I have these types

type Asset = {
    id: string,
    name: string,
    recordedBy: string
}

type User = {
    id: string,
    name: string,
    dob?: Date
}

type Device = {
    id: string,
    name: string,
    location: [number, number]
}

// etc...

I have a Class

type Name = 'asset' | 'user' | 'device' // etc.

type Convert<N extends Name> =
    N extends 'asset' ? Asset
    : N extends 'user' ? User
    : N extends 'device' ? Device : N

class Read<N extends Name>
{
    name: N;

    constructor(name: N)
    {
        this.name = name;
    }

    get = async (): Promise<Convert<N>> =>
    {
        // code here
    };
}

When I use the Class above

const read = new Read('user');
const user = await read.get();

The type of the variable user is what I expect (User).

But I have a function like this

const build = <N extends Name>(names: N[]): Read<N>[] =>
{
    return names.map(name => new Read(name));
};

const [readAsset, readDevice] = build(['user', 'device']);

Types of readAsset and readDevice aren’t what I expect

const readAsset: Read<"asset" | "device">
const readDevice: Read<"asset" | "device">

So when I run get in each ones.

const asset = await readAsset.get();
const device = await readDevice.get();

Types of those results are

const asset: Asset | Device
const device: Asset | Device

What should I do in order to change results to

const readAsset: Read<"asset">
const readDevice: Read<"device">

As well as

const asset: Asset
const device: Device

Without casting

I also expect we use the function build. Thank everbody.