Avoiding nix flake update in stand-alone flake

[refaelsh]

Here are my dotfiles: https://github.com/refaelsh/dotfiles.
I have a Nixvim flake on my hard drive that I created like this: nix flake init --template github:nix-community/nixvim, the so-called stand-alone configuration.

The question is: when ever I change my stand-alone Nixvim flake and rebuild NixOS, the changes are not taking effect. I need to do nix flake update and then rebuild NixOS, and only then the changes will take effect.
I want to avoid running nix flake update because it will update the lock files of all the flakes and I might wait a while for the NixOS rebuilding to finish if there were many changes in various flakes. Also, I want to run nix flake update as less frequently as possible.

[MattSturgeon]

This is the intended way to use flakes. The entire point of a lockfile is that your downstream flake is not affected by changes in your upstream flake until it explicitly updates its lockfile.

You can however bump specific inputs instead of updating all of them:

nix flake lock --update-input nixvim

Although, if you want the two projects to stay in sync, perhaps it makes more sense for them to be both combined into a single flake with multiple outputs?

[MattSturgeon]

Although, if you want the two projects to stay in sync, perhaps it makes more sense for them to be both combined into a single flake with multiple outputs?

I don't understand that. Can you please elaborate?

TL;DR: To get a standalone nixvim, you don't need a standalone flake.

A flake can contain any number of "inputs" and "outputs".

You may find the following helpful:

• flakes manual
• flakes wiki page
• Blog post
• nix.dev flakes overview
• The Nix Hour #4 [comparing flakes to traditional Nix] (youtube)

[refaelsh]

Blog post

Oh! This one looks interesting.

The Nix Hour #4 [comparing flakes to traditional Nix]

And this one too.

All the rest I know and read.

[refaelsh]

TL;DR: To get a standalone nixvim, you don't need a standalone flake.
A flake can contain any number of "inputs" and "outputs".

A light bulb just went over my head. I think, I know what you mean, and I think I will be able to do it. But then I will not be able to tell a friend to just do nix run github:refaelsh/dotfile?ref=nixvim to get the same Neovim as I do.

[MattSturgeon]

But then I will not be able to tell a friend to just do nix run github:refaelsh/dotfile?ref=nixvim to get the same Neovim as I do.

Assume you combine things into your top-level flake's outputs:

If you have many packages, and don't want your neovim to be your default package, then you can tell a friend to do:

nix run github:refaelsh/dotfile#package-name

# e.g:
nix run github:refaelsh/dotfile#nvim

# or locally:
nix run .#nvim

If neovim is what you would consider your "default" build, then you can alias your packages.*.nvim output as packages.*. default and the following will also work:

nix run github:refaelsh/dotfile

# which is shorthand for:
nix run github:refaelsh/dotfile#default

[MattSturgeon]

Essentially, ?ref is saying "this flake is in a subdirectory" while #foo is saying "use the output foo on the specified flake".

You can be even more explicit, too, but it's usually unnecessary:

nix run github:refaelsh/dotfile#packages.x86_64-linux.nvim

[refaelsh]

Yep, that was the missing piece. I should have thought about nix run github:refaelsh/dotfile#package-name myself.

Thank you very much! :-)