mod.ex

# attr.exs

# using module attributes as compile-time constants
defmodule M do
  @constant 13

  def a, do: @constant

  @constant 44

  def b, do: @constant
end

IO.puts "a = #{M.a}; b = #{M.b}"

---

λ elixir attr.exs
a = 13; b = 44