!

! “…Kotlin is a new JVM language…”

! “…Kotlin is a new JVM language…”

! “…Kotlin is a new JVM language…”

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made by JetBrains open source, non-profit foundation pragmatic safe(r than Java) “good” magic ✨ FUN

packages optional no need to match folder files multiple classes top level functions

// src/main/kotlin/covfefe/Whatever.kt fun main(args: Array) { } println("Hello World!")

fun main(args: Array) { val immutable = 0 immutable += 1 }

fun main(args: Array) { var mutable = 0 mutable += 1 }

fun main(args: Array) { val nullable: String? = null val alternative = nullable ?: "¯\_(ϑ)_/¯" val lengthOrNull = nullable?.length if (nullable != null) { println(nullable.length) } } }

fun Int.twice() = this * 2 fun test() = 1.twice() // 2

inline fun Map.getOrElse( key: K, defaultValue: () -> V ) = get(key) ?: defaultValue()

abstract class NetworkResult { object Cancelled : NetworkResult() data class Success(val json: String) : NetworkResult() data class Error(val error: Throwable) : NetworkResult() } fun test(result : NetworkResult) = when (result) { NetworkResult.Cancelled -> null is NetworkResult.Success -> result.json is NetworkResult.Error -> throw result.error else -> error("WTF") }

sealed object Cancelled : NetworkResult() data class Success(val json: String) : NetworkResult() data class Error(val error: Throwable) : NetworkResult() } fun test(result : NetworkResult) = when (result) { NetworkResult.Cancelled -> null is NetworkResult.Success -> result.json is NetworkResult.Error -> throw result.error class NetworkResult { }

why?

everything you can do in Kotlin can be done in Java

everything you can do in Java can be done in bytecode

high level abstractions, enforced by the compiler extend the language through DSL built in symbiosis with tools moving fast, but carefully change of mindset

myths

slow compilation runtime overhead learning curve not knowing what’s really going on confusing without IDE

cons

occasional rough edges around tooling not being able to go back to Java, ever

future

immutable collections universal serialization type classes multiplatform metaprogramming

Official website goo.gl/xL99fk Kotlin and Android (blog) goo.gl/FQYAcW Introduction to Kotlin (video) goo.gl/3n6wic Life is Great and Everything Will Be Ok, Kotlin is Here (video) goo.gl/NTaYqi Using Project Kotlin for Android (doc) goo.gl/T0SDTJ The Future of Kotlin (video) goo.gl/INLPDl Kotlin 1.1 (video) goo.gl/iKojmn

BIT .LY /KO TLIN -M O RE -TH A N -A N -ISLA N D Eugenio Marletti @workingkills