Scala is a statically typed programming language for the Java Virtual Machine that aims to be concise, object-oriented, and functional. Some key features of Scala include type inference, pattern matching, actors for concurrency, and compiling to Java bytecode. Scala improves on Java by handling null values safely by default and providing more concise syntax for working with collections, XML, and other common tasks. Scala is growing in popularity as a potential successor to Java due to its interoperability while improving on Java in several ways.

1. Liftweb Łukasz Kuczera

2. Scala the next Java ? Łukasz Kuczera

3. Scala Statically typed with types inferention Object-functional Compiles to Java bytecode And CLI .Net

4. Historia Pizza GJ EPFL

5. Pizza

8. Scala Type Inference Uniform Access Principle Closures Higher Order Functions Pattern Matching Actors Generics Native XML support Abstract control structures Implicit conversions and parameters Advanced for expressions Annotations Combinator parsing Traits Duck typing Null „safety”

9. „If I where to choose language other than Java it would be Scala”

10. „I can honestly say if someone had shown me the Programming in Scala book by Martin Odersky, Lex Spoon & Bill Venners back in 2003 I'd probably have never created Groovy”

11. „Scala, it must be stated, is the current heir apparent to the Java throne. No other language on the JVM seems as capable of being a "replacement for Java" as Scala, and the momentum behind Scala is now unquestionable”

13. Scala - Basics class Test { // variable definition var n = 5 // value definition val i = 10 // function definition def printit(x: Any) = println(x) def sum(i: Int, n: Int) = i+n } object Test extends Test { def main(args: Array[String]): Unit = { printit(sum(i,n)) } }

14. Class Parameters - Java publicclass Person { private String name; privateintage; publicPerson(String name, int age) { this.name = name; this.age = age; } public String getName() { returnname; } publicvoid setName(String name) { this.name = name; } publicint getAge() { returnage; } publicvoid setAge(int age) { this.age = age; } }

15. Class Parameters - Scala classPerson(var name: String, var age: Int)

16. Working with arrays Java publicclass Partition { Person[] all; Person[] adults; Person[] minors; { ArrayList<Person> minorsList = new ArrayList<Person>(); ArrayList<Person> adultsList = new ArrayList<Person>(); for(int i=0; i<all.length; i++ ) { (all[i].age<18 ? adultsList: minorsList).add(all[i]); } minors = (Person[]) minorsList.toArray(); adults = (Person[]) adultsList.toArray(); } }

17. Working with arrays Scala val all: Array[Person] val (minors, adults) = all.partition(_.age<18)

18. Null’s – Java Map<String, String> capitals = newHashMap<String, String>(); capitals.put("Poland", "Warsaw"); System.out.println(capitals.get("Polska").trim()); Exception in thread "main" java.lang.NullPointerException

19. Null’s - Scala val capitals = Map("Poland" -> "Warsaw"); val capitalOption: Option[String] = capitals.get("Polska") capitalOption match { case Some(value) => println(value) case None => println("Not found") case _ => } if(capitalOption.isDefined) println(capitalOption.get) println(capitalOption getOrElse "Not found")

20. XML val xml = <a href="http://example.com"> <customTagb="foo"> <deepTagb="bar" /> Custom content </customTag> </a> println(xml "customTag") println(xml "deepTag") println(xml "@b") println(xml "customTag" "deepTag" "@b") Outputs: <customTag b="foo"><deepTag b="bar"></deepTag>Custom content</customTag> <deepTag b="bar"></deepTag> foobar bar

21. XML val xml =<divclass="rsswidget"> <ul> <liclass="rsswidgettitle"><ahref="http://www.quotationspage.com/qotd.html">Quotes of the Day</a></li> <liclass="rsswidgetitem"><ahref="http://www.quotationspage.com/quotes/C._P._Snow">C. P. Snow</a></li> <liclass="rsswidgetitem"><ahref="http://www.quotationspage.com/quotes/unknown">unknown</a></li> <liclass="rsswidgetitem"><ahref="http://www.quotationspage.com/quotes/Frederick">Frederick</a></li> </ul> ... </div> (xml "@href").slice(1,4).foreach(url => println("URL:"+url) val con = new URL(url.toString).openConnection val reader = newBufferedReader(newInputStreamReader(con.getInputStream, "ISO-8859-1")) var line = ""; while(line != null) { line = reader.readLine if(line != null) println(line) } con.getInputStream.close )

22. Actors Easier concurrency Message passing instead of locks Asynchronus Implemented using Java threads ScalaActors, Akka, Lift - CometActor

23. Actors class ActorUser { def send(msg: Any) = ScalaActor ! msg } object ScalaActor extends Actor { /* The $actor's mailbox. */ // private[actors] val mailbox = new MQueue[Msg]("Reactor") def act() { receive { case"ping!" => println("pinged!"); case ("ping!", actor: Actor) => actor ! "pong!" case msg => println("unhandled message type:"+msg) } } }

24. Guice Minimize mutability Avoid static state @Nullable JSR 308 - @NonNull

25. Lift Chat Application Using Comet

26. Build Tools SBT Maven Gradle JRebel

27. IDE IntelliJ IDEA Netbeans Eclipse

28. HTTP GET

29. Ajax

30. Comet

32. Links http://days2010.scala-lang.org/node/136 - lots of Scala videos http://twit.tv/floss125 - Lifts Creator interview http://www.youtube.com/watch?v=01rXrI6xelE – Scala creator speak at Google tech talks

33. Thank You Q&A