CoreCLR VS SharpLab

Yes, that is true. I'm not sure about JVM implementation details but the reason the comment says "virtual and interface" calls is to outline the difference. Virtual calls in .NET are sufficiently close[0] to virtual calls in C++. Interface calls, however, are coded differently[1].

Also you are correct - virtual calls are not terribly expensive, but they encroach on ever limited* CPU resources like indirect jump and load predictors and, as noted in parent comments, block inlining, which is highly undesirable for small and frequently called methods, particularly when they are in a loop.

* through great effort of our industry to take back whatever performance wins each generation brings with even more abstractions that fail to improve our productivity

[0] https://github.com/dotnet/coreclr/blob/4895a06c/src/vm/amd64...

[1] https://github.com/dotnet/runtime/blob/main/docs/design/core... (mind you, the text was initially written 18 ago, wow)

Sort of, some topic are not relevant anymore, consider this - https://github.com/dotnet/coreclr/tree/master/Documentation/botr

Fairly advanced stuff but the Book Of The Runtime (BOTR) it's a invaluable resource

After that you can check out the The Book of the Runtime, which is the CoreCLR version of the previous book.

Technically the restrictions already exist, just as a part of the development experience.

- .NET Hot Reload is only implemented on Windows. It requires support in the .NET runtime, which is technically possible to implement, but the team has not gotten around to implementing it for years. This doesn't have to do with the issue around MS removing the "dotnet watch" command, it's for the "Edit and Continue" feature in IDEs.[1][2]

- MS was considering deprecating Omnisharp, the open-source language server that implements C# support for VS Code, and replacing it with a closed-source version. Since the announcement, commits to omnisharp-vscode have dropped off significantly. The lack of Omnisharp would mean there would be no real open-source C# development environment for Linux anymore, since MonoDevelop was abandoned a few years ago. [3]

[1] https://youtrack.jetbrains.com/issue/RIDER-31366/EditContinu...

[2] https://github.com/dotnet/coreclr/issues/23685

[3] https://github.com/omnisharp/omnisharp-vscode/issues/5276

The next step is to realize everything you think you know about .NET is just an abstraction. Next step is to learn about what is going on behind all that syntax sugar and facades. 1st step might be https://github.com/dotnet/coreclr/tree/master/Documentation/botr then go down the rabbit hole and have fun

Book of the Runtime

As for the books, back in the days I really enjoyed reading “CLR via C#" by Jeffrey Richter which helped a lot to understand what is under the hood. Other from that, try The Book of the Runtime

Do these all compile to the exact same thing?

https://sharplab.io/#v2:CYLg1APgAgTAjAWAFBQMwAJboMLoN7LpHoCW...

Yes, so you are right.

Recently, while creating some experimental C# source code generators (xafero/csharp-generators), I was just concatenating strings together. Like you do, you know, if things have to go very quickly. If you have a simple use case, use a formatted multi-line string or some template library like scriban. But I searched for a way to generate more and more complicated logic easily - like for example, adding raw SQL handler methods to my pre-generated DBSet-like classes for my ADO.NET experiment. You could now say: Use Roslyn and that's really fine if you look everything up in a website like SharpLab, which shows immediately the syntax tree of our C# code.

One results in MOVSX, the other in MOVZX [1]. The difference thus is sign/zero extension when moving to the larger register. However, they seem to perform pretty much identical if I'm reading Agner Fog's instruction tables correctly.

[1] https://sharplab.io/#v2:C4LghgzgtgPgAgJgIwFgBQcDMACR2DC2A3ut...

If you don't have an IDE, you can use SharpLab.io or dotnet fiddle

The closest online tool I can think of would be SharpLab, but you can only choose between Roslyn's git branches instead of C# versions.

Your code is destructuring two properties and discarding one of them. It doesn't work with a single property: https://sharplab.io/#v2:C4LgTgrgdgNAJiA1AHwAICYAMBYAUBgRj2Nw...

I think that records don't generate a deconstruct method when they only have one property, but even if you manually define one you'll get an error on `var (varName) = ...`

- LinqPad is great and I love, but, IMO, it is not the best tool to start with. It does not provide intellisense or debugger in the free version. Assuming you do not want to pay for this licence just to play a little with the language, I'd suggest https://sharplab.io/. It is not as powerfull as LinqPad, but at least it gives you suggestions.