error-tolerance.js

const Future = require('fluture')
const Either = require('fantasy-eithers')
const r = require('ramda')

const lefts = r.reduce(
  (memo, either) => {
    let extract
    either.bimap(x => extract = x, r.identity)
    return extract ? r.append(extract, memo) : memo
  },
  []
)

const rights = r.reduce(
  (memo, either) => {
    let extract
    either.bimap(r.identity, x => extract = x)
    return extract ? r.append(extract, memo) : memo
  },
  []
)

var handleJobs = futures => 
  Future.parallel(
    5,
    futures.map(future => future.fold(Either.Left, Either.Right))
  )
  .value(eithers => {
    var successes = rights(eithers)
    var failures = lefts(eithers)
    
    console.log(successes, failures)
  })