I’m trying to construction a function where you pass an object, and an array of keys (This is a simplified example to illustrate what im trying to achieve). Then return is an array that contain those keys, and has the type of a tuple. The problem that I’m struggling with is that the return type is the union of all types in the interface, not the actual value of the given key.

I tried adding the const parameter to the function but to no avail. I guess the error lies in the K parameter not infering the key granular enough..?

type User = {
    name: string,
    location: string
    age: number    
}

const fooUser: User = {
    age: 30,
    name: "Foo",
    location: "Bar",
}

const getSelected = <T extends User, const K extends readonly(keyof User)[]>(user: T, keys: K) => {
    return keys.map((key) => user[key]);
}

const [age, userName] = getSelected(fooUser, ['age', 'name'])
        //  ^? const age: string | number

// Would want the array typed as [string, number]