Equivalent Rx example

[xgrommx]

Hi @dyoder. How can I convert this example to your library?

const {fromEvent} = Rx.Observable;

const inc = fromEvent(incEl, 'click').map(_ => 1);
const dec = fromEvent(decEl, 'click').map(_ => -1);

dec.merge(inc).scan((a, b) => a + b, 0).subscribe(::console.log);

[dyoder]

Thanks for your question!

We have something roughly equivalent in the web app counter example.

The closest direct port would look like:

const {start, flow, events, map, observe} = FairmontReactive;

var counter = { value: 0 };

start(flow([
  events('click', incEl), 
  map(_ => counter.value++)
]));

start(flow([
  events('click', decEl),
  map(_ => counter.value--)
]));

start(flow([
  events('change', observe(counter)),
  map(::console.log)
]));

There's no equivalent at present of merge or scan. Adding them seems like a reasonable thing to do. If we did that, we could then do something more directly comparable.

const {start, flow, events, map, observe, merge, scan} = FairmontReactive;

var inc = flow([
  events('click', incEl), 
  map(_ => 1)
]);

var dec = flow([
  events('click', decEl),
  map(_ => -1)
]);

start(flow([
  merge(inc, dec),
  scan((a, b) => a + b, 0),
  map(::console.log)
]));

[dyoder]

We're also considering a function go that would get rid of the constant start(flow([ bits and allowing flow to take argument lists as well as arrays. In that case, the last version would become:

const {start, flow, events, map, observe, merge, scan} = FairmontReactive;

var inc = flow(events('click', incEl), map(_ => 1)));

var dec = flow(events('click', decEl), map(_ => -1)));

go(
  merge(inc, dec),
  scan((a, b) => a + b, 0),
  map(::console.log)
);

[dyoder]

Made a bunch of minor corrections to the code above.

[dyoder]

merge is now coded in master as combine (because there's already a merge in fairmont-helpers that does an unrelated thing)

[dyoder]

Also coded up accumulate.

[xgrommx]

@dyoder What is accumulate?

[dyoder]

@xgrommx accumulate is scan.

This is implemented and available in Beta 29. There is a bug: see #8.

So the equivalent of your original example is now:

var inc = flow(events('click', incEl), map(_ => 1)));

var dec = flow(events('click', decEl), map(_ => -1)));

go(
  combine(inc, dec),
  accumulate((a, b) => a + b, 0),
  map(::console.log)
);

Thanks again for your question and for motivating these new additions.

[xgrommx]

@dyoder Nice! Also your library was added to my book http://xgrommx.github.io/rx-book/content/similar_libraries/index.html =)

[dyoder]

@xgrommx that is amazing list. by far the most comprehensive i've seen. thank you!