Today is the day all the pieces came together and I figured out the capability-passing UI library 🎉 The idea has been obvious to me for a while, but the details (if you want to the type system to be useful) had eluded me.

man pages are basically Jeopardy: if you know the answer they'll tell you the question.

I'm a committee member this year, and I would rank >90% of the current proposals more highly if they fixed some basic mistakes. The number one mistake is not including enough information to allow me to properly assess the proposal. I'll be at this event, and will offer all the advice I can.

This year's @scaladays.org is accepting 2 hour workshop proposals, in addition to the more usual 30 minute talks. I'm thinking a workshop on building terminal apps using Scala Native could be fun. What do you think? What workshops would you like to see at the conference?

Interested in speaking at Scala Days? Join us this evening at the Scala Days proposal hack! Informally discuss your proposal with members of the program committee and other speakers. Join us online at 7PM BST / 6PM UTC: meet.google.com/uay-ynsm-djx Find out more: www.meetup.com/london-scala...

Scala Days CFP is open and the London Scala User Group is running an online event to help people create a proposal: www.meetup.com/london-scala... I'll be attending to help out. I'm also on the program committee this year. I encourage any potential speakers to attend!

It's time to take capture checking for a spin. I know this should work in theory, which in theory is the same as practice.

Coding agents are great at minutiae, but lack taste. Given the chance, they will quickly turn a code base into a big ball of mud. The question is, is this a limitation of the reasoning ability of LLMs, or is it replicating the patterns in the training data?

I hold this truth to be self evident (until I get around to writing it up): Capability passing is a great way to structure a UI toolkit. In fact it's the model implicitly behind many current frameworks. Capability passing effect handlers formalize what is already going on, and add expressive power

IIUC, capability passing effects (see Effekt language) are another example of def/use distinction, in this case pushing requirements for effects from point of definition to point of use. Interesting how often this comes up, but it doesn't seem to be widely recognized as a general pattern.

What are the best practices for creating APIs in a post-LLM world? I think that was is good for humans is also, broadly, good for LLMs. But what about a builder API, that optimizes for dot-driven development (press . and follow the autocomplete). Does that still make sense, or is it unnecessary?

Thank you for attending last week's Scala Talks! Thanks go to Medidata for having us round for pizza, drinks and a beautiful venue. Special thanks go to our fantastic speakers Tomasz Godzik and @noelwelsh.bsky.social . See you next time!

🗒 from us docs.google.com/presentation... 🗒 from "Metals Version 2!" by Tomasz Godzik : slides.com/tomekgodzik/... 🗒 from "Code as Communication: Lessons from Crashing Production" by @noelwelsh.bsky.social : noelwelsh.com/talks/commun...

@shriram.bsky.social Looks like your grousing about train refunds on social media has paid off! www.bbc.co.uk/news/article... Myself and other Brits will now be queuing up with other policy suggestions we'd like publicized 👍

I wrote up some thoughts on Zig's comptime: Parametricity, or Comptime is Bonkers noelwelsh.com/posts/compti... I think comptime is great (staging!) but it's not the right approach to generic types in my opinion.

Just installed speech-to-text (Voxtype) on my Linux PC. It's incredible that this is all free and runs locally. It feels like magic.

🛠️ sbt 2 is nearing stable release - let’s migrate the plugin ecosystem together! The new sbt2-compat plugin was developed by the Scala Center to simplify cross-building sbt plugins for sbt 1 and sbt 2. Learn more on how to migrate:

Claude makes an incredible writing companion. I took @shriram.bsky.social's advice and installed Claude code, and I'm using it a sounding board for working on my book. What would have been a day or two kicking around a concept until it crystalizes has become tens of minutes of discussion.

Subtle effect of the rise of LLMs: I can no longer write "the person writing the code".

OH so like a functional programmer to not have class consciousness

I don't normally post my email newsletter, but I thought this one was a banger: on the dualities between constructor injection, the reader monad, comonads, and effect handlers. If that sounds like your jam: buttondown.com/functionalpr... (Or just grab the book! functionalprogrammingstrategies.com)

come join us again @feelingof.london for demos and good vibes! 😌💚

🎯🎯🎯 "When you start to treat an LLM with cruelty, the only thing you're really revealing is what you have in your heart, not whether the machine has one... Practicing this language - even toward AI - normalizes the social patterns that enable cruelty toward humans."

AGI is when everyone is using emacs

I wrote up my recent exploration of OxCaml: noelwelsh.com/posts/a-quic... This is a quick overview, and an example and discussion of unboxed types. More to follow, if time allows!

