rxjs used with burrido as do notation

rxburrido.js

/**
 * This demonstrates problems of using burrido with most (and in fact with any 
 * other multi-answer monads). It works only if `most` doesn't contain other 
 * effect besides pure stream comprehension effects, or effects we don't care 
 * about.
 */
import {Observable} from 'rx'
import Monad from 'burrido'
const { just: pure, fromPromise,from } = Observable

const { Do: doMerge } = Monad({
  pure,
  bind: (x, f) => x.flatMap(f)
})

let cnt = 0

/**
 * This is a symple and typical use case, we want to update something 
 * in DB before some other actions. It is simulated just with promise 
 * with timeout
 */
function updateDb() {
  return new Promise(resolve => {
    setTimeout(
      () => {
        console.log(`DB UPDATED ${cnt}`)
        resolve(cnt++)
      }, 0)
  })
}

doMerge(function*() {
  // first we want to update something in DB
  const m = yield fromPromise(updateDb())
  const x = yield from([1,2])
  return `${x} ${m}`
}).subscribe(function(res) {
  console.log(res)
})
/*
 and the output is
```
DB UPDATED 0
1 0
2 0
DB UPDATED 1
DB UPDATED 2
DB UPDATED 3
```
so we updated DB 4 times instead of 1
*/

/*
Things are much worth if the block contains JS side effects. It is of course
nice if there is none, but I don't see why not to use this useful tool in 
right places. It also may be accidental making debugging to be very painful.
*/

let i = 0;
doMerge(function*() {
  const x = yield from([1,2])
  if (i++) {
    const y = yield from(['in then'])
    return `then ${x} ${y}` 
  } else {
    const y = yield from(['in else'])
    return `else ${x} ${y}` 
  }
}).subscribe(function(res) {
  console.log(res)
})

/*
outputs:
```
then 1 in else
then 2 in then
```
so it combined output of `then` branch with value yielded in `else` branch
*/

/**
 * And alternative is to use [mfjs compiler](https://github.com/awto/mfjs-compiler), 
 * it has optionally support for generators syntax. So the source code for generators
 * is absolutely the same like in burrido but outpurs correct results in both cases.
 * https://gist.github.com/awto/d71bc466884dc9a9a6a93026ce363d17
 * 
 * Namely:
 * ```
 * DB UPDATED 0
 * 1 0
 * 2 0
 * ```
 * and
 * ```
 * else 1 in else
 * then 2 in then
 * ```
 */