Which means that a solution more robust than <=> will have to compare numbers using arbitrary precision (and that just pushes the threshold a few orders of magnitude farther out). Which means that numbers will have to be recognized as such, so that -123.4e-45.6E789 would not be taken as a single number, but -123.4e-456 will be. And then we get into whether whitespace, underscores, and commas/decimals (depending on locale) are allowed, and what they mean.

It's a long tee shot, onto a glacier, and only transparent golf balls are available.