Posts Tagged ‘K2Compiler’
[DevoxxUK2025] Kotlin: The New and Noteworthy
Anton Arhipov, a developer advocate from JetBrains, captivated the DevoxxUK2025 audience with an overview of Kotlin’s recent advancements and future roadmap. Focusing on Kotlin 2.0’s K2 compiler and upcoming features like guard conditions, context parameters, rich errors, and name-based destructuring, Anton highlighted how Kotlin balances conciseness, safety, and expressiveness. His interactive talk, enriched with personal anecdotes and live demos, underscored Kotlin’s evolution as a versatile, multi-platform language that empowers developers to write robust, readable code.
Kotlin 2.0 and the K2 Compiler
Anton introduced Kotlin 2.0, released nearly a year ago, emphasizing the K2 compiler’s new front-end intermediate representation (FIR) and control flow engine. K2 improved compilation performance by 40% in IntelliJ IDEA Ultimate, fixed numerous small bugs, and provided a scalable foundation for future features. By desugaring complex constructs (e.g., if to when expressions, for loops to iterators), K2 enhances smart casts and type inference, enabling seamless handling of nullable types and complex expressions without manual casting.
Guard Conditions for Safer Control Flow
Set to stabilize in Kotlin 2.2, guard conditions enhance when expressions by allowing conditional checks without variable binding. In a demo, Anton showed processing orders with guard conditions to handle subscriptions and discounts, reducing repetition and ensuring exhaustiveness. Unlike Java’s pattern matching, Kotlin leverages existing destructuring to avoid redundancy, with guard conditions adding logical safety by enforcing checks (e.g., amount > 100) directly in when branches, minimizing errors in complex control flows.
Name-Based Destructuring for Robustness
Anton discussed name-based destructuring, planned for experimental release in Kotlin 2.4. Unlike positional destructuring, which risks logical errors during refactoring, name-based destructuring matches variable names to class properties, improving readability and safety. This feature extends to non-data classes and sealed hierarchies, with plans to deprecate positional destructuring in future versions (e.g., Kotlin 3.0), ensuring long-term language consistency while maintaining backward compatibility.
Context Parameters for Scoped APIs
Context parameters, entering beta in Kotlin 2.2, enable scoped extension functions for type-safe builders, often mistaken for DSLs. Anton demonstrated a client-building DSL where an infix extension function for dates (e.g., 10 March 2000) was restricted to a specific context, preventing global namespace pollution. This feature supports library developers in creating intuitive APIs, such as dependency injection-like logger scoping, reducing boilerplate and enhancing code clarity without compromising safety.
Rich Errors for Expressive Error Handling
Planned for experimental release in Kotlin 2.4, rich errors (previously called union types for errors) introduce a new error class syntax to distinguish error types explicitly. In a demo, Anton showed how rich errors improve over null-based error handling in functions like fetchUser and parseUser, enabling clear differentiation between network and parsing errors. Using when expressions, developers gain exhaustiveness checks and readable error handling, avoiding the verbosity of sealed hierarchies or result types.
Enhancing Compiler Safety with Return Value Checks
Anton highlighted a Kotlin 2.2 feature that mandates checking return values for standard library functions, preventing logical errors like missing return statements or incorrect function calls (e.g., using sort instead of sorted). By marking core functions with annotations, the compiler issues warnings for unused return values, reducing bugs like those in a demo where sorting a mutable list failed due to an overlooked return. This opt-in feature will expand to application code, enhancing reliability.
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[KotlinConf2023] KotlinConf’23 Keynote: The Future of Kotlin is Bright and Multiplatform
KotlinConf’23 kicked off with an energizing keynote, marking a much-anticipated return to an in-person format in Amsterdam. Hosted by Hadi Hariri of JetBrains, the session brought together key figures from both JetBrains and Google, including Roman Elizarov, Svetlana Isakova, Egor Tolstoy, and Grace Kloba (VP Engineering for Android Developer Experience at Google), to share exciting updates and future directions for the Kotlin language and its ecosystem. The conference also featured a global reach with KotlinConf Global events in 41 countries. The main announcements from the keynote are also available in a blog post on the Kotlin blog.
