Example of dynamic (at compile time) delegation from Erlang-style module to Elixir module

lib_demo.exs

# Actual Elixir module with all the functions
defmodule LibDemo do
  def hello(), do: IO.puts "Hello, World!"
  def hello(name), do: IO.puts "Hello, #{name}!"
end

defmodule LibDemo.Utils do
  def make_args(0), do: []
  def make_args(n) do
    Enum.map(1..n, fn n -> {String.to_atom("arg#{n}"), [], Elixir} end)
  end
end

# Erlang module delegating to the Elixir module
defmodule :lib_demo do
  funs =
    LibDemo.module_info()[:exports]
    |> Enum.filter(fn {fun, _arity} -> not fun in [:__info__, :module_info] end)

  for {fun, arity} <- funs do
    defdelegate unquote(fun)(unquote_splicing(LibDemo.Utils.make_args(arity))), to: LibDemo
  end
end

LibDemo.hello()
LibDemo.hello("Foo")

:lib_demo.hello()
:lib_demo.hello("Foo")