Umbrellas are already halfway there: compact as possible, they deploy in a quick motion and retract almost as easily. But problems remain: they are wet when you walk indoors, and their intentionally-then structure remains fragile.
Thus the Air Umbrella (or perhaps: unbrella) by Je Sung Park & Woo Jung Kwon which forces an artificial wind up through its handle that shoots out the top and deflects incoming raindrops before they can hit your head.
Adjustable by design, the power of the air pushed through the system can be varied based on conditions or the desire to extend your protective canopy to a walking companion. Likewise, the rod you hold can telescope based on need and for portability.
The feasibility remains to be seen – one could imagine it would be difficult if even possible to produce the kind of force required, and that batteries might drain too fast for it to be broadly useful. Still, technology has a way of catching up to good design. Another point of skepticism: its creators pitch it as a green alternative to plastic bags or one-use ponchos, but what about regular umbrellas? Perhaps, depending upon the durability of the latter versus the power usage of the Air Umbrella alternative.