type MyPick<Obj, Keys extends keyof Obj> = {
    [Key in Keys]: Obj[Key];
};

import { e } from 'type-exp';

function MyPick<T, K>(Obj: any, Keys: e.keyof<K>) {
    return e.map(Keys, (Key) => [Key, Obj[Key]]);
}

const todo = {
    title: e.string(),
    description: e.string(),
    completed: e.boolean(),
};

// Equivalent to =>
type TodoPreview = MyPick<Todo, "title" | "completed">;
console.log(MyPick(todo, e.union('title', 'description'));

// The result should be
// { title: 'string', description: 'string' }