C# value types vs reference types: class vs struct vs record explained

// ======================================================================
// Q: Value types vs reference types. class vs struct vs record?
//
// - Value types (int, struct, enum): the value is copied on assignment. They
//   live inline (on the stack or inside the object that contains them).
// - Reference types (class, string, arrays): the variable holds a reference to
//   an object on the heap, which the GC cleans up.
// - struct: for small, immutable values (e.g. readonly struct Point). class: for
//   objects with identity and behavior. record: a reference type with value
//   equality, with-expressions and immutability. Ideal for DTOs and value
//   objects. There is also record struct.
// ======================================================================

public record Money(decimal Amount, string Currency);

var a = new Money(10, "EUR");
var b = a with { Amount = 20 };                 // new object, a does not change
Console.WriteLine(a == new Money(10, "EUR"));  // True: compares values, not references