Talking Kotlin

Sebastian and Márton talk to Vadim Briliantov, the Technical Lead for Koog: an agentic framework built by JetBrains. We learn about what AI agents are, and why building them in Kotlin with Koog is a great choice. We also discuss all the different ways AI agents can connect to other systems and your existing code, and look at advanced features for agents like custom strategies, model switching, and history compression.Resources: JetBrains/koog on GitHub Koog DocumentationHosts: Sebastian Aigner – Website | Bluesky Márton Braun – Website | Bluesky Guest: Vadim Briliantov – LinkedIn | Medium | GitHub | Bluesky | Twitter/X Timeline:(0:00) Intro(1:11) Vadim’s history at JetBrains(4:21) What’s an AI Agent?(5:47) Koog!(7:12) Applications for agents(12:43) Koog’s building blocks(15:05) Strategies, feedback loops(23:55) The Kotlin DSL(26:12) Persistent state(29:48) Subgraphs(32:33) Tools(39:52) MCP support (and A2A)(44:01) Entry point and type safety(49:39) Spring and Ktor support(51:27) LLM Providers(53:30) Model switching(56:02) History and memory(59:22) Enterprise-ready(1:02:12) History compression(1:11:47) Markdown?!(1:14:37) What’s next?(1:18:22) Going open-source(1:20:32) Conclusion

Sebastian and Márton chat with Marcin Moskała about coroutines.Resources: Coroutines Mastery course Coroutines | Kotlin Documentation kotlinx.coroutines Taming Asynchronous Beasts | Marcin Moskała Coroutine Debugging in IntelliJ IDEA | Alexey Merkulov Lifecycles, Coroutines and Scopes | Alejandro Serrano Mena Collect Like a Pro | Manuel Vivo Untangling Coroutine Testing | Márton Braun JetBrains/lincheck – Concurrent testing framework #talking-kotlin on Kotlin SlackHosts: Sebastian Aigner – Website | Bluesky Márton Braun – Website | Bluesky Guest: Marcin Moskała – kt.academy Timeline:(0:00) Introduction(1:18) Branding discussion(3:23) Handling preconceptions(4:54) What are coroutines?(7:17) Lightweight threads?(11:07) Where coroutines live(13:27) Sequence Builder Example(17:37) The design of coroutines(20:52) What Makes Coroutines special vs other languages?(26:56) Coroutines vs Loom(34:55) Easy to start, hard to master(41:07) Common mistakes(49:33) Flows(58:52) Thinking about Flows(1:02:41) Derailing the conversation(1:03:55) Flows for single values(1:12:27) Structured concurrency(1:18:53) The 4 advantages(1:24:40) Seb tries web dev / The web is broken?!(1:31:15) collectAsStateWithLifecycle(1:32:00) Gardening break(1:36:23) Scopes and contexts(1:43:22) Testing coroutines(1:50:29) Lincheck(1:51:32) Turbine(1:55:05) Coroutines Mastery course(2:01:43) Wrap-up

Sebastian and Alex chat about the kotlinx.rpc project, in a special episode recorded in the Munich JetBrains office. They explore all the different components of the library, how you can use it to define RPC services and clients, integrate with Ktor and existing gRPC definitions, and more. While the library is still experimental, it’s already feature-packed, and it has ambitious plans for the future!kotlinx-rpc on GitHub#kotlinx-rpc on Slackkotlinx.serialization on GitHub gRPC Host: Sebastian AignerWebsiteBlueskyGuest: Alex SysoevLinkedInGitHub

