Moving full steam towards Kotlin 1.3, we’re happy to announce the second milestone release, Kotlin 1.3-M2, which unveils new features and improves the stability of those already announced. Some highlights: Contracts improve smart-casts and other compile-time analyses New Standard Library functions for unsigned types and collections Reflection for coroutines A migration layer to aid migration onto new coroutines being graduated in 1.3 Numerous bugfixes related to inline classes (more…)

Today, after a long chain of incremental 1.2.X updates, it's time to see what's coming in Kotlin 1.3. We are happy to announce the first preview version of the new major release: Kotlin 1.3-M1. Kotlin 1.3 brings many advancements including graduation of coroutines, new experimental unsigned arithmetic, and much more. Please read on for the details. (more…)

We're excited to announce the start of the early access program for Kotlin 1.2: today its first milestone release 1.2-M1 is out. This release enables by default new language features that were previously available in 1.1.x releases under experimental 1.2 language version setting. Also in the standard library you can preview the new API. The complete though not so big list of changes in this release can be found in the changelog. (more…)

Java 9 preparations Java 9 is coming and brings Project Jigsaw to the table — the Java platform module system. One of the constraints it imposes is that no two modules can declare public API in the same package. The situation, when there are two modules that contribute to the same package, is called “split” package. We face this issue with split packages in our runtime artifacts: first, kotlin-runtime and kotlin-stdlib modules share a lot of kotlin.* packages, second, kotlin-runtime and kotlin-reflect share kotlin.reflect package. What we're going to do to make our artifacts more friendly to

Standard Library continues its evolution: Lazy<T> type has been introduced More concise syntax for storing properties in a Map Final changes in the Char arithmetics Plus and minus operations on a collection now depend on its type New scope functions: apply and run Right-open ranges Trimming indents in multiline strings literals and more Read details

Kotlin is undergoing finalization, and as part of the process we are cleaning up: revising the language and its libraries. The biggest changes have been made in M12, but some more are coming. The point is to perform all the necessary breaking changes before we release 1.0, so that we can keep the language and libraries backwards-compatible after the release. The trick is both we, ourselves, and you, our users, have quite a bit of code written in Kotlin already, and we don't want all that code broken hopelessly on each update (some breakages are inevitable, unfortunately, but we are doing our