Then you'd have to learn to read Nix expressions. The original expression that builds all ruby versions is here: https://github.com/NixOS/nixpkgs/blob/6120ac5cd

Then you'd have to learn to read Nix expressions. The original expression that builds all ruby versions is here: https://github.com/NixOS/nixpkgs/blob/6120ac5cd201f6cb593d1b80e861be0342495be9/pkgs/development/interpreters/ruby/default.nix https://github.com/NixOS/nixpkgs/blob/6120ac5cd201f6cb593d1b... Here's an example that shows how to build a customized version for NodeJS https://www.breakds.org/post/nix-shell-for-nodejs https://www.breakds.org/post/nix-shell-for-nodejs