Is anyone using kotlin with scala ? I am planing to eventually migrate 10 Million LOC from scala to kotlin. I know that the interoperability with scala isn't good. But just wanted to know if any one has experienced some hurdles/extreme pain points in doing so

IMO I wouldn't do it.

Thanks for your advice We dont use apache spark as of yet, but we plan to add it But personally i am looking at various annotation processors and intellij support for kotlin

sbt also has conflict too AFAIK...Scala generates Java interop and Kotlin can't reach it. At least that's one of the coworkers told me...

Scala and Kotlin don't work very well together in my experience. That was possibly because the project I used them in had inter dependencies. If you could convert a stand alone module then you might be alright. And the first thing I'd do is ditch ShitBT if you're using that.