macro_as_arg.ex

defmodule Foo do
  defmacro foo_macro(i) do
    quote do
      unquote(i)
    end
  end

  def bar(foo_macro(1) = i), do: IO.puts(i)
  def bar(foo_macro(2) = i) do
    IO.puts "This better be 2: #{i}"
  end
end

Foo.bar(1)
# => 1

Foo.bar(2)
# => This better be 2: 2

Foo.bar(3)
#** (FunctionClauseError) no function clause matching in Foo.bar/1
#    foo.exs:8: Foo.bar(3)
#    (elixir) lib/code.ex:370: Code.require_file/2

@wobh yeah, that was my position, but others at the meeting didn't think it works work that way. This is a small POC to show them it actually worked.