Scalaで文字列配列の二分探索

def search(sortedArray:Array[Any], target:String): Int = {
  var upper = sortedArray.length - 1
  var lower = 0
  while (upper >= lower) {
    var i = lower + (upper - lower) / 2
    if (sortedArray(i) == target) return i
    if (sortedArray(i) <  target) lower = i + 1　else upper = i - 1
  }
  return -1
}

型をAnyにしてComparetor的なものを導入すれば更に一般的になる