Data Types

Atom

:error

{:error, reason} = {:error, "file not found"}
reason

{:ok, msg} = {:ok, "status 200 ok"}
msg

Strings

name = "Octallium"
name

is_binary(name)

msg = "Hello " <> name
msg

"Hello " <> name = msg
name

<> = name
head

head == ?O

<<"O", rest::binary>> = name
rest

<<"Oc", rest::binary>> = name
rest

<> = name
head

Charlist

chars = 'Octallium'

Processes

my_pid = self()
my_pid

Lists

# Lists in elixir are singly linked lists.

list = ["a", "b", "c"]

# we have linked lists in elixir because they are recursive in nature.
# we can work with them with recusrsive functions or some modules.

Enum.at(list, 0)

[first, second, third] = list

[_, _, third] = ["a", "b", "c"]
third

[ h | t ] = list
h

Tuple

{ a,b } = { 1,2 }
a

{:reply, msg, state} = {:reply, "Octallium found!", ["Octallium", "Louis", "Chiko"]}
state

Keyword List

data = [a: 1, b: 2]

[{:a, a}] = [a: 1]

Maps

my_map = %{a: 1, b: 2, c: 3}
my_map

%{a: first, b: second, c: third} = my_map
first

%{b: second} = my_map
second

my_map.a

map2 = %{"a" => 1, "b" => 2, "c" => 3}

%{"c" => c} = map2
c

map2 = %{map2 | "c" => 4}

my_map = %{my_map | c: 4}

Struct

defmodule User do
  defstruct username: "", email: "", age: nil
end

user1 = %User{username: "Octallium", age: 14, email: "octobot@sample.com"}

%{username: username} = user1
username

user1 = %{user1 | age: 21}

Control Flow

Case

list = [1, 2, 3]

case Enum.at(list, 2) do
  1 -> "This won't print"
  3 -> "3 is a match!"
  _ -> "Catch all"
end

defmodule Post do
  defstruct(
    id: nil,
    title: "",
    description: "",
    author: ""
  )
end

post1 = %Post{id: 1, title: "Title No 1", author: "Julius Ceaser"}

case post1 do
  %{author: "Ocatllium"} -> "Got a post from Ocatllium"
  %{author: "Arnold"} -> "Got a post from Arnold"
  _ -> "Got a post from #{post1.author}"
end

post1 = %{post1 | author: "Anil Kulkarni"}

case post1 do
  %{author: "Ocatllium"} -> "Got a post from Ocatllium"
  %{author: "Arnold"} -> "Got a post from Arnold"
  _ -> "Got a post from #{post1.author}"
end

Cond

cond do
  post1.author == "Ocatllium" -> "Editing a post from Octallium"
  post1.author == "Arnold" -> "Editing a post from Arnold"
  true -> "This is a catch all"
end

cond do
  hd(list) == 1 -> "Got a 1"
  true -> "Head is #{hd(list)}"
end

If/Else

if true do
  "This will work"
else
  "Else this will work"
end