@civodul I mean, while true, isn't it bit too simple way to put it? My understanding is that Guix does not need SAT solver because basically any single dependency is hard-coded version (via its package definition).
If your pip --freeze produced requirements.txt is full of only pkg==1.2.3 style records, you also technically do not require SAT solver to figure it out, no?
Actually, *most* linux package manager do not require SAT solver no? At least pacman and apk do not have it afaik. Which one does out of curiosity?