Full code for https://medium.com/@drboolean/divide-and-conquer-with-algebraic-structures-14070106fb4#.8w7z7ze2s

full-divide-and-conquer.js

const {Map} = require('immutable-ext')
const Id = require('fantasy-identities')
const Task = require('data.task')

const defs = {
  Band: {
    dino_jr: {
      name: 'Dinosaur Jr',
      members: 3,
    },
    amanset: {
      name: 'American Analog Set',
      members: 7
    }
  },
  Event: {
    dino_stubbs: {
      band_id: 'Band.dino_jr.id',
      venue_id: 'Venue.stubbs.id',
      age_limit: 18,
      date: '4/12/16'
    }
  },
  Venue: {
    stubbs: {
      name: 'Stubbs',
      address: '801 Red River St'
    },
    independent: {
      name: 'The Independent',
      address: '628 Divisadero'
    }
  }
}

const createRecord = tablename => attrs =>
  Id.of(Object.assign({id: Math.random(2)}, attrs))

const associateRels = fixtures => instance =>
  instance
  .traverse(Id.of, (v, k) =>
    k.match(/_id$/ig)
    ? Id.of('finding in fixtures and updating db')
    : Id.of(v))

const makeFixtures = defs =>
  Map(defs)
  .traverse(Id.of, (instances, tablename) =>
    Map(instances).traverse(Id.of, createRecord(tablename)))
  .chain(fixs =>
    fixs.traverse(Id.of, instances =>
      Map(instances).traverse(Id.of, associateRels(fixs))))

console.log(makeFixtures(defs).x.toJS())