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Matej Cerny

@matejcerny

Scala & Functional Programming Engineer. Database/SQL Veteran.

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26.11.2024
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Latest posts by Matej Cerny @matejcerny

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Scala 3 compiler in the browser? No problem! (thanks for the tip @kozlowski)

Unfortunately, I don't have any background story about this project, so if you happen to have a link to the repo - please share! scalac.univalence.xyz #scala

12.03.2026 12:39 πŸ‘ 0 πŸ” 1 πŸ’¬ 0 πŸ“Œ 0
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Hardening Scoverage Support in Scala 3 | The Scala Programming Language We've enabled systematic coverage testing in the Scala 3 compiler's CI pipeline, uncovering and fixing latent bugs that blocked enterprise adoption.

Scoverage is one of the first plugins I add to any new project. The compiler team finally did the same and found some breakages - but they're already fixing them! πŸ‘ Hopeful that Scoverage in Scala 3 hits full parity with Scala 2 very soon.🀞 #scala scala-lang.org/blog/2026/03...

11.03.2026 14:32 πŸ‘ 0 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0
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pgmq4s/core/src/main/scala/pgmq4s/PgmqClient.scala at main Β· matejcerny/pgmq4s Β· GitHub Contribute to matejcerny/pgmq4s development by creating an account on GitHub.

Side note: The library is a Scala client for Postgres messaging. Here is the codebase πŸ‘‡
github.com/matejcerny/p...

10.03.2026 12:26 πŸ‘ 0 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0
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I'm trying to implement Noel Welsh's better encoding, but I'm not sure if it's suitable for such a small library. Also, I honestly don't think I fully understand it! πŸ˜€ I would appreciate any comments or feedback. πŸ™ #scala

10.03.2026 12:26 πŸ‘ 0 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0
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Pure functional HTTP APIs in Scala [Leanpub PDF/iPad/Kindle] A book about developing purely functional HTTP APIs with Scala using http4s, Doobie, Cats and other libraries including a chapter about upgrading to Scala 3.

http4s is a backbone for many mission-critical systems. I'm pleased to share that "Pure functional HTTP APIs in #Scala" by Jens Grassel is free once again, and this time it's for good! πŸ“–

It's a fantastic resource for anyone looking to build robust, battle-tested web backends.

leanpub.com/pfhais

09.03.2026 18:53 πŸ‘ 0 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0
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Boring Tech May Become Irrelevant Tech On programming and personal projects

What you really need is a language that catches the AI's mistakes. You need strong compilers and strict types (like #Rust or #Scala) to act as safety nets when the AI messes up.

This article changed my perspective πŸ‘‡

alexn.org/blog/2026/03...

09.03.2026 09:17 πŸ‘ 1 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0

I used to think LLMs would make #Python and other mainstream languages dominate forever. But if AI is writing the code, you don't need a language just because it's easy for beginners or hiring. You don't even need to fear refactoring anymore.

09.03.2026 09:17 πŸ‘ 0 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0
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Release v3.7.0 Β· typelevel/cats-effect This is the fifty-ninth release in the Cats Effect 3.x lineage. It is fully binary compatible with every 3.x release and fully source-compatible with the 3.7.x lineage. What's Changed This is a rel...

Cats Effect v3.7.0 is officially here! πŸŽ‰ We've been waiting since the RC dropped back in July 2025 and it finally brings what we wanted: support for Scala Native 0.5. πŸš€

What does that mean? Full multithreading on LLVM! ⚑️

#Scala

github.com/typelevel/ca...

08.03.2026 22:30 πŸ‘ 2 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0
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Typelevel Foundation is a 501(c)(3) public charity

typelevel.org/blog/charity...

07.03.2026 19:36 πŸ‘ 0 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0

In short:
βœ… Donations are now tax-deductible in the US & Europe
βœ… Zero tax paid on raised funds
βœ… Free tools (saving thousands on GitHub alone)
βœ… Access to major institutional grants

07.03.2026 19:33 πŸ‘ 0 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0

The @typelevel.org Foundation is officially a public charity! Why should we care about their tax status? πŸ€”

Because it means way more resources for functional programming and way less overhead! πŸ“‰ #scala

07.03.2026 19:33 πŸ‘ 1 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0
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GitHub - alexandru/skills Β· GitHub Contribute to alexandru/skills development by creating an account on GitHub.

Custom skills for Claude and Copilot put together by Alexandru Nedelcu. They explicitly teach the agent how to handle Cats Effect IO, MTL typed errors, and proper Resource lifecycles. πŸ‘‡ #scala github.com/alexandru/sk...

06.03.2026 09:49 πŸ‘ 2 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0
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GitHub - guizmaii-opensource/zio-spark: A functional wrapper around Spark to make it works with ZIO Β· GitHub A functional wrapper around Spark to make it works with ZIO - guizmaii-opensource/zio-spark

The milestone v1.0.0 release of the zio-spark wrapper has landed! πŸŽ‰ Featuring a major migration to Spark 4. github.com/guizmaii-ope... #scala

04.03.2026 15:05 πŸ‘ 1 πŸ” 1 πŸ’¬ 0 πŸ“Œ 0
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Elm Camp An Elm unconference taking place at Park Hotel PrachΓ‘rna, Olomouc, Czechia. Mon 15th - Thur 18th June

Hey FP enthusiasts, if you don't have plans for June 15–18, you have two options:

1️⃣ You can be my emotional support when my second son is born πŸ‘Ά, or
2️⃣ you can visit Elm Camp in one of the most beautiful cities in Czechia πŸ‡¨πŸ‡Ώ

elm.camp #elm

04.03.2026 06:20 πŸ‘ 0 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0
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Metals v1.6.6 - Osmium | Metals We're happy to announce the release of Metals v1.6.6, which brings a standalone

Check out the full release here: πŸ‘‡
scalameta.org/metals/blog/...

