import { List } from 'linqts';

let arr = new List<number>([1, 2, 3, 4, 5])
    .Where(x => x > 3)
    .Select(y => y * 2)
    .ToArray(); // > [8, 10]

let query = people.Join(pets,
    person => person,
    pet => pet.Owner,
    (person, pet) =>
        ({ OwnerName: person.Name, Pet: pet.Name }));