The author, Mario Carniero, is both one of the top three smartest and nicest people I know (and many other Ohio State students where he did his undergrad would agree). Glad to see his research getting Hacker News recognition.
And then I looked over and Mario had implemented a graphing calculator (as in, take "y = x^2 + 4x -10" and emit a graph) in the windows command prompt. Then, when that was boring, he started researching and implementing the graphics algorithms for drawing lines at various slopes with minimal distortion. And then, when that was boring, he made his graphing calculator support polar coordinates (something I understood only as "oops, my graphing calculator is misconfigured").
Also, he was ~12 years old (IIRC) having skipped a few grades.
I've met a lot of smart people between Carnegie Mellon, Facebook Infrastructure, and the Linux Kernel community, but Mario's one of two or maybe three at the absolute top in terms of intellectual horsepower.