gistfile1.txt

import scala.reflect.macros.whitebox._
import scala.language.experimental.macros

object Macros {
  def impl(c: Context)(fn: c.Tree) = {
    import c.universe._
    val Typed(Block(List(ClassDef(_, _, _, Template(_, _, stats))), _), _) = fn
    val List(_, DefDef(_, TermName("applyOrElse"), _, _, _, Match(_, clauses :+ _)), _) = stats
    val pfs = clauses.map(clause => {
      object betterUntypecheck extends Transformer {
        override def transform(tree: Tree): Tree = tree match {
          case UnApply(Apply(Select(qual, TermName("unapply")), List(Ident(TermName("<unapply-selector>")))), args) =>
            Apply(transform(qual), transformTrees(args))
          case _ => super.transform(tree)
        }
        def apply(tree: Tree): Tree =  c.untypecheck(transform(tree))
      }
      val clause1 = betterUntypecheck(clause)
      q"_root_.scala.PartialFunction[${clause.pat.tpe}, ${clause.body.tpe}]({ case $clause1 })"
    })
    q"List(..$pfs)"
  }

  def split(fn: PartialFunction[Int, Int]): Any = macro impl
}

object Test extends App {
  object Foo { def unapply(x: Int) = Some(x) }
  Macros.split{ case Foo(Foo(x)) => x; case x => x }
}