## Output Format

### Expanded Code

When expanding a file like this:

TypeScript

```
/** @derive(Debug) */
class User {
  name: string;
  age: number;

  constructor(name: string, age: number) {
    this.name = name;
    this.age = age;
  }
}
```

The CLI outputs the expanded code with the generated methods:

TypeScript

```
class User {
  name: string;
  age: number;

  constructor(name: string, age: number) {
    this.name = name;
    this.age = age;
  }

  [Symbol.for("nodejs.util.inspect.custom")](): string {
    return `User { name: ${this.name}, age: ${this.age} }`;
  }
}
```

### Diagnostics

Errors and warnings are printed to stderr in a readable format:

Text

```
[macroforge] error at src/user.ts:5:1: Unknown derive macro: InvalidMacro
[macroforge] warning at src/user.ts:10:3: Field 'unused' is never used
```