A programming language, like wood, has a ”grain”. In both programming and carpentry, when you work with the grain, things go smoothly; when you work against the grain, things are more difficult.

A language's grain forms as its designers and users learn how language features interact, and encode their understanding and preferences in libraries and tools. It changes over time, as new language features don’t just add to the language, they interact with existing features. The new features change the relative value of the old features.

Join Nat and Duncan, authors of Java to Kotlin: A Refactoring Guidebook, as they explore the grain of Kotlin, tracing its evolution from the first released version through to the present day. They will show how their coding style became outdated as the language changed, how they modernized it, and why it is important to refactor existing code to make the most of the changing grain.