print_type(num) when num < 0 do IO.puts "#{num} - I’m negative!" end def print_type(num) when num == 0 do IO.puts "I’m 0!" end def print_type(num) when num > 0 do IO.puts "#{num} - I’m positive!" end end • NumberType.print_type(1) => 1 - I’m positive! • NumberType.print_type(0) => I’m 0! • NumberType.print_type(-1) => -1 - I’m negative!

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Pipe operator - |> ps awux | grep spring | awk '{print $2}' | xargs kill

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List comprehensions

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List comprehensions for x <- [1, 2, 3], y <- [10, 20, 30], x * y > 20, do: x + y => [31, 22, 32, 13, 23, 33]

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Cond, if, case

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Cond, if, case if 1 == 1 do ”I’m truthy” else ”I’m falsey” end

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Cond, if, case if 1 == 1 do ”I’m truthy” else ”I’m falsey” end unless 1 == 1, do: ”error”, else: ”ok”

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Cond, if, case cond do rem(number, 3) == 0 and rem(number, 5) == 0 -> "FizzBuzz" rem(number, 3) == 0 -> "Fizz" rem(number, 5) == 0 -> "Buzz" true -> number end

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Cond, if, case case File.open(”some_ﬁle.exs”) do { :ok, ﬁle } => IO.puts ”success” { :error, reason } => IO.puts ”error: #{reason}” end

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Structs

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Structs defmodule User do defstruct fullname: "", email: "" end

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Structs defmodule User do defstruct fullname: "", email: "" end user = %User{fullname: ”name”}

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Structs defmodule User do defstruct fullname: "", email: "" end user = %User{fullname: ”name”} user.fullname = > ”name”

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Structs defmodule User do defstruct fullname: "", email: "" def has_email?(user) do String.length(user.email) > 0 end end

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Macros

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Macros defmodule Test do require Plus Plus.add_n(3) Plus.add_n(4) end Test.add_3(4) => 7 Test.add_4(5) => 9

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Macros defmodule Plus do defmacro add_n(number) do name = String.to_atom("add_#{number}") quote do def unquote(name)(other_number) do other_number + unquote(number) end end end end

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Concurrency

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Concurrency defmodule Spawnee do def hi do receive do { sender, message } -> send sender, { :ok, "Hi #{message}!"} end end end

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Concurrency defmodule Spawnee do def hi do receive do { sender, message } -> send sender, { :ok, "Hi #{message}!"} end end end pid = spawn(Spawnee, :hi, []) send pid, { self, "Elixir" }

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Concurrency defmodule Spawnee do def hi do receive do { sender, message } -> send sender, { :ok, "Hi #{message}!"} end end end pid = spawn(Spawnee, :hi, []) send pid, { self, "Elixir" } receive do { :ok, message } -> IO.puts message end

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Encapsulating state by processes

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Encapsulating state by processes defmodule Counter do def start do do_count(0) end defp do_count(current_number) do receive do { :increment, listener } -> send listener, current_number + 1 do_count(current_number + 1) end end end counter_pid = spawn(Counter, :start, []) send(counter_pid, { :increment, self }) receive do count -> count end => 1