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Kotlin — A deeper look

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We already love Kotlin Data classes, extension functions, immutability, … Modern and thriving Interoperable with Java

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We already love Kotlin Data classes, extension functions, immutability, … Modern and thriving Interoperable with Java

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We already love Kotlin Data classes, extension functions, immutability, … Modern and thriving Interoperable with Java

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We already love Kotlin Data classes, extension functions, immutability, … Modern and thriving Interoperable with Java

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We already love Kotlin Data classes, extension functions, immutability, … Modern and thriving Interoperable with Java

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How… … does the Kotlin compiler produce Java-compatible bytecode? … can we trust the compiler? … much overhead does the interoperability introduce?

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How… … does the Kotlin compiler produce compatible bytecode? … can we trust the compiler? … much overhead does the interoperability introduce?

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How… … does the Kotlin compiler produce compatible bytecode? … can we trust the compiler? … much overhead does the interoperability introduce?

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How… … does the Kotlin compiler produce compatible bytecode? … can we trust the compiler? … much overhead does the interoperability introduce?

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How… … does the Kotlin compiler produce compatible bytecode? … can we trust the compiler? … much overhead does the interoperability introduce?

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Kotlin Standard Library Extension functions String/char sequences utilities High-order functions

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Kotlin Standard Library Extension functions String/char sequences utilities High-order functions

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Kotlin Standard Library Extension functions String/char sequences utilities High-order functions

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Kotlin Standard Library Extension functions String/char sequences utilities High-order functions

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Kotlin Standard Library Extension functions String/char sequences utilities High-order functions Apply — With — Let — Run

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/** * Calls the specified function [block] with `this` * value as its receiver and returns `this` value. */ @kotlin.internal.InlineOnly public inline fun T.apply(block: T.() -> Unit): T { block(); return this }

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/** * Calls the specified function [block] with `this` * value as its receiver and returns `this` value. */ @kotlin.internal.InlineOnly public inline fun T.apply(block: T.() -> Unit): T { block(); return this } enum class Orientation { VERTICAL, HORIZONTAL } class LayoutStyle { var orientation = Orientation.HORIZONTAL init { if (System.currentTimeMillis() < 1) { main() } } fun main() { val layout = LayoutStyle().apply { orientation = Orientation.VERTICAL } layout.orientation } }

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NEW kotlindeepdive/LayoutStyle DUP INVOKESPECIAL kotlindeepdive/LayoutStyle. ()V ASTORE 2 ALOAD 2 ASTORE 3 ALOAD 3 GETSTATIC kotlindeepdive/Orientation.VERTICAL : Lkotlindeepdive/Orientation; INVOKEVIRTUAL kotlindeepdive/LayoutStyle.setOrientation (Lkotlindeepdive/Orientation;)V ALOAD 2 ASTORE 1

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enum OrientationJ { VERTICAL, HORIZONTAL; } class LayoutStyle { private Orientation orientation = HORIZONTAL; public Orientation getOrientation() { return orientation; } public LayoutStyle() { if (System.currentTimeMillis() < 1) { main(); } } public void setOrientation(Orientation orientation) { this.orientation = orientation; } public Orientation main() { LayoutStyle layout = new LayoutStyle(); layout.setOrientation(VERTICAL); return layout.orientation; } }

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NEW kotlindeepdive/LayoutStyle DUP ASTORE 1 ALOAD 1 GETSTATIC kotlindeepdive/Orientation.VERTICAL : kotlindeepdive/Orientation; INVOKEVIRTUAL kotlindeepdive/LayoutStyle.setOrientation (kotlindeepdive/Orientation;)V

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/** * Calls the specified function [block] with the given [receiver] as its * receiver and returns its result. */ @kotlin.internal.InlineOnly public inline fun with(receiver: T, block: T.() -> R): R = receiver.block()

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enum class Orientation { VERTICAL, HORIZONTAL } class LayoutStyle { var orientation = HORIZONTAL } object SharedState { val previousOrientation = VERTICAL } fun main() { val layout = with(SharedState) { LayoutStyle().apply { orientation = previousOrientation } } } /** * Calls the specified function [block] with the given [receiver] as its * receiver and returns its result. */ @kotlin.internal.InlineOnly public inline fun with(receiver: T, block: T.() -> R): R = receiver.block()

