Emerging Languages Bowl

Speaker: Trisha Gee (JetBrains) and Eugene Petrenko (JetBrains) – moderated by Raghavan “Rags” Srinivas

For more blog posts, see The Oracle Code One table of contents

Rags talked about how this is a different format than the usual “script bowl”. I’ve never been so not disappointed

Java (Trisha)

• Inspired features from scripting languages
  • Lambdas
  • Streams – would be hard to use without lambdas because would need anonymous inner classes
  • RPEL
  • var
• Not a functional language, but idioms that came from functional languages
• Not in Java
  • Immutable “var” – do you use var/val, var/let, var/final var? We have “final var”, but it isn’t immutable. Just prevents re-assignment. But are getting immutable collections.
• Future
  • data classes [records]- Kotlin has this. Preview feature in Java 12
  • multi-line strings – Groovy has this.
  • Switch statements/pattern matching. Preview feature as well
• Preview features are a good thing because can discuss with real code

Kotlin (Eugene)

• Statically typed
• Now official on Android
• Concise – minimal boilerplate
• Safe – avoid classes of errors like null pointers
• Interoperable – use JVM and Android libraries
• Tool friendly – works with any Java IDE
• Can combine Java and Kotlin in same module
• Kotlin invented in 2000. Version 1 came out in 2005
• Can target Java 1.6 (or higher if want)

“The only way to learn a new programming language is by writing programs in it” -Dennis Richie

IntelliJ has plugin which gives sample tasks

Kotlin demo

• fun main() {} – function – defaults to void return type
• fun main() : ReturnType {} – function with return type. Can use generics in types
• “Hello ${abc}” – string interpolation
• Triple quotes – multi line string
• trimIndent() – extra method
• var/val – mutable/immutable
• var x : String – not nullable
• var x : String? – nullable
• if ( x is Type) – auto casts inside if statement
• fun Class.method() = impl – add method from outside class. It can even use instance variables from inside the class.
• sealed class – all subclasses must be defined in same file
• when/is – pattern matching

My take: I don’t know what the session was supposed to be, but this was fine. It was 10 minutes of Trisha and Eugene introducing Kotlin for 30. I have seen the intro to Kotlin talk before though. That said, I still needed Google for what one thing did.