Kotlin Multiplatform

Given at an internal company knowledge sharing meeting.

This presentation is about the "basics" behind Kotlin Multiplatform.

Transcript

1. Kotlin Multiplatform
   

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2. Kotlin
   Kotlin/JVM
   Kotlin/Native
   Kotlin/JS
   Kotlin Multiplatform
   Easter Egg
   

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3. Kotlin
   Kotlin/JVM
   Kotlin/Native
   Kotlin/JS
   Kotlin Multiplatform
   Easter Egg
   

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4. Warning:
   The next slides are not 100% accurate
   but give you a visualisation about how
   Kotlin Multiplatform works
   

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5. Fact:
   Kotlin is a Programming language.
   

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6. Fact:
   Each language has to converted to something which can be
   understand by "a computer".
   We call these converters compiler.
   

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7. Fact:
   Jetbrains provides different compilers for one language.
   

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8. Fact:
   Jetbrains provides different compilers for one language.
   1. JVM
   2. Native
   3. JS
   

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9. Fact:
   Kotlin can be converted to
   Java Bytecode (via JVM compiler)
   Machine code (via Native compiler)
   JavaScript (via JS compiler)
   

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10. fun main() {
    println("HelloWorld")
    }
    Example
    $ kotlinc HelloWorld.kt -include-runtime -d hello.jar
    $ java -jar hello.jar
    HelloWorld
    $ konanc HelloWorld.kt -o hello
    $ ./hello.kexe
    HelloWorld
    $ kotlinc-js HelloWorld.kt -output hello.js
    $ cat hello.js
    // JS Code nobody wants to see
    

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11. Please note that we talk about pure Kotlin code.
    No dependencies to other worlds (like JVM, C or JS).
    

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12. But - because the compiler knows about other worlds it is
    possible to use the respective dependencies!
    

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13. Example
    expect currentTime: Long
    fun printTime() {
    println("It is $currentTime o'clock")
    }
    common.kt // No dependencies to other worlds
    actual currentTime: Long =
    java.lang.System.currentTimeMillis()
    fun main() = printTime()
    jvm.kt
    actual currentTime: Long =
    platform.posix.time(null)
    fun main() = printTime()
    native.kt
    actual currentTime: Long =
    kotlin.js.Date.now()
    fun main() = printTime()
    js.kt
    

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14. Now we can compile each target (jvm, native, js)
    with the respective compiler
    

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15. Questions so far?
    

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