http://reactivex.io/

https://github.com/ReactiveX/rxjs

import { range } from 'rxjs';
import { map, filter } from 'rxjs/operators';

range(1, 200).pipe(
  filter(x => x % 2 === 1),
  map(x => x + x)
).subscribe(x => console.log(x));

https://github.com/ReactiveX/RxPHP

$source = \Rx\Observable::fromArray([1, 2, 3, 4]);

$source->subscribe(
    function ($x) {
        echo 'Next: ', $x, PHP_EOL;
    },
    function (Exception $ex) {
        echo 'Error: ', $ex->getMessage(), PHP_EOL;
    },
    function () {
        echo 'Completed', PHP_EOL;
    }
);

//Next: 1
//Next: 2
//Next: 3
//Next: 4
//Completed