spxtr

@sebastian@jittr.click I wrote out the state machine for lexing numbers in Hare. It's pretty gnarly, but it is only LL(2) (or whatever the equivalent is for lexers, where you only have to unlex at most twice), so it's not the worst thing in the world.

I plotted line cuts in magnetic field at nearby constant densities, each slightly offset from the next. The quantum Hall plateaus look like a staircase coming out of a body of water and walking around the side of a mountain.