Экспериментальные и релизные фичи в Kotlin 1.3

Станислав Ерохин рассказал про "экспериментальные и релизные фичи в 1.3".

Поговорили про будущий релиз Kotlin 1.3 — что нового будет добавлено, почему некоторое фичи будут экспериментальными и что это вообще означает. Обсудили новый back-end и зачем он нужен. Ну и напоследок Станислав рассказал про новый type inference и возможности, которые он привнесет.

Transcript

1. Current work in Kotlin language Stanislav.Erokhin@jetbrains.com
2. Disclaimer • Kotlin 1.3 in active developement • Everything in this talk just plans • Everything can be changed • No guarantees
3. Coroutines • kotlin.coroutines.experimental→kotlin.coroutine • For old coroutines – support library since ~1.4 • In ~1.3 old/new coroutines interop these are just plans – no promises
4. Coroutines changes • Performance improvements - do not generate state-machine where it isn’t nesesary • Supported all inline-related functionality • Callable reference on suspend function • API changes these are just plans – no promises
5. Coroutines: Continuation interface Continuation<in T> { fun resume(value: T) fun resumeWithException(exception:Throwable) } class Result<out T> { val value: T? val exception: Throwable? } interface Continuation<in T> { fun resume(result: Result<T>) } these are just plans – no promises
6. Inline class Result inline class Result<out T>(val o: Any?) { val value: T? get() = if (o is Box) null else o as T val exception: Throwable? get() = (o as? Box).exception } private class Box(val exception: Throwable) these are just plans – no promises
7. Inline classes • Only one field allowed • Runtime representation – inner object or box wrapper • Box wrapper for generics – List<Result> vs List<Any?> • Primitive types supported these are just plans – no promises
8. Unsigned arithmetics • For every primitive create corresponding inline class • Define arithmetics operations for them • Handle toString properly • Experimental in some future version inline class UInt(val i: Int) inline class ULong(val l: Long) these are just plans – no promises
9. @JvmDefault • Like default in java 8 • In 1.2.x you can use it with opt-in flag • Probably will be released in 1.3 these are just plans – no promises
10. Contract system fun test(x: Any) { check(x is String) println(x.length) } fun check(value: Boolean) { contract { returns() implies value } if (!value) throw … } these are just plans – no promises
11. Contract system fun test() { val x: String run { x = "Hello” } println(x.length) } fun <R> run(block: () -> R): R { contract { callsInPlace(block, EXACTLY_ONCE) } return block() } these are just plans – no promises
12. Type inference tweak: @NoInfer fun print(c: Collection<Any>) { ... } val c: Collection<Any> print(c.filterIsInstance()) print(c.filterIsInstance<String>()) fun <R> Iterable<*>.filterIsInstance(): List<@NoInfer R> these are just plans – no promises
13. Type inference tweaks • @NoInfer, @Exact, @OnlyInputTypes • Now used in stdlib • Will be available with opt-in flag in 1.2.x these are just plans – no promises
14. SAM for java methods static void test(Factory f, Runnable r) interface Factory { String produce(); } fun use(f: Factory) { test(f) { } // Factory != () → String } // fun test(Factory, Runnable) // fun test(() → String, () → Unit) these are just plans – no promises
15. SAM for kotlin methods & interfaces fun test(r: Runnable) {…} sam interface Predicate<T> { fun test(t: T): Boolean } fun Collectio<T>.filter(p:Predicate<T>) :Collection<T> {…} fun use() { test { println(“Hello”) } val l = listOf(-1, 2, 3) l.filter { it > 0 } } these are just plans – no promises
16. Smart inference for builders fun <T> buildList(l: MutableList<T>.()→ Unit) :List<T> {…} val list = buildList { add("one") add("two") } these are just plans – no promises
17. New type inference engine • Experimental in ~1.3 • A lot of bugs fixed (~ ½ inference bugs) • Supported SAM conversion for Kotlin classes • Improved SAM conversion for java classes • Smart inference for builders these are just plans – no promises
18. Progressive mode • One key that enable all experimental features • Compiler fixes in patch versions (1.2.x) • Fast deprecation cycle these are just plans – no promises
19. Compiler scheme Front-end PSI + semantic info map JVM BE JS BE .class .js bin BE IR JVM Codogen JS Codogen LLVM Common BE FE IR these are just plans – no promises
20. IR Back-end’s • JVM/JS BE by IR will be experimental in ~1.3.x • Native BE already use IR • Multiplatform libraries contains IR • IR as public API: - plugins for IR transformations - “replacement” for annotation processors these are just plans – no promises
21. Questions?