scala> import scala.reflect.macros.blackbox.Context
import scala.reflect.macros.blackbox.Context

scala> import language.experimental.macros
import language.experimental.macros

scala> 

scala> def impl1(c: Context) = { import c.universe._; c.Expr[Unit](q"()") }
impl1: (c: scala.reflect.macros.blackbox.Context)c.Expr[Unit]

scala> def foo1: Unit = macro impl1
defined term macro foo1: Unit

scala> foo1

scala> 

scala> def impl2(c: Context)() = { import c.universe._; c.Expr[Unit](q"()") }
impl2: (c: scala.reflect.macros.blackbox.Context)()c.Expr[Unit]

scala> def foo2(): Unit = macro impl2
defined term macro foo2: ()Unit

scala> foo2()

scala> 

scala> def impl3(c: Context)(x: c.Expr[Int])(y: c.Expr[Int]) = { import c.universe._; c.Expr[Unit](q"()") }
impl3: (c: scala.reflect.macros.blackbox.Context)(x: c.Expr[Int])(y: c.Expr[Int])c.Expr[Unit]

scala> def foo3(x: Int)(y: Int): Unit = macro impl3
defined term macro foo3: (x: Int)(y: Int)Unit

scala> foo3(2)(3)

scala> :quit