...and I have another question: As this is a prett...

# getting-started

[Peter]

...and I have another question: As this is a pretty busy channel, I will open a new thread 😉

[Peter]

I have a hard time understanding the different ways how to call main functions of Kotlin code:

a) if I have a global fun main(args: Array<String>) then kotlinc Main.kt include-runtime -d Main.jar
will produce the MainKt.class, and the Main.jar. So kotlin MainKt or java -jar Main.jar
need to be called. Why MainKt in the Kotlin case? The Kt suffix is normally only produced for Java?

b) if the main function lives inside an object, that function needs to be annotated w/ @JvmStatic,
but then it can be called w/ kotlin Main without th Kt suffix (as a MainKt.class does not exist).
This still is not sufficient for Java (albeit the annotation), as the runtime dependency needs to be
added again.

[Peter]

This is pretty asymmetrical, IMHO...

[Vampire]

Where do you see any asymmetry?
Top-level things in a Foo.kt file are not in any class, so an artifical class called FooKt is generated and the function put there.
If it is inside a class, it is an instance function of that class unless you define it as @JvmStatic which makes it a static function of that class.
The Kotlin runtime is of course always needed to run a Kotlin program with the Java interpreter just like any other dependency. The --include-runtime just builds a bad-practice fat-jar with the Kotlin runtime included, so that you do not have to add it to the classpath manually.

[Peter]

Hey @Vampire Thank you again for your support! If the code is only run by Kotlin, why the hassle generating a *Kt named bytecode file?

[Peter]

That's the asymmetry I mean; ...

[Peter]

And how would the classpath look like, without packaging the stuff into a JAR?

[Vampire]

Hey @Vampire Thank you again for your support! If the code is only run by Kotlin, why the hassle generating a *Kt named bytecode file?

Who says it is only run by Kotlin?
If you run with java -jar ... it is still run by Java.
Or you could still use it as library in some other Java project.
...

And how would the classpath look like, without packaging the stuff into a JAR?

Depends on which of the runtime libraries you use.
That -include-runtime just packs everything in afair, even things you don't use or need.
I'd usually simply use a proper build tool, especially Gradle, and let it build a proper distribution, e.g. using the application plugin in Gradle.