Elixir (programming language)

Elixir

Paradigm	multi-paradigm: functional, concurrent, distributed, process-oriented
First appeared	2011 (2011)
Stable release	1.7.3 / 24 August 2018 (2018-08-24)[1]
Typing discipline	dynamic, strong
Platform	Erlang
License	Apache License 2.0[2]
Filename extensions	.ex, .exs
Website	elixir-lang.org
Influenced by
Erlang, Ruby, Clojure
Influenced
LFE

Elixir is a functional, concurrent, general-purpose programming language that runs on the Erlang virtual machine (BEAM).^[3] Elixir builds on top of Erlang and shares the same abstractions for building distributed, fault-tolerant applications. Elixir also provides a productive tooling and an extensible design. The latter is supported by compile-time metaprogramming with macros and polymorphism via protocols.^[4]

Elixir is used by companies such as E-MetroTel, Pinterest^[5] and Moz.^[6] Elixir is also used for web development, by companies such as Bleacher Report, Discord, and Inverse,^[7] and for building embedded systems.^[8][9] The community organizes yearly events in United States^[10], Europe^[11] and Japan^[12] as well as minor local events and conferences.^[13][14]

On July 12, 2018, Honeypot released a mini-documentary on Elixir.^[15]

History

José Valim is the creator of the Elixir programming language, an R&D project of Plataformatec. His goals were to enable higher extensibility and productivity in the Erlang VM while keeping compatibility with Erlang's ecosystem.^{[16] [17]}

Features

• A language that compiles to bytecode for the Erlang Virtual Machine (BEAM)^[18]
• Everything is an expression^[18]
• Erlang functions can be called from Elixir without run time impact, due to compilation to Erlang bytecode, and vice versa
• Meta programming allowing direct manipulation of AST^[18]
• Polymorphism via a mechanism called protocols. Like in Clojure, protocols provide a dynamic dispatch mechanism. However, this is not to be confused with multiple dispatch as Elixir protocols dispatch on a single type.
• Support for documentation via Python-like docstrings in the Markdown formatting language^[18]
• Shared nothing concurrent programming via message passing (Actor model)^[19]
• Emphasis on recursion and higher-order functions instead of side-effect-based looping
• Lightweight concurrency utilizing Erlang's mechanisms^[18]
• Railway oriented programming via the with construct
• Built-in tooling for managing dependencies, code compilation, running tests, formatting code, remote debugging and more
• Lazy and async collections with streams
• Pattern matching^[18] to promote assertive code^[20]
• Unicode support and UTF-8 strings

Examples

The following examples can be run in an iex shell or saved in a file and run from the command line by typing elixir <filename>.

Classic Hello world example:

iex> IO.puts("Hello World!")
Hello World!

Comprehensions

iex> for n <- [1,2,3,4,5], rem(n, 2) == 1, do: n*n
[1, 9, 25]

Pattern Matching (destructuring)

iex> [1, a] = [1, 2]
iex> a
2

iex> {:ok, [hello: a]} = {:ok, [hello: "world"]}
iex> a
"world"

Pattern Matching (multiple clauses)

iex> case File.read("path/to/file") do
iex>   {:ok, contents} -> IO.puts("found file: #{contents}")
iex>   {:error, reason} -> IO.puts("missing file: #{reason}")
iex> end

Pipe Operator

iex> "1" |> String.to_integer() |> Kernel.*(2)
2

Modules

defmodule Fun do
  def fib(0), do: 0
  def fib(1), do: 1
  def fib(n), do: fib(n-2) + fib(n-1)  
end

Sequentially spawning a thousand processes

for num <- 1..1000, do: spawn fn -> IO.puts("#{num * 2}") end

Asynchronously performing a task

task = Task.async fn -> perform_complex_action() end
other_time_consuming_action()
Task.await task

Noteworthy Elixir projects

• Absinthe is a GraphQL implementation for Elixir
• Ecto is a database wrapper and language integrated query for Elixir
• Mix is a build automation tool for Elixir projects
• Nerves is framework and platform for embedded software
• Phoenix is a web framework built on Elixir
• Plug is a specification and conveniences for composable modules between web applications

See also

• Concurrent computing
• Distributed computing
• Erlang (programming language)

References

External links

• Elixir language website
• Code on GitHub
• Elixir - A modern approach to programming for the Erlang VM (video presentation)
• Dave Thomas: "Programming Elixir ≥ 1.6 Functional |> Concurrent |> Pragmatic |> Fun" (book)
• Simon St. Laurent, J. David Eisenberg: "Introducing Elixir" (book)
• Chris McCord: "Metaprogramming Elixir " (book)