IP to long and reverse on Scala

ip.scala

import collection.mutable.ListBuffer

object NetworkUtils {
  def ip2Long(ip: String): Long = {
    val atoms: Array[Long] = ip.split("\\.").map(java.lang.Long.parseLong(_))
    val result: Long = (3 to 0 by -1).foldLeft(0L)(
      (result, position) => result | (atoms(3 - position) << position * 8))

    result & 0xFFFFFFFF
  }

  implicit def long2String(value: Long): String = value.toString

  def long2IP(ip: Long): String = {
    val resultBuilder = new ListBuffer[String]()
    var ipBuffer = ip

    for (position <- 0 to 3) {
      resultBuilder.prepend(ipBuffer & 0xFF)
      ipBuffer >>= 8
    }

    resultBuilder.mkString(".")
  }
}

I only tried "long2ip" but the original gist doesn't compile for me and the comment returns an invalid IP. The answer on http://stackoverflow.com/questions/34798559/how-to-convert-ipv4-addresses-to-from-long-in-scala seems to work.