The double slit experiment confirms the wavelike nature of the universe at macro scale. A completely stateful universe where a photon discretely moves through spacetime could not exhibit self interference, only if the photon takes all paths (suggesting 'functions' that describe its movement) could it then collapse into a discrete position after being observed (aka. evaluated)

What I'm getting at is that in between emission and observation the photon is not in any one state, at best it's state could be described as a superposition.

To take the analogy one step too far, perhaps worst of all this suggests a lazily evaluated haskellian universe with a giant state monad whose NUMA architecture updates at the speed of light.

I hesitate to admit photons into the macro realm, considering they are elementary particles and essentially massless.

Given the de Broglie hypothesis, I must of course admit macroscopic objects do have wavelengths, and thus macroscopic uncertainty (your statelessness) is a nonzero vlue. For all intents and purposes though, the denominator of the equation causes the wavelength to go very close to 0, as the mass value dwarfs the Planck constant and velocity is always non-zero due to brownian motion.

Wave function collapse is interesting and I must admit when it is not induced by momentum, I don't understand it very well.