03.03.2026 19:34 πŸ‘ 0 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0

This release also brings some highly pragmatic quality-of-life updates:

βœ… Explain feature - access detailed errors on the fly without touching your build definition
βœ… Shut down Bloop directly - no more zombie processes
βœ… Twirl templates - proper support for the Play Framework

03.03.2026 19:34 πŸ‘ 0 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0

Metals just dropped the standalone MCP server! πŸš€

Not opening an editor is becoming a standard these days. If you live in the terminal, your DX just got significantly better! #scala

03.03.2026 19:34 πŸ‘ 0 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0
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I shared this awesome library called layoutz a few months back... The newest version just added Scala.js and Native support! πŸš€ #scala

03.03.2026 09:20 πŸ‘ 19 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0
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Migrating sbt plugins to sbt 2 with sbt2-compat plugin A case study of how sbt-assembly uses sbt2-compat to cross-build for sbt 1 and sbt 2, and a guide of how to use it for your own plugins.

πŸ’‘You can use this new sbt2-compat plugin to help with the breaking changes and cross-version publishing.

www.scala-lang.org/blog/2026/03...

02.03.2026 14:55 πŸ‘ 2 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0

☝️Migrating to sbt 2 is going to be the biggest challenge this year in the Scala ecosystem.

Major build tool bumps are historically brutal, but luckily, you don't need to rely entirely on LLMs to rewrite your sbt plugins. #scala

02.03.2026 14:55 πŸ‘ 1 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0
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How Is Scala Used for Data Science β€” Scala Teams Wondering how Scala is used for data science? Learn how Apache Spark, MLlib, Breeze, Smile, and other Scala libraries compare for analytics, machine learning, and NLP.

This article asks the hard questions about when data science teams should stop pretending and just write Scala.

Worth a read if your data pipelines are outgrowing simple scripts. At what scale do you make the switch? πŸ€”

www.scalateams.com/blog/scala-p... #scala

02.03.2026 09:17 πŸ‘ 1 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0
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Dualities in Dependency Injection β€’ Buttondown Hello! Last email I announced early access sales for the book. I'm both surprised and delighted that so many of you went and purchased a copy. Thank you! It...

πŸ“– A new book by Noel Welsh is in the making. Read a preview about the approaches to dependency injection in FP and OOP to fully understand the connection between them. πŸ‘‡ buttondown.com/functionalpr... #scala #functionalprogramming

01.03.2026 07:44 πŸ‘ 1 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0
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sbt-config/README.md at b4abb50e52374ca12f52ee208be2d63a4affbde8 Β· matejcerny/sbt-config Β· GitHub Configure sbt project via HOCON. Contribute to matejcerny/sbt-config development by creating an account on GitHub.

Here is the base64 version, but you can always just save it as an image: github.com/matejcerny/s...

25.02.2026 19:31 πŸ‘ 0 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0
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Add this badge to your repository if your library is already prepared for the upcoming sbt 2. You did a great job! 🫢 #scala

25.02.2026 19:21 πŸ‘ 1 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0

The stabilization milestone in form of Scala 3.8.2 is officially out. πŸš€ Are you already running the 3.8 branch in production, or have you been waiting until the edges smooth out? #scala

24.02.2026 19:08 πŸ‘ 0 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0
Scala Survey 2026 Turn data collection into an experience with Typeform. Create beautiful online forms, surveys, quizzes, and so much more. Try it for FREE.

Please take a few minutes to fill this out πŸ™ so we can get some hard data on how the ecosystem has actually evolved since the last survey, especially regarding real-world Scala 3 adoption. #scala virtuslab.typeform.com/ScalaSurvey2...

24.02.2026 16:09 πŸ‘ 1 πŸ” 1 πŸ’¬ 0 πŸ“Œ 0
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GitHub - matejcerny/sbt-config: Configure sbt project via HOCON Configure sbt project via HOCON. Contribute to matejcerny/sbt-config development by creating an account on GitHub.

Go and steal the setup for your own projects πŸ‘‡ github.com/matejcerny/s...

23.02.2026 21:40 πŸ‘ 1 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0

Zero TypeScript or Node boilerplate. Unlike modern JS-heavy generators, you don't need a local dev server just to see a preview. You can literally open index.html right from your file system and almost everything works. (Except the search, of course.)

23.02.2026 21:13 πŸ‘ 1 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0
website of sbt-config plugin

website of sbt-config plugin

So I tried the new Scaladoc static site generator... The verdict: mdoc is dead ☠️ #scala

23.02.2026 21:13 πŸ‘ 2 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0
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State of the TASTy reader and Scala 2.13 ↔ Scala 3 compatibility

🚨 With Scala 3.8, this forward compatibility is officially ending. Don't panic, though.

βœ… Backward compatibility remains rock solid - Scala 3 still happily consumes your existing 2.13 jars.

Read the wrap-up here πŸ‘‡ www.scala-lang.org/blog/state-o...

22.02.2026 17:22 πŸ‘ 1 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0