I'm curious what your use case is for using a suspend function in spark. I have written several spark jobs with Kotlin and have never had a reason to create one. The only difference from the Scala/Java jobs is that I had to be much more explicit with certain things (encoders in higher order funcs, etc.).
All of the reasons you'd want to use a suspend function at all - e.g. mutually recursive functions, async I/O (e.g. database queries), error handling - suspend functions seem to be kotlin's answer to anything even slightly non-vanilla. Writing in Scala I can, with care, use async and iteratees in spark and be able to reason about what's going to get executed where and when, because these things are represented as values.
