SharpLab VS csharplang

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.

Certain parts of Microsoft Learn are permissive, for example the .NET BCL documentation is Creative Commons Attribution: https://github.com/dotnet/dotnet-api-docs as is ASP.NET Core: https://github.com/dotnet/AspNetCore.Docs (a good hint if documentation is permissively licensed and on GitHub is if there's an edit button at the top.)

The C# language specification is unfortunately a bit fuzzier: https://github.com/dotnet/csharplang/discussions/4855

The updated unified C# language specification is CC, but it's still catching up to modern C#: https://github.com/dotnet/csharpstandard

No OP, but for example you still see the C# folks still struggling to add discriminated unions to the language because of complex interactions due to its too many features[1]. Virtual threads are easier to use than async/await is another example.

[1] https://github.com/dotnet/csharplang/issues/113

For example, C# had a research fork called Spec# that had compile-time support for contracts, with keywords such as requires (for arguments) and ensures (for return values), all the way back in 2004. While still being discussed, it doesn't seem to be shipping any time soon.

Hi there. I'm the language designer who created the 'Collection Expression' design/specification: https://github.com/dotnet/csharplang/issues/5354

You can see the entire history of the proposal there. To answer you specific question, we went with `..` because that's what the language already uses for the complimentary 'pattern matching deconstruction' form for collection patterns.

In other words, you can already say this today:

    if (x is [var start, .. var middle, .. var end]) { ... }

You must specify concrete type.

There was a plan to have "natural type" so "var list = [1,2,3]" would be of type "List" but it was postponed to C# 13 (https://github.com/dotnet/csharplang/issues/5354#issuecommen...)

While C# currently lacks direct support for this kind of functionality, there's a glimmer of hope with an active proposal under discussion that aims to bring this feature to the language. This potential addition promises a future where C# can natively offer similar robust type narrowing.

Given few people anticipated ValueTuple and C# adding a more direct tuple syntax, I feel like it is only a matter of time before C# adds discriminated unions.

(There are multiple proposals tracking the idea. This seems the most comprehensive and "central": https://github.com/dotnet/csharplang/issues/7016)

I always liked list abbreviations in python, but I absolutely love Linq. I believe there is a feature proposal for C# 12, which makes collection initialization better imo.