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Reposted by Mateusz Kubuszok

Matej Cerny @matejcerny.bsky.social · 1d

This is probably the most complete tutorial on typeclasses in Scala 3, it's basically a short book. Bookmark it, as it has everything: givens, derivation, mirrors, inline defs, macros... you name it. #scala kubuszok.com//2025/sanely...

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Mateusz Kubuszok @kubuszok.com · 2d

#scala #metaprogramming #typeclasses because, of course, I forgot

Mateusz Kubuszok @kubuszok.com · 2d

I haven't blogged in a while, but this needed to be written:

kubuszok.com/2025/sanely-...

Sanely-automatic derivation - or how type class derivation works and why everyone else is doing it wrong

In Scala, we generate quite a lot of code. A lot of that involves the compiler generating so-called type class instances. This mechanism is quite widespread, yet, very few people actually understand i...

kubuszok.com

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Mateusz Kubuszok @kubuszok.com · 2d

It also reminded my why, I stopped - putting everything I know into 1 writeup is such a PITA but I do not want it any other way.

Mateusz Kubuszok @kubuszok.com · 2d

I haven't blogged in a while, but this needed to be written:

kubuszok.com/2025/sanely-...

Sanely-automatic derivation - or how type class derivation works and why everyone else is doing it wrong

In Scala, we generate quite a lot of code. A lot of that involves the compiler generating so-called type class instances. This mechanism is quite widespread, yet, very few people actually understand i...

kubuszok.com

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Mateusz Kubuszok @kubuszok.com · 15d

Chimney 2.0.0-M2 for 2.13.17+ and 3.7+ just landed!

* sanely-automatic derivation backported to 2.13
* aligned with featues/bugfixes up till 1.8.2

Try out, if you had any issues with semiauto on Scala 3.7 or if you want to test sanely-auto on 2.13!

github.com/scalalandio/...

Release v2.0.0-M2 · scalalandio/chimney

Important Since Chimney got affected by 3.7.0 change in givens resolution we had to analyze the possible ways of fixing the issue. While there is a temporary workaround the proper fix requires rele...

github.com

Mateusz Kubuszok @kubuszok.com · 18d

Great thanks to all organizers of @scalaio.bsky.social! It was a great experience I am happy I could be there.

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Mateusz Kubuszok @kubuszok.com · Oct 3

The first release is done, better macros are possible

github.com/MateuszKubus...

Release 0.1.0 - Inintial release · MateuszKubuszok/hearth

It took longer than I hoped but 0.1.0 is live and with some scaffolded documentation. There are some gaps in the documentation, e.g. no examples for utilities usage, no mention of sources and debug...

github.com

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Reposted by Mateusz Kubuszok

Scala.IO @scalaio.bsky.social · Sep 25

Can we have the Standard Library for Macros? (@kubuszok.com): makes simple things simple, and hard things (at least) possible 🚀

Event Sourcing is just a foldLeft on Events and a decide function! Or is it? (Matthieu Baechler & Thomas Hilaire): master of immutability but UPDATE db all day long ? 👀

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Mateusz Kubuszok @kubuszok.com · Aug 21

Thank you everyone who came to my talk at @scaladays.org ! It was amazing to be here!

You can find my slides at mateuszkubuszok.github.io/ScalaStandar...

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Mateusz Kubuszok @kubuszok.com · Aug 10

That #Scala code does something, that many considered impossible. Could you guess why?

github.com/MateuszKubus...

hearth/hearth-tests/src/main/scala/hearth/demo/ShowMacrosImpl.scala at f4b7828eaecd6b154514832a51b1756f6a29fd37 · MateuszKubuszok/hearth

The first Scala macros' standard library. Contribute to MateuszKubuszok/hearth development by creating an account on GitHub.

github.com

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Mateusz Kubuszok @kubuszok.com · Jul 25

Feedback reaches authors faster when they don't have to use a mix of "search by string in random social media" (no mentions, hashtags, etc) combined with Google Translate :P

Discussions, issues and PRs are welcome at github.com/scalalandio/...

GitHub - scalalandio/chimney: Scala library for boilerplate-free, type-safe data transformations

Scala library for boilerplate-free, type-safe data transformations - scalalandio/chimney

github.com

Mateusz Kubuszok @kubuszok.com · Jul 16

If you're missing some feature in Chimney - contribute it!

github.com/scalalandio/...

The future of Chimney · scalalandio chimney · Discussion #762

TL;DR - I intent to develop only what is necessary to keep the library working (when changes in the compiler would make the currently working code make it no-longer working code, like with 3.7-give...

github.com

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Mateusz Kubuszok @kubuszok.com · Jul 16

Some time ago I made a presentation that wasn't recorded...

