Type aliases and higher order functions with Typescript

Thing.ts

type Thing = {
    shape: Shape,
    size: number,
}

enum Shape {
    Circle,
    Square,
    Rectangle,
    Triangle,
}

type ThingOption = (thing: Thing) => void;

function WithShape(shape: Shape) {
    return function(thing: Thing) {
        thing.shape = shape;
    }
}

function WithSize(size: number): ThingOption {
    return function(thing: Thing) {
        if (size < 1) {
            throw new Error("size can't be less than 1");
        }

        thing.size = size
    }
}

function NewThing(...options: ThingOption[]): Thing {
    let thing: Thing
    options.forEach(option => option(thing));
    return thing;
}

const thing = NewThing(
    WithShape(Shape.Square),
    WithSize(3),
);