Records describe values, but with is a shallow copy

First, build a mental model

A record supplies value-oriented equality and convenient copying. A record class is still a reference type; its generated equality and a with expression do not recursively redesign the members you put inside it.

1. A positional record class supplies properties and generated value equality for its members.
2. with creates a new record instance with selected changes, leaving the original top-level values alone.
3. ReferenceEquals asks whether two references identify the same object; record == can report equal data for distinct instances.
4. A mutable referenced collection can still be shared after with. Ordinary List equality is not automatic sequence equality.

var original = new Player("Ada", 10);
var changed = original with { Score = 20 };
var equalData = new Player("Ada", 10);
Console.WriteLine(original.Score);
Console.WriteLine(changed.Score);
Console.WriteLine(original == equalData);
Console.WriteLine(ReferenceEquals(original, equalData));

record Player(string Name, int Score);

1. Copy with change

   changed is a new record with Score 20; original retains Score 10.

2. Value equality

   original and equalData have equal member values, so == is true.

3. Identity

   They are different instances, so ReferenceEquals is false.