Looking through the Zone API documentation, this is a reimplementation of what most Promise libraries already provide (Zones even support "then" and "catch" methods, but don't follow the chaining standard). The only new feature is "Gates," which the documentation admits are awkward and need to be revisited — and many Promise libraries already provide simple mechanisms for sharing resources similar to what Gates allow, but with more-consistent APIs. Zones also don't work several important Node-core libraries (cluster, fs, zlib, and more), whereas Promise libraries solved interop long ago.<p>Promises/A+ is already standardized and is shipping in browsers. Yes, Promises/A+ is more complicated than it needs to be, and I wish a simpler, more monadic approach had won out. But this is an unnecessary flow-control fork, and it's not even a particularly good one by comparison. If Zones were built on top of the ES6 standard, all ES6-compatible promise libraries would immediately work with it (and there are many mature ones that already exist). No existing libraries work with Zones, and the existing ones will need to be amended to add Zone-specific interop.<p>God knows nobody needs a zone-to-promise converter; there are enough ways to do asynchronous flow control as it stands. This blog post seems to hope that Zones will some day make it into Node core; I sincerely hope they don't in their current state.