import fs from 'fs/promises'
import { Observable } from 'rxjs'

const myFunc = async function (observer) {
  const result = await fs.readFile('package.json', 'utf8')
  observer.next(result)
}

const observer = x => console.log(x)

const myObs = new Observable(myFunc)

myObs.subscribe(observer)

import fs from 'fs/promises'
import { Observable } from 'rxjs'
import { map, distinctUntilChanged } from 'rxjs/operators'

const myFunc = async function (observer) {
  const handler = async () => {
    const result = await fs.readFile('package.json', 'utf8')
    observer.next(result)
  }
  setInterval(handler, 1000)
}

const observer = x => {
  console.log(Array(100).join('-'))
  console.log('   my observer')
  console.log(Array(100).join('-'))
  console.log(x)
}

const myObs = new Observable(myFunc)

const myMappedObs = myObs.pipe(map(pkg => parseInt(JSON.parse(pkg).version)))

const distinctObs = myMappedObs.pipe(distinctUntilChanged())

distinctObs.subscribe(observer)

interfaceint  Observable {

    constructor(subscriber : SubscriberFunction);

    // Subscribes to the sequence with an observer
    subscribe(observer : Observer) : Subscription;

    // Subscribes to the sequence with callbacks
    subscribe(next : Function,
              error? : Function,
              complete? : Function) : Subscription;
}

interface Subscription {
    // Cancels the subscription
    unsubscribe() : void;
}

#include <iostream>
#include <vector>

int main ()
{
  // constructors used in the same order as described above:
  std::vector<int> first;                                // empty vector of ints
  std::vector<int> second (4,100);                       // four ints with value 100
  std::vector<int> third (second.begin(),second.end());  // iterating through second
  std::vector<int> fourth (third);                       // a copy of third

  // the iterator constructor can also be used to construct from arrays:
  int myints[] = {16,2,77,29};
  std::vector<int> fifth (myints, myints + sizeof(myints) / sizeof(int) );

  std::cout << "The contents of fifth are:";
  for (std::vector<int>::iterator it = fifth.begin(); it != fifth.end(); ++it)
    std::cout << ' ' << *it;
  std::cout << '\n';

  return 0;
}