Sources: 1. Kotlin learning materials 2. Effective Java 3. Atomic Kotlin 4. Kotlin for Java Developers RE (1), I found the Kotlin Koans course particularly useful for learning syntax as well as some nuances about null safety, equality, and mutable vs read-only collections. ✅ RE (2), the course content seems quite similar to Kotlin Koans. RE (3), My first impression of Effective Java is that the recommended patterns are useful for both Java and Kotlin. Some examples: • public static factory methods or builders with private constructors (chapters 1-4) • design for inheritance across package boundaries or, more commonly, prohibit it (chapters 18-19) • prefer interfaces to abstract classes (chapter 20) RE (4), My first impression of Atomic Kotlin is that it's more of a resource for learning syntax (e.g. how to create an abstract class), and less of a resource for learning effective+safe type (e.g. prefer interfaces to abstract classes) Are my first impressions of (2), (3), and (4) way off? Or are they generally consistent with the ways y'all use these learning resources?

Kotlin in Action is also a good book, deeply about language, but also not about practices like interfaces vs abstract classes, though it really need second edition with all new Kotlin features