A sip of Elixir

An introduction to Elixir

Transcript

1. A sip of Elixir @emadb
2. What language is this?
3. Erlang • 1987 - First version written in Prolog. Good but slow • Early ’90 - BEAM • 1992 - Erlang in production • In 1998 Ericsson announced the AXD301 switch, containing over a million lines of Erlang and reported to achieve a high availability of nine “9"s. • 1999 Ericsson banned the use of Erlang • 2004 Ericsson lifted the ban
4. Erlang
5. Concurrency Oriented Programming Languages
6. COP Languages In languages like <noname> they forgot about concurrency. It either wasn’t designed in from the beginning or else it was added on as an afterthought.
 Armstrong, 2002
7. COP Languages • Processes are truly independent • No penalty for massive parallelism • No unavoidable penalty for distribution • Concurrent behaviour of program same on all OSs • Can deal with failure
8. COP is nice • The world is parallel • The world is distributed • Things fail • Make more powerful by adding more processors • Our brain intuitively understand parallelism
9. Erlang is COP
10. Open Telecom Platform • Delivered with Erlang and written in Erlang, it contains: • an Erlang interpreter (which is called BEAM) • an Erlang compiler • a protocol for communication between servers (nodes) • An Object Request Broker • a static analysis tool called Dialyzer • a distributed database server (Mnesia) • many other libraries and utilities
12. Elixir • R&D project form Plataformatec (2011) • His goals were to enable higher extensibility and productivity in the Erlang VM while keeping compatibility with Erlang's ecosystem
13. Features • Compiles to bytecode for the BEAM • Functional language, everything is an expression • Erlang functions can be called without costs • Metaprogramming with macros • Polymorphism via a mechanism called protocols and behaviours • Pattern matching • Expressive language that programmers love (like Ruby!)
14. Elixir today • Version 1.6.5 • New version every 6 months (1.7 in July) • Hex package management (~6k packages) • Vibrant community
15. A tour of the language
16. Processes • Everything runs in a process • Process is isolated • Process communicate using messages • Inside a process code runs in a single thread
17. GenServer • The basic behaviour for a general purpose process • Has state • A “public interface” (client api vs. server callbacks) • Callbacks to handle messages and send responses • Terminate callback
18. GenServer • init(args) :: {:ok, state}
 A sort of “constructor” for the server • handle_call(request, from, state) :: {:reply, reply, new_state}
 Handle synchronous messages • handle_cast(request, state) :: {:noreply, new_state}
 Handle asynchronous messages Redux?
19. GenServer and… • GenStage: Producer-Consumer pipelines • GenStatem: Event driven state machine • Agent: State management
20. Actor model • GenServer is the basic block for the actor model • Code inside GenServer is single thread • GenServer has it’s own message queue • GenServer can create other Genservers
21. Supervisor • A process to monitor other processes • Handle failures and restarts child as needed
22. Supervisor • Restarting strategy • :one_for_one - if a child process terminates, only that process is restarted. • :one_for_all - if a child process terminates, all other child processes are terminated and then all child processes are restarted. • :rest_for_one - if a child process terminates, the “rest” of the child processes are terminated. Then the terminated child process and the rest of the child processes are restarted.
23. Applications • Applications are a bundle of sub-application • Application consists of a manifest • Dependencies are sub-application • Usually it starts the main supervisors and the dependent applications
24. Other gems • Macros • Hot code swapping • Umbrella projects • Remote debugging and inspection • Community ❤
25. Tooling • mix is rake for Elixir • https://hex.pm is the package registry • Spec and Dyalizer • Release with distillery (erts inside…no prerequisites!)
26. Libraries and Frameworks
27. Phoenix
28. Ecto
29. Nerves
30. Absinthe
31. Online Multiplayer game In few lines of Elixir
32. Mars Rovers Application RoverSup rover_1 rover_2 rover_n WorldMap
33. Is it production ready?
34. FAQ • Should I learn Erlang to use Elixir? • Is it fast? • To spawn or not to spawn? • Does it run on windows?
35. Thank you