[tialaramex]

You can write your "r64" type today. You would need a perma-unstable compiler-only feature to give your type a huge niche where the missing bit patterns would go, but otherwise there's no problem that I can see, so if you don't care about the niche it's just another crate - there is something similar called noisy_float

[zevets]

I can do it, and I do similar such things in C++ - but the biggest benefit of "safe defaults" is the standardization of such behaviors, and the resultant expectations/ecosystem.