[stewbrew]

"One thing I found out is that you really have to write a library in Java if you want it to be used in both Java and Kotlin. Java -> Kotlin is effectively one-way interop."

Could you please explain this.

[dradtke]

I think it means that a library written in Kotlin is difficult or impossible to use from Java.

[EddieRingle]

Not really true from my experience. For example, here's a Markdown library written in Kotlin that you can use with a plain Java interface: https://github.com/valich/intellij-markdown

[edem]

No no no no. Kotlin provides a lot of tools to make your library usable from Java and it works.

[pdpi]

You have to write your Kotlin anticipating it'll be called from Java though (e.g. by using SAM interfaces instead of function types for your arguments)

[edem]

This does not mean that it is a one-way interop. When you write it the right way, it will work from Java.

[lmm]

Is Kotlin's function not an SAM interface? I'm pretty sure Scala's is.