I find the acceptance and defense of mediocrity to be deeply depressing. This is true not just in the context of large language models, but particularly in the case of certain scholars and politicians.

Have you tried #fsharp yet? Give it a spin with AI is easy, cheap, and you can quickly compare it with other code or ask AI why it could be better than other programming languages as a choice for your next project or side script for fixing a bug! 🤓 deterministic type inference🩵 + type providers💘

F# Weekly #20, 2026 - .NET 11 Preview 4 and SwaggerProvider 4.0 #fsharp sergeytihon.com/2026/05/16/f...

Oh nice, Scott Wlaschin's Domain Modeling Made Functional is in the Functional Programming Humble Bundle! #fsharp https://www.humblebundle.com/books/ultimate-functional-programming-pragmatic-programmers-books

Situation 1: dev A thinks approach X is correct, dev B thinks Y is the right way. They argue and try to convince each other. Situation 2: dev A thinks approach X is correct, tells the LLM to implement it. There is SO MUCH learning in Situation 1, lost when using LLMs....

In the sixth part of my blog post series on event sourcing, we'll take a look at event versioning and migration. I show 4 different approaches. Today, a deep dive is included into zero downtime migration of event streams. www.planetgeek.ch/2026/05/19/e... #EventSourcing #fsharp #dotnet

I GET LOGGED OUT. BUT I LOG IN AGAIN

If you know, you know: ✋🔺🤚 😄

#fsharp 👇

When people say they can build 10 times as many features now with AI as in pre-AI days, I wonder what they mean by "building a feature". For me, building a feature means: - Selecting what to invest time into next (hopefully the most valuable thing). 1/5

I'll be speaking at the .NET Day Switzerland (dotnetday.ch ) on Tuesday, August 25th, in Zurich, about "Mis-Estimating – why estimating effort does not work" So, if you need arguments for getting rid of effort estimation, join this session; I have plenty. 😅

The fifth part in my event sourcing series is about compensating unsuccessful commands and why we don't (only) use transactions. Today, again with a deep dive into code and some SQL. As always with the reasoning behind our decisions. www.planetgeek.ch/2026/05/12/e... #EventSourcing #dotnet #fsharp

OH “The talk had two parts: Things I already knew and things I didn’t understand.”

AI is great. Yes, I think AI is great - even if my posts sometimes might suggest otherwise. 😅 AI is a non-stop companion during my work hours: AI completes code lines for me, acts as my rubber duck, helps me analyse code and bugs, does research for me, finds me acceptable names for stuff, ... 1/7

Part 4 of my event sourcing series is about preventing long event streams. Why it is important, what alternatives exist and when to choose what. www.planetgeek.ch/2026/05/05/e... #EventSourcing

So you say that to use agents to produce software, I need a rather detailed, clear spec. Detailed enough so that the agent doesn't invent stuff on its own - no assumptions needed to fulfil the spec.

Most languages let you pattern-match on what data IS. #FSharp lets you pattern-match on what data MEANS. Active Patterns reshape data so you can match on business concepts instead of raw structure. And they compose. 🔗 rdeneau.gitbook.io/safe-clean-a... #DotNet #PatternMatching #FuncProg

The third post in my event sourcing series covers read models and their benefits and drawbacks: www.planetgeek.ch/2026/04/28/e... It also includes a deep dive into an example. #dotnet #fsharp #EventSourcing

And back home.

Reached the highest point (1172m gain). Now, a lot of trails ahead.

Second climb done (now at 1000m elevation gain). Time for a brookie (mix of brownie and cookie made by my daughter). And again a couple of trails ahead). #eMTB

First climb done (599m elevation gain). Time for lunch. Afterwards the first nice downhill trail. #eMTB

Current situation #eMTB

Model-Shootout: I built a custom AI agent using #fsharp that turns #GitHub Issues into Pixograms for our #pxlclock. Same idea run with Frontier models (#claude) and self-hosted like #Qwen and #gpt-oss. Results: schlenkr.github.io/pxl-clock/ (buy a clock if you like it: www.pxlclock.com/?ref=RONALD)

The second post in my event sourcing series is about how to enable better query capabilities to find the needed event streams while still holding back on read models. Of course, with the reasoning why this is a good idea in the right context. www.planetgeek.ch/2026/04/21/e...

F# Weekly #16, 2026 - .NET 11 Preview 3 & SwaggerProvider 4.0 beta #fsharp sergeytihon.com/2026/04/19/f...

