Advanced Pattern Matching

Pattern matching has evolved C# from a purely Imperative language into a powerful Functional hybrid. It allows you to 'Deconstruct' and 'Branch' your logic with extreme precision.

1. Switch Expressions

Forget giant `switch` blocks. Expressions are cleaner and return a value:

string message = result switch {
    Success { Data: var d } => "Got " + d,
    Error { Code: 404 } => "Not Found",
    _ => "Unknown"
};

2. Relational & Logical Patterns

You can match values based on ranges and logic directly:

if (temp is > 0 and <= 30) { ... }
if (user is not null and { IsAdmin: true }) { ... }

This makes validation logic incredibly readable and hard to mess up.

4. Interview Mastery

Q: "What is 'Recursive Pattern Matching'?"

Architect Answer: "Recursive matching is when you match on the *properties* of an object inside a pattern. For example, `person is { Address: { City: "NY" } }`. This 'Deep Dive' allows you to validate complex object graphs in a single `if` or `switch` statement without writing multiple nested null checks. It is the gold standard for clean, defensive programming in .NET."