Created in 2012, Elixir is functional and dynamic language, which make a real option if we want to create a web application. Since, Elixir runs under Erlang virtual machine (BEAM), which make it really stable and mature.

Created by José Valim, who is a Ruby on Rails enthusiastic and had helped the community a lot. So, he took the the best of Rails and merge it with the efficiency of Elixir + Erlang.

The first two meanings we have to forget are objects and classes. It’s all about functions that operate and transform data, pure functions. But, We can not rely on Elixir being a pure functional language.

Elixir variables don’t need to be declared as an specifics data type, It checks at runtime.

Data structure won’t change. For example:

# It creates a total new value for the new variable
name = “Luke Skywalker”

Concurrency

Reliability

Easy to read and write

Modules or classes ?

defmodule HelloModule do def say_hi do IO.puts "Hello World !" end end

Structs

defmodule User do
  defstruct name: "John", roles: []
end

iex> %User{name: "Han", roles: [:pilot, :shooter]}
User{name: "Steve", roles: [:pilot, :shooter]}

Strings

Lenght.

iex> String.length "Walter White"
12

Replace

iex> String.replace("Seed","e","i")"Siid"

Duplicate

iex> String.duplicat("Hello",3)"Hello Hello Hello "

Split

iex> String.split("Hello, I'm Bond, James Bond", ",")["Hello", " I'm Bond", " James Bond"]

Collections

List

iex> ["String", 12.3 , :atom]["String", 12.3, :atom]

List Concatenation

iex> ["Luke", "Leia"] ++ ["Han"]
["Luke", "Leia", "Han"]

List Subtraction

iex> ["String", 12.3 , :atom] -- [:atom]
["String", 12.3]

Head / Tail

iex> hd ["Head", 222, :tail]
"Head"

iex> tl ["Head", 222, :tail]
[222, :tail]

Keyword Lists

iex> [foo: "bar", hello: "world"]
[foo: "bar", hello: "world"]

iex> list = [{:a, 1}, {:b, 2}]
[a: 1, b: 2]

iex> list ++ [{:c, 3}]
[a: 1, b: 2, c: 3]

Maps

iex> key = :one

iex> list = %{key => 1, :two => 2, "three" => 3, 4 => 4}
%{:one => 1, :two => 2, "three" => 3, 4 => 4}

# Get an specific value from a given key.
iex> Map.get(list, key)
1

# Add a tuple to the current list.
iex> Map.put(list, :five, 5)
%{:one => 1, :two => 2, "three" => 3, 4 => 4, :five => 5}

# Return the map on list format. 
iex> Map.to_list(list)
[{4, 4}, {:atom, 1}, {:five, 5}, {:two, 2}, {"three", 3}]

Enum

All

iex> Enum.all?([1,2,3], fn(number) -> number < 5 end )
true

iex> Enum.all?([1,2,3], fn(number) -> number < 2 end )
false

Any

iex> Enum.any?([1,2,3], fn(number) -> number < 2 end )
true

iex> Enum.any?([1,2,3], fn(number) -> number == 5 end )
false

Chunk By

iex> Enum.chunk_by(["one", "two", "three", "four", "five"], fn(x) -> String.length(x) end)

[["one", "two"], ["three"], ["four", "five"]]

Each

iex> Enum.each(["one", "two", "three"], fn(x) -> IO.puts(x) end)
one
two
three
:ok

Map

iex> Enum.map(["one", "two"], fn(x) -> String.upcase(x) end)
["ONE", "TWO"]

Member

iex>  Enum.member?(["one", "two", "three"], "three")
true

Reject

iex> Enum.reject([1,2,3,4,5,6], fn(x) -> Integer.is_even(x) end)
[1, 3, 5]

Sort

iex> Enum.sort([%{:val => 2}, %{:val => 3}, %{:val => 1}], fn(x, y) -> x[:val] > y[:val] end)

[%{val: 3}, %{val: 2}, %{val: 1}]

Unique By

iex> Enum.uniq([1, 2, 3, 2, 1]) 
[1, 2, 3]

Pipe Operator

The pipe operator |> passes the result of an expression as the first parameter of another expression.

Our problem:

# Return the final value of a product
formated_price(taxes(commision(product_value(), 0.01), 0.13))

prod_val = product_value()
prod_commision = commision(prod_val, 0.01)
prod_taxes = taxes(prod_commision, 0.13)
prod_final_value = formated_price(prod_taxes)
prod_final_value

Our Elixir Solution:

product_value()
|> commision(0.01)
|> taxes(0.13)
|> formated_price()

Pattern Matching. Isn’t it just assignment?

iex> x = 1
1

iex> 1 = x
1

iex>  2 = x
** (MatchError) no match of right hand side value: 1

Useful approaches

# We want to assign to match value with te number 2
iex> {:ok, value} = {:ok, 2}
{:ok, 2}

iex> value
2

# If the atom value :ok doesn't match It will return a fail

iex> {:ok, value} = {:none, 2}
** (MatchError) no match of right hand side value: {:none, 2}

defmodule Greet do
  def say_hi(tuple) do
    case tuple do
      {:morning, name} ->
        "Morning #{name} !"
      {:evening, name} ->
        "Good evening #{name} !"
      _ ->
        "Default Hi !!"
    end
  end
end

iex> Greet.say_hi({:morning, "Luke"})
"Morning Luke !"

iex> Greet.say_hi({:morning, "Han"})
"Morning Han !"

iex> Greet.say_hi({:defaut, "Nobody"})
"Default Hi !!"

defmodule Greet do
  def say_hi(:morning, name) do
    "Morning #{name} !"
  end

  def say_hi(:evening, name) do
    "Good Evening #{name} !"
  end

  def say_hi(name) do
    "Default Hi #{name} !"
  end
end

iex> Greet.say_hi(:morning, "Luke")
"Morning Luke !"

iex> Greet.say_hi(:morning, "Han")
"Morning Han !"

iex> Greet.say_hi("Leila")
"Default Hi Leila !"

Conclusion