wordwrap in scala

wordwrap.scala

import scala.annotation.tailrec

val sentence = "Four score and ten years ago our fathers brought forth upon this " +
  "continent a new nation conceived in liberty and dedicated to the " +
  "proposition that all men are created equal"

def wrap(source: String, len: Int):String = {

  val wordChunks = sentence.split(" ").flatMap(x => x.grouped(len)).toList

   def concatenate(word: String,  line: String):(Option[String], String) = {
     def wrappedLine(): Option[String] = {if ((line.length + word.length) < len) None else Some(line)}
     def remaining(): String = {if ((line.length + word.length) < len && !line.isEmpty) line + " " + word else word}
     (wrappedLine, remaining)
   }
  

  @tailrec
  def loop(words: List[String], partialLine: String, wrappedLines: List[String]): List[String] = {
    words match {
      case x :: xs => {
        val c = concatenate(x, partialLine)
        loop(xs, c._2, c._1.fold(wrappedLines)(wrappedLine => wrappedLine + "\n" :: wrappedLines))
      }
      case Nil => {
        (partialLine + "\n") :: wrappedLines
      }
    }
  }

 loop(wordChunks, "", List()).reverse.mkString
}
System.out.println(wrap(sentence, 10))