Flyd-Eithers

A utility library for working with Eithers in flyd streams.

This allows for error bubbling and safe transformations within flyd streams. Examples below.

API

Dependencies

You need to provide your own Either constructor/lib/implementation. This lib was tested with Eithers from both Sanctuary and Data.Either.

Example Usage

var S = require('Sanctuary');
var flydEithers = require('flyd-eithers')(S);
var flyd = require('flyd');
 
var a = flyd.stream();
var c = flydEithers
  .toEither(a)
  .map(function(x) { return x + 1; })
  .scan(function(acc, x) { return acc + x; }, S.Right(10));
 
flyd.on(function(x) {
  console.log(x);
}, c);
 
var count = 0;
setInterval(function() {
  count++;
  a(count);
}, 1000);
 
// Right(12);
// Right(15);
// etc..

Error Example

var S = require('Sanctuary');
var flydEithers = require('flyd-eithers')(S);
var flyd = require('flyd');
 
var a = flyd.stream();
var c = flydEithers
  .toEither(a)
  .map(function(x) { return x + 1; })
  .scan(function(acc, x) { return acc + x; }, S.Right(10));
 
flyd.on(function(x) {
  console.log(x);
}, c);
 
function mockHttpRequest() {
  setTimeout(function() {
    a(S.Left('error 404'));
  }, 100);
}
 
mockHttpRequest();
 
// Left('error 404') // Safe travel through map and scan :)