3. there are very powerful hooks to allow you to easily customize derivations by various means (look at some more complex derivation, like php, which defines dozens of options and there are other mechanisms as well).
1. Brew also has, but not 2 or 3 (it's definitely more customizable than say debian packages, but much less so than nix)
https://github.com/NixOS/nixpkgs/blob/master/pkgs/applicatio...
Maybe the three most noteworthy things are:
1. it's not hard to write your own nix expression
2. you get a reproducible build
3. there are very powerful hooks to allow you to easily customize derivations by various means (look at some more complex derivation, like php, which defines dozens of options and there are other mechanisms as well).
1. Brew also has, but not 2 or 3 (it's definitely more customizable than say debian packages, but much less so than nix)