WeirdMacro.scala

import language.experimental.macros
import reflect.macros.Context

object WeirdMacro {
  def show_structure(something: Any): String = macro show_structure_impl

  def show_structure_impl(c: Context)(something: c.Expr[Any]): c.Expr[String] = {
    import c.universe._

    c.Expr[String](Literal(Constant(something.tree.toString)))
  }
}

WeirdMacroTest.scala

import WeirdMacro._

object WeirdMacroTest extends App {
  val expr = show_structure {
    a -> b
  }

  println(expr)
}

@macro def show_structure(something: Any): String = q"${something.toString}"