Shawn Livebook freecode camp

Section

Atom

:error

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

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

name = "Shawn"
msg = "Hello " <> name

<<head, rest::binary>> = name
head

?s
?h
?a
?w
?n

head == ?S

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

chars = "Mumbo"
'Hello ' ++ chars

my_pid = self()
my_pid

Linked lists

list = ["a", "b", "c"]
Enum.at(list, 0)

[first, second, third] = list
second

[.., .., third]

hd(list)

tl(list)

[h | t] = list
h

Tuple

{a, b, c} = {1, 2, 3}
a

{:reply, msg, state} = {:reply, "Spirit of Ecstacy", ["Shawn", "Albert", "Owino"]}

msg

Keyword List

data = [a: 1, b: 2]

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

data[:a]

Maps

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

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

%{c: third} = my_map
third

my_map.a

map2 = %{"s" => 1, "h" => 2, "a" => 3, "w" => 4, "n" => 5}

%{"w" => w} = map2
w

map2 = %{map2 | "a" => 10}

my_map = %{my_map | c: 7}

Struct

The keyword list used with defstruct defines what fields the struct will have along with their default values.

Structs take the name of the module they’re defined in. In the example above, we defined a struct named User.

We can now create User structs by using a syntax similar to the one used to create maps:

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

user1 = %User{username: "Shawn", age: 26, email: "MUmbo@shawn.owino"}

%{username: username} = user1
username

user1 = %{user1 | age: 21}

Flow Control

case

list = [1, 2, 3]

case Enum.at(list, 2) do
  1 -> "This will not print"
  3 -> "Found your match"
  _ -> "catch hands"
end

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

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

case post1 do
  %{author: "Shawn"} -> "Got a post from Shawn"
  %{author: "Anil Mumbo"} -> "Got a post from Anil Mumbo"
  %{author: author} -> "Got a post from #{author}"
end

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

Cond

cond do
  post1.author == "Shawn" -> "Editing a post from Shawn"
  post1.author == "Anil Mumbo" -> "Editing a post from Anil Mumbo"
  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