Scala 3 - A Quick Tour - Scala Italy 2021

Transcript

1. Scala 3 A Quick Tour @DanielaSfregola Scala Italy - October

   2021

2. Hellooooo • Software Engineer 
 living in London UK •

   Scala Lover ❤ • OS Maintainer • Author of 
 "Get Programming with Scala" by Manning
 
 35% OFF on EVERYTHING
 with code "ctwscalait21"

3. Scala 3 is here! • After 8 years of work

   • 28,000 commits • 7,400 pull requests • 4,100 closed issues • ...released on May 13th, 2021! https://www.scala-lang.org/blog/2021/05/14/scala3-is-here.html

4. An overview • https://dotty.ep fl .ch/docs/reference/overview.html

5. @main Annotation object HelloWorld extends App { println("Hello World!" )

   }

6. @main Annotation object HelloWorld extends App { println("Hello World!" )

   } object HelloWorld { @main def hello: Unit = { println("Hello world!" ) } }

7. @main Annotation object HelloWorld extends App { println("Hello World!" )

   } object HelloWorld { @main def hello: Unit = { println("Hello world!" ) } } object Hello { @main def echo(n: Int, word: String): Unit = { println(word * n ) } }

8. Parametrized Traits trait Nameable { def name: Strin g }

9. Parametrized Traits trait Nameable { def name: Strin g }

   trait Nameable(name: String)

10. Intersection Types class A class B def foo: A &

    B = ???

11. Union Types class A class B def foo: A |

    B = ???

12. Package Object // in file my/demo/package.scal a package m y

    package object demo { def customLog(msg: String) { println(s"Customised package log: $msg" ) } }

13. Package Object // in file my/demo/package.scal a package m y

    package object demo { def customLog(msg: String) { println(s"Customised package log: $msg" ) } } [ DROPPED ]

14. Enums sealed abstract class Color(val rgb: Int)
 case object Red

    extends Color(0xFF0000 ) case object Green extends Color(0x00FF00 ) case object Blue extends Color(0x0000FF)

15. Enums sealed abstract class Color(val rgb: Int)
 case object Red

    extends Color(0xFF0000 ) case object Green extends Color(0x00FF00 ) case object Blue extends Color(0x0000FF) enum Color(val rgb: Int) : case Red extends Color(0xFF0000 ) case Green extends Color(0x00FF00 ) case Blue extends Color(0x0000FF)

16. Improved Type Inference Map("Scala" -> 3).map { (k, v) =>

    s"$k$v" }

17. Improved Type Inference Map("Scala" -> 3).map { (k, v) =>

    s"$k$v" } Scala 2.13.4

18. Improved Type Inference Map("Scala" -> 3).map { (k, v) =>

    s"$k$v" } Scala 2.13.4

19. Improved Type Inference Map("Scala" -> 3).map { (k, v) =>

    s"$k$v" } Scala 3.0.0

20. Improved Type Inference Map("Scala" -> 3).map { (k, v) =>

    s"$k$v" } Scala 3.0.0 Scala 2.13.4

21. Procedure Syntax def echo(str: String) { st r }

22. Procedure Syntax def echo(str: String) { st r } Scala

    2.13.4

23. Procedure Syntax def echo(str: String) { st r } Scala

    2.13.4

24. Procedure Syntax def echo(str: String) { st r } Scala

    3

25. Procedure Syntax def echo(str: String) { st r } Scala

    3

26. Improved Error Messages Arrested Developers What the Scala Compiler &

    Lucille Bluth 
 Have In Common by Fiona Condon, NeScala 2017 https://www.youtube.com/watch?v=78iIbiRwFTM

27. Improved Error Messages def echo(str: String): Unit = { st

    r } def echoTwice(str: String): String = { echo(str) match { case x: String => s"$x$x " } }

28. Improved Error Messages Scala 2.13.4

29. Improved Error Messages Scala 2.13.4 Scala 3

30. Strict Equality List("Scala", "3").headOption == "Scala"

31. Strict Equality List("Scala", "3").headOption == "Scala" Scala 2.13.4

32. Strict Equality List("Scala", "3").headOption == "Scala" Scala 2.13.4 Scala 3

33. Compatibility with 2.13 Migrating to Scala 3 is easy* !

    * if you are using Scala 2.13 * if you don't have macros in your code Scala 3 Migration Guide https://docs.scala-lang.org/scala3/guides/migration

34. Thank You! •Twitter: @DanielaSfregola •"Get Programming with Scala" 
 by

    Manning
 
 35% OFF on EVERYTHING 
 with code "ctwscalait21"