Jon Pretty

I am very happy to announce that will be speaking at Scala.io in Paris on 17 October! This will be my first conference talk since 2019, and I'm going to try to make it the best ever! I will introduce soundness.dev to the world: a tour de force of all the wonderful things you can do with Scala 3. I will show you an exciting, optimistic and realistic future for Scala. I will show you how to build CLI and web applications with code that's as easier to read than Python or JavaScript, but just as safe as Haskell. Thank you to the conference team for giving me this opportunity. Scala.io has a special place in my heart: it's always been a delightful, independent and friendly event, and I'm excited to be coming back to Paris! If you want to see the pinnacle of coding elegance, then please come along!

Teaching Scala makes me appreciate this programming language even more. The features really fit together like nowhere else.

I know I complain a lot about the issues with my OSS work but the freedom to build is nothing like anything else! I was considering dropping Scala Native from Kyo because of the maintenance burden. If this was at a job, I'd drop it for sure. But in OSS, I can just decide to "take a look" 🤓 I'm now porting modules to pure Scala to support Native and having fun with optimization challenges 😂 You know the rumors about a Scala library beating native languages? It might actually become true after all!

The most successful agent-friendly OSS libraries will leverage strong types, detailed & actionable error messages, superb docs, and discoverable, predictable, and compositional designs.

I revamped my blog with a new look and feel. 🌻 There are articles about #Scala, #Java, #Kotlin, functional programming, and software engineering. EST. 2013 ⭐️ blog.rcard.in

S. Valentine is approaching for #Scala lovers ❤️, and it brings version 0.13.0 of the #YAES library. 🥁 We added an HTTP server this time...yes, we did it! A fully effectful server, based on virtual threads, with graceful shutdown! 😱 It's still in its experimental phase, so any feedback is welcome 🤝 Here are the docs: blog.rcard.in/yaes/#/http/se… Here are the release notes: github.com/rcardin/yaes/r… cc @petr_zapletal cc @ScalaTimes

@matej_cerny I have also barely used anything other than scm.HashMap from the mutable collections, and I probably ought to be using the concurrent TrieMap instead in a few of those places...

@matej_cerny Have you ever written a var of an immutable collection? As one of the outliers who said I use s.c.mutable "frequently" (but much less frequently than the immutable collections), they definitely have their uses, but I almost never use them in non-local, non-private contexts.

I'm not saying it's illegal, but I haven't directly used mutable collections ever in my entire career. Not once 🤷

"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. 🎯 Check out the new Forms4s library by @Krever01. It ships with Tyrian 👾 support out of the box, but because it's composable, you aren't locked into a specific UI framework.

There are coders and there are engineers. They are not the same. Backend, frontend, OS, mobile, embedded, whatever: If people (you included) would trust you + your skills to write software for a plane, a bank, or anything with actual consequences, you're an engineer. Otherwise you're a coder. As an industry, we've mistaken coders for engineers (and vice versa), and paid them almost the same. AI will fix that, permanently. If you're a coder, AI is coming for your job. If you can vibe-code an app in a weekend, so can a 12-year old. Your competition is about to grow 100x. You need to either - get famous - start a business - or get crushed. If you're an engineer, keep calm and carry on. This is the best time yet to be an engineer. When the system goes banana, you're the adult in the room, and they'll pay you your weight in gold. As a bonus, AI will be your friend.

🎉 Scala 3.8 is here! It shifts focus from new features to core infrastructure. By moving away from JDK 8 and implementing several internal refactorings, it lays a modern, stable foundation for the upcoming LTS. #Scala #JDK

@matej_cerny I think this is my favourite new feature in 3.8. It's just what I need for constructing HTML trees.

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

Took a while to figure out how, because of limitations of Scala 3, but we finally have automatic derivation of optics for case classes, sealed traits, and enums--all cross Scala 2/Scala3 source-compatible!! 👀 For you smarty-pants out there, how did we do it? Don't cheat. 😉

A mantra from 2025 was “programming languages don’t matter” - if true we should just be using natural language and machine code. Maybe at some point AI is the compiler for natural language to machine code. But I’m not convinced yet that will happen. Until it does, programming languages still definitely matter.

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

@paulg People can usually find the wildest explanations to fill the uncertain voids between their unflinching beliefs, just to pacify cognitive dissonance. Unfortunately, when they do, they usually count it as a new datapoint on the wrong side of the ledger.

Initially I was surprised at people's ability to ignore evidence leading to conclusions they don't like, even with multiple videos of the scene. But then I remembered that 34% of Americans don't believe in evolution.

I say, don't change: turn the grandiloquence up to 11 and go full-on magniloquent.

That was Claude's summary. The full feedback is; I know you are having fun with this but... maybe tone it down with the grandiloquence language (yep i had to look that up also). Like who says "elide"? Non native english speakers might find this confusing. So yes, they were being ironic and funny 😅! But I've gotta do what feels right. I'm bound to disappoint some people (particularly the person who hates my voice).

I will address Feedback No. 51. But, I'm afraid I can remain grandiloquent longer than you can remain solvent.

@kamilogorek @kitlangton I'm not sure if that's a good thing...

@propensive @kitlangton You're one of few people that I cannot read tweets of without hearing the voice anymore

It is time → effect.institute. 2026, the year of 𝚎𝚏𝚏𝚎𝚌𝚝. I'm extremely proud of how this turned out. There are many chapters to add, but I do hope you enjoy what's there so far. Let me know what you think. 🫡

@kitlangton 😂 Anyway, just to confirm, the highlighting has been enabled by my brain now the sun has gone down and dark mode is on.

@propensive This has been happening to me for as long as I can remember.

@kitlangton Having just gone through the tutorial, I now hear your voice while I read your tweets. I'll let you know when the words start highlighting while you speak.

Now we wait 🧘