a.exs

defmodule A do                                  
  defmacro left >| right do                     
    quote do                                    
      :math.pow unquote(left), unquote(right)   
    end                                         
  end                                           
end                                             

foo.exs

Code.require_file("a.exs")        
defmodule Foo do                  
                                  
  Code.require_file("a.exs")      
  def pow do                      
    Code.require_file("a.exs")    
    2 >| 3                        
  end                             
end                               
                                  
IO.inspect Foo.pow