product.ts

type Tuple<Iterables extends Iterable<any>[]> = {
  [K in keyof Iterables]: Iterables[K] extends Iterable<infer A> ? A : never
}

export const product = <Iterables extends Iterable<any>[]>(...t: Iterables): Iterable<Tuple<Iterables>> =>
  t.length === 0 ? [] : prod(t, [])

export function* prod<Iterables extends Iterable<any>[]>([h, ...t]: Iterables, r: any[]): Iterable<Tuple<Iterables>> {
  if (t.length === 0) for (const a of h) yield [...r, a] as Tuple<Iterables>
  else for (const a of h) yield* prod(t, [...r, a]) as Iterable<Tuple<Iterables>>
}

for (const x of product()) console.log(x)
for (const x of product([true, false])) console.log(x)
for (const x of product([true, false], ['a', 'b', 'c'])) console.log(x)
for (const x of product([true, false], ['a', 'b', 'c'], [1, 2, 3])) console.log(x)

test-output.txt

│ ts-node ./src/iterable.ts
[ true ]
[ false ]
[ true, 'a' ]
[ true, 'b' ]
[ true, 'c' ]
[ false, 'a' ]
[ false, 'b' ]
[ false, 'c' ]
[ true, 'a', 1 ]
[ true, 'a', 2 ]
[ true, 'a', 3 ]
[ true, 'b', 1 ]
[ true, 'b', 2 ]
[ true, 'b', 3 ]
[ true, 'c', 1 ]
[ true, 'c', 2 ]
[ true, 'c', 3 ]
[ false, 'a', 1 ]
[ false, 'a', 2 ]
[ false, 'a', 3 ]
[ false, 'b', 1 ]
[ false, 'b', 2 ]
[ false, 'b', 3 ]
[ false, 'c', 1 ]
[ false, 'c', 2 ]
[ false, 'c', 3 ]