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Johannes Weiss

@jweiss.io

Computer programmer (http://github.com/weissi). Distributed systems, ML infrastructure/eval, Swift, previously #SwiftNIO — ♥ snowboarding London, UK

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17.07.2023
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Latest posts by Johannes Weiss @jweiss.io

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Swift Compiler Backend Engineer - Jobs - Careers at Apple Apply for a Swift Compiler Backend Engineer job at Apple. Read about the role and find out if it’s right for you.

The Swift Performance team isn’t *my* team, but they’re in my hallway. Or in London if you’d prefer. They’re looking for an engineer who’s not afraid of optimizers. jobs.apple.com/en-us/detail...

27.02.2026 23:58 👍 24 🔁 16 💬 2 📌 0

😔 feel better!

30.01.2026 07:46 👍 1 🔁 0 💬 0 📌 0

No, I really was not ready for this. Why? What? Please, humans, be better.

30.01.2026 07:34 👍 13 🔁 1 💬 0 📌 0
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Who's secretly filming fake TikToks inside Londoners' homes? We tracked down the viral video account invading people's houses to spread false claims about immigrants.

This is one of the strangest and most screwed-up stories I’ve worked on. www.londoncentric.media/p/tiktok-lon...

24.01.2026 06:55 👍 1166 🔁 546 💬 33 📌 133

Yes, that's right, they do not converge. Currently, I only care for ethernet in one place which works fine. If I need it elsewhere, I'll need to place two extra switches throughout the flat. Essentially daisy chaining the switches.

24.01.2026 19:23 👍 0 🔁 0 💬 1 📌 0
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Doing Gigabit Ethernet Over My British Phone Wires Disclaimer: None of this is written by AI, I’m still a real person writing my own blog like its 1999 I finally figured out how to do Gigabit Ethernet over my existing phone wires. Powerline adapter…

Good day! Inspired by thehftguy.com/2026/01/22/d... I took off my phone sockets to check what's behind. Turns out: CAT 5e! Found three separate cables, previously daisy chained. Ordered RJ45 sockets to replace phone sockets and undid daisy chains. Soon Ethernet in the flat, psyched!

24.01.2026 18:25 👍 3 🔁 0 💬 1 📌 0

Quite a few groups seem to be rather successful making many of us believe the opposite.
So please note! Some things are getting meaningfully better.

12.01.2026 11:47 👍 2 🔁 0 💬 0 📌 0
Swift @ FOSDEM 2026

FOSDEM, the legendary open source gathering in Brussels, is coming soon, and we'd love to see you there! We've got multiple talks on Swift plus a pre-FOSDEM community meetup. Whether you're a longtime attendee or new to the event, come say hi! 👋 swiftlang.github.io/event-fosdem/ #FOSDEM

09.01.2026 19:05 👍 32 🔁 8 💬 0 📌 0
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What's new in Swift: December 2025 Edition Welcome to the latest digest of news from the Swift project.

Happy New Year, @swift.org crew! So happy to be back, I hope everyone enjoyed some time off.


If you're looking to catch up on Swift news, check out the December digest: www.swift.org/blog/whats-n... and let me know what you think!

02.01.2026 07:15 👍 17 🔁 6 💬 0 📌 0
Wholewheat bread labelled 'German bread'

Wholewheat bread labelled 'German bread'

What should we call wholewheat (partially rye?) bread?
I guess only Germans like that, so let's go with 'German bread' 😅.

It's really yummy btw!

31.12.2025 08:59 👍 3 🔁 0 💬 0 📌 0

👏 Super cool to get Swift on the server showcased at reInvent

06.12.2025 09:36 👍 9 🔁 1 💬 0 📌 0
import Foundation

let calendar = Calendar.current

let openSourceDay = calendar.date(from: DateComponents(year: 2015, month: 12, day: 3))!
let anniversary = calendar.date(byAdding: .year, value: 10, to: openSourceDay)!

if calendar.isDateInToday(anniversary) {
    print("10 Years of Swift open source! 🎉")
}

import Foundation let calendar = Calendar.current let openSourceDay = calendar.date(from: DateComponents(year: 2015, month: 12, day: 3))! let anniversary = calendar.date(byAdding: .year, value: 10, to: openSourceDay)! if calendar.isDateInToday(anniversary) { print("10 Years of Swift open source! 🎉") }

🎉 10 years of open source Swift! A decade ago today, we opened Swift to the world with a simple blog post: swift.org/blog/welcome

What's grown since—thanks to an incredible community of contributors—has been extraordinary. Here's to the next ten years. 🧡

04.12.2025 00:08 👍 88 🔁 29 💬 1 📌 2
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Swift for Wasm Community Hour (3rd of December 2025) I'm excited to announce the inaugural Swift for Wasm Community Hour! We welcome everyone at this event, no matter your background or experience. This is an open space to ask questions and to learn fr...

We'd be happy to see you at the inaugural Swift for Wasm Community Hour on 3rd of December! More details in this post on Swift Forums: forums.swift.org/t/swift-for-...

