[smilliken]

The reason someone changes a dependency at all is because they expect a difference in behavior. No one would feel the motivation to go update a dependency if they aren't getting something out of it, that's a waste of effort and an unnecessary risk.

Each person doesn't have to perform the build on their own. A build server will evaluate it and others will pull it from the cache.

The greater waste that nix eliminates is the waste of human time spent troubleshooting something that broke in production because of what should have been an innocent change, and the lost business value from the decreased production. When you trust your dependencies are what you asked for, it frees the mind of doubt and lets you focus on troubleshooting more efficiently towards a problem.

Aside, I spent over a decade on Debian derived distros. I never once had one of these distros complete an upgrade successfully between major versions, despite about 10 attempts spread over those years, though thankfully always on the first sacrificial server attempted. They always failed with interesting issues, sometimes before they really got started, sometimes borking the system and needing a fresh install. With NixOS, the upgrades are so reliable they can be done casually during the workday in production without bothering to check that they were successful. I think that wouldn't be possible if we wanted the false efficiency of substituting similar but different packages to save the build server from building the exact specification. Anything short of this doesn't get us away from the "works on my machine" problem.

[nialv7]

> With NixOS, the upgrades are so reliable

Yeah they may be reliable _for you_. And do note this reliability doesn't come automatically with Nix's model, it is only possible because many people put a lot of effort into making it working correctly.

If you use the unstable channels, you would know. My NixOS upgrades break _all_ the time. On average, probably once a month.

[gf000]

Yep, anyone not getting how absolutely huge the Nix model is should just install the whole KDE desktop, the Gnome desktop, and uninstall both. Only nix can make it basically a no-op.