Optimistic concurrency using AtomicReference

MiniSTM.scala

  class MiniSTM[T <: AnyRef](initialValue: T) {
    private val value = new AtomicReference[T](initialValue)

    def apply(fun: T => T) {
      @tailrec def update(expect: T): Unit = 
         if ( !value.compareAndSet(expect, fun(expect)) ) update(value.get)
         
      update(value.get)
    }
    
    def apply() = value.get
  }