This talk by Marty Pitt has low-key blown my mind:

Despite the type-aliases in the title, that seems to be the least important part of the talk. Some quick notes:

The result is:

My concerns:

Overall what orbital does is impressive. I don't think I have seen it elsewhere. Nothing here is really Kotlin specific besides the fact that you can define taxi lang constructs (contracts and queries) with type safe Kotlin which actually is convenient as well.