given that most of the thinks added seem more inspired by other languages then "moved over" from F# the "other languages struggle with" part makes not that much sense
like some languages which had been ahead of C# and made union type a "expected general purpose" feature of "some kind":
- Java: sealed interfaces (on high level the same this C# features, details differ)
- Rust: it's enum type (but better at reducing boilerplate due to not needing to define a separate type per variant, but being able to do so if you need to)
- TypeScript: untagged sum types + literal types => tagged sum types
- C++: std::variant (let's ignore raw union usage, that is more a landmine then a feature)
either way, grate to have it, it's really convenient to represent a `TYPE is either of TYPES` relationship. Which are conceptually very common and working around them without proper type system support is annoying (but very viable).
I also would say that while it is often associated with functional programing it has become generally expected even if you language isn't functional. Comparable to e.g. having some limited closure support.
The only things that I wish for are: rusts borrow-checker and memory management. And the AOT story would be more natural.
Besides that, for me, it is the general purpose language.
I honestly have no idea where you would get this idea from. C# is a pretty opinionated language and it's worst faults all come from version 1.0 where it was mostly a clone of Java. They've been very carefully undoing that for years now.
It's a far more comfortable and strict language now than before.
`.ConfigureAwait(bool)` is another where it is relevant, but only in some contexts.
This is precisely because the language itself operates in many runtime scenarios.
But I'm not sure that's really a problem. Does the OP expect everyone to use an entirely different languages every single context? I have web applications and desktop applications that interact with Office that share common code.
Even `dynamic` is pretty nice as far as weird dynamic language features are concerned.
Interestingly enough `.ConfigureAwait(bool)` is entirely the opposite of `dynamic` -- it's not a language feature at all but instead a library call. I could argue that might instead be better as a keyword.
The reason I bring it up is that it is another one of those things where it matters in some cases depending on what you're doing.
Look at the depths that Toub had to go through to explain when to use it: https://devblogs.microsoft.com/dotnet/configureawait-faq/
David Fowl concludes in the comments:
> That’s correct, most of ASP.NET Core doesn’t use ConfigureAwait(false) and that was an explicit decision because it was deemed unnecessary. There are places where it is used though, like calls to bootstrap ASP.NET Core (using the host) so that scenarios you mention work. If you were to host ASP.NET Core in a WinForms or WPF application, you would end up calling StartAsync from the UI thread and that would do the right thing and use ConfigureAwait(false) internally. Request processing on the other hand is dispatching to the thread pool so unless some other component explicitly set a SynchronizationContext, requests are running on thread pool threads.
>
> Blazor on the other hand does have a SynchronizationContext when running inside of a Blazor component.
This is a good example of C# light-touch on language design. Async/await creates a state machine out of your methods but that's all it does. The language itself delegates entirely to platform/framework for the implementation. You can swap in your own implementation (just as it possible with this union feature)
> So I bring this up as a case of how supporting multiple platforms and runtime scenarios does indeed add some layer of complexity.
I agree that's true. A language that doesn't support multiple platforms and runtime scenarios can, indeed, be simpler. However that doesn't make the task simpler -- now you just have to use different languages entirely with potentially different semantics. If your task is just one platform and one runtime scenario, the mental cost here is still low. You don't actually need to know those other details.
Yes, C# is a jack of all trades and can be used at many things. Web, desktop mobile, microservices, CLI, embedded software, games. Probably is not fitted for writing operating systems kernels due to the GC but most areas can be tackled with C#.
Midori would like to have a word with you: