Mateusz Kubuszok

Mateusz Kubuszok

@kubuszok.com

Hearth Core Macro Hacker Blog @ https://kubuszok.com JVM-Scala Book @ https://leanpub.com/jvm-scala-book Chimney @ https://chimney.scalaland.io

222 followers 63 following58 posts

Mateusz Kubuszok reposted

Catch the recap of Mateusz Kubuszok's session at #Scaladays on the deep platform-engineering challenges he faced while trying to build a Scala game engine with LibGDX. And how to port a large Java ecosystem to Scala with LLMs. Link: youtu.be/obzSWcm_VH0...

youtu.beMateusz Kubuszok – Scala's LibGDX: A Report from the Trenches #ScalaDaysMore: https://scaladays.org/sessions/Scala-s-LibGDX-A-Report-from-the-Trenches Speaker: Mateusz Kubuszok Java has LibGDX. Scala has powerful platforms, but n...

Mateusz Kubuszok

Here are the slides from my @scaladays.org talk mateuszkubuszok.github.io/ScalasLibGDX/

mateuszkubuszok.github.ioScala’s LibGDX

Mateusz Kubuszok

It seems that the video from #scaladays is already online :) www.youtube.com/watch?v=obzS...

youtube.comMateusz Kubuszok – Scala's LibGDX: A Report from the Trenches #ScalaDaysYouTube video by Scala Days Conferences

Mateusz Kubuszok

So... tomorrow Sonatype publishing limits start being applied. I've got quota increate as OSS, which lets me afford as much as 1 Hearth+Kindlings release per month. Need to spend it wisely!

Mateusz Kubuszok reposted

Mateusz Kubuszok shares the engineering lessons behind SGE, covering Java ecosystem porting, cross-platform tooling, Scala Native, and native dependencies. Learn more: scaladays.org/sessio... 12-13 October. Berlin

Mateusz Kubuszok

Chimney 2.0.0-RC1 just dropped, with the final improvements and targeting 3.9.0 - if no serious issues are found it will be promoted to 2.0.0! github.com/scalalandio/...

github.comRelease v2.0.0-RC1 · scalalandio/chimneyImportant 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...

Mateusz Kubuszok reposted

@matejcerny.bsky.social

There is a new #Scala 3 optics library worth checking out: cats-eo. It unifies optic families under a single trait, features macro derivation backed by Hearth and delivers massive performance gains (such as traversals running up to 11x faster compared to Monocle).

Mateusz Kubuszok

This migration was an opportunity to benchmark the compilation and improve a thing or 2 in Hearth, so we're dropping new releases of: Hearth: github.com/kubuszok/hea... Kindlings: github.com/kubuszok/kin...

github.comRelease 0.4.1 - Compile-Time Performance, 30+ Fixes, and copyMethod / Expr.annotated / Type.Lazy APIs · kubuszok/hearth0.4.1 is a polish and quality-of-life release. Chimney is now Hearth-powered — and it got there on 0.4.0, without waiting for anything in this release; where it met a rough edge it simply worked ar...

Mateusz Kubuszok@kubuszok.com

New Chimney(s) dropped: 1.x line supporting 2.12/2.13/3.3: github.com/scalalandio/... and 2.0.0-M4 supporting 2.13/3.8 freshly migrated to Hearth: github.com/scalalandio/...

github.comRelease v1.11.0 · scalalandio/chimneyNoteThis release was sponsored completely by users' contributions! It will also probably be the last release in 1.x line where I contributed anything, and where changes were ported into the 2.x lin...

Mateusz Kubuszok

New Chimney(s) dropped: 1.x line supporting 2.12/2.13/3.3: github.com/scalalandio/... and 2.0.0-M4 supporting 2.13/3.8 freshly migrated to Hearth: github.com/scalalandio/...

github.comRelease v1.11.0 · scalalandio/chimneyNoteThis release was sponsored completely by users' contributions! It will also probably be the last release in 1.x line where I contributed anything, and where changes were ported into the 2.x lin...

Mateusz Kubuszok

Hearth 0.4.0 once again is pushing the limits of what you can do with macros (without going insane): - reworked method callers that could let you build every call - expression destructuring enabling quicklens-like patterns - creating anonymous instance of an arbitrary type

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Mateusz Kubuszok

These new abilities power a new Kindlings release, which adds Hearth-bases: - macwire-like DI - mocking - lenses - cats-tagless derivation - Tapir module for OpenAPI rendering with Jsoniter that would not pull-in Circe! and more! github.com/kubuszok/kin...

github.comRelease 0.3.0 - Compile-time DI, mocking, optics & OpenAPI-jsoniter modules, cats-tagless derivation, built on Hearth 0.4.0 · kubuszok/kindlingsFour brand-new Hearth-based modules — compile-time dependency injection (macwire-style), mocking (ScalaMock-style), optics (quicklens-style), and a Circe-free OpenAPI jsoniter serializer — plus a n...

