pythagorean-triples-rxjs.ts

import { interval, Observable } from 'rxjs';
import { map, withLatestFrom } from 'rxjs/operators';

function addOne(n: number): number {
  return (n + 1);
}

function toOdd(n: number): number {
  return ((n * 2) + 1);
}

function toNatural(n: number): number {
  return ((n - 1) / 2);
}

function toSquare(n: number): number {
  return (n ** 2);
}

function generateNaturalNumbers(): Observable <number> {
    return interval(500);
}

const naturalNumbers = generateNaturalNumbers();

const smallCathetuses = naturalNumbers.pipe(
  map(addOne),
  map(toOdd),
);

const bigCathetuses = smallCathetuses.pipe(
  map(toSquare),
  map(toNatural),
);

const hypotenuses = bigCathetuses.pipe(
  map(addOne),
);

const pythagoreanTriples = smallCathetuses.pipe(
  withLatestFrom(bigCathetuses, hypotenuses),
);

pythagoreanTriples.subscribe((value) => {
  console.log(value);
});