gojy

GO style control flow in Javascript with Yieldable actions.

gojy is redux style middleware that treats generators as sequential blocking threads. These threads will block on yielded promises and generator - very much like co. gojy however, uses a different concurrency mechanism. Whereas co utilizes arrays and objects, gojy uses the go action. When a go action is yielded a promise is returned that resolves when the go routine completes. This promise can then be yielded at a later point in time to wait for the result.

gojy's concurrency mechanism provides three advantages over co:

it's more powerful
it doesn't overload objects and arrays so that they can be used as actions
it pools goroutines run by an instance of a runner, so that they can all be killed

Installation

$ npm install gojy

Usage

const {run, go, join} = require('gojy')

run(function * () {
  // launch go routine without blocking
  const promise1 = yield go(function * () {
    yield fetch('google.com')
    yield fetch('facebook.com')
  })

  // launch go routine without blocking
  const promise2 = yield go(function * () {
    yield fetch('segment.io')
    yield fetch('mixpanel.io')
  })

  // block
  yield join([promise1, promise2])
})

API

gojy runners

.run(process)

A pure runner with no additional action processing.

process - generator to run

Returns: result of generator

.compose(...middleware)

Creates a runner with additional action processing handled by middleware.

middleware - redux style middleware

Returns: a gojy runner

.middleware()

Returns: the gojy middleware for use in redux middleware stacks

gojy actions

.go(goroutine)

Launch a goroutine

goroutine - goroutine to run

Returns: a promise that resolves on goroutine completion

.kill()

Kill running goroutines launched by runner.

control flow helpers

Helpers for managing control flow.

.join(collection)

Turn collection to a promise and block on it.

collection - the promise or collection of promises to block on

Returns: result of promise

implementation:

function * join (collection) {
  return yield toPromise(collection)
}

.forEach(generator, collection)

Async sequential for each.

generator - async iteratee
collection - collection to iterate over

.map(generator, collection)

Async sequential map.

generator - async iteratee
collection - collection to iterate over

Returns: mapped collection

.now(collection)

Run collection in parallel and block. Gives you similar behavior to co yielded arrays and objects.

collection - the collection of goroutines to run in parallel

Returns result of collection goroutines

implementation:

function * now (collection) {
  return yield join(yield map(go, collection))
}

goisms

Some handy dandy goisms.

.delay(time)

Sleep for time.

.channel()

Simple promise based channel implementation.

Returns: take and put functions for the created channel

.poss(generator)

Go inspired error handling by matthewmueller

Returns: error first array ([err, ...])

.select(cases)

Wait on multiple promises and selects first.

cases - array of cases to wait on. Each case is a tuple of the form [promise, cb].

Returns: result cb of fasest promise

Example:

const res = yield select([
  [fetch('google'), _ => 'google is better'],
  [fetch('facebook'), _ => 'facebook is better']
])
console.log(res) // => `google is better`

License

MIT

joshrtay / gojy