Only Android is missing from that list (marked as "Experimental"). We could argue about maturity but this is a bit subjective.
> Go also has somewhat better control over data layout
How? C# supports structs, ref structs (stack allocated only structures), explicit stack allocation (`stackalloc`), explicit struct field layouts through annotations, control over method local variable initialization, control over inlining, etc. Hell, C# even supports a somewhat limited version of borrow checking through the `scoped` keyword.
> This is meant to be something of a 1:1 port rather than a rewrite, and the old code uses plain functions and data structures without an OOP style.
C# has been consistently moving into that direction by taking more and more inspiration from F#.
The only reasonable reason would be extensive usage of structural typing which is present in TS and Go but not in C#.
That's sort of the problem with C#. It couples the type (struct vs class) with allocation. C# started life by copying 1990's Java "everything-is-a-reference". So it's in a weird place where things were bolted on later to give more control but still needs to support the all-objects-are-refs style. C# is just not ergonomic if you need to care about data layout in memory.
Go uses a C-like model. Everything is a value type. Real pointers are in the language. Now you can write a function that inputs pointers and does not care whether they point to stack, heap, or static area. That function can be used for all 3 types, no fuss.
> It couples the type (struct vs class) with allocation
Agree. Where things are allocated is a consumer decision.
> C# is just not ergonomic if you need to care about data layout in memory
I disagree. I work on a public high performance C# code and I don't usually face issues when dealing with memory allocations and data layout. You can perfectly use structs everywhere (value types) and pass references when needed (`ref`).
> Now you can write a function that inputs pointers and does not care whether they point to stack, heap, or static area.
You can do this perfectly fine in C#, it might not be what some folks consider "idiomatic OOP" but I could not care less about them.
Chances are it was just personal preference of the team and decades of arguing about language design have worn out Anders Hejlsberg. I don't think structural typing alone is enough of an argument to justify the choice over Rust. Maybe the TS team thought choosing Go would have better optics. Well, they won't have it both ways because clearly this decision in my opinion is short-sighted and as someone aptly pointed on twitter they will be now beholden to Google's control over Go should they ever need compiler to support a new platform or evolve in a particular way. Something they would've gotten easily with .NET.
On the topic of preference, this thread has really shown me that there is a HUGE preference for a native-aot gc language that is _not_ Go. People want AOT because of the startup and memory characteristics, but do not want to sacrifice language ergonomics. C# could fill that gap if Microsoft would push it there.
> While C# does have AOT capabilities nowadays this is not as mature as Go's and not all platforms support it
https://learn.microsoft.com/en-us/dotnet/core/deploying/nati...
Only Android is missing from that list (marked as "Experimental"). We could argue about maturity but this is a bit subjective.
> Go also has somewhat better control over data layout
How? C# supports structs, ref structs (stack allocated only structures), explicit stack allocation (`stackalloc`), explicit struct field layouts through annotations, control over method local variable initialization, control over inlining, etc. Hell, C# even supports a somewhat limited version of borrow checking through the `scoped` keyword.
> This is meant to be something of a 1:1 port rather than a rewrite, and the old code uses plain functions and data structures without an OOP style.
C# has been consistently moving into that direction by taking more and more inspiration from F#.
The only reasonable reason would be extensive usage of structural typing which is present in TS and Go but not in C#.