kefir/src/interop/static-land.js

Reactive Programming library for JavaScript inspired by Bacon.js and RxJS with focus on high performance and low memory usage

import constant from '../primary/constant'
import never from '../primary/never'
import combine from '../many-sources/combine'

const Observable = {
  empty() {
    return never()
  },

  // Monoid based on merge() seems more useful than one based on concat().
  concat(a, b) {
    return a.merge(b)
  },

  of(x) {
    return constant(x)
  },

  map(fn, obs) {
    return obs.map(fn)
  },

  bimap(fnErr, fnVal, obs) {
    return obs.mapErrors(fnErr).map(fnVal)
  },

  // This ap strictly speaking incompatible with chain. If we derive ap from chain we get
  // different (not very useful) behavior. But spec requires that if method can be derived
  // it must have the same behavior as hand-written method. We intentionally violate the spec
  // in hope that it won't cause many troubles in practice. And in return we have more useful type.
  ap(obsFn, obsVal) {
    return combine([obsFn, obsVal], (fn, val) => fn(val))
  },

  chain(fn, obs) {
    return obs.flatMap(fn)
  },
}

export {Observable}