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Scala 3 - A Quick Tour - Scala Italy 2021
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Daniela Sfregola
October 23, 2021
Programming
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Scala 3 - A Quick Tour - Scala Italy 2021
Daniela Sfregola
October 23, 2021
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Transcript
Scala 3 A Quick Tour @DanielaSfregola Scala Italy - October
2021
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"
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
An overview • https://dotty.ep fl .ch/docs/reference/overview.html
@main Annotation object HelloWorld extends App { println("Hello World!" )
}
@main Annotation object HelloWorld extends App { println("Hello World!" )
} object HelloWorld { @main def hello: Unit = { println("Hello world!" ) } }
@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 ) } }
Parametrized Traits trait Nameable { def name: Strin g }
Parametrized Traits trait Nameable { def name: Strin g }
trait Nameable(name: String)
Intersection Types class A class B def foo: A &
B = ???
Union Types class A class B def foo: A |
B = ???
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" ) } }
Package Object // in file my/demo/package.scal a package m y
package object demo { def customLog(msg: String) { println(s"Customised package log: $msg" ) } } [ DROPPED ]
Enums sealed abstract class Color(val rgb: Int) case object Red
extends Color(0xFF0000 ) case object Green extends Color(0x00FF00 ) case object Blue extends Color(0x0000FF)
Enums sealed abstract class Color(val rgb: Int) case object Red
extends Color(0xFF0000 ) case object Green extends Color(0x00FF00 ) case object Blue extends Color(0x0000FF) enum Color(val rgb: Int) : case Red extends Color(0xFF0000 ) case Green extends Color(0x00FF00 ) case Blue extends Color(0x0000FF)
Improved Type Inference Map("Scala" -> 3).map { (k, v) =>
s"$k$v" }
Improved Type Inference Map("Scala" -> 3).map { (k, v) =>
s"$k$v" } Scala 2.13.4
Improved Type Inference Map("Scala" -> 3).map { (k, v) =>
s"$k$v" } Scala 2.13.4
Improved Type Inference Map("Scala" -> 3).map { (k, v) =>
s"$k$v" } Scala 3.0.0
Improved Type Inference Map("Scala" -> 3).map { (k, v) =>
s"$k$v" } Scala 3.0.0 Scala 2.13.4
Procedure Syntax def echo(str: String) { st r }
Procedure Syntax def echo(str: String) { st r } Scala
2.13.4
Procedure Syntax def echo(str: String) { st r } Scala
2.13.4
Procedure Syntax def echo(str: String) { st r } Scala
3
Procedure Syntax def echo(str: String) { st r } Scala
3
Improved Error Messages Arrested Developers What the Scala Compiler &
Lucille Bluth Have In Common by Fiona Condon, NeScala 2017 https://www.youtube.com/watch?v=78iIbiRwFTM
Improved Error Messages def echo(str: String): Unit = { st
r } def echoTwice(str: String): String = { echo(str) match { case x: String => s"$x$x " } }
Improved Error Messages Scala 2.13.4
Improved Error Messages Scala 2.13.4 Scala 3
Strict Equality List("Scala", "3").headOption == "Scala"
Strict Equality List("Scala", "3").headOption == "Scala" Scala 2.13.4
Strict Equality List("Scala", "3").headOption == "Scala" Scala 2.13.4 Scala 3
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
Thank You! •Twitter: @DanielaSfregola •"Get Programming with Scala" by
Manning 35% OFF on EVERYTHING with code "ctwscalait21"