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JavaOne2012: Kotlin: Practical Aspects of JVM Language Implementation
This document summarizes a talk on practical aspects of implementing the Kotlin programming language on the Java Virtual Machine (JVM). The talk discusses Kotlin extensions, bridges between Kotlin and Java generics and primitives, default arguments, traits, collections and variance, and nullable types. The speaker explains how Kotlin provides features like extensions, traits and improved collection types while maintaining compatibility with Java code and the JVM.
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JavaOne2012: Kotlin: Practical Aspects of JVM Language Implementation
- 1. Kotlin: How ThingsWork Practical Aspects of JVM Language Implementation Andrey Breslav Tuesday, October 2, 12
- 2. Why you shouldcare • Language is an abstraction ➡ thus it leaks abstraction • When something weird happens ➡ you may need to "see through the Matrix" 2 Tuesday, October 2, 12
- 3. tetris is waytoo easy when played this way 3 Tuesday, October 2, 12
- 4. JVM & ItsLanguages What's i n... otl e , K possible? sur Clo vy, G roo , Sc ala Java t 1995 2012 4 Tuesday, October 2, 12
- 5. About Me • Project lead of Kotlin ➡ at JetBrains since 2010 (not (RICH HICKEY)) • EG member of JSR-335 ➡ Project Lambda 5 Tuesday, October 2, 12
- 6. Kotlin Modern Language for Industry • Smart compiler • Static typing ➡ Less boilerplate • Readability • Flexible abstractions • Tool support ➡ Powerful libraries • Interoperability 6 Tuesday, October 2, 12
- 7. Outline • Extensions • Bridges of All Sorts • Types: Collections and Nulls • Dreams... (maybe) 7 Tuesday, October 2, 12
- 8. Extensions • Live Demo ➡ Extension syntax ➡ How it is compiled ➡ Multiple files in a package 8 Tuesday, October 2, 12
- 9. Bridges 9 Tuesday, October 2, 12
- 10. Bridges for Generics (Lj/l/Object;)Lj/l/Object; overrides (I)I (Lj/l/Object;)Lj/l/Object; "synthetic bridge method" (JLS) 10 Tuesday, October 2, 12
- 11. Kotlin Brides &Primitives Java 1 1 & Kotlin Kotlin foo(t: T) = t foo(t: Int) = t 1 1 11 Tuesday, October 2, 12
- 12. Default Arguments 12 Tuesday, October 2, 12
- 13. Masks for Defaults foo(a, b) foo(a, b, mask: Int) if (mask & 1) a = 0 if (mask & 2) b = 0 foo(a, b) 13 Tuesday, October 2, 12
- 14. Traits: Code inInterfaces class Trait$Impl { static foo()V { println("Hi") } } 14 Tuesday, October 2, 12
- 15. Trait Hierarchy T1 foo() { println() } T2 foo() { T1$Impl.foo() } C foo() { T2$Impl.foo() } 15 Tuesday, October 2, 12
- 16. Summary • Sometimes you need just one more method... 16 Tuesday, October 2, 12
- 17. Collections How Data-Compatible is Your Language? Tuesday, October 2, 12
- 18. Collections & Variance Java: Kotlin: 18 Tuesday, October 2, 12
- 19. Kotlin's Collections 19 Tuesday, October 2, 12
- 20. Declaration-Site Variance 20 Tuesday, October 2, 12
- 21. Translation Ø java.util.List 21 Tuesday, October 2, 12
- 22. Translation: Inheritance 22 Tuesday, October 2, 12
- 23. Translation: Variance 23 Tuesday, October 2, 12
- 24. Calling Java FromKotlin 24 Tuesday, October 2, 12
- 25. Summary • Kotlin's collections ➡ Better than Java's ➡ Still Compatible 25 Tuesday, October 2, 12
- 26.
- 27. Demo • Kotlin is null-safe • Java code can be annotated for safe access 27 Tuesday, October 2, 12
- 28. Talk Summary • Languages are about tradeoffs • Kotlin is cool :) 28 Tuesday, October 2, 12
- 29. Kotlin Resources • Docs: http://kotlin.jetbrains.org • Demo: http://kotlin-demo.jetbrains.com • Code: http://github.com/jetbrains/kotlin • Twitter: ➡ @project_kotlin ➡ @abreslav 29 Tuesday, October 2, 12