nint nativeInt = 55; take 4 bytes when I compile in 32 Bit host.  
nint nativeInt = 55; take 8 bytes when I compile in 64 Bit host with x64 compilation settings. 

public class Point3D(double X, double Y, double Z);  
public class Demo   
{  
 public void CreatePoint()  
 {  
 var p = new Point3D(1.0, 1.0, 1.0); 
 } 
} 

public class Point3D  
{  
private readonly double <X>k__BackingField;  
private readonly double <Y>k__BackingField;  
private readonly double <Z>k__BackingField;  
public double X {get {return <X>k__BackingField;}}  
public double Y{get{return <Y>k__BackingField;}}  
public double Z{get{return <Z>k__BackingField;}}  
  
 public Point3D(double X, double Y, double Z)  
 {  
 <X>k__BackingField = X;  
 <Y>k__BackingField = Y;  
 <Z>k__BackingField = Z;  
 }  
  
 public bool Equals(Point3D value)  
 {  
 return X == value.X && Y == value.Y && Z == value.Z;  
 }  
   
 public override bool Equals(object value)  
 {  
 Point3D value2;  
 return (value2 = (value as Point3D)) != null && Equals(value2);  
 }  
  
 public override int GetHashCode()  
 {  
 return ((1717635750 * -1521134295 + EqualityComparer<double>.Default.GetHashCode(X)) * -1521134295 + EqualityComparer<double>.Default.GetHashCode(Y)) * -1521134295 + EqualityComparer<double>.Default.GetHashCode(Z);  
 }  
}  
   
Using Records:  
   
public class Demo  
{  
 public void CreatePoint()  
 {  
 Point3D point3D = new Point3D(1.0, 1.0, 1.0);  
 }  
} 

var newPoint3D = Point3D.With(x: 42); 

type Greeter(name: string) = member this.SayHi() = printfn "Hi, %s" name 

class Greeter(name: String)   
{  
  def SayHi() = println("Hi, " + name)  
} 

class Greeter(val name: String)   
{  
 fun sayhi()   
 {  
 println("Hi, ${name}");  
 }  
}

public class Greeter
{
 private readonly string _name;
 public Greeter(string name)
 {
 _name = name;
 }
 public void Greet()
 {
 Console.WriteLine($ "Hello, {_name}");
 }
}

ublic class Greeter(name: string)   
{  
 public void Greet()   
 {  
 Console.WriteLine($ "Hello, {_name}");  
 }  
} 

class Eq a where   
(==) :: a -> a -> Bool  
(/=) :: a -> a -> Bool 

interface Num<A>   
{  
 A Add(A a, A b);  
 A Mult(A a, A b);  
 A Neg(A a);  
}  
   
struct NumInt : Num<int>   
{  
 public int Add(int a, int b) => a + b;   
 public int Mult(int a, int b) => a * b;   
 public int Neg(int a) => -a;  
} 

shape Num<A>  
{  
 A Add(A a, A b);  
 A Mult(A a, A b);  
 A Neg(A a);  
}  
   
instance NumInt : Num<int>  
{  
 int Add(int a, int b) => a + b;   
 int Mult(int a, int b) => a * b;   
 int Neg(int a) => -a;  
} 

public shape SGroup<T>   
{   
 static T operator +(T t1, T t2);   
 static T Zero {get;}    
}

public extension IntGroup of int: SGroup<int>  
{  
 public static int Zero => 0;  
} 

public static AddAll<T>(T[] ts) where T: SGroup<T> // shape used as constraint  
{  
 var result = T.Zero; // Making use of the shape's Zero property  
 foreach (var t in ts) { result += t; } // Making use of the shape's + operator  
 return result;  
} 

int[] numbers = { 5, 1, 9, 2, 3, 10, 8, 4, 7, 6 };    
WriteLine(AddAll(numbers)); // infers T = int 

// C# 1..8  
var x = new Dictionary <string,int> () { { "foo", 4 }, { "bar", 5 }};  
// C# 9  
var x = ["foo":4, "bar": 5]; 

void Foo(params Span<int> values); 

public struct Rational  
{  
 private long numerator;  
 private long denominator;  
  
 public Rational(long num, long denom)  
 { /* Todo: Find GCD etc. */ }  
  
 public Rational(long num)  
 {  
 numerator = num;  
 denominator = 1;  
 }  
   
 public Rational() // This is not allowed  
 {  
 numerator = 0;  
 denominator = 1;  
 }  
} 

public fixed DXGI_RGB GammaCurve[1025]; 

[FixedBuffer(typeof(DXGI_RGB), 1024)]  
public ConsoleApp1.<Buffer>e__FixedBuffer_1024<DXGI_RGB> GammaCurve;  
  
// Pack = 0 is the default packing and should result in indexable layout.  
[CompilerGenerated, UnsafeValueType, StructLayout(LayoutKind.Sequential, Pack = 0)]  
struct <Buffer>e__FixedBuffer_1024<T>  
{  
 private T _e0;  
 private T _e1;  
 // _e2 ... _e1023  
 private T _e1024;  
 public ref T this[int index] => ref (uint)index <= 1024u ?  
 ref RefAdd<T>(ref _e0, index):  
 throw new IndexOutOfRange();  
} 

System.UTF8String myUTF8string ="Test String"; 

interface I1
{ 
  void M(int) { }
}

interface I2
{
  void M(short) { }
}

interface I3
{
  override void I1.M(int) { }
}

interface I4 : I3
{
  void M2()
  {
    base(I3).M(0) // Which M should be used here? What does this do?
  }
}