interfval.js

var {Task} = require('./Task')
var interval = (frame, mailbox) => {
  let next
  let id

  const handler = (time=Date.now()) => {
    if (log) {
      console.log('> handler', fork && fork.abortHandle)
    }
    next({ time })
  }

  const init = () => new Task((succeed, fail) => {
    id = setInterval(handler, frame)
    succeed()
  })

  const wait = () => new Task(succeed => {
    if (log) {
      console.log('> wait', id == null, fork &&  fork.abortHandle)
    }
    next = succeed
    return id
  }, clearInterval)

  const loop = (message) => {
    if (log) {
      console.log('> loop', fork && fork.abortHandle)
    }
    return Task.send(mailbox, message).chain(wait).chain(loop)
  }

  return init().chain(wait).chain(loop)
}

var fork = Task.fork(interval(3000, msg => console.log(`>>>`, msg)), a => console.log('!!!', a), e => console.error(e))