Sebastian and Márton are joined by Denis Borisevich from RIEDEL Communications, and learn about how Kotlin is used behind-the-scenes to power media, sports, and entertainment broadcasts watched by millions around the globe. Tune in for an exciting story about how Kotlin, Ktor, and Arrow are being used in production for a use case where robust software is mission-critical.Resources: Riedel Communications TornadoFX Unsigned integer types Arrow Ktor EurovisionHosts: Sebastian Aigner – Website | Bluesky Márton Braun – Website | Bluesky Guest: Denis Borisevich – LinkedIn Timeline:(0:00) Introductions(2:42) Events powered by Riedel(3:50) The Kotlin part(6:44) Routing video signals(9:12) Error handling in milliseconds(10:31) The Kotlin part, continued(13:29) TornadoFX!(19:19) On introducing Compose(23:30) Java to Kotlin migration(26:30) Learning Kotlin after C++(28:44) Unsigned ints in Kotlin(32:09) Arrow!(33:00) Server-side Kotlin(36:25) Functional programming(42:10) Why Kotlin over others?(45:55) Kotlin/Java interop(47:12) A 2-week long test suite(51:35) Confidence in Kotlin(53:05) Future plans(56:00) Wrap-up

Sebastian and Márton chat with Rod Johnson, the creator of the Spring Framework. Rod tells the story of how Spring was born more than two decades ago, and shares his recent journey of coming back to the JVM and discovering all the fun of being a newcomer to Kotlin.Resources: Expert One-on-One J2EE Design and Development: Rod Johnson Oh the Places You'll Go! Shoulders of Giants: Languages Kotlin Learned From | Andrey Breslav Revamping and Extending Kotlin's Type System | Ross Tate Scala in 2018 Keynote | Rod Johnson But Java has pattern matching! | Alejandro Serrano MenaHosts: Sebastian Aigner – Website | Bluesky Márton Braun – Website | Bluesky Guest: Rod Johnson – Twitter | LinkedIn Timeline:(0:00) Intro(0:52) The origins of Spring(6:40) You need a business model(8:21) Consistency is key(9:39) Sustainable open source(14:22) Parallels with JetBrains and Kotlin(15:29) Rod’s journey around the JVM(20:48) Shoulders of giants(22:34) The newcomer experience(24:40) LLMs write great Kotlin(30:34) “You can start without great pain”(33:32) Extension functions(36:15) Too much magic?(37:56) Rod’s feature wishlist(39:37) Versioning and compatibility(41:19) Ecosystems and interop(43:34) Kotlin type system evolution(46:27) Kotlin with Spring(52:24) Learning Spring with Kotlin(54:46) Kotlin in 5 years?(1:00:39) Rod’s current work(1:03:58) Wrap-up

Sebastian and Márton discuss building KMP libraries with Jay Shortway, the author of RevenueCat’s Kotlin Multiplatform SDK for in-app purchases.Resources: RevenueCat KMP SDK How we built the RevenueCat SDK for Kotlin Multiplatform Hybrid SDK Architecture at RevenueCat ttypic/swift-klib-plugin on GitHub RevenueCat/purchases-kmp on GitHub Consider moving `Instant` and `Clock` to the standard library · Kotlin/kotlinx-datetime RevenueCat openingsHosts: Sebastian Aigner – Website | Bluesky Márton Braun – Website | Bluesky Guest: Joop Korteweg – Twitter Timeline:(0:00) Intro(0:44) What’s RevenueCat(4:00) In-app purchases are hard(7:22) The multiplatform SDK(12:44) The demand for KMP(16:30) Hiring and team structure(18:42) SDKs for any framework(21:27) Building on native SDKs(23:45) Improving iOS linking(24:54) The SDK is on GitHub(26:05) Benefits of building on native(28:18) Designing a common API(33:21) Add-on modules for SDKs(37:30) Instant in the standard library(38:04) Returning results from the API(39:53) API design decisions(44:57) Codegen opportunities(45:48) The best things about KMP(47:07) KMP improvements wishlist(48:28) The KMP journey(49:45) Wrap-up

