Emacs via Nix with mu4e

I've been running development versions of Emacs ever since I switched to Wayland and needed the PGTK code. The various X-git packages on AUR makes that easy, as long as one doesn't mind building the packages locally, and regularly. Building a large package like Emacs does get a bit tiring after a while though so I started looking at the emacs overlay to see if I could keep up without building quite that much.

The first attempt at this failed as I couldn't get my email setup working; emacs simply refused to find the locally installed mu4e package. I felt I didn't have time to solve it at the time, reverted back to doing the builds myself again. It kept irritating me though, and today I made another attempt. This time I invested a bit more time in reading up on how to install emacs via Nix with packages. Something that paid off.

I'm managing my packages using nix profile and a flake.nix. To install emacs with a working mu4e I started with adding the emacs overlay to the inputs

inputs = {
  nixpkgs.url = "github:nixos/nixpkgs?ref=nixpkgs-unstable";
  ...
  community-emacs.url = "github:nix-community/emacs-overlay";
};

and in my outputs I made sure to use the overlay on nixpkgs

outputs = inputs@{ nixpkgs, community-emacs, ... }:
  let
    system = "x86_64-linux";
    pkgs = import nixpkgs {
      inherit system;
      overlays = [ community-emacs.overlays.emacs ];
    };
    ...

and in the list of packages passed to pkgs.buildEnv I added

...
((emacsPackagesFor emacs-pgtk).emacsWithPackages
  (epkgs: [ epkgs.mu4e ]))
mu
...

That's all there's to it. After running nix profile update 0 I had a build of emacs with Wayland support that's less than a day old, all downloaded from the community cache. Perfect!