gistfile1.scala

object foo {
  var comparisons = 0                             //> comparisons  : Int = 0
  class Foo {
    override def equals(other: Any) = { comparisons += 1; super.equals(other) }
  }
  class Bar extends Foo
  class Baz extends Foo
  val s1: Set[Foo] = Seq.fill(10)(new Bar).toSet  //> s1  : Set[foo.Foo] = Set(foo$$anonfun$main$1$Bar$1@1529d183, foo$$anonfun$ma
                                                  //| in$1$Bar$1@7d1f0c98, foo$$anonfun$main$1$Bar$1@1740f55, foo$$anonfun$main$1$
                                                  //| Bar$1@c8a3c71, foo$$anonfun$main$1$Bar$1@6a9a9631, foo$$anonfun$main$1$Bar$1
                                                  //| @2009d3af, foo$$anonfun$main$1$Bar$1@47862525, foo$$anonfun$main$1$Bar$1@548
                                                  //| ccbe7, foo$$anonfun$main$1$Bar$1@37f0c4d2, foo$$anonfun$main$1$Bar$1@4afaa1a
                                                  //| 4)
  println(comparisons)                            //> 20
  comparisons = 0
  s1 contains (new Baz)                           //> res0: Boolean = false
  println(comparisons)                            //> 0
}