But at least some of the points from it could be showcased with this gist

gist.github.com/MateuszKubus...

Newtypes and tagged types

Newtypes and tagged types. GitHub Gist: instantly share code, notes, and snippets.

gist.github.com

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Mateusz Kubuszok @kubuszok.com · May 30

It seems #Scala folks are interested in macros once more!

So, let's meet at the @scaladays.org 2025 to talk why we would want some standard library for them and how!

Scala Days 2025
Can we have the Standard Library for Macros
Mateusz Kubuszok
8.21.2025 | Track 4, 11am, Hall 1

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Mateusz Kubuszok @kubuszok.com · May 21

I had hardly any exposure to Apache Spark, and Databricks is mostly irrelevant to me...

Still I am curious why nobody in my circle noticed that Databricks released runtime for Scala 2.13. Now only sbt is the reason to keep publishing for 2.12
docs.databricks.com/aws/en/relea...

Databricks Runtime 16.4 LTS | Databricks Documentation

Release notes about Databricks Runtime 16.4 LTS, powered by Apache Spark.

docs.databricks.com

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Reposted by Mateusz Kubuszok

Scala Space @scalaspace.bsky.social · May 13

🚀 Metals v1.5.3 is here!

Introducing:
- MCP server support for AI agents
- new inlay hints for named/by-name parameters
-improved test discovery for ZIO
- better auto-fill arguments
- using directives worksheet support.

Try it now! #Scala #IDE

scalameta.org/metals/blog...

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Mateusz Kubuszok @kubuszok.com · May 8

Since we had to make a new major - and we would have to maintain 2 major versions for a while - we made some cleanups in 2.x and refactors in 1.x. You find 1.x changes in 1.8.0.

github.com/scalalandio/...

Release v1.8.0 · scalalandio/chimney

Important Since Chimney got affected by 3.7.0 change in givens resolution we had to analyze the possible ways of fixing the issue. While there is a temporary workaround the proper fix requires rele...

github.com

Mateusz Kubuszok @kubuszok.com · May 8

If you've been affected by Scala 3.7.0 given resolution change, and Chimney started failing in some case - try out 2.0.0-M1.

github.com/scalalandio/...

Release v2.0.0-M1 · scalalandio/chimney

Important Since Chimney got affected by 3.7.0 change in givens resolution we had to analyze the possible ways of fixing the issue. While there is a temporary workaround the proper fix requires rele...

github.com

1

Reposted by Mateusz Kubuszok

Scalar @scalar-conf.com · Apr 14

Slow-Auto, Inconvenient-Semi: escaping false dichotomy with sanely-automatic derivation by @kubuszok.com

Subscribe to our our YouTube channel so you don't miss the rest of #scalarconf videos.

Slow-Auto, Inconvenient-Semi: escaping false dichotomy with sanely-automatic derivation

YouTube video by SoftwareMill

www.youtube.com

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Reposted by Mateusz Kubuszok

Matej Cerny @matejcerny.bsky.social · Apr 11

Really interesting comparison between automatic vs. semi-automatic type class derivation and their impact on performance. #scala https://youtu.be/M54ux51H6Fo

Slow-Auto, Inconvenient-Semi: escaping false dichotomy with sanely-automatic derivation

youtu.be

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Reposted by Mateusz Kubuszok

Scala Space @scalaspace.bsky.social · Apr 10

As promised we are working hard on providing you with the Scala MCP server, we already have a WiP pull request ready and some courageous souls are actually testing it!

You can take a look and already give some feedback at github.com/scalameta/m...

WIP: MCP support by kasiaMarek · Pull Request #7390 · scalameta/metals

resolves: scalameta/metals-feature-requests#430

github.com

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Reposted by Mateusz Kubuszok

Scala Space @scalaspace.bsky.social · Apr 2

With our new Scala MCP server we are able to eliminate hallucinations and unproductive guesswork for code that LLMs aren't familiar with by exposing API shapes from the caches of Metals and the Scala compiler.

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Mateusz Kubuszok @kubuszok.com · Mar 29

I am back home! But I took a bit of Scalar with me :)

Mateusz Kubuszok @kubuszok.com · Mar 28

Thank you @scalar-conf.com for yet another amazing conference and for having me there! See you next year!

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Mateusz Kubuszok @kubuszok.com · Mar 15

Scala 3.7.0-RC1: Expr.summonIgnoring works! (vide github.com/scala/scala3...)

I updated my benchmarks, now I'll have to update my slides for Scalar

Proposal: Add Expr.summonIgnoring method to use in macros · scala scala3 · Discussion #21909

Motivation: Typeclass derivation libraries have long been using the implicit resolution feature in scala. It: allows for easier developer experience where derivation library designers are able comp...

github.com

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