macro_failing.ex

defmodule Tst do
  defmacro mymacro(fname) do
    quote do
      def run(unquote(fname)) do
        IO.inspect(unquote(fname))
      end
    end
  end

  mymacro("one")
end

macro_in_module.ex

defmodule Tst.Macro do
  defmacro mymacro(fname) do
    quote do
      def run(unquote(fname)) do
        IO.inspect(unquote(fname))
      end
    end
  end
end

defmodule Tst do
  import Tst.Macro
  mymacro("one")
end

macro_ok.ex

defmodule Tst do
  defmacro mymacro(arg) do
    quote do
      "==" <> unquote(arg) <> "=="
    end
  end

  def run(arg) do
    IO.inspect mymacro(arg)
  end
end