ValueOf VS csharplang

As we anticipate advancements in C#, we can still forge ahead with crafting resilient applications by utilizing the "ValueOf" package as a provisional solution. Below, we create a validated EmailAddress class leveraging the package:

Probably better to use something like https://github.com/mcintyre321/ValueOf until we get a better solution (if we ever do). I agree that this is a pitfall.

The problem you’re describing here I think is ‘primitive obsession’, and the solution you’ve described is I think essentially a value object. This library might be useful https://github.com/mcintyre321/ValueOf

It lacks compile-time validation (though an analyzer that at least detects validation errors in the constructor should be fairly easy; more complicated flow control cases are probably hard), but at runtime, https://github.com/mcintyre321/ValueOf would let you do that.

If you want to wrap a small number of properties in a type to avoid primitive obsession, consider using ValueOf.

You might be able to create a wrapper type with something like ValueOf.

I good library I've found for addressing this issue is https://github.com/mcintyre321/ValueOf

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.