cycle-contrib.ts

export function mix<
  COMB extends {
    [CS in keyof ComponentSinks]?: (arg: {
      [K in keyof COMPONENTS]: Stream<any>
    }) => ComponentSinks[CS]
  },
  COMPONENTS extends {
    [COMPNAME in keyof COMPONENTS]: {
      [SINKNAME in keyof ComponentSinks]?: (COMB[SINKNAME] extends (arg: infer STREAMS) => any ? (
        COMPNAME extends keyof STREAMS ? STREAMS[COMPNAME] : ComponentSinks[SINKNAME]
      )
      :
      ComponentSinks[SINKNAME])
    }
  },
>
(componentSinks: COMPONENTS, combines?: COMB): Partial<ComponentSinks>{
  // Get all unique keys present in the array of sinks
  const keys = _.flow([
    _.values,
    o => _.map(o, _.keys),
    _.flatten,
    _.uniq
  ])(componentSinks)

  // array of arrays containing key & mixed sinks, or each key
  const arrys = _.map(keys, key => {
    // get object of sinks for the key containing undefineds in the right places
    const streams = _.flow([
      sinks => _.map(sinks, (sink, component) => [component, sink[key]]),
      _.fromPairs
    ])(componentSinks)

    const mixed$ = doCombine(combines, key, streams)

    const memoryMixed$ = key == "Layout" ?
      mixed$.remember()
      :
      mixed$

    return [key, mixed$]
  })

  //  Create an object with keys as keys and values as merged streams
  return _.fromPairs(arrys)
}