cycle-server.js

const http = require('http')
const Rx = require('rxjs')

const main = ({ HTTP }) => ({
  HTTP: HTTP.map(req => `Hello ${req.url}`)
})

const makeHttpEffect = _ => {
  const requests$ = new Rx.Subject()

  http.createServer((req, res) => requests$.next({ req, res }))
    .listen(3000, _ => console.log(`listening on 3000`))

  return {
    writeEffect: model$ => {
      return model$.zip(requests$, (model, { req, res }) => ({ model, res }))
        .subscribe(({ model, res }) => res.end(model))
    },
    readEffect: requests$.map(({ req, res }) => req)
  }
}

const run = (main, drivers) => {
  const sources = { HTTP: drivers.HTTP.readEffect }
  const sinks = main(sources)
  Object.keys(drivers).map(key => drivers[key].writeEffect(sinks[key]))
}

run(main, { HTTP: makeHttpEffect() })