Queue.scala

// git clone https://github.com/stanch/reftree && cd reftree
// sbt demo

def add(n: Int)(q: Queue[Int]) = Utils.iterate(q, n + 1)(q => q :+ (q.max + 1)).tail
def remove(n: Int)(q: Queue[Int]) = Utils.iterate(q, n + 1)(q => q.tail).tail
def addRemove(n: Int)(q: Queue[Int]) = Utils.flatIterate(q)(add(n), rm(n))

val queues = Utils.flatIterate(Queue(1, 2, 3), 3)(addRemove(2))

diagram.renderAnimation(
  "queue", _.copy(
    onionSkinLayers = 0, diffAccent = true, interpolationFrames = 21,
    density = 100, delay = 200, silent = false
  )
)(queues)