So I tried to make a macro for Scala 2.10.3, to create collections for sealed case objects (basically the One Big Thing that Java's enums still had going for them). Found a solution on Stack Exchange (at http://stackoverflow.com/questions/13671734/iteration-over-a-sealed-trait-in-scala). Eight hours later, it works!

gistfile1.scala

package org.pierzchalski.util

import scala.language.experimental.macros
import scala.reflect.macros.Context
import scala.collection.immutable

object Util {
  def values[A]: immutable.Set[A] = macro valuesImpl[A]

  def valuesImpl[A](c: Context)(implicit ev: c.WeakTypeTag[A]): c.Expr[immutable.Set[A]] = {
    import c.universe._
    val symbol = weakTypeOf[A].typeSymbol
    if (!symbol.isClass) {
      c.abort(
        c.enclosingPosition,
        "Can only enumerate values of a sealed trait or class (the provided symbol is not a trait or class)."
      )
    } else if (!symbol.asClass.isSealed) {
      c.abort(
        c.enclosingPosition,
        "Can only enumerate values of a sealed trait or class (this trait or class is unsealed)."
      )
    } else {
      val childObjects =
        for { sym <- symbol.asClass.knownDirectSubclasses.toList if sym.isModuleClass }
        yield Ident(c.mirror.staticModule(sym.fullName))
      c.Expr[immutable.Set[A]](Apply(Select(reify(immutable.Set).tree, newTermName("apply")), childObjects))
      /*original:
      if (!children.forall(_.isModuleClass)) c.abort(
        c.enclosingPosition,
        "All children must be objects."
      ) else c.Expr[Set[A]](
        Apply(Select(reify(Set).tree, "apply"), children.map(New(_)))
      )
      //time to fix: 8 hours.
      */
    }
  }
}