Interesting. I don't find the Nix language itself especially complex, however, the whole system built with it is not that easy. For instance, packaging process is very well documented, making a derivation looked simple and reasonable until I decided package some code for myself. At this point things stopped being smooth. According to the documentation I needed to explicitly import my nix file from the top-level list of all packages which was not what I wanted, I'm unsure anybody except me would want my package (at least at the early stage of development). Intuitively, I was sure it wasn't necessary, there definitely must be a simpler way to toy with packaging but skimming through the documentation didn't reveal any answer. Looking at the source code left the impression that I needed a lot more time to understand how things worked behind the hood. On the other hand replacing pyenv with Nix was very pleasant experience. Overriding an existing package with my fork on github was almost a one-liner.