Mateusz Kubuszok

There are also new releases of refined-compat and pipez, migrated to newest Hearth 0.4.0: github.com/kubuszok/ref... github.com/kubuszok/pip... And as a bonus new scala-newtype-compat with fixes to JDK version used for each Scala version: github.com/kubuszok/sca...

github.comRelease 0.2.0 - Hearth 0.4.0 and the sbt 2.0 Migration · kubuszok/refined-compatThe second release of refined-compat — compile-time refinement validation for refined types on both Scala 2.13 and Scala 3, powered by Hearth's Expr.semiEval. This is a maintenance release. There a...

Mateusz Kubuszok

Hearth 0.4.0 once again is pushing the limits of what you can do with macros (without going insane): - reworked method callers that could let you build every call - expression destructuring enabling quicklens-like patterns - creating anonymous instance of an arbitrary type

Mateusz Kubuszok

- smart A <=> Expr[A] transformations - and more! github.com/kubuszok/hea...

github.comRelease 0.4.0 - Method Builder Chain, DestructuredExpr, AnonymousInstance, ExprCodec.derived, Union Soundness, and Call-Site Scopes · kubuszok/hearthAfter the 0.3.x line wrapped up with the "more exciting things to come in 0.4.0!" promise, here it is — the release where Hearth grew the building blocks for real derivation and metaprogramming lib...

Mateusz Kubuszok

There was no e-mail, and I learned it by accident, but I feel all #Scala OSS devs should learn ASAP: Maven is introducing publishing limits. We most likely will have to apply for exemption: - www.sonatype.com/blog/open-pu... - central.sonatype.org/publish/mave...

sonatype.comOpen Publishing, Commercial ScaleOpen source registries are evolving for commercial-scale use. Learn why Maven Central publishing limits aim for open access and sustainable infrastructure.

Mateusz Kubuszok

Today we managed to push out Hearth 0.3.1 with support for evaluating Expr values without an actual compilation (semiEval). github.com/kubuszok/hea...

github.comRelease 0.3.1 - Expr.semiEval, Type.CtorK1, JDK Futureproofing, and a New Logo · kubuszok/hearthThe 0.3.1 release adds a few things to the 0.3.x line, that I didn't waned to wait with, but also ones that should not break existing libraries based on 0.3.0. (More exciting things to come in 0.4....

Mateusz Kubuszok

What it unlocked was a new release of Kindlings 0.2.0 where derivation configs start to be parsed by a macro -> so less runtime overhead to dispatch the behavior -> better performance! github.com/kubuszok/kin...

github.comRelease 0.2.0 - Diff derivation, full Cats algebra, benchmarks, documentation site, and a new logo · kubuszok/kindlingsThe biggest Kindlings release so far: a new structural-diff module, a much larger Cats type class roster, a single derived-only API, a documentation site with runnable examples, JMH benchmarks agai...

Mateusz Kubuszok

And another thing it enabled was this first release of refined-compat 0.1.0 - where we kicked off the work to make Refined library macros cross-compilable for Scala 2.13 and 3! github.com/kubuszok/ref...

github.comRelease 0.1.0 - Compile-Time Refined Validation on Scala 3 · kubuszok/refined-compatThe first release of refined-compat — compile-time refinement validation for refined types on Scala 3, powered by Hearth's Expr.semiEval. On Scala 2, refined's import eu.timepit.refined.auto._ vali...

Mateusz Kubuszok

The recording of my @scalar-conf.com presentation about civilising #macros in #Scala is online! youtu.be/Hbknc_dc4KQ

youtu.beCan we have the Standard Library for Macros? by Mateusz Kubuszok | Scalar 2026YouTube video by SoftwareMill

Mateusz Kubuszok reposted

@matejcerny.bsky.social

Hearth aka the Scala unified macro for 2.13 and 3 has a new version out! 🎉 I'm definitely no macro expert, so go read the changelog yourself to see all the magic. 🪄 It's huge! github.com/kubuszok/hea... #scala

github.comRelease 0.3.0 - Standard Extensions, Union Types, Rules, Flame Graphs, MIO Timeouts, hearth-munit, and Much More · kubuszok/hearth · GitHubThis is the biggest Hearth release so far: a major feature release that introduces Standard Extensions — a pluggable type-inspection framework — along with union types support, rule-based derivatio...

