Elixir: When to use .ex and when .exs files

Question

Elixir\'s documentation states that

In addition to the Elixir file extension .ex, Elixir also supports .exs files for scripting. Elixir treats both

Answer 1

Elixir will compile the whole .ex file. .exs Files are compiled as well but are meant to be executed when invoked. So, most use cases of .exs files are to execute code immediately when called. Think of using .exs files for testing, migrating data and running scripts. Think of .ex files as being used for your application's main business logic.

Consider this example

.ex sample

sum.ex

defmodule Sum do
  add(a, b) do
     a + b
  end
end

$ iex sum.ex

iex> Sum.add(1,2)
3

.exs sample

sum.exs

defmodule Sum do
  def add(a,b)  do
    a + b
  end
end

#within same file

IO.puts "The sum of 3 + 2 is: #{inspect Sum.add(3, 2}"

$ elixir sum.exs

 ->> "The sum of 3 + 2 is: 5"