A functional implementation of distributing Auto-Scaling-Groups to different AZs in the us-east-1 region

distribute.scala

import scala.annotation.tailrec

sealed trait UsEast1AvailabilityZone
case object UsEast1a extends UsEast1AvailabilityZone
case object UsEast1b extends UsEast1AvailabilityZone
case object UsEast1c extends UsEast1AvailabilityZone

type Count = Int
def distribute(nrOfAsgs: Int, regions: List[UsEast1AvailabilityZone]): Map[UsEast1AvailabilityZone, Count] = {
  @tailrec
  def inner(remaining: Int, regions: Stream[UsEast1AvailabilityZone], acc: Map[UsEast1AvailabilityZone, Count]): Map[UsEast1AvailabilityZone, Count] =
    if (remaining == 0) acc
    else {
      val region = regions.head
      inner(remaining - 1, regions.tail, acc + (region -> (acc.getOrElse(region, default = 0) + 1)))
    }
  inner(nrOfAsgs, Iterator.continually(regions).flatten.toStream, Map.empty[UsEast1AvailabilityZone, Count])
}

distribute(nrOfAsgs = 5, List(UsEast1a, UsEast1b, UsEast1c))