Mastering Scala Machine Learning

Working with pattern matching

No Scala book would be complete without mentioning the match/case statements. Scala has a very rich pattern-matching mechanism. For instance, let's say we want to find all instances of a sequence of page views that start with a homepage followed by a products page—we really want to filter out the determined buyers. This may be accomplished with a new function, as follows:

scala> def findAllMatchedSessions(h: Seq[Session[PageView]], s: Session[PageView]) : Seq[Session[PageView]] = {
     |     def matchSessions(h: Seq[Session[PageView]], id: String, p: Seq[PageView]) : Seq[Session[PageView]] = {
     |       p match {
     |         case Nil => Nil
 | case PageView(ts1, "mycompanycom>homepage") :: PageView(ts2, "mycompanycom>plus>products landing") ...