Collection of objects in Linked list O(n)

Here is an example of a list in Elixir: [1, 2, 3, 4]

This may look exactly like an array if you are familiar with Ruby or Javascript, however they’re a little different in the details. We’ll get into that later.

Lists in Elixir are created by surrounding a list of values with brackets []. Try creating a list in the console by typing [1, 2, 3].

Lists don’t need to contain only one type. They can hold on to multiple different types in the same list.

[1, 2, 3]
["a", "b", "c"]
[1, :b, "c", "c"]

We create the list with the brackets, and by typing literal values into the items; you can also use variables in lists.

Type the following:

iex> foo = "bar"
iex> [1, foo, 3]
[1, "bar", 3]

As you can see, Elixir replaces the variable with the literal value in the list it creates.

We have a bunch of built-in methods we can use to interact with and manipulate lists in Elixir.


We often will want to figure out the first item in a list

[h | tail] = [1, 2, 3]

Notice we have a list with two variables on the left. The h variable will match to the first value on the right. tail will hold the rest of the values in the list.

Try typing the following into the command line:

[h | tail] = [1, 2, 3]

now type in h

you should see:

iex> h

If we type in tail - we should see the rest of the list.

iex> tail
[2, 3]

List Concatenation

Try adding and removing items from lists.

Adding lists To concantenate list we use the ++ operator.

 [1] ++ [2] # [1, 2]

Type the following:

iex> [1] ++ [2] # [1, 2]

Subtracting Lists

Let’s take a look

[1, 2, 3] – [2] # [1, 3]

If we have duplicate values we want to remove like so:

It will only remove one of the duplicates

[1, 2, 2, 2] -- [2]


Tuples in Elixir are datatypes similar to lists. But they are used to store a fixed number of elements. Let’s look at how to create a tuple.

Tuples are created by using the curly brackets with elements separated by commas.

Type the following into the console:

iex> {:ok, "hello"}

If we want to retrieve the first element in the tuple which is located at index 0, we can pass the index into the function below.

Type the following into the console:

iex> elem({:ok, "hello"}, 0)

As you can see, the function returns :ok.

We can check the size of a tuple using the tuple_size/1 function:

Type the following:

iex> tuple_size({:ok, "hello"})

And we can replace elements in a tuple by using the put_elem/3 function, which takes the tuple, the argument, and the value:

Type the following:

iex> put_elem({:ok, "hello"}, 1, "world")
{:ok, "world"}

Tuples vs Lists?

  • Lists are slow to modify/read, but fast creation
  • Tuples are expensive to modify but good for pattern matching and additional information