Should interfaces and their properties be implicitly `readonly`?

With the readonly-keyword rule, Interfaces throw errors if their properties don't have the keyword. Should interfaces and their properties be implicitly readonly?

// Error
export interface IUserAuthenticationResponse {
  result: boolean;
  data: any;
  errors: any[];
}

// Happy
export interface IUserAuthenticationResponse {
  readonly result: boolean;
  readonly data: any;
  readonly errors: any[];
}

// Error
readonly export interface IUserAuthenticationResponse {
  result: boolean;
  data: any;
  errors: any[];
}

[jonaskello]

I don't think you can put the readonly modifier directly on an interface like that?

If I compile your last example I get this:

error TS1024: 'readonly' modifier can only appear on a property declaration or index signature.

Right, but that's what I'm asking. Should that be the case? When are people mutating interfaces? They aren't instantiated by other instances. They're just adhered to within typed entities.

[jonaskello]

Sure, if you ask me interfaces (and everything else) should be immutable by default in typescript :-).

However if I understand what you are asking correctly this is nothing we can change within the scope of tslint-immutable. Perhaps this discussion should be moved to the typescript repo? Or do you have some action in mind that fits within the scope of this repo?

[jonaskello]

I'm closing this as I cannot see any action we can take but feel free to continue with the discussion.

If anyone stumbles upon this, an ignore-interface option has been added to the readonly-keyword rule. https://github.com/jonaskello/tslint-immutable#using-the-ignore-interface-option