Kotlin got right what Scala is still trying to get right. In some ways the languages are similar. But Scala focuses on mathematical purity, it seems, at the expense of being straightforward. While the same one-liner for properties works in Scala, it’s all the rest that tends to confound most of our engineers until a good couple of years.
Also worth looking at is the much loved/hated Ruby. For the type safety crowd, Ruby is unthinkable. It took me at least two years to get over my fears. But I have yet to find a language as expressive and delightful to code in as Ruby. Maybe Kotlin will be the answer.
(At least with Kotlin I wouldn’t have to convince all those Sublime users out there to use a proper IDE like IntelliJ :-)