Matej Cerny
@matejcerny.bsky.social
Scala & Functional Programming Engineer. Database/SQL Veteran.
Testing in Zed is finally seamless with the newest version of the Scala plugin! 🎉
Basic tasks and test buttons now work straight out of the box. No setup required.
Watch it in action 👇 #scala
Basic tasks and test buttons now work straight out of the box. No setup required.
Watch it in action 👇 #scala
February 2, 2026 at 7:09 AM
Testing in Zed is finally seamless with the newest version of the Scala plugin! 🎉
Basic tasks and test buttons now work straight out of the box. No setup required.
Watch it in action 👇 #scala
Basic tasks and test buttons now work straight out of the box. No setup required.
Watch it in action 👇 #scala
Good engineering teams own their mistakes.
What went wrong with the initial release of Scala 3.8 and how the compiler team fixed it in such a short time?
Detailed breakdown 👇 #scala
www.scala-lang.org/blog/post-mo...
What went wrong with the initial release of Scala 3.8 and how the compiler team fixed it in such a short time?
Detailed breakdown 👇 #scala
www.scala-lang.org/blog/post-mo...
Postmortem of scala/scala3#24994 | The Scala Programming Language
www.scala-lang.org
January 30, 2026 at 7:42 PM
Good engineering teams own their mistakes.
What went wrong with the initial release of Scala 3.8 and how the compiler team fixed it in such a short time?
Detailed breakdown 👇 #scala
www.scala-lang.org/blog/post-mo...
What went wrong with the initial release of Scala 3.8 and how the compiler team fixed it in such a short time?
Detailed breakdown 👇 #scala
www.scala-lang.org/blog/post-mo...
Scala tooling has definitely rough edges, but name me a single ecosystem where the dependency bot can seamlessly update your dependencies, rewrite the codebase to match the newer API, and send a green PR?
I'm talking about Scala Steward + Scalafix rules, of course. 🚀 #scala
I'm talking about Scala Steward + Scalafix rules, of course. 🚀 #scala
January 28, 2026 at 9:35 AM
Scala tooling has definitely rough edges, but name me a single ecosystem where the dependency bot can seamlessly update your dependencies, rewrite the codebase to match the newer API, and send a green PR?
I'm talking about Scala Steward + Scalafix rules, of course. 🚀 #scala
I'm talking about Scala Steward + Scalafix rules, of course. 🚀 #scala
Big shoutout to the German tax payers for funding the future of Scala! 🇩🇪💸
The budget won't only go to the Standard Library, but will also impact the tooling we use daily:
📊 scoverage
⚙️ sbt 2.0
Danke schön!
www.scala-lang.org/blog/2026/01... #scala
The budget won't only go to the Standard Library, but will also impact the tooling we use daily:
📊 scoverage
⚙️ sbt 2.0
Danke schön!
www.scala-lang.org/blog/2026/01... #scala
The Sovereign Tech Fund invests in Scala | The Scala Programming Language
www.scala-lang.org
January 27, 2026 at 4:22 PM
Big shoutout to the German tax payers for funding the future of Scala! 🇩🇪💸
The budget won't only go to the Standard Library, but will also impact the tooling we use daily:
📊 scoverage
⚙️ sbt 2.0
Danke schön!
www.scala-lang.org/blog/2026/01... #scala
The budget won't only go to the Standard Library, but will also impact the tooling we use daily:
📊 scoverage
⚙️ sbt 2.0
Danke schön!
www.scala-lang.org/blog/2026/01... #scala
"Scala.js doesn’t need to compete with TypeScript and React for customer-facing products. There is a much better and more realistic opportunity: internal tools."
I completely agree. The sweet spot for Scala.js isn't the landing page. It's the Admin Panel. 🎯 #scala
I completely agree. The sweet spot for Scala.js isn't the landing page. It's the Admin Panel. 🎯 #scala
January 27, 2026 at 9:06 AM
"Scala.js doesn’t need to compete with TypeScript and React for customer-facing products. There is a much better and more realistic opportunity: internal tools."
