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"