Kotlin 1.7.20 programming language brings open intervals and compiler plugins

Open at the top

With regard to the syntax, the release brings only one noteworthy addition: the operator ..< indicates an open-ended range. The values ​​in the interval are at least as large as the start and smaller than the end:

when (value) {
    in 0.0..<0.5 -> // offener Range: ohne 0.5
    in 0.5..1.0 ->  // geschlossener Range: mit 1.0
}

With the new operator, Kotlin’s standard library also receives an addition: the interface OpenEndRange<T> is also the counterpart to ClosedRange<T> how ..< the opposite of the closed one .. is.

Extensions for the compiler

The K2 compiler is one of the biggest innovations in Kotlin 1.7. However, it didn’t work with compiler plugins on the first serve. That changes in the current release, even if K2 still has alpha status. The compiler can initially use seven plugins, including the extension for Project Lombok.

Kotlin has been able to work with the Java library since version 1.5.20. Project Lombok takes care of generating boilerplate code at the bytecode level: through the annotation @Data Lombok creates getters and setters, among other things, under the hood. The compiler plugin does not replace the Lombok library, but takes care of the clean interaction when using the library for mixed Java and Kotlin code.

Other plugins for K2 include all-open an extension that allows Kotlin to interact with frameworks like Spring AOP (Aspect Oriented Programming) that require open classes. Because Kotlin’s classes and their methods by default final are, they require explicit markup as open. That all-openplugin annotates classes and their members as open, so no manual insertion of open is required.

Memory management for Kotlin/Native

Besides the compiler, Kotlin 1.7 replaced the memory manager for Kotlin/Native applications running without a JVM. In version 1.7.20 it is now enabled by default and transitioning from alpha to beta status. Among other things, it brings advantages for concurrent programming by removing restrictions on the sharing of objects between threads.

Most notably, the new storage manager aims to open the door to Kotlin Multiplatform Mobile, which is designed for cross-platform mobile development for Android and iOS. Kotlin uses the JVM on Google’s operating system, which is missing on iOS, which is why the applications are implemented in Kotlin/Native. With the connection to the new memory manager, Kotlin Multiplatform Mobile will soon receive beta status.