Lists and Tuples

Mix.install([
  {:kino, "~> 0.14.0"}
])

Lists

We create lists with [] Actually we created a list in previous examples

orders = [1, 70, 110]

We can store mixed values in a List

my_school_bag = ["pens", 11, :rock, :pencil_box, "books", 55.7, true]

List manipulation

We are using ++ to concatenate lists.

[:clay] ++ my_school_bag

We can use -- to subsctract from a list

my_school_bag -- [:rock]

The result is a new list, it never modifies the original

In elixir Data Structures are Immutable, means we never modifies the original

> Don’t worry BEAM VM, Elixir’s VM is smart enough to handle this in an efficient way

# so it means my_school_bag is unchanged

my_school_bag

Prepending

[:water_bottle | my_school_bag]

Appending

my_school_bag ++ [:water_bottle]

Immutability in action 💪

my_school_bag = ["pens", 11, :rock, :pencil_box, "books", 55.7, true]
extra_books = ["Sherlock Holmes", "Robin Hood"]

bag = my_school_bag ++ extra_books

Original data is not modified

my_school_bag

extra_books

We get a new list instead

bag

There are special modules in Elixir to make your life easier

Enum and List modules can help you manipulate lists

Enum.at(bag, 3)

List.replace_at(bag, 1, "atlas pens")

If we check bag its still unchanged

bag

So its immutable 🫢

Tuples

Tuples are created using {}

> Do NOT confuse this with a object in JS

{"gandalf", "frodo", "sam", "tom bombadil", :sauron}

Often we use this with functions to return multiple values

{:ok, "Here are some details you like"}

For example lets try to read a File

content =
  Kino.FS.file_path("random_names.csv")
  |> File.read()

Here you can see it has returned a tuple with {:ok, "content"} format

File.read("404.txt")

In here you can see we have {:error, reason} tuple

There are functions like put_elem, elem also Tuple module for dealing with tuples… Most of the time you wont use them…but good to know 🤓