Learning Elixir as a Rubyist
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Elixir is good for fault tolerance, high concurrency, and distribution. It is built on Erlang and shares Erlang's strengths like robustness and distribution. Elixir brings Erlang's strengths with a syntax inspired by Ruby and Clojure, making it more approachable. Key features include immutable data structures, pattern matching, pipe operators, metaprogramming with macros, lightweight processes and message passing, and the OTP framework for building fault-tolerant systems. Popular companies like WhatsApp and RabbitMQ use Elixir for its robustness in handling large numbers of concurrent connections.
![Beyond Ruby...
Pattern Matching
[h | _] = [1, 2, 3]
Immutability
socket
|> read_line()
|> write_line(socket)
Pipe Operator
socket
|> read_line()
|> write_line(socket)
Protocols
defprotocol Blank do
@doc "Returns true if empty"
def blank?(data)
end
LW Processes
send self(), {:hello, "world"}
receive do
{:hello, msg} -> msg
{:world, msg} -> "won't match"
end
Metaprogramming
quote do: sum(1, 2 + 3, 4)](https://image.slidesharecdn.com/learningelixir-150915033212-lva1-app6892/85/Learning-Elixir-as-a-Rubyist-10-320.jpg)
Learning Elixir as a Rubyist
- 2. What is it good for? ■ Fault tolerance - maximum uptime ■ Large number of connections / IO ■ High level of concurrency ■ Distributed across machines
- 4. Erlang - 1986 It was originally designed by Ericsson to support distributed, fault-tolerant, soft real-time, highly available, non-stop applications. It supports hot swapping, thus code can be changed without stopping a system.
- 5. WhatsApp Messaging app acquired by Facebook for $19 billion. Used Erlang for handling 2 million connections a server. 10 team members work on Erlang and they handle both development and ops. RabbitMQ RabbitMQ is an open source message broker software that implements the Advanced Message Queuing Protocol (AMQP). It is fault tolerant and distributed. Riak is a distributed NoSQL key-value data store that offers high availability, fault tolerance, operational simplicity, and scalability. Erlang in the Wild
- 6. Erlang downsides? ■ Learning Curve ■ Syntax based on Prolog, not as approachable (to some)
- 8. About Elixir ■ Invented by José Valim, Rails committer ■ Syntax inspired by ○ Ruby ○ Clojure ■ Nicely bring together strengths of these languages while gaining benefits of Erlang VM
- 10. Beyond Ruby... Pattern Matching [h | _] = [1, 2, 3] Immutability socket |> read_line() |> write_line(socket) Pipe Operator socket |> read_line() |> write_line(socket) Protocols defprotocol Blank do @doc "Returns true if empty" def blank?(data) end LW Processes send self(), {:hello, "world"} receive do {:hello, msg} -> msg {:world, msg} -> "won't match" end Metaprogramming quote do: sum(1, 2 + 3, 4)
- 11. Immutability
- 12. Immutable data structures Potential source of errors in Ruby:
- 13. Immutable data structures What’s wrong with this? ■ You don’t know what to expect of your data when you call a method ■ Especially painful for threading ○ Concurrent modification errors ○ Race conditions
- 14. Immutable data structures In Elixir all data structures are immutable!! ■ You can safely share with other processes ■ Don’t have to worry about data changing under the covers
- 16. Pattern Matching
- 17. Pattern Matching ‘=’ operator in action:
- 18. “ You Keep Using That Word, I Do Not Think It Means What You Think It Means
- 19. Pattern Matching The ‘=’ operator handles assignment and comparison at the same time. Can “destructure” complex types and assign variables automatically.
- 20. Pattern matching Fail when error code is not as expected: Pluck out variables from complex structures
- 21. Pattern matching in methods Multiple method definitions, match params: No need for guards inside methods
- 22. Pipe Operator
- 23. Pipe Operator ■ Functional Programming: Series of data transformations. ■ Pipe operator makes this cleaner: |>
- 24. Pipe Operator
- 25. Metaprogramming
- 27. Macros ■ Allow extension of the language in a clean way ■ Can control execution of passed in code ■ Gives you access to passed in AST
- 28. Processes
- 29. Lightweight processes / Message passing ■ Native support for lightweight processes ■ Can start tens of thousands of processes ■ Processes are isolated ■ Communicate via messages
- 30. Lightweight processes / Message passing
- 31. OTP
- 32. OTP / Supervision hierarchy ■ OTP= “Rails” of event driven architecture ■ Supervision hierarchies help you define fault tolerance ■ “Let it crash” - reboot with known state ■ Define supervisors for processes and the process / dependencies for restarting
- 33. Fault tolerance / supervision
- 34. Distribution ■ Distribution is free! ■ Can send and receive messages from other nodes ■ Can supervise other nodes
- 35. Tooling
- 36. Growing Ecosystem Number of tools is growing Rails Phoenix ActiveRecord Ecto Rack Plug irb iex rake / bundler mix
- 37. Benchmarks
- 38. Phoenix
- 39. Working on Exq library - Sidekiq for Elixir Feel free to help out!
- 40. Try it out!
- 41. Resources ■ http://elixir-lang.org/crash-course.html ■ http://learnyousomeerlang.com/ ■ https://pragprog.com/book/elixir/programming-elixir ■ https://www.manning.com/books/elixir-in-action ■ http://www.infoq.com/presentations/Value-Identity-State-Rich-Hickey ■ https://github.com/mroth/phoenix-showdown