Note that Java also allows you to write that as words.filter(w -> !w.isEmpty()).count() And they just end up calling the same methods. The author probably

Note that Java also allows you to write that as words.filter(w -> !w.isEmpty()).count() And they just end up calling the same methods. The author probably used "expressive" and "efficient" to refer to the underlying APIs for the fact that you can compose operations without fully evaluating the whole stream until the terminal one.