Demo of simple DSL

dsl.exs

#!/usr/bin/env elixir
defmodule DSL do
  defmacro action(match, [do: body]) do
    quote do
      def handle_info(unquote(match) = arg, state) do
        unquote(body)
        {:ok, state}
      end
    end
  end
  defmacro createhandler(name, [do: body]) do
    quote do
      defmodule unquote(name) do
        unquote(body)
      end
    end
  end
  def compile(namespace, file) do
    content = File.read!(file)
    content =
      """
        defmodule #{namespace} do
          #require #{inspect __MODULE__}
          import #{inspect __MODULE__}
          #{content}
        end
      """
    {_module, _} = Code.eval(content)
    :ok
  end
end

[file_name] = System.argv
DSL.compile "MyHandlers", file_name

# Below is how you test it from elixir
MyHandlers.TestHandler.handle_info({:x, 5}, {SomeState})
MyHandlers.TestHandler.handle_info({:y, 3, :erlang.now}, {SomeState})

output

./dsl.exs test.dsl 
x: 5
random.uniform(3) -> 1 

test.dsl

createhandler TestHandler do
  action {:x, x} do
    # printToScreen
    IO.puts "x: #{inspect x}"
  end
  action {:y, y, seed} do
    # example of calling erlang modules
    :random.seed(seed)
    value = :random.uniform(y)
    IO.puts "random.uniform(#{y}) -> #{value} "
  end
end