Sebastian and Pamela discuss what it means to be an expert in Kotlin Multiplatform, with the help of a panel of experts! Learn about why it's interesting to dive deep into a certain technology, recommendations on how to learn advanced topics, and general advice on how to get the most out of using KMP.SKIEKMP libraries: whyoleg/cryptography-kotlinInteresting code to explore: JetBrains/kotlin Kotlin/kotlinx-datetime Kotlin/kotlinx-io Kotlin/kotlinx.coroutines Cartesian product by Jake Get an invite!Ecosystem wishlist: wasmJs support in SQLDelight Compose Multiplatform support in MapLibreLearning resources: Kotlin Multiplatform build setup from scratch with Sebastian Sellmair KEEP - Kotlin Evolution and Enhancement Process HexFormat proposal and discussion Uuid proposal and discussionMore KMP experts: Kevin Galligan Bluesky Twitter Russell Wolf GitHub Twitter multiplatform-settings Jesse Wilson GitHub Sebastian Sellmair Twitter Salomon Brys TwitterHosts: Sebastian Aigner Website Pamela Hill Blog BlueskyGuests: Jake Wharton Website John O'Reilly Website KMP samples on GitHub Konstantin Tskhovrebov Mastodon Tadeas Kriz Mastodon Bluesky(0:00) Introductions(1:40) Why be a KMP expert?(9:14) First steps to being an expert(16:38) Respecting each platform(24:04) Libraries for KMP(27:45) Advanced learning resources(38:18) Ecosystem wishlist(43:03) Exercising your KMP skills(48:15) Shoutouts to other experts(51:34) Wrap-up

In a slightly unconventional episode, Sebastian and Márton talk to the founders of Skip, an iOS-to-Android, Swift-to-Kotlin transpiler solution. Marc and Abe have a background working on both Apple platforms and the JVM, and their latest project is a bridge across these two ecosystems. Skip Skip.tools on GitHub Contributing to SkipUI webinar kdoctor Hosts: Sebastian Aigner Website Bluesky Márton Braun Website Bluesky Guests: Abe White Twitter Mastodon Marc Prud'hommeaux GitHub (0:00) Weather (2:02) Introductions (3:10) ⁠Elevator pitch⁠ (3:45) The initial idea(6:14) Pivot around the server-side (8:35) Skip(.tools) (8:56) The target audience (9:58) What about Android devs? (12:11) The current state (14:57) Pricing and components (16:43) ⁠Contributing to SkipUI⁠ (18:55) Reimplementing everything (23:07) ⁠The Skip stack⁠ (26:17) Wrapping JVM types (28:27) Writing Kotlin in Swift?! (29:56) Tooling support (32:02) There’s a Gradle project! (34:39) iOS API coverage (38:24) Platform differences (40:10) Data storage (44:31) Building on JVM libraries (46:42) JSON problems (48:00) Testing the Skip stack (51:42) SwiftUI to Compose (58:21) IDE experiences (1:03:35) Conclusion 

Sebastian introduces the new co-host of the podcast, in a special episode recorded on location at droidcon New York! Joined by Russell Wolf, author of the multiplatform-settings library, we discuss the conference, different code sharing approaches for Kotlin Multiplatform, and how to build great multiplatform libraries. droidcon New York When sharing isn’t caring: Using platform-specific code in Kotlin Multiplatform (Russell’s talk) Compose Multiplatform on iOS: On the Road to Stable (Seb’s talk) Composing an API the *right* way (Márton’s talk) The deprecated Accompanist WebView implementation for Jetpack Compose russhwolf/multiplatform-settings on GitHub Kotlin Multiplatform database libraries Room SQLDelight Dependency injection libraries Koin Kotlin-inject ViewModel for Kotlin Multiplatform Hosts: Sebastian Aigner Website Márton Braun Website Guest: Russell Wolf GitHub Twitter Timestamps 0:00 Intro at home 2:02 Intro at droidcon NYC 4:23 Russell’s talk topic 8:14 Code sharing approaches 12:28 Wrapping native APIs 16:18 Attempted segue 16:35 Designing reusable APIs 18:02 Actual segue 18:14 multiplatform-settings 20:23 Supported platforms 24:05 SharedPreferences challenges 26:20 Observable preferences 29:51 Secure storage 30:55 Windows again 31:36 Library code as reference 33:15 Testable library code 35:05 Initializing a KMP library 38:18 Database libraries 40:55 Dependency injection 44:40 Outro

In this episode, we talk about the future of Kotlin and its development after the 2.0 version.