Why Elixir? (Intro to Elixir)

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WHY ELIXIR? Elixir Soﬁa Meetup May 2017

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WHY ELIXIR? INTRO TO ELIXIR

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Ventsislav Nikolov @ventsislaf

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DISCLAIMER NO GIFs

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WHAT IS ELIXIR?

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• functional programming language • compiles to erlang bytecode • immutable data • dynamically typed • concurrency, distribution, fault tolerance • hot code swapping

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DATA TYPES (NOT ALL) 1_000_000 # Integer 314159.0e-5 # Float :apple # Atom "Jon Snow" # String {:error, 404} # Tuple [1, 2, 3] # (Linked) List %{name: "Jon", age: 21} # Map

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MODULES AND FUNCTIONS

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ANONYMOUS FUNCTIONS add = fn(a, b) -> a + b end add.(2, 5) # => 7

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MODULES defmodule Math do def add(a, b) do a + b end defp multiply(a, b) do a * b end end # warning: function multiply/2 is unused Math.add(2, 5) # => 7 Math.multiply(2, 5) # ** (UndefinedFunctionError) function Math.multiply/2 is undefined or private

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IMMUTABILITY

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colors = ["green", "apple", "red"] List.delete(colors, "apple") # => ["green", "red"] colors # => ["green", "apple", "red"]

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PATTERN MATCHING

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= x = 1 # => 1 1 = x # => 1 2 = x # ** (MatchError) no match of right hand side value: 1 x = 2 # => 2

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DECOMPOSITION [x, y] = [1, 2] # x => 1, y => 2 [1, x] = [1, 2] # x => 2 [_, x] = [1, 2] # x => 2 [head | tail] = [1, 2, 3] # head => 1, tail => [2, 3] %{name: name} = %{name: "Jon Snow", age: 21} # name => "Jon Snow"

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RECURSION

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def sum([]) do 0 end def sum([head | tail]) do head + sum(tail) end

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PIPE OPERATOR

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Enum.sort(String.codepoints(String.downcase(word)))

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lowercase = String.downcase(word) chars = String.codepoints(lowercase) ordered = Enum.sort(chars)

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word |> String.downcase() |> String.codepoints() |> Enum.sort()

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Elixir + Erlang = ❤

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# Erlang rand:uniform(10). # Elixir :rand.uniform(10)

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CONCURRENCY

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PROCESSES (not OS) spawn fn -> IO.puts "Hello from another process" end

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LIGHTWEIGHT • created for couple of microseconds • 1-2 KB initial memory footprint • up to hundreds of millions processes per VM

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ISOLATION name = "Jon Snow" spawn fn -> IO.puts "Hello, #{name}" end

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MESSAGES pid = spawn fn -> receive do msg -> IO.puts "received a message: #{msg}" end end send pid, "You know nothing, Jon Snow."

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msg 1 msg 2 msg 3 mailbox

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FAULT TOLERANCE

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:one_for_one :one_for_all

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DISTRIBUTION

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$ iex --name one@host $ iex --name two@host $ iex --name three@host # in node one iex> Node.connect :two@host iex> Node.connect :three@host iex> Node.list # => [:two@host, :three@host] # in node two iex> Node.list # => [:one@host, :three@host] iex> Node.spawn :three@host, fn -> IO.puts("hello") end

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TOOLING

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IEx (demo) $ iex iex> 2 + 5 7

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MIX mix new app_name mix compile mix test mix deps.get mix hex.publish

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OBSERVER :observer.start

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WHERE TO GO NEXT?

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THANK YOU!