Mateusz Kubuszok

I wanted to release Hearth 0.3.0 after Scala 3.3.8 is out, and Kindlings 0.1.0 after that. But overwhelmingly positive reception (and a horse head in my bed) convinced my to release them much earlier, so...

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Mateusz Kubuszok

The first release of Kindlings is also out! github.com/kubuszok/kin...

github.comRelease 0.1.0 — Type class derivation that just works, on Scala 2.13 and 3 · kubuszok/kindlingsWe're excited to announce the first release of Kindlings — a collection of type class derivation modules built on Hearth that are cross-compiled for Scala 2.13 and Scala 3, on JVM, Scala.js, and Sc...

Mateusz Kubuszok

When I also mention that I vibe coded Scala 3 plugin to use Scala Newtypes on Scala 3 (who knows, maybe it will even work!), this was my most productive conference so far! github.com/kubuszok/sca... @scalar-conf.com, most inspiring #scala conference!

github.comGitHub - kubuszok/scala-newtype-compat: Scala compiler plugin to let you use Scala Newtype on Scala 3Scala compiler plugin to let you use Scala Newtype on Scala 3 - kubuszok/scala-newtype-compat

Mateusz Kubuszok

I wanted to release Hearth 0.3.0 after Scala 3.3.8 is out, and Kindlings 0.1.0 after that. But overwhelmingly positive reception (and a horse head in my bed) convinced my to release them much earlier, so...

Mateusz Kubuszok

Hearth 0.3.0 just dropped! github.com/kubuszok/hea... and right behind it...

github.comRelease 0.3.0 - Standard Extensions, Union Types, Rules, Flame Graphs, MIO Timeouts, hearth-munit, and Much More · kubuszok/hearthThis is the biggest Hearth release so far: a major feature release that introduces Standard Extensions — a pluggable type-inspection framework — along with union types support, rule-based derivatio...

Mateusz Kubuszok

Here are slides from by talk at @scalar-conf.com about #macros in #scala mateuszkubuszok.github.io/ScalaStandar...

mateuszkubuszok.github.ioCan we have the Standard Library for Macros?

Mateusz Kubuszok

Last year: - at @scalar-conf.com I introduced sanely-automatic derivation with macros - at @scaladays.org I showed that macros in #scala can be tamed Now: I wanted to repeat the latter prez but with recent developments I had to update it! Join me on @scalar-conf.com to see new GOTY edition!

Mateusz Kubuszok

Thanks to Guo Yubin Chimney now supports NamedTuples! Grab it at: - github.com/scalalandio/... - github.com/scalalandio/...

github.comRelease v1.9.0 · scalalandio/chimneyChangelog: Add supports for NamedTuple (#766). by @ETCHKILI in #852

Mateusz Kubuszok

One more proof by construction that we can improve derivation in #scala with #macros: github.com/nguyenyou implemented sanely automatic derivation for Circe, and got some really nice numbers. github.com/nguyenyou/ci...

github.comGitHub - nguyenyou/circe-sanely-auto: Sanely-automatic Encoder/Decoder derivation for Circe on Scala 3Sanely-automatic Encoder/Decoder derivation for Circe on Scala 3 - nguyenyou/circe-sanely-auto

Mateusz Kubuszok

Last week I went out for a Friday night beer with friends, and left Claude running. After recent batches of improvements I hoped that Hearth was finally at the stage when I would be able to write a whole type class derivation with no bugs in my macro utilities. #scala #macros

Mateusz Kubuszok

I was drinking beer and approving the runs on the phone (via Happy) xD What I saw was really encouraging. How encouraging? This is what I have one week later: github.com/MateuszKubus...

github.comgithub.com

Mateusz Kubuszok

I wish cross-compilable macros, with potential to provide UX that mops the floor with all these shapeless/mirrors based-libraries were not just a hypothetical possibility... Oh, wait. Scala 2.13: scastie.scala-lang.org/MateuszKubus... Scala 3: scastie.scala-lang.org/MateuszKubus...

