> Proper IEnumerable with proper iterators that in turn enables Linq
Are you referring to generators?
> Properties
As far as I'm aware, it is a deliberate choice not to implement them, and I can see their point of view.
> object initialisers
I believe the same justification applies here, it's mainly syntactic sugar, and can result in certain undesired behavior by bypassing constructors where validation can happen.
> extension methods
Typeclasses are currently being explored, which are a superior approach.
> named and optional arguments in functions
Those would be nice (at least named arguments). I can see how optional arguments could complicate things.
> generics over primitive types
As you mentioned, it's in the works
> async/await... verbiage could still probably be hidden behind a friendlier syntax
The approach they took does not need any extra syntax.
> Are you referring to generators?
Both I guess.
Main thing is https://learn.microsoft.com/en-us/dotnet/api/system.collecti... which seems to be everywhere in the language and the library.
> I believe the same justification applies here, it's mainly syntactic sugar, and can result in certain undesired behavior by bypassing constructors where validation can happen.
This is mostly due language design. Java heavily relies on properties and provides no facilities for them. Hence the builder pattern instead of object initializers.
In C# object initializers synergize with properties: https://learn.microsoft.com/en-us/dotnet/csharp/programming-...
> The approach they took does not need any extra syntax.
You mean it needs 15 lines whete C# needs one? ;)