As you can see in the comment section below the commits, despite there being an import java.util.StringBuilder the resulting Javscript code
works just fine since there is an implementation of StringBuilder in the js-stdlib.
So it would be ok to start suggesting a std lib for kotlin and perhaps implement those classes in pure Kotlin?
This makes me glad, I was starting to feel that Kotlin had been tainted by JVM-ness.
For me, Kotlin feels like something like a cross of C# and Ruby, and the std lib should reflect that and not blindly copy atrocious API’s like Java’s StringBuilder class.