elixir for Rubyists

The lovechild of ruby & erlang

+ =

What’s similar

Syntaxdefmodule Underscore.Enum do!! def pull(list, other) do!! ! Enum.reject(list, fn(item)-> item in other end)!! end!end!

Meta-Programmingdefmodule MyMacro do! defmacro unless(clause, options) do! quote do: if(!unquote(clause), unquote(options))! end!end!

And other fun stuff• Huge, expressive standard lib

• Heredocs, Multiline Strings, String Interpolation

• Sigils(i.e %w/%c etc)

• Great documentation

• ITS FUN(C) TO WORK WITH

Whats different

Functional• Functions are first level citizens

!

!

• List Comprehensions

iex> square = fn x -> x * x end!#Function<6.17052888 in :erl_eval.expr/5>!iex> Enum.map(1..10, square)![1, 4, 9, 16, 25, 36, 49, 64, 81, 100]!

iex> lc x inlist [1, 2], y inlist [3, 4], do: x * y![3, 4, 6, 8]!

Immutableiex> list = [:a, :b, :c]![:a, :b, :c]!iex> List.delete(list, :b)![:a, :c]!iex> list![:a, :b, :c]!iex> list = List.delete(list, :b)![:a, :c]!iex> list![:a, :c]!

Pattern matchingiex> {[head | tail], {:atom, msg}} = !! ! ! ! {[1, 2, 3], {:atom, "PATTERN MATCHING FTW!"}} !{[1, 2, 3], {:atom, "PATTERN MATCHING FTW!"}}!

iex> head!1!iex> tail![2, 3]!iex> msg!"PATTERN MATCHING FTW!"!

Pattern matching functions are amazing

defmodule MyEnum do! def sum([]), do: 0! def sum([head | tail]), do: head + sum(tail)!end!

Whats AMAZING

The pipe operatorWe all wrote code like this from time to time:

!

!

Or worse, this:

people = DB.find_customers!orders = Orders.for_customers(people)!tax = sales_tax(orders, 2013)!filing = prepare_filing(tax)!

filing = prepare_filing(sales_tax(Orders.for_customers(DB.find_customers)))!

Ta daa

filing = DB.find_customers!! |> Orders.for_customers!! |> sales_tax(2013)!! |> prepare_filing!

Function captureEnum.map [1,2,3], fn(x) -> x * x end!!!!Enum.map [1,2,3], &(&1 * &1)!

Guard clausesdefmodule Factorial do! def of(0), do: 1! def of(n) when n > 0 do! n * of(n-1)! end!end!

Optional(!) type checking@spec add(integer, integer), do: integer!def add(a, b), do: a + b!

Concurrency

Actor baseddefmodule Greeter do! def greet do ! receive do ! {:english, name} -> ! IO.puts "Hello, #{name}."! greet! {:chinese, name} -> ! IO.puts "你½ 好¥½, #{name}."! greet! {:spanish, name} -> ! IO.puts "¡Hola!, #{name}."! greet! :exit -> ! IO.puts "Bye bye!"! _ -> ! IO.puts "I don't understand ... but Hello anyway!"! greet! end! end!end

!iex> greeter = spawn(Greeter, :greet, [])!#PID<0.52.0>!!iex> greeter <- {:english, 'Amy'}!Hello, Amy.!{:english, ‘Amy'}!!iex> greeter <- {:chinese, 'Ben'}!{:chinese, 'Ben'}!你½ 好¥½, Ben.!!iex> greeter <- {:spanish, 'Charlie'}!{:spanish, 'Charlie'}!¡Hola!, Charlie.!!iex(31)> greeter <- {:klingon, 'David'}!I don't understand ... but Hello anyway!!

Few notes about actors

• They’re fast & lightweight - you can have 10,000 of them on a tiny machine.

• The queue is managed by the VM

• Support hot-swapping

Native support for multi machine distribution

• Actors can be on a local or remote VM, and it’s transparent to you!

on machine1!~> iex --name node1@machine1.com --cookie a_cookie_string!on machine2!~> iex --name node2@machine2.com --cookie a_cookie_string!!iex(node1@machine1.com)1> Node.connect :"node2@machine2.com"!true!!iex(node1@machine1.com)2> print_node_name = fn -> IO.puts Node.self end!#Function<erl_eval.20.80484245>!!iex(node1@machine1.com)3> Node.spawn(:"node2@machine2.com", print_node_name)!node2@machine2.com!#PID<7789.49.0> !

The OTPOpen Telecom Platform - but nobody cares

Reliability• Linked processes/Supervisor tree

• Failover nodes

• Hot code reload

• 20 years of battle-tested code, it’s VERY hard to break.

• used by a very huge scale applications:

• Facebook Messages/ WhatsApp

• Riak/ CouchDB/ RabbitMQ

Summery• Functional and fun

• FAST

• Low/high level language

• Mature VM/young language

• Scalable