Possible to get a "difference" type i.e. type A - type B ?

[AJamesPhillips]

Given:

interface Base {
  field1: string;
}
interface ConcretePartial {
  field2: string;
}
interface Concrete extends Base, ConcretePartial {
}

var some_base_fields: Base = {field1: ''};
var extra_fields_for_concrete: ConcretePartial = {field2: ''};
var new_object: Concrete = _.assign<{}, Base, ConcretePartial>({}, some_base_fields, extra_fields_for_concrete)

I'm wondering if it is possible to get a type with the structure of Concrete ∖ Base (i.e. {field2: string }) so that instead you could use:

var new_object: Concrete = _.assign<{}, Base, Concrete ∖ Base>({}, some_base_fields, extra_fields_for_concrete)

I've read https://www.typescriptlang.org/docs/handbook/advanced-types.html and checked the issues and it doesn't seem possible. I wanted to confirm that that's the case and if there were any plans for this "shorthand" type difference notation? Also if there's a better pattern to use when dealing with extended interfaces, for example the OOP class approach would simplify this but I was curious if it's possible to do easily with interfaces?

[kitsonk]

Dupe of #4183