I completely agree. The sweet spot for Scala.js isn't the landing page. It's the Admin Panel. 🎯 #scala
I completely agree. The sweet spot for Scala.js isn't the landing page. It's the Admin Panel. 🎯 #scala
💡 I finally installed zoxide last week. If you haven't, do it now!
It's a smarter cd command that learns your habits. No AI involved, just good old-fashioned statistics.
Go watch this video, I promise you'll love it! ❤️
youtu.be/aghxkpyRVDY
It's a smarter cd command that learns your habits. No AI involved, just good old-fashioned statistics.
Go watch this video, I promise you'll love it! ❤️
youtu.be/aghxkpyRVDY
zoxide has forever improved the way I navigate in the terminal.
youtu.be
January 26, 2026 at 7:44 AM
💡 I finally installed zoxide last week. If you haven't, do it now!
It's a smarter cd command that learns your habits. No AI involved, just good old-fashioned statistics.
Go watch this video, I promise you'll love it! ❤️
youtu.be/aghxkpyRVDY
It's a smarter cd command that learns your habits. No AI involved, just good old-fashioned statistics.
Go watch this video, I promise you'll love it! ❤️
youtu.be/aghxkpyRVDY
Prague friends! 🇨🇿 The next Functional JVM meetup is happening on Feb 9th at Adastra.
The topic is spicy, they are pitching it as "modern abstractions" that aren't just a copy of Haskell 😼
🏖️ I’ll be enjoying some time off so I can't make it.
Register here: www.meetup.com/functional-j...
#Scala
The topic is spicy, they are pitching it as "modern abstractions" that aren't just a copy of Haskell 😼
🏖️ I’ll be enjoying some time off so I can't make it.
Register here: www.meetup.com/functional-j...
#Scala
Fun JVM: Modern abstractions for FP with ZIO Prelude + other Scala/Clojure talks, Mon, Feb 9, 2026, 6:30 PM | Meetup
**NOTE: we had to change to the 9th from the originally advertised 2nd.**
*We'll meet at Adastra office, Mississippi House at Karlín. We'll gather at the ground floor at t
www.meetup.com
January 25, 2026 at 6:03 PM
Prague friends! 🇨🇿 The next Functional JVM meetup is happening on Feb 9th at Adastra.
The topic is spicy, they are pitching it as "modern abstractions" that aren't just a copy of Haskell 😼
🏖️ I’ll be enjoying some time off so I can't make it.
Register here: www.meetup.com/functional-j...
#Scala
The topic is spicy, they are pitching it as "modern abstractions" that aren't just a copy of Haskell 😼
🏖️ I’ll be enjoying some time off so I can't make it.
Register here: www.meetup.com/functional-j...
#Scala
This video should have been called "The most complicated implementation of a Counter". I'm leaving with more questions than answers 😀 #scala youtu.be/cTKWpYMciV8
Scoped Error Capabilities in cats-mtl
youtu.be
January 25, 2026 at 12:17 AM
This video should have been called "The most complicated implementation of a Counter". I'm leaving with more questions than answers 😀 #scala youtu.be/cTKWpYMciV8
The newest release of Metals is one step closer to feature parity with IntelliJ! 🎉
Version 1.6.5 can now suggest methods from implicit classes that are not yet imported. This is a long-awaited feature! #scala
Version 1.6.5 can now suggest methods from implicit classes that are not yet imported. This is a long-awaited feature! #scala
January 23, 2026 at 9:34 PM
The newest release of Metals is one step closer to feature parity with IntelliJ! 🎉
Version 1.6.5 can now suggest methods from implicit classes that are not yet imported. This is a long-awaited feature! #scala
Version 1.6.5 can now suggest methods from implicit classes that are not yet imported. This is a long-awaited feature! #scala
I just tried Slack AI, and it’s arguably the best use case for LLMs I’ve seen in a SaaS product.
