In Elixir, functions are grouped by modules that play the role of namespaces. For example, in the previous exercise we used the function puts(text) from module IO:

IO.puts("Hello, World!")

Modules are defined with a special contstruct defmodule/do/end:

# use CamelCase for name
defmodule HexletBasics do
  # Here goes module contains
end

Elixir allows the creation of multiple modules in the same file, but there is a convention to have only one module per file with the same name as the module but in snake_case.

Modules can be nested. By convention, we create nested modules when they are located in a directory. For example, there's the module HexletBasics.Application located in lib/hexlet_basics/application.ex directory.

defmodule HexletBasics.Application do
  # Function
  def hello do
    IO.puts("Hello, World!")
  end
end

Function calls for nested modules are the same as for flat modules. First, we put the module's full name, then a function call.

HexletBasics.Application.hello()

There is a special module Kernel which functions we can call directly.

is_number(13) # true

Kernel contains basic language primitives for arithmetic operations, spawning processes, data type handling, macros for defining new functionality, and more.

Create module My.Super.Module and put the function hello() we defined above