my_receive.exs

defmodule MyReceive do
  defmacro my_receive(do: clauses) do
    extra = quote do
      other -> IO.puts "got #{inspect other}"
    end
    
    quote do
      receive do: unquote(clauses ++ extra)
    end
  end
end

defmodule Sample do
  import MyReceive
  
  send self, :world
  
  my_receive do
    :hello -> IO.puts "hello"
  end
end