Given a sequence of directory paths, what is the best way to find their most common base directory?

Here is the code I wrote.

 def commonPrefix(paths: String*): String = {
    paths.reduce((left: String, right: String) => {
      left.split('/')
        .zip(right.split('/'))
        .takeWhile((tuple: (String, String)) => tuple._1.equals(tuple._2))
        .map(_._1).mkString("/")
    })
  }

Is there any better way of doing this?

UPDATE

Following the comments to this question, I have changed the code to address a few issues:

1. Over splitting
2. Empty input
3. Other separators

Ended up with:

def commonPrefix(paths: String*)(implicit separator: Char = '/'): String = {
    paths.map(s => s.split(separator))
      .reduceOption((left: Array[String], right: Array[String]) => {
        left
          .zip(right)
          .takeWhile(tuple => tuple._1.equals(tuple._2))
          .map(_._1)
      }).getOrElse(Array[String]())
      .mkString("/")
  }

I chose to use reduceOption over changing the signature to commonPrefix(path: String, paths: String*), because then I can use the following syntax:

val paths = Seq("/a/b", "/a/c")
val baseDir = commonPrefix(paths:_*)

Looks OK to me now.

I guess there is no existing Java/Scala library that already does all this, right?