I was reading this thread and now I finally understood what you mean by plugins. Plugins kind of exist in Nix, except they're not called that. They are functions available in some specific module.

For example, `dockerTools` provides different functions like creating an image and other things. There is a module of fetchers, functions that retrieve source files from GitHub and other sources.

But I don't think there are many language-specific functions, like the ones you are describing. I can't think of any, except for the ones that build a Nix package from a language-specific package.