A minimal utility belt for streaming with async iterables.
This is an experimental package which recreates pull-streams
using asynchronous iterators, which are available in Node 10.
We aim to retain many of the nice properties of pull-streams, without
sacrificing usability.
import pull, {from, map, reduce, head} from 'barfle';
import got from 'got';
const stream = pull(
from([1, 2]),
map((index) => `https://raw.githubusercontent.com/skeggse/barfle/master/examples/fixtures/sample-${index}.txt`),
map(async (url) => (await got(url)).text),
deadline(10000),
reduce((a, b) => `${a} ${b}`));
const {value} = await stream.next();
console.log(value); // prints "Hello world"We don't yet have the preemptive abort semantics that pull-stream provides.
Namely, an abort signal does not propagate through things like the reduce
through, because it reads from its upstream until exhausted. This breaks the
deadline through, which tries to abort the upstream if it hasn't produced a
within a given time delay. This limitation arises because the implicit
backpressure runs both directions, and the yield that should signal an abort
doesn't get read by the upstream iterator until it goes to produce a new value.
The core library isn't fleshed out, and needs several more primitives before it can be considered useful. Nothing is well documented, even in inline documentation.
Also we don't have tests. We need those.
There are already a lot of packages with names that include "async," "promise,"
and "stream" on the npm registry, and I gave up looking for one that felt
right. The word barfle (pronounced ['bar,flɛ]) roughly translates as an
'outflow stream' in Lojban.