Four ways to retrieve Scala Option value

Suppose you have the Scala value assignment below, and wish to append " World", but only if the value is not None (from Option[]).

val s = Some("Hello")

There are four different Option[] idioms to accomplish this:

1. The Java-like way
   
   if (s.isDefined) s.get + " World" else "No hello"
    
   
2. The Pattern Matching way
   
   s match { case Some(s) => s + " World"; case _ => "No hello" }
    
   
3. The Classic Scala way
   
   s.map(_ + " World").getOrElse("No hello")
    
   
4. The Scala 2.10 way
   
   s.fold("No hello")(_ + " World")