Mateusz Kubuszok

Claude just finished writing me a sbt codegen, which generates >17 000 lines of code of macros and compiler plugins... which would be expanded in other macros to provide cross-compilable type constructor representation. When I started Hearth I didn't expect to go so meta

Mateusz Kubuszok

On this day ten years ago, I gave my first public presentation... Fast forward ten years, I still suck :) kubuszok.com/presentation...

kubuszok.comMy presentationsPersonally, just a

Mateusz Kubuszok reposted

🔍 A thoughtful, down-to-earth look at what a shared macro library could mean for Scala developers. Here’s "Can we have the Standard Library for Macros?" by Mateusz Kubuszok

youtube.comMateusz Kubuszok: Can we have the Standard Library for Macros? [Scala Days 2025]Do you like it when compiler generates the boring code for you? Fast, mundane, boring-but-error-prone code? Do you need to implement such a code generator yourself? Have you found out that Shapeless/Mirrors bend your brain a bit too much? Congratulations! You might have a valid use case for writing

Mateusz Kubuszok reposted

The Scala Programming Language

@scala-lang.org

🔍 A thoughtful, down-to-earth look at what a shared macro library could mean for Scala developers. Here’s "Can we have the Standard Library for Macros?" by Mateusz Kubuszok

youtube.comMateusz Kubuszok: Can we have the Standard Library for Macros? [Scala Days 2025]Do you like it when compiler generates the boring code for you? Fast, mundane, boring-but-error-prone code? Do you need to implement such a code generator yourself? Have you found out that Shapeless/Mirrors bend your brain a bit too much? Congratulations! You might have a valid use case for writing

Mateusz Kubuszok reposted

Jakub Kozłowski

@kubukoz.mstdn.party.ap.brid.gy

New video, with Łukasz Biały from @scala_space! https://www.youtube.com/watch?v=K_omndY1ifI

Mateusz Kubuszok

@scaladays.org videos are online! If you wish #scala #macros were a bit easier, and wonder what "this Hearth library" is about, go see: youtu.be/VOdeXTpw3m0

youtu.beMateusz Kubuszok: Can we have the Standard Library for Macros? [Scala Days 2025]YouTube video by Scala Days Conferences

Mateusz Kubuszok reposted

@scalatimes.com

Scala Times Issue #604 - scalatimes.com/f99e9094b8

Mateusz Kubuszok

Hearth 0.2.0 just dropped continuing the quest for user-friendly macros. #scala #macros github.com/MateuszKubus...

github.comRelease 0.2.0 - Overall improvements, ValDefs builders and cache, Better Printers, more robust Cross Quotes and More · MateuszKubuszok/hearthThis release delivers the full scope planned for the 0.2.x milestone: refining everything introduced in 0.1.0, strengthening stability, improving ergonomics, and expanding documentation and tooling...

Mateusz Kubuszok reposted

Scalar Conference

@scalar-conf.com

Welcome Mateusz Kubuszok as the #Scalarconf 2026 speaker! 🎙️ Can we have the Standard Library for Macros? 🎟️ Grab your ticket here: scalar-conf.com/tickets #scala #scalarconf #functionalprogramming

Mateusz Kubuszok reposted

@matejcerny.bsky.social

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...

Mateusz Kubuszok

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

Mateusz Kubuszok@kubuszok.com

I haven't blogged in a while, but this needed to be written: kubuszok.com/2025/sanely-...

kubuszok.comSanely-automatic derivation - or how type class derivation works and why everyone else is doing it wrongIn 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...

Mateusz Kubuszok

I haven't blogged in a while, but this needed to be written: kubuszok.com/2025/sanely-...

kubuszok.comSanely-automatic derivation - or how type class derivation works and why everyone else is doing it wrongIn 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...

Mateusz Kubuszok

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

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/...

github.comRelease v2.0.0-M2 · scalalandio/chimneyImportant 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...

Mateusz Kubuszok

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

Mateusz Kubuszok

The first release is done, better macros are possible github.com/MateuszKubus...

github.comRelease 0.1.0 - Inintial release · MateuszKubuszok/hearthIt 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...

Mateusz Kubuszok reposted

@scalaio.bsky.social

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 ? 👀

Mateusz Kubuszok

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...

Mateusz Kubuszok

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

github.comhearth/hearth-tests/src/main/scala/hearth/demo/ShowMacrosImpl.scala at f4b7828eaecd6b154514832a51b1756f6a29fd37 · MateuszKubuszok/hearthThe first Scala macros' standard library. Contribute to MateuszKubuszok/hearth development by creating an account on GitHub.

Mateusz Kubuszok

If you're missing some feature in Chimney - contribute it! github.com/scalalandio/...

github.comThe future of Chimney · scalalandio chimney · Discussion #762TL;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...