pultil

Granular Utilities for pull-streams

Funnel

A funnel is a convenient way to create pull.Sink (a.k.a reader, a.k.a writable) streams

Requiring funnel

Minimal code generation

Generates least amount of code when browserified/webpacked

var funnel = require('pultil/funnel');

Full package:

var funnel = require('pultil').funnel;

Funnel API

funnel(fn:(data) => end?) => Sink Factory

Funnel provides a quick and easy way to create sinks (i.e. write streams).

End signalling

To abort a stream, simply return true from the funnel

var count = 0;
funnel(function (data) {
  if (count++ > 100) { return true; }
  console.log(data);
})

Funnel Example

var funnel = require('pultil/funnel');
var src = getSomePullSourceStream();

var sink = funnel(function (data) {
  console.log(data);
})

src().pipe(sink());

The above could be created with the more advanced wsps.Sink stream factory (as inherited from pull-stream)

var wsps = require('websocket-pull-stream')
var ws = new WebSocket('ws://localhost:8081')

var src = wsps(ws);

var sink = wsps.Sink(function (read) {
  read(null, function next (end, data) {
    if (end) { return }
    console.log(data);
    read(null, next)
  })
})

src().pipe(sink());

Evidently, funnel takes away much of the boiler plate involved with creating a Sink factory. We only need use Sink when funnel doesn't supply the required flexibility.

Tunnel

A tunnel is convenient way to create pull.Through streams.

Requiring tunnel

Minimal code generation

Generates least amount of code when browserified/webpacked

var tunnel = require('pultil/tunnel');

Full package:

var tunnel = require('pultil').tunnel;

Tunnel API

tunnel(fn:(data, cb?:(mutation)) => mutation?) => Through Factory

Synchronous Tunnel

var syncTransformStream = src.Tunnel(function (data) {
  return data * 100;
})

Asynchronous Tunnel

var asyncTransformStream = src.Tunnel(function (data, cb) {
  cb(data / 2)
})

Passthrough style

var logStream = src.Tunnel(function (data) {
  console.info('data passing through:', data)
})

Tunnel Example

var tunnel = require('pultil/tunnel')
var src = getSomePullSourceStream();

var sink = funnel(function (data) {
  console.log('final', data);
})

var throughA = tunnel(function (data) {
  console.debug('initial', data)
  return data * 100;
})

var throughB = tunnel(function (data) {
  console.info('intermediate', data)
})

var throughC = tunnel(function (data, cb) {
  cb(data / 2)
})

src()
  .pipe(throughA())
  .pipe(throughB())
  .pipe(throughC())
  .pipe(sink());