cartesian product using transducers

cartestian_product.ts

import * as tx from '@thi.ng/transducers';

const product = <T>(first?: T[], ...args: T[][]): IterableIterator<T[]> =>
  first === undefined
    ? tx.asIterable([[]])
    : args.length === 0
    ? tx.partition(1, first)
    : tx.mapcat((x) => tx.map((y) => [x, ...y], product(...args)), first);