Because it certainly looks like the things you listed are separate/orthogonal and should be in separate modules/files.
Having many years of Java experience this is the reason why I stick to Maven (not moving to Gradle) - it is opinionated and strongly encourages fine grained modularisation.
Having said that - Java is in general IDE targeted language and once you have an IDE - many small files is not an issue anymore.
Nix absolutely allows that, to the point where I'm surprised that the linked example doesn't separate them. Most of my flakes have a flake.nix that's just a thin wrapper around a block that looks like
devShell = import ./shell.nix { inherit pkgs; };
defaultPackage = import ./default.nix { inherit pkgs; };
...I am aware of flake-parts that are supposed to offer that but the ecosystem of flake-parts is on the smaller side of things...
You can pull in arbitrary code from pretty much anywhere as an input
https://ryantm.github.io/nixpkgs/languages-frameworks/maven/
nix is a build tool a similae way that docker is a build tool. You define build scripts that call the tools you already use. The major difference is that a docker file gives you no way tl be sure you can reproduce that build in the future. A flake on the other hand gives you a high degree of trust.
What we have today is that there is a multitude of dependency managers and - what's worse - all of them are _also_ build tools targeted at specific language.
Nix has a unique position because it is not language specific. Where it is lacking is missing standards and reusable libraries that would simplify common tasks.
I am comparing to Maven because I am looking for multi-platform Maven alternative. There is Bazel but its dependency management is non-existent. There is Buck2 which is great in theory but the lack of ecosystem makes it a non-starter.
Nix is the only contender in the space that offers almost everything and has a chance to become a de-facto standard of software delivery thanks to this.
What's missing though is... easy to use canned solutions similar to maven plugins.
EDIT: grammar
Nix has composable, reusable, and shareable functions. Nix is a full, be awkward, programming language. You'll find functions and flakes for nearly everything you might want to do. An example of one that is more plugin like is sops-nix.
Though have never used maven or maven plugins, I may be missing your overall point.
Want a packaged spring boot application? There is a plugin for that. Want to package it in a container image? Just add a plugin dependency. Want to build an RPM or deb package? Add another two plugin dependencies. All various artifacts are going to be uploaded to a repository and made available as dependencies.
Missing a specific plugin? You can easily implement it in Java as a module and use it inside your project (and expose it as a standalone artifact as well).
I can’t find anything similar in Nix ecosystem.
Having a language allowing for this is not the same as having solutions already available.
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.
or
https://github.com/nix-community/flakelight
Their aim is to create an ecosystem of reusable Nix libraries. But it is tiny.
Writing a Maven plugin (ie. a reusable piece of configuration management logic) is easy because you can use any library from the vast Java ecosystem (just add a library as a dependency of your plugin).
Doing the same in Nix requires recreating these libraries in Nix.
Looks like Maven might simply be the right choice...
And don't get me wrong - I know it _can_ be done in Nix (as it is a programming language) - the question is _how easy_ it is to create/maintain it.
Let's say my solution requires a Java Spring Boot application, React client, custom Postgres extension and Python ML code.
- Java stuff
- node and npm
- I don't know what you would need for Postgres extensions
- Python, pip or poetry (or whatever you use for Python package management)
Here is an example flake: https://bpa.st/ZUQQ
Under `devShells`, you have `packages`. You can put there any package from nixpkgs, not just Python packages like I have there.
To make it cleaner, you could have a variable for each platform and concatenate them under packages like
`packages = javaPkgs ++ nodePkgs ++ pgPkgs ++ pyPkgs`.