Got my website running live on my zero-allocation (ish) OxCaml webserver! First of a series of posts on building out our planetary computing system infrastructure using the performance extensions in the Jane Street fork of OCaml. anil.recoil.org/notes/oxcaml... (and thanks @thenumb.at for tips)

For five years I convinced myself I was a boring Linux user who would stick with Ubuntu. One week ago I cracked, installed Arch, and now I'm onto my second window manager (Niri) and in love with tweaking little dotfiles (and keyboard oriented workflows)

¡ʎɐp ɐᴉlɐɹʇsn∀ ʎddɐH Getting ready for the traditional Australia Day barbie! 🇦🇺🐨🦘🪃🪰🦈🐊🐍🕷️

Used OxCaml unboxed types to create a very simple arithmetic interpreter with ~zero allocation. The documentation is lacking but the overall vision is compelling! I find it more ergonomic to work with than Rust; there is a very gentle slope from writing normal GC'ed code to optimized code.

Thanks for some help from @jonoabroad.bsky.social, Doodle now supports tags and attributes in SVG drawings! A few examples here in the documentation: www.creativescala.org/doodle/svg/t...

COW TOOLS COW TOOLS COW TOOLS

Yesterday Evening, I gave a talk about using #Haskell for #3DPrinting at the London #Scala User Group @londonscala.bsky.social https:// doscienceto.it/cad-talk-scala/

Finished the chapter on types in the book! This was a fun one. Got to revisit the @lexi-lambda.bsky.social classic "Parse, don't validate" and waffle a bit about extensional versus intensional view points. This duality comes up surprisingly often! It's the same thing as FP (data) vs OO (codata).

Early Christmas present from me if you're reading this and you're a: - Senior web developer - In London - Really into books and libraries - Looking for work rn I am excited to inform you that the British Library is hiring a new head of web development ce0752li.webitrent.c...

This is how you nerd!

@kubukoz.mstdn.party.ap.brid.gy made this very nice video about the web framework I've been working on in my spare time: youtu.be/lY88Z1JnUpI You should check it out! (The framework itself is at www.creativescala.org/krop/)

🧪 Streaming can feel intimidating until you see it broken down clearly. This talk takes a deep dive into fs2 with a focus on real usage. Here’s "Taking the plunge: a deep dive into streaming with fs2" by Zainab Ali

Get your #Haskell fix at the London #Scala User Group! We're excited to hear from Joe Warren, creator of the 3D printed London Scala User Group logo.

The festive season is upon us and we have something special... a Christmas social event on Dec 12th (Fri) at the Science Museum!! 🎄 Come for some drinks (free entry, sign up required) or Power Up and enjoy a night of fun retro games 🎮🤖 (£20). Details below 🧵

The more complicated types become, the more value there is in writing them down. The more complicated types become, the less I want to write them down. Such is the duality of programming.

“The Software Paper fills a gap for the computational and digital humanities communities...” Thank you to research software engineer extraordinaire @suttonkoeser.bsky.social for leading this initiative for Computational Humanities Research journal. Please share!

This is in collaboration with @scalabridgelondon.bsky.social . If you're in London and Scala / FP inclined it would be great to see you there!

The French just keep raising the heist bar.

This "Tiger Style" coding philosophy reminds me of 1990s / early 2000s era Code Complete advice: tigerstyle.dev For example: the only discussion of types is "use explicitly sized types" but then we have a big section on implementing an ad-hoc runtime "type" / contract system using assertions.

We love to visit our local French fry restaurant. The maitre d' is always happy to suggest the best sauce to complement the season's potatoes. The chef, however, is very passionate about food and has been known to leave the kitchen to shout at customers who ask for their fries "well done".

Thoughts on the Cloudflare incident [1] from a PL perspective. Some file had an implicit limit of 200 lines. If this could be typed checked that would be great. Types are cheap and prevent all instances of a problem. [1]: blog.cloudflare.com/18-november-...

XML as syntax for a programming language was a bad idea in Ant back in the early 2000s, and it's still a bad idea in the CSL I'm working on now. (Same thing applies to YAML, modulo changing the years.)

After fixing up a bunch of citations (DBLP saved me with the ACM being unusable due to the Cloudflare incident) I think I can make the Typst version of Functional Programming Strategies live, replacing the older Latex version. I'll never use Latex again if I can help it. Another win for FP! 😆

Reworking some of the bibliographical notes in Functional Programming Strategies, and I discovered that regular expression derivatives are behind the current .NET regex engine, and a best-in-class Rust engine! E.g. dl.acm.org/doi/pdf/10.1... It's nice when theory matches up with practice. 😁