The keynote celebrated Kotlin’s impressive growth, with statistics highlighting its widespread adoption, particularly in Android development where it’s the most popular language, used in over 95% of the top 1000 Android apps. A major focus was the upcoming Kotlin 2.0, centered around the new K2 compiler, which promises significant performance improvements, stability, and a foundation for future language evolution. The K2 compiler is nearing completion and is set to be released as Kotlin 2.0. The IntelliJ IDEA plugin will also adopt the K2 frontend, aligning with IntelliJ releases.
The Evolution of Kotlin: K2 Compiler and Language Features
The K2 compiler was a central theme of the keynote, marking a major milestone for Kotlin. This new compiler front-end, which also powers the IDE, is designed to be faster, more stable, and enable the development of new language features and tooling capabilities more rapidly. Kotlin 2.0, built on K2, is expected to bring these benefits to all Kotlin developers, enhancing both compiler performance and IDE responsiveness.
Looking beyond Kotlin 2.0, the speakers provided a glimpse into potential future language features that are under consideration. These included:
* Static Extensions: Allowing extension functions to be resolved statically, potentially improving performance and clarity.
* Collection Literals: Introducing a more concise syntax for creating collections, like using square brackets for lists, with efficient implementations.
* Name-Based Destructuring: Offering a more flexible way to destructure objects based on property names rather than just position.
* Context Receivers: A powerful feature for providing contextual information to functions in a more implicit and structured manner. This feature, however, is being approached carefully to ensure it aligns well with Kotlin’s principles.
* Explicit Fields: Providing more control over backing fields for properties.
The team emphasized a careful approach to evolving the language, ensuring new features are well-designed and maintainable. Compiler plugins were also highlighted as an avenue for extending Kotlin’s capabilities.
Kotlin in the Ecosystem: Google’s Investment and Multiplatform Growth
Grace Kloba from Google took the stage to reiterate Google’s strong commitment to Kotlin. She shared insights into Google’s investments in the Kotlin ecosystem, including the development of Kotlin Symbol Processing (KSP) and the continued focus on making Kotlin the default choice for Android development. Google officially supported Kotlin for Android development by early 2017. The Kotlin DSL is now the default for Gradle build scripts in Android Studio, enhancing developer experience with features like semantic highlighting and code completion. Google also actively contributes to the Kotlin Foundation and encourages the community to participate through programs like the Kotlin Foundation Grants Program, which focuses on supporting multiplatform libraries and frameworks.
Kotlin Multiplatform (KMP) was another major highlight, showcasing its growing maturity and adoption. The vision for KMP is to allow developers to share code across various platforms—Android, iOS, desktop, web, and server-side—while retaining the ability to write platform-specific code when needed. The keynote celebrated the increasing number of multiplatform libraries and tools, including KMM Bridge, that simplify KMP development. The future of KMP looks bright, with efforts to further improve the developer experience and expand its capabilities.
Compose Multiplatform and Emerging Technologies
The keynote also showcased the advancements in Compose Multiplatform, JetBrains’ declarative UI framework for building cross-platform user interfaces. A significant announcement was the alpha release of Compose Multiplatform for iOS, enabling developers to write their UI once in Kotlin and deploy it on both Android and iOS, and even desktop and web. This opens up new possibilities for code sharing and faster development cycles for mobile applications.
Finally, the team touched upon Kotlin’s expansion into emerging technologies like WebAssembly (Wasm). JetBrains is developing a new compiler backend for Kotlin targeting WebAssembly with its garbage collection proposal, aiming for high-performance Kotlin code in the browser. Experiments with running Compose applications in the browser using WebAssembly were also mentioned, hinting at a future where Kotlin could offer a unified development experience across an even wider range of platforms. The keynote concluded with an invitation for the community to dive deeper into these topics during the conference and to continue contributing to Kotlin’s vibrant ecosystem.