Nix package management, any opinions?
 

I discovered the Nix package management system recently (cross platform) www.nixos.org/nix

Assuming space isn't an issue, and you don't have root access, it seems appealing.

Has anyone had experience using it in a company?

For example, whilst the build design is very well thought out, they state that haven't thought much about runtime design. I found it appears to build everything with RPATH (not RUNPATH), which would preclude you from using LD_LIBRARY_PATH if you needed to fix something.

I've also briefly looked at Gentoo Prefix. What does Nix solve which Prefix doesn't?

I know a few people who use and really like Nix (OS, specifically). Personally I still have yet to try Nix itself. I keep meaning to but never seem to get round to it.

I'm not sure I have whatever problem is being solved by Nix. I can install and update, or uninstall and re-install, applications as I please. If I really really need two versions of the same app installed, I can modify the output of gcc so that I have a uniquely named binary (although, in theory, I might also have to then link it to uniquely named dependencies...which could get complicated, but since I've never needed this functionality, it's not really a selling point that Nix allows me to avoid this work).

I also don't need a versioned history of everything I've ever built or the state of my system. Maybe for a developer who needs to test things frequently would find it useful, but as for me, I don't seem to require that level of package management.

It looks like Gentoo Prefix (your post is the first I'd heard of it) is more like a consistent CONFIG hack than anything having to do with version controlled, statically linked binaries like Nix is. In fact, Prefix is something anyone could theoretically do with laborious changes to Makefiles, so I don't think it really has much in common with Nix aside from installing to a non-default location. Otherwise, it has none of the versioning stuff that Nix has.

Both are interesting projects, and wery appealing to me in theory. But so far I just have not needed the benefits they provide. I'd be interested in hearing from people who do find them useful.