The start of my new blog post series about Event Sourcing. The first post starts with a simple projection-only approach: www.planetgeek.ch/2026/04/14/e... You'll see why we don't use event numbers for ordering, but timestamps, and why this is our default approach. #EventSourcing #dotnet #fsharp

Obviously, I spent some time on my #eMTB in the last 12 months (and the 12 before as well) 🙈

The Mega Drive game I believe has aged the worst.

I love that FSharp.Data is being worked on again #fsharp github.com/fsprojects/F...

Lately, I see a lot of posts saying we need a robust suite of automated tests to ensure AI agents produce high-quality results. Please keep in mind that one cannot test quality into a software product. Automated tests are a necessity, but they are by far not sufficient as a sole approach. 1/2

@schlenkr.bsky.social regarding @PXLclock: is the currently running Random Colour Wheel still the F# version, or the C# one? I'm asking because there are some colour errors from time to time.

Grab the #pxlclock VS Code extension ("PXL Clock), code your own pixogram in #csharp, and ping me here: I'll record it on the real hardware and post the video. Who makes the coolest one? VS Code: marketplace.visualstudio.com/items?itemName=pxlclock.pxl-clock #pxlclock #csharp #fsharp

F# Weekly #14, 2026 - Serde.FS Brings Compile-Time RPC to F# #fsharp sergeytihon.com/2026/04/05/f...

Happy 83rd birthday to Christopher Walken.

We started using event sourcing over ten years ago. One of the hardest lessons was that there is a kind of events that is not obvious at first but have a big impact on your system design. I call this kind secondary domain events. www.planetgeek.ch/2026/04/01/t... #EventSourcing

F# Weekly #13, 2026 - Deedle 4.0 is out! #fsharp sergeytihon.com/2026/03/29/f...

I'm not a fan of "let's throw more resources at the problem" solutions. What currently happens in the AI-assisted software development community is, however, exactly this: 1/3

From sourcecode to step-by-step tutorial: I wanted to advertise the #pxlclock using programming tutorials. So I built this: - AI breaks the #csharp code into steps; thanks @ursenzler.bsky.social - Renders animations - Writes tutorial - Remotion makes the reel Want a video about how I did that?

The 5th and final part of my post series about "to test, or not to test" takes a look at why the shown concepts help with LLMs and concludes the series. www.planetgeek.ch/2026/03/24/t... Do you like these longer topics, or do you prefer short single posts?

🎉 Deedle 4.0.1 is out! The F# data frame library just got a massive update - new packages, new operations, better stats, performance wins, and many long-standing bugs squashed. A huge amount of community-originated requests in one release. Full notes 👇 github.com/fslaborg/Dee... #fsharp #dotnet

Part 4 of my blog post series about "to test, or not to test" is about making manual testing easy, and why it matters: www.planetgeek.ch/2026/03/19/t.... Can you run your system locally and/ or test things quickly, or do you have to wait for a test environment?

In part 3 of my blog post series on "to test or not to test", I take a look at how to recover from a defect if it finds its way into production anyway: www.planetgeek.ch/2026/03/17/t... What are your approaches to recovering easily from a defect?

“It is the next plausible-sounding token predictor's assumptions which get shipped to production” is a present-day twist to @ziobrando.bsky.social's quote: “It is the developer’s assumptions which get shipped to production.” If the original one was worrying, the latter is scary.

Second part of my series on "To test or not to test": What if we weren't allowed to write automated tests? What concepts, approaches, and tools would help us? www.planetgeek.ch/2026/03/12/t...

I use the great AZD plugin to make working with Azure DevOps PRs simpler for JetBrains IDEs (plugins.jetbrains.com/plugin/22319... ). One of its many features is an AI-driven PR review. It gave me many good pointers, but it should sharpen its F# knowledge 😀 1/3 #fsharp #dotnet #JetBrains

To test or not to test? Start of my blog post series about testing and other ways to ensure quality: www.planetgeek.ch/2026/03/10/t...

"We don't need software engineers anymore; AI agents can generate the code from specifications. We only need people who can write a precise specification that can be understood by an agent." What you need is a software engineer, then. #AI #LLMs #Agents

RE#: how we built the world's fastest regex engine in F# iev.ee/blog/resharp... #regex #fsharp

A typical Monday, which is also the first day of the month, is ending for our application for time-tracking and the like. The first two days of every month see higher loads because people close their previous month's accounts. Thanks to Azure, everything scales automatically with load. #Cloud