Elixir for rubysts

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Information about Elixir for rubysts

Published on March 4, 2014

Author: DanniFriedland

Source: slideshare.net


A basic quick intro to elixir for ruby programmers

elixir for Rubyists

The lovechild of ruby & erlang + =

What’s similar

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

Meta-Programming defmodule 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 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]! ! • List Comprehensions iex> lc x inlist [1, 2], y inlist [3, 4], do: x * y! [3, 4, 6, 8]!

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

Pattern matching iex> {[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!


The pipe operator We all wrote code like this from time to time: people ! orders tax filing ! = = = = DB.find_customers! Orders.for_customers(people)! sales_tax(orders, 2013)! prepare_filing(tax)! Or worse, this: 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 capture Enum.map [1,2,3], fn(x) -> x * x end! ! ! ! Enum.map [1,2,3], &(&1 * &1)!

Guard clauses defmodule 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!


Actor based defmodule 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 • on ~> on ~> ! Actors can be on a local or remote VM, and it’s transparent to you! machine1! iex --name node1@machine1.com --cookie a_cookie_string! 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 OTP Open 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

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