Alejandro Serrano Mena

Lambda World, there we go! Two days of fun fun functional programming 🤖 and the sun of Andalucía ☀️

It's that time of year again! Tell me what your biggest problems are with adopting Kotlin Multiplatform or building KMP apps in the replies. Is it something with Compose? Is it the build system? Something around iOS? I'm all ears.

Arrow 2.3.0 is out! arrow-kt.io/community/bl... Highlights: 🔮 Arrow Optics is now a compiler plugin, giving us better integration and IDE support ⛓️ Non-empty collection literals 🪂 Improvements in SuspendApp

Want to see KotlinConf 2027 from the inside? Join the volunteer team for a backstage pass (well, a volunteer badge). Meet fellow Kotlin fans, catch great talks, and help bring the conference to life. The call for volunteers is open! Apply here: https://kotl.in/8b9tdz

In a few weeks I’ll be taking about Kotlin contracts in Amsterdam www.meetup.com/dutch-kotlin...

We're looking for amazing talks to put into the KotlinConf 2027 agenda, with submissions open until Nov 27! You can find more info, plenty of inspiration, and everything else you need to submit a talk on the Speakers page:

We have some really cool improvements coming up for companions in Kotlin 2.5. Get a sneak peak from Alejandro's blog post now:

Kotlin’s companions are getting an upgrade. 👀 Kotlin 2.5.0 introduces experimental companion blocks – a lightweight alternative to companion objects. Learn what they unlock and how to enable them 👇 https://kotl.in/aby7vp

Companion Blocks & Extensions are ready for testing in Kotlin 2.5.0-Beta1. I've spent a good chunk of the last months working on this feature, so I'm very excited for the experimental release. blog.jetbrains.com/kotlin/2026/...

In case it's not clear from the example, this plug-in has 100% arisen from me getting tired of writing `.build()` when using Spring AI.

“Companion extensions and blocks” 🔥 This is a feature many of us have been waiting a long time for! Maybe years before I even knew this is what I wanted 😄

It's out! Learn more about Name-Based Destructuring in Kotlin. I promise not to make you sing. www.youtube.com/watch?v=He8J...

📢 Kotlin devs, we want to hear from you! We're running a survey to understand your day-to-day challenges and experiences with Kotlin – whether it's the language, the tools, or the IDEs. It only takes 15 minutes! Share your thoughts with us here: https://kotl.in/hajfxg

📍 The Kotlin roadmap has been updated! The four directions we're focused on: ✨ Language evolution 📱 Kotlin Multiplatform 🧩 Staying agnostic 📦 The experience of third-party ecosystem authors See what's behind each one 👇 https://kotl.in/rv5too

🔥 The Kotlin community is already planning the next reunion! 📍 Kraków, Poland 📅 April 21-23 KotlinConf 2027 Super Early Bird tickets are now on sale – it’s the lowest price for the biggest Kotlin event of the year. 🎟️ Get yours today! kotl.in/conf27-seb-x

The 2026 Kotlin Developer Survey is live! Use this chance to send feedback directly to the team, on everything Kotlin-related 👇

📢 Kotlin 2.4.20 is out! Learn more: ➡️ kotl.in/2-4-20

Kotlin Toolchain 0.12 was just released! It includes... 📚 KMP library publication (!) 🌐 Wasm app support 🖼️ Compose Preview support + more Android tooling 🔥 Better Compose Hot Reload 🍎 iOS improvements ... and much more! Learn about the rest here:

🎉 Good news: You have more time to learn Kotlin! Free access to select Kotlin courses on Hyperskill has been extended until October 9. Learn through hands-on projects, whether you're just getting started with Kotlin or looking to level up your skills. Explore the courses 👇 https://kotl.in/a1ityw

lnkd.in/p/eXjmAb5c Tickets to this ridiculously good ROI workshop are still available, albeit in short supply. Visit ktconf.be to get yours, for Amanda’s workshop on the 17th of September in Leuven. #kotlin #coroutines

⚠️ A function signs a document. What could go wrong? The function signature won’t give you any ideas. Sergey Chernov from Salmon shows how sealed error types keep expected failures in the function contract. Read the full post 👇 https://kotl.in/5wawvp

Here's a great video from Dave, with an overview of some exciting still-experimental Kotlin language features:

My latest video for the Kotlin channel is out! There are some nice juicy features in this release - check it out! www.youtube.com/watch?v=RI4J...

Check out @pamelaahill.bsky.social's video on #Kotlin 2.4! She covers so many topics. My favourites: - Context parameters & explicit context arguments - Collection literals - Compile-time constants - Uuid - New Map functions - Swift import & Concurrency Blog: kotlinlang.org/docs/whatsne...

Have you caught up with everything that's new in Kotlin 2.4 yet? Collection literals, new standard library functions, multiplatform improvements, and more! All detailed in the video 👇

My "Context parameters and API design" talk at @kotlinconf.com is now available www.youtube.com/watch?v=O1nT...

Let me share the '.kar' (Kotlin Archive) file format 🙇‍♂️! A single binary you can publish, which shall carry everything necessary to build your project! While this is a prototype, I really would like to share some of our early measurements! 🥳

Who here is using agents extensively with #Kotlin/Java and #Gradle? Have you ever seen agents `unzip jar`, or parse `build/reports/test`? Or any other silly things? I've been trying to streamline these scenarios to make working with agents more efficient. Check it out. github.com/nomisRev/age...

Haskell Wizard by Alejandro Serrano Mena is the featured bundle of ebooks 📚 on Leanpub! Become a real Haskell wizard with these two books! On the one hand, get your hands dirty with every major library in the ecosystem. On the other hand, climb the ivory … leanpub.com/b/haskell-wi...

⏰ Just two weeks left! Apply by July 14 for a 2026 Kotlin Foundation Grant for Library Authors. Building an open-source Kotlin library, tool, or framework? Your project could receive funding – especially if it advances Multiplatform, AI, or LLM development. Apply now 👇 https://kotl.in/muii75

We've been looking forward to this one! Kotlin 2.4 introduces collection literals. Create lists as easy as `val x = [1, 2, 3]`. They can even be combined with name-based destructuring for a neat effect. Today's 6-minute video is all about 'em: www.youtube.com/watch?v=cXg4... #Kotlin #AndroidDev

🎉 Kotlin turns 15 this year! 🎉  As part of the celebration, we've brought the Kotlin Effect into real life – making everyday situations more concise, efficient, and fun. Explore the Kotlin Effect further: kotl.in/6xzc69

It must be... the Kotlin Effect. www.youtube.com/watch?v=4Qey...

Kotlin 2.4.0 ships with a HUGE power-assert update I've been slowly working on for *years*. It's the culmination of efforts I started before joining JetBrains. It's subtle from the user's perspective, but it helped fixed a bunch of problems and unblocks tons of future improvements! 🚀

Arrow 2.2.3 is out! arrow-kt.io/community/bl...

Today I’m speaking at J-Spring about Kotlin! @nljug.bsky.social

📢 Kotlin 2.4.0 is out! Learn more: ➡️ kotl.in/2-4-0

Ever upgraded Kotlin? We’d love your feedback! Tell us about your experience with Kotlin releases, including EAPs, stable versions, and patches! ⏱️ It takes just 12 minutes. Share your thoughts with us here: https://surveys.jetbrains.com/s3/Kotlin-release-1

Kotlin is moving toward name-based destructuring – new syntax that will make reordering and moving properties a breeze. No worries: There will be a long migration period with compiler and IDE support. Learn what’s changing and how the migration will work 👇 https://kotl.in/8nny1l