How does this scheme of yours work with m/s and seconds.

IIUC, rust would NOT let you do a type checked m/s * s => m, so using the type system for these kinds of games is silly and dangerous (I presume you would have to do the dumb thing and typeconvert to the same type -- e.g.

    (m) (speed * ((m/s) seconds))

iiuc zig has thought about this specifically and there is a safe async-cancel in the new design that wasn't there in the old one.

yes indeed true. but the standard library is in the end just a library, you could reimplement the "pre-io" patterns in the new std if you wanted.

> So how else do you propose we compare countries

dCO2/dt

> If you allocate too much stack in advance, you end up being not much cheaper than OS threads;

Maybe. a smart event loop could track how many frames are in flight at any given time and reuse preallocated frames when their frames dispatch out.