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GETSTATIC kotlindeepdive/SharedState.INSTANCE : Lkotlindeepdive/SharedState; ASTORE 1 ALOAD 1 ASTORE 2 NEW kotlindeepdive/LayoutStyle DUP INVOKESPECIAL kotlindeepdive/LayoutStyle. ()V ASTORE 3 ALOAD 3 ASTORE 4 ALOAD 4 ALOAD 2 INVOKEVIRTUAL kotlindeepdive/ SharedState.getPreviousOrientation ()Lkotlindeepdive/ Orientation; INVOKEVIRTUAL kotlindeepdive/LayoutStyle.setOrientation (Lkotlindeepdive/Orientation;)V ALOAD 3 ASTORE 0 RETURN

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/** * Calls the specified function [block] with `this` value as its * argument and returns its result. */ @kotlin.internal.InlineOnly public inline fun T.let(block: (T) -> R): R = block(this)

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enum class Orientation { VERTICAL, HORIZONTAL } class LayoutStyle { var orientation = HORIZONTAL } object SharedState { val previousOrientation: Orientation? = VERTICAL } fun main() { val layout = LayoutStyle() SharedState.previousOrientation ?.let { layout.orientation = it } } /** * Calls the specified function [block] with `this` value as its * argument and returns its result. */ @kotlin.internal.InlineOnly public inline fun T.let(block: (T) -> R): R = block(this)

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NEW kotlindeepdive/let/LayoutStyle DUP INVOKESPECIAL kotlindeepdive/let/LayoutStyle. ()V GETSTATIC kotlindeepdive/let/SharedState.INSTANCE : Lkotlindeepdive/let/SharedState; INVOKEVIRTUAL kotlindeepdive/let/ SharedState.getPreviousOrientation ()Lkotlindeepdive/ let/Orientation; DUP IFNULL L2 ASTORE 1 ALOAD 1 ASTORE 2 ALOAD 0 ALOAD 2 INVOKEVIRTUAL kotlindeepdive/let/ LayoutStyle.setOrientation (Lkotlindeepdive/let/ Orientation;)V GOTO L9 L2 POP L9 RETURN

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/** * Calls the specified function [block] with `this` value as * its receiver and returns its result. */ @kotlin.internal.InlineOnly public inline fun T.run(block: T.() -> R): R = block()

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enum class Orientation { VERTICAL, HORIZONTAL } class LayoutStyle { var orientation = HORIZONTAL } object SharedState { val previousOrientation = VERTICAL } fun main() { val layout = LayoutStyle().run { orientation = SharedState.previousOrientation this } } /** * Calls the specified function [block] with `this` value as * its receiver and returns its result. */ @kotlin.internal.InlineOnly public inline fun T.run(block: T.() -> R): R = block()

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NEW kotlindeepdive/LayoutStyle DUP INVOKESPECIAL kotlindeepdive/LayoutStyle. ()V ASTORE 0 ALOAD 0 ASTORE 1 ALOAD 1 ASTORE 2 ALOAD 2 GETSTATIC kotlindeepdive/SharedState.INSTANCE : Lkotlindeepdive/SharedState; INVOKEVIRTUAL kotlindeepdive/ SharedState.getPreviousOrientation ()Lkotlindeepdive/ Orientation; INVOKEVIRTUAL kotlindeepdive/LayoutStyle.setOrientation (Lkotlindeepdive/Orientation;)V RETURN

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Standard functions — Cheat sheet ← We can thank this guy

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Superfluous for production environments ASTORE / ALOAD Inserted by the compiler to allow debugging Can be stripped with tools

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ASTORE / ALOAD Inserted by the compiler to allow debugging Superfluous for production environments Can be stripped with tools

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ASTORE / ALOAD Inserted by the compiler to allow debugging Superfluous for production environments Can be stripped with tools

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Inserted by the compiler to allow debugging Superfluous for production environments ASTORE / ALOAD Can be stripped with tools

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Inserted by the compiler to allow debugging Superfluous for production environments ASTORE / ALOAD Can be stripped with tools ProGuard!

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Thank you! @rotxed http://bit.ly/kotlin-deeper-look-article