21.11.2025 11:57 👍 7 🔁 4 💬 0 📌 0
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⚙️ Swift progress on embedded Swift, for memory-safe, fast code in resource-constrained environments. The latest updates are coming to Swift 6.3, and you can read more here: www.swift.org/blog/embedde... #IoT

17.11.2025 21:29 👍 74 🔁 14 💬 0 📌 1
Introducing SlopStop: Community-driven AI slop detection in Kagi Search | Kagi Blog ------------------------------------------------------------------- Your collective defense against AI-generated spam and content farms ----------------------------------------------------------------...

Kagi is trying that: blog.kagi.com/slopstop

16.11.2025 21:26 👍 2 🔁 1 💬 0 📌 0

Yes!? I don't understand it either. Seems actively bad unless there are situations where there's no other solution.

14.11.2025 12:06 👍 1 🔁 0 💬 0 📌 0

Ever since the parliamentary wars of Brexit, the UK media and Westminster bubble craving for drama seems to have increased exponentially.

What is technically still a relatively 'new' Labour government with a huge absolute majority is already (portrayed?) as fighting with its lasts gasps.

12.11.2025 07:08 👍 36 🔁 9 💬 2 📌 1
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The Swift AWS Lambda Runtime moves to AWSLabs | Amazon Web Services We’re excited to share that the Swift AWS Lambda Runtime project has officially moved to the AWS Labs organization. You can now find it here: 👉 https://github.com/awslabs/swift-aws-lambda-runtime This...

Very cool to see AWS and the Swift community work on this together aws.amazon.com/blogs/openso...

06.11.2025 18:56 👍 7 🔁 1 💬 0 📌 0

www.cat.com/en_US/by-ind...

06.11.2025 07:48 👍 0 🔁 0 💬 0 📌 0
In every region of the globe, Solar Turbines is a world leader in mid-range industrial gas turbines for use in power generation, natural gas compression, and pumping systems. Our systems last for decades, and so do our service and support.

In every region of the globe, Solar Turbines is a world leader in mid-range industrial gas turbines for use in power generation, natural gas compression, and pumping systems. Our systems last for decades, and so do our service and support.

Cat's marketing department is ... something. Seems like they're making gas turbines in a facility they call "Solar Turbines". Under the Oil & Gas category, of course.

06.11.2025 07:47 👍 1 🔁 0 💬 1 📌 0
Observability in Server-Side Swift - Si Beaumont & Moritz Lang
Observability in Server-Side Swift - Si Beaumont & Moritz Lang 🎥 Recorded at the ServerSide.swift conference in London in 2025. 🙌 Sponsored by Broken Hands: https://www.brokenhands.io 🐥 Twitter: https://twitter.com/swiftserverconf 🐘 Mastodon:…

Observability is the key to understanding how your system performs and where problems are occurring. Moritz Lang and Si Beaumont gives us the run down on how it works in Swift!

www.youtube.com/watch?v=HSxI...

05.11.2025 16:02 👍 4 🔁 3 💬 1 📌 0
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Roadmap for improving the type checker Roadmap for improving the type checker In the past, we've released various "manifestos" and "roadmaps" to discuss planned improvements to the language. This post is also a roadmap of sorts, but instead, the focus is on the implementation rather than user-visible language changes (however, I will briefly mention a few potential language changes at the very end). Specifically, I'm going to talk about some work we are doing to improve expression type checking in the Swift compiler. This includes c...

Nice writeup about plans wrt. the #swift typechecker by @slava@mathstodon.xyz

30.10.2025 22:47 👍 12 🔁 5 💬 0 📌 0
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Announcing the Swift SDK for Android Swift has matured significantly over the past decade — extending from cloud services to Windows applications, browser apps, and microcontrollers. Swift powers apps and services of all kinds, and thank...

A post from @joannis on the #Swift blog about the new preview of the Android SDK for Swift

www.swift.org/blog/nightly...

24.10.2025 21:33 👍 16 🔁 3 💬 0 📌 1

Good luck!! And thank you

12.10.2025 20:52 👍 4 🔁 0 💬 1 📌 0

Do you have an FB number with the crash report attached? Possibly even a repro you can share?

06.10.2025 19:29 👍 0 🔁 0 💬 1 📌 0

Made a little thing that may help you profile your services from within their own process -- no extra privileges or tools required.

06.10.2025 19:24 👍 10 🔁 5 💬 0 📌 0

Yeah, will switch to daytime pyro when we're all out for 4 hours or more too!

06.10.2025 17:39 👍 0 🔁 0 💬 0 📌 0
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Isn't that too beautiful? PM2.5 of an overnight pyrolytic oven clean starting at 1am.

Still woke up at 3am on account of bad air, despite closed doors and open windows in kitchen...

06.10.2025 06:37 👍 4 🔁 0 💬 2 📌 0

It's been an incredible year for the conference. We had attendees from 6(!) continents come together for an amazing 3 days of workshops, talks and meeting each other face to face. Thank you to all the volunteers and speakers, it's been truly special

03.10.2025 21:30 👍 20 🔁 6 💬 0 📌 1
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The new Swift configuration API makes the most of Swift's type checking and expressivity to make it eady to solve common config tasks. @czechboy0.dev walks us through its features @serversideswift.info

forums.swift.org/t/introducin...

03.10.2025 15:28 👍 11 🔁 3 💬 0 📌 1