Future URL fetching

retry-future.js

const Future = require('fluture');

// (Number -> Number) -> Number -> Future a b -> Future (List a) b
const retry = (time, max, task) => {
  const failures = new Array(max);
  return (function recurse(i) {
    return task.chainRej(function(failure) {
      failures[i] = failure;
      const total = i + 1;
      return total === max
        ? Future.reject(failures)
        : Future.after(time(total), total).chain(recurse);
    });
  })(0);
};

// Number -> Number -> Number
const linearly = t => n => t * n;

// Number -> Number -> Number
const exponentially = t => n => t * Math.pow(n, 2);

// getHtml :: Url -> Future Err Html
const getHtml = url => retry(linearly(1), 3, requestF(url)); //requestF is just request-promise wrapped in a future

// will retry starting at a 1 sec gap increasing linearly up to 3 times max
getHtml('http://google.com') 
  .map(doStuffToHTML) // if the site failed to fetch this is a noop
  .fork(console.error, console.log) // The Future doesn't actually execute until a `.fork` call is made