This talk covers the core concepts of reactive programming by looking at a minimalistic implementation in just a few dozen lines of code. The gained insights can be of help when adopting any of the popular reactive programming libraries to your own projects. Presented at the CocoaHeadsNL meetup on August 23rd, 2017 at the Blendle Office in Utrecht. PS: We are very sorry for the bad audio quality for the majority of the video. The primary audio recording was accidentally interrupted.