![New trait encoding
trait PriceAlgorithm[Item] {
def apply(item: Item): Double =
???
}
Let’s compare Scala 2.11 vs 2.12 bytecode](https://image.slidesharecdn.com/scalapastpresentfuture-161210121502/85/Scala-Past-Present-Future-19-320.jpg)
![trait PriceAlgorithm[Item] {
def apply(item: Item): Double =
???
}
Compiled with Scala 2.11
interface PriceAlgorithm<Item> {
abstract double apply(Item);
}
abstract class PriceAlgorithm$class {
static double apply(PriceAlgorithm,
java.lang.Object);
static void $init$(PriceAlgorithm);
}
Two
classfiles](https://image.slidesharecdn.com/scalapastpresentfuture-161210121502/85/Scala-Past-Present-Future-20-320.jpg)
![trait PriceAlgorithm[Item] {
def apply(item: Item): Double =
???
}
Compiled with Scala 2.12
interface PriceAlgorithm<Item> {
public double apply(Item);
static double apply$(PriceAlgorithm,
java.lang.Object);
static void $init$(PriceAlgorithm);
}
Only one
classfile!](https://image.slidesharecdn.com/scalapastpresentfuture-161210121502/85/Scala-Past-Present-Future-21-320.jpg)
![Java8 API from Scala
Scala λ assignable to Java 8 λ
scala> import java.util.stream.{Stream, IntStream}
scala> import java.util.{Arrays, List}
scala> val myList = Arrays.asList("a1", "a2", "b1", "c2", "c1")
myList: java.util.List[String] = [a1, a2, b1, c2, c1]
scala> myList.stream.
filter(_.startsWith("c")).
map(_.toUpperCase).
sorted.
forEach(println)
C1
C2](https://image.slidesharecdn.com/scalapastpresentfuture-161210121502/85/Scala-Past-Present-Future-22-320.jpg)
Scala Past, Present & Future
- 2. Who am I? • Felt in love with Scala in 2005 • Open Source contributor: Scala compiler & IDE, Lagom, Play, etc. • Recently co-founded a Scala tooling company! • Available for trainings (Akka/Play/ Scala/Spark) and consulting.
- 3. Whoever wishes to foresee the future must consult the past Macchiavelli
- 4. Scala: The Past • Scala first release in 2003 • But, what’s the story before Scala?
- 6. Pizza • 1995-19981 • Superset of Java with generics, first- class functions, case classes and patter matching. • Why the name? • Java was hacker’s drink • Hacker’s food was needed ;-) 1. www.slideshare.net/Odersky/scala-evolution/3-Pre_History1980s_Modula2_Oberon199095_Functional
- 8. Java 1.5 • Pizza led to Martin Odersky working on the Java compiler (javac). • Martin co-designed the first version of generics in Java, and has written the recent javac.
- 9. Scala origins • Goal: unify object-oriented and functional paradigms. • Java was too constraining, hence the motivation to start fresh.
- 10. 2003
- 11. Scala Martin’s mantra • A language with a small core, few constructs but high abstraction power. • Fact: Scala has less keywords than Java!
- 12. Scala evolution First release 2003 Twitter adoption Scala 2.0 released 2006 Akka first release 2009 Lightbend (formerly Typesafe) commercial support Scala 2.9 released & Scala project moved to GitHub 2011
- 13. Scala evolution 2012 Scala 2.10 released Scala Actor deprecated and replaced by Akka 2013 Scala.JS released 2014 Scala 2.11 released 2016 Scala 2.12 (currently RC2) Scala Centre Foundation created!
- 14. Scala 2.9 to 2.11 • Releases are mainly about stability. • Only new features: • Value classes • Implicit classes • String interpolation • macros (experimental)
- 16. Scala 2.12 • No additions to the language. • So… ?
- 18. Scala 2.12 • Scala 2.12 requires Java8. • trait compiled to Java8 interface. • Binary compat & reduced bytecode! • scalac λ bytecode mimics javac’s. • scala.FunctionN compiles to SAM type (Java8 λ). • New backend & optimiser1 1. https://dl.dropboxusercontent.com/u/4881107/website/scala-user-group-2016.pdf
- 19. New trait encoding trait PriceAlgorithm[Item] { def apply(item: Item): Double = ??? } Let’s compare Scala 2.11 vs 2.12 bytecode
- 20. trait PriceAlgorithm[Item] { def apply(item: Item): Double = ??? } Compiled with Scala 2.11 interface PriceAlgorithm<Item> { abstract double apply(Item); } abstract class PriceAlgorithm$class { static double apply(PriceAlgorithm, java.lang.Object); static void $init$(PriceAlgorithm); } Two classfiles
- 21. trait PriceAlgorithm[Item] { def apply(item: Item): Double = ??? } Compiled with Scala 2.12 interface PriceAlgorithm<Item> { public double apply(Item); static double apply$(PriceAlgorithm, java.lang.Object); static void $init$(PriceAlgorithm); } Only one classfile!
- 22. Java8 API from Scala Scala λ assignable to Java 8 λ scala> import java.util.stream.{Stream, IntStream} scala> import java.util.{Arrays, List} scala> val myList = Arrays.asList("a1", "a2", "b1", "c2", "c1") myList: java.util.List[String] = [a1, a2, b1, c2, c1] scala> myList.stream. filter(_.startsWith("c")). map(_.toUpperCase). sorted. forEach(println) C1 C2
- 23. Why an optimiser? • Some well-known patterns are not optimised by HotSpot (Oracle JIT). • Transform the code to please HotSpot. • Inlining vs binary resilience. • Optimiser is not a magic wand, but rather a tool for experts. • Compile with the -optimise flag.
- 26. Scala future 2016 Scala 2.12 Scala 2.13 (Aida) Improve the library! Smaller core & stabilise Q1 2018 (Don Giovanni) Faster compiler Improve binary compatibility (TASTY) 2020?
- 27. Dotty? • Dotty is the new Scala compiler Martin is working on with his group at EPFL. • It’s research work, but a first release should be available soon. • https://github.com/lampepfl/dotty • Goal is to simplify the language.
- 28. The future of Scala on a A4 paper Credit goes to @malweene https://twitter.com/malweene/status/743117270948274176