Look at this summary: 👇
Does MS Teams have the same feature?
Look at this summary: 👇
Does MS Teams have the same feature?
January 23, 2026 at 7:37 AM
I just tried Slack AI, and it’s arguably the best use case for LLMs I’ve seen in a SaaS product.
Look at this summary: 👇
Does MS Teams have the same feature?
Look at this summary: 👇
Does MS Teams have the same feature?
Hey, Scala early adopters! 🚀 Version 3.8.1 is technically out, but let's wait until everything is officially settled and announced, okay? The upgrade is huge, so it's completely understandable that there might be some minor linkage problems. 🛠️ #scala
January 22, 2026 at 10:45 AM
Hey, Scala early adopters! 🚀 Version 3.8.1 is technically out, but let's wait until everything is officially settled and announced, okay? The upgrade is huge, so it's completely understandable that there might be some minor linkage problems. 🛠️ #scala
I realized today while watching my son 🧒 try to get dressed:
The peak of humanoid robotics isn't doing a backflip or writing code.
It’s the ability to successfully put on a t-shirt and shoes 👕👟
The peak of humanoid robotics isn't doing a backflip or writing code.
It’s the ability to successfully put on a t-shirt and shoes 👕👟
January 21, 2026 at 8:14 PM
I realized today while watching my son 🧒 try to get dressed:
The peak of humanoid robotics isn't doing a backflip or writing code.
It’s the ability to successfully put on a t-shirt and shoes 👕👟
The peak of humanoid robotics isn't doing a backflip or writing code.
It’s the ability to successfully put on a t-shirt and shoes 👕👟
🚨 Scala 3.8 deprecates `-Xfatal-warnings` in favor of `-Werror`.
Be aware if you rely on `sbt-tpolecat` or `typelevel/scalac-options`, as they need to update their default flag sets.🚩
The fix is already in progress 👇
github.com/typelevel/sc... #scala
Be aware if you rely on `sbt-tpolecat` or `typelevel/scalac-options`, as they need to update their default flag sets.🚩
The fix is already in progress 👇
github.com/typelevel/sc... #scala
Deprecate -Xfatal-warnings option for Scala 3.8+ by EnviousSwan · Pull Request #225 · typelevel/scalac-options · GitHub
Closes #219
Getting this error with Scala 3.8.0 and sbt-tpolecat 0.5.2
[warn] Option -Xfatal-warnings is a deprecated alias: use -Werror instead
[error] No warnings can be incurred under -Werror
github.com
January 21, 2026 at 4:52 PM
🚨 Scala 3.8 deprecates `-Xfatal-warnings` in favor of `-Werror`.
Be aware if you rely on `sbt-tpolecat` or `typelevel/scalac-options`, as they need to update their default flag sets.🚩
The fix is already in progress 👇
github.com/typelevel/sc... #scala
Be aware if you rely on `sbt-tpolecat` or `typelevel/scalac-options`, as they need to update their default flag sets.🚩
The fix is already in progress 👇
github.com/typelevel/sc... #scala
The first thing that hits you when starting with Go:
"Wait, how do I implement this interface?"
Well, you can't. Not explicitly. Go's philosophy is: If you walk like a Duck and quack like a Duck, the compiler just assumes you are a Duck. 🦆 #golang
"Wait, how do I implement this interface?"
Well, you can't. Not explicitly. Go's philosophy is: If you walk like a Duck and quack like a Duck, the compiler just assumes you are a Duck. 🦆 #golang
January 20, 2026 at 12:20 PM
The first thing that hits you when starting with Go:
"Wait, how do I implement this interface?"
Well, you can't. Not explicitly. Go's philosophy is: If you walk like a Duck and quack like a Duck, the compiler just assumes you are a Duck. 🦆 #golang
"Wait, how do I implement this interface?"
