//primary constructors - 
public class Point(int x, int y) { }
//read only auto-properties - 
public int X { get; } = x;
//static type using statements - 
using System.Math;
//property expressions - 
public double Distance => Sqrt(X * X + Y * Y);
//method expressions - 
public Point Move(int dx, int dy) => new Point(X + dx, Y + dy);
//params for enumerables - 
public Point Average(params IEnumerable<Point> points) { }
//monadic null checking - 
if (points?.FirstOrDefault()?.X ?? -1) { }
//constructor type parameter inference - 
var t = new Tuple(1,2); // infers Tuple<T1, T2>
//inline declarations for out params - 
public void Foo(out var x, out var y) { }