stream-foreach.js

const noop = () => {}
Stream.prototype.forEach = function(onNext, onError=noop, onComplete=noop) { 

  return this.isEmpty ? onComplete() 
       : this.isAbort ? onError(this.error) :
       : this.isCons  ? (
           onNext(this.head),
           this.tail.forEach(onNext, onError, onComplete))
       : this.promise.then( 
           stream => stream.forEach(onNext, onError, onComplete),
           onError);
}