Well, you can't. Not explicitly. Go's philosophy is: If you walk like a Duck and quack like a Duck, the compiler just assumes you are a Duck. 🦆 #golang
Java doesn't support Higher Kinded Types.
But with enough determination, boilerplate and type gymnastics, you can technically emulate them. 🤸♂️
#Java #Scala
blog.scottlogic.com/2025/04/11/h...
But with enough determination, boilerplate and type gymnastics, you can technically emulate them. 🤸♂️
#Java #Scala
blog.scottlogic.com/2025/04/11/h...
Higher Kinded Types with Java and Scala
In this post we will see how Higher Kinded Types types can help increase the flexibility of our code and reduce duplication.
blog.scottlogic.com
January 20, 2026 at 8:42 AM
Java doesn't support Higher Kinded Types.
But with enough determination, boilerplate and type gymnastics, you can technically emulate them. 🤸♂️
#Java #Scala
blog.scottlogic.com/2025/04/11/h...
But with enough determination, boilerplate and type gymnastics, you can technically emulate them. 🤸♂️
#Java #Scala
blog.scottlogic.com/2025/04/11/h...
Arguably the best resource for learning how to structure production-grade applications with Cats Effect and Fs2 is now completely free! 📖 Huge contribution to the community by @gvolpe.com 🙌 #Scala
leanpub.com/pfp-scala
leanpub.com/pfp-scala
Practical FP in Scala
The missing guide to designing and writing a purely functional application in Scala using the best libraries available in the Typelevel Cats ecosystem.
leanpub.com
January 17, 2026 at 7:24 AM
Arguably the best resource for learning how to structure production-grade applications with Cats Effect and Fs2 is now completely free! 📖 Huge contribution to the community by @gvolpe.com 🙌 #Scala
leanpub.com/pfp-scala
leanpub.com/pfp-scala
This feature in Scala 3.8 is so experimental that it doesn't even have a SIP yet! 😀 I hope I don't need to explain the code, but be warned: exhaustivity checking is currently broken for this 👇 #Scala
January 16, 2026 at 9:14 AM
This feature in Scala 3.8 is so experimental that it doesn't even have a SIP yet! 😀 I hope I don't need to explain the code, but be warned: exhaustivity checking is currently broken for this 👇 #Scala
Next on the list of Scala 3.8 experimental features: Flexible Varargs. Until now, passing multiple collections to a varargs method required manual concatenation. With this change, you can mix multiple splices and single arguments freely ✨#scala
January 12, 2026 at 3:16 PM
Next on the list of Scala 3.8 experimental features: Flexible Varargs. Until now, passing multiple collections to a varargs method required manual concatenation. With this change, you can mix multiple splices and single arguments freely ✨#scala
How to access method default parameters via macro? 🧐
Pretty niche topic, but after reading you will learn:
✅ How some JVM internals work
✅ What the Selectable trait is
✅ About the transparent keyword
halotukozak.github.io/posts/scala-...
Pretty niche topic, but after reading you will learn:
✅ How some JVM internals work
✅ What the Selectable trait is
✅ About the transparent keyword
halotukozak.github.io/posts/scala-...
January 12, 2026 at 8:36 AM
How to access method default parameters via macro? 🧐
Pretty niche topic, but after reading you will learn:
✅ How some JVM internals work
✅ What the Selectable trait is
✅ About the transparent keyword
halotukozak.github.io/posts/scala-...
Pretty niche topic, but after reading you will learn:
✅ How some JVM internals work
✅ What the Selectable trait is
✅ About the transparent keyword
halotukozak.github.io/posts/scala-...
Scala 3.8 will bring several experimental features. One of them is the relaxed lambda syntax, where you don't need to put a newline after the colon. Haters of the braceless syntax will hate it even more! 😀 #scala
January 8, 2026 at 5:00 PM
Scala 3.8 will bring several experimental features. One of them is the relaxed lambda syntax, where you don't need to put a newline after the colon. Haters of the braceless syntax will hate it even more! 😀 #scala