// A.scala
import scala.reflect.macros.Context
object A {
  def hello_impl(c:Context)() :c.Expr[Unit] = {
    import c.universe._
    reify {
      println("hello world")
    }
  }
}

// B.scala
import scala.language.experimental.macros
class B{
def hello():Unit = macro A.hello_impl
}

// C.scala
object C extends App{
  type greeter = {
    def hello():Unit;
  }
  val g:greeter= new B
  g.hello()
}