Hey #dotnet people! Exciting news! I've launched my YouTube channel: "Dissecting the Code".

It's going to be very similar to my blog, where I'll cover .NET internals, performance tips & tricks, and more deep dives. #csharp

I've already published the first two videos:
➡️ Episode 0: W➡️ Episode 1: Dissecting Variable Lifetime
I hope you'll like it! Please share, subscribe, and let me know what you think! Your support means a lot to me. 🙏
Links to the channel & videos are 👇

Heya! 🥳 Today I released CodeAlta 1.0.0, the AI coding agent developed in C# .NET (mostly) which includes a brand-new desktop frontend! 🚀 Works with your ChatGPT / Copilot subscriptions and more. Single file C# plugins also supported there! 🤯

A very nice read. I have a different experience using LLMs day-to-day, but, boy, love Mark’s take on this!

Opus 5, Medium reasoning.

I have a skill that explicitly asks to use a dedicated skill for creating a PR. The agent ignored the instruction.

The reason? ¯_(ツ)_/¯

But the coding is definitely solved, folks!

It's been just over a month since my first Dometrain course, Mastering C#, was released.

I wasn't sure how a 3.5-hour deep dive into C# would land, but it's #2 trending course today and was one of Dometrain's five most-viewed courses last month!

Use code MASTERING40 for 40% comment.

And here is the link to the course: dometrain.com/course/masteri…

On a non-technical side (that I very rarely share here). I’ve started bouldering about a year ago, and Yesterday I did my first V6!
This one definitely matched my style: physical, not particularly technical with very grippy holds. But still, it was amazing to do it!

.NET Team should pay better attention to the docs, since a lot of people assume the examples are best practices.

Here is an anti-example: don't extend IEnumerables with indexers that calls ElementAt.

Indexer has an assumption that the cost is O(1).

Here is the link to the doc: learn.microsoft.com/en-us/dotnet/c…

Ok scrap that. Had a chat and it turns out it is 100% happening but they’ve been slow announcing it. We need more transparency on the biggest .NET event of the year but I’m so glad they’re doing it

I'm super happy to announce that, after 4 months working on it, my course Mastering C# is now live on Dometrain!

The internals of records, structs, classes, union types, pattern matching, LINQ and much more: all covered in 3+ hours of advanced content.

If you love to understand rse is definitely for you.

#dotnet #csharp

Here is the link to the course with a 30% discount automatically applied:
dometrain.com/course/masteri…

And happy learning to you all!

New video on Dissecting the Code YouTube Channel: "How LINQ works?" - youtu.be/hFKCOeUfZaA?si…

I've seen too many cases when misunderstanding of IEnumerables was causing confusion for devs and the desire to ban LINQ in the codebases altogether.

To understand LINQ we should understand iterator blocks. And this is what I'm covering for almost 20 minutes! :)

"Zero" cost delegates in .NET 10

JIT in .NET 10 in some cases can fully eliminate the abstraction cost of using delegates.

Enumerable.Any can be as efficient as hand-written loop that takes a span out of a list!

More information in my latest episode on Dissecting the Code YouTube channel: youtu.be/-h5251IWv-Y?si…

Next video on Dissecting the Code channel. This time I cover .NET 10 performance improvements around de-abstracting the delegates.

In .NET 10, the LINQ Any method can easily outperform a manual loop over a list! Awesome job, .NET team!

youtu.be/-h5251IWv-Y?si…

As always, would appreciate spreading the word and sharing the video.

And if you have recommendations on what I can cover next, I'll be happy to hear that!

I wanted to understand how GPT works, so I ported Karpathy's microgpt.py to C# from scratch. No frameworks and NuGet packages, just plain math in ~600 lines of code.

It builds a tiny GPT that learns from 32K human names and invents new ones. Every piece is there: autograd, attention, Adam optimizer, the works. Just at a scale you can actually sit down and read.

I also wrote a prerequisites guide that walks through all the math and ML you need, starting at a high school level. If you've ever wanted to peek under the hood of ChatGPT without drowning in linear algebra textbooks, this might help.

github.com/milanm/AutoGra…

Another video on Dissecting the Code YouTube channel: "ConfigureAwait best practices".

I feel we have a cargo cult on using ConfigureAwait without thinking too much.

I've seen cases when the application code was filled with it "to improve performance" or "to avoid deadlocks". And it was very hard to convince that this is not how ConfigureAwait should be used.

In this video I'm covering why we have ConfigureAwait in the first place and how to use it correctly.

youtu.be/bUHQeY-DlBc?si…

And, as always, thanks for sharing the video!

/cc: @davidfowl, @shanselman, @dotnet, @VisualStudio

New issue of .NET R&D Digest! Thx to @rfleury, @unmeshjoshi, @martinfowler, @simonw, @ricomariani, @andrewlocknet, @AntonMartyniuk, @stevejgordon, @KooKiz, @chnasarre, @meziantou, @markrichardssa, @STeplyakov and other g8 authors for g8 content!

olegkarasik.wordpress.com/2026/02/02/net…

#dotnet