The Complete Computing Environment

Arroyo Emacs Generator


Arroyo developed out of a system originally designed to assemble an Emacs init.el, and now it has some super-powers. The Arroyo Emacs configuration is pretty opinionated as it's a system designed to work around Evil Mode and EXWM.

Arroyo Emacs configuration is designed to work closely with the Arroyo Home Manager generator, nearly all system dependencies are installed through Home Manager, and certain submodules may require the use of Home Manager. No Arroyo Emacs features should require running NixOS though, and I'd like to maintain that as much as possible since getting Nix running everywhere is much more feasible than running NixOS everywhere.

Users of the Arroyo Home Manager generator will have access to features available in nix-community/emacs-overlay like:

Arroyo System Cache Emacs table

(require 'arroyo-utils)

(defcustom arroyo-emacs-init-location (expand-file-name "~/arroyo-nix/files/init.el")
  "Where `arroyo-emacs-generate-init' writes the amalgamated init file."
  :group 'arroyo
  :type 'string)

  (add-to-list 'arroyo-db-keywords kw nil #'equal))

(add-to-list 'arroyo-db--schemata
               [(file     :not-null)
                (tangled  :not-null)
                (module   :not-null)])) 
(defun arroyo-emacs-update-db (&optional keywords-too)
  (interactive "P")
  (when keywords-too
  (if (org-roam-file-p)
      (arroyo-db-query [:delete :from emacs :where (= file $s1)]
    (arroyo-db-query [:delete :from emacs]))
  (when-let* ((module-args
               (if (org-roam-file-p)
                   (list [:select [file "" value] :from keywords
                          :where (= keyword $s1) :and (= file $s2)]
                 (list [:select [file "" value] :from keywords
                        :where (= keyword $s1)]
              (modules (apply #'arroyo-db-query module-args)))
    (arroyo-db-query [:insert :into emacs :values $v1]
                     (-map (pcase-lambda (`(,file ,_ ,module))
                                (vector file (arroyo-emacs--figure-tangled-location file) module))

(defun arroyo-emacs--figure-tangled-location (file-path)
  (->> file-path
       (arroyo-db-query [:select value :from keywords
                         :where (= file $s1)
                         :and (= keyword "ARROYO_EMACS_MODULE")])
       (format "%s/cce/%s.el" org-roam-directory)))

(add-to-list 'arroyo-db-update-functions #'arroyo-emacs-update-db)

Arroyo Emacs init.el generator

arroyo-emacs-generate-init can be called interactively1 to assemble an init.el file which will have the dependencies ordered in such a way as to allow the user to user Emacs.

(defun arroyo-emacs-generate-init ()
  "Write an emacs `init.el' to `arroyo-emacs-init-location' using
   tangled files spread throughout an org-roam wiki."
  (let ((dest arroyo-emacs-init-location)
        (files (arroyo-emacs--ordered-files)))
    (with-current-buffer (find-file-noselect dest)
      (dolist (file files)
        (insert-file-contents file)
        (goto-char (point-max)))

(defun arroyo-emacs--module-pair-for-rel-file (unordered rel-file)
  (second (-find (lambda (elt)
                   (equal (expand-file-name rel-file org-roam-directory)
                          (car elt)))

(defun arroyo-emacs--ordered-files ()                                                     ;; (ref:ordered-files)
  (let* ((unordered (arroyo-db-query [:select [file tangled] :from emacs]))               ;; (ref:unordered)
         (unordered-filenames (-map #'car unordered))                                     ;; (ref:unordered-filenames)
         (order (arroyo-utils-order-modules unordered-filenames))                         ;; (ref:order-modules)
         (partialfn (apply-partially #'arroyo-emacs--module-pair-for-rel-file unordered))
         (ordered (-map partialfn order)))
     (-filter #'identity)

This (ordered-files) function is a little bit dense to read, so let's take this apart let-binding by let-binding:

In total, this takes the unordered dataset and returns them with a topological sort applied to them, the edges of the topology are pulled from the Arroyo Dependency Sorting cache.

The interactive function is more or less as it says on the tin – it writes the init.el to a local directory for the arroyo-flood.

Arroyo Home Manager support for Emacs

This Nix home-manager import installs Emacs with my generated init.el file included, packages installed, and custom overrides included. The versions come out of my Nix Version Pins.

The Emacs package uses, currently 28.0.90 which supports native compilation – the so-called GccEmacs and the packages from the init.el, natively compiled and ready to go. This is overlayed in to nixpkgs using Arroyo Nix Support

{ pkgs, lib ? pkgs.lib, ... }:

  versions = import ../versions.nix {};
in pkgs.emacsWithPackagesFromUsePackage {
  package = pkgs.emacsNativeComp;
  config = <<arroyo-emacs-init-location()>>;
  alwaysEnsure = true;

  override = epkgs: epkgs // rec {

  extraEmacsPackages = epkgs: [
let emacsOverlay = (import ../versions.nix {}).emacsOverlay null;
in {
  nixpkgs.overlays = [
    (import emacsOverlay)
{ config, pkgs, lib, ...}:

  myEmacs = pkgs.myEmacs; # loads via overlay
  home.file.".emacs.d/init.el".source = <<arroyo-emacs-init-location()>>; = true;

  services.emacs = {
    enable = false;
    package = myEmacs;

  programs.emacs = {
    enable = true;
    package = myEmacs;

Enable ccache for emacsGcc builds in My NixOS configuration

,#+ARROYONIXOSMODULE: nixos/ccache.nix

{ ... }:
  programs.ccache = {
    packageNames = ["emacs-unstable"];
  nix.extraOptions = ''
    extra-sandbox-paths = /nix/var/cache/ccache

NEXT fix ccache support

DONE reenable ccache

Literate Programming helpers

I want to be able to construct a home-manager import dynamically which can be used to install with emacs-overlay functionality. I also want it to be able to inject arbitrary packageOverrides in to it via references in stored in documents' ARROYO_HOME_EPKGS property keyword.

(defun arroyo-emacs-epkgs ()
  (->> (arroyo-db-query [:select [file value] :from keywords
                         :where (= keyword "ARROYO_HOME_EPKGS")])
       (-map #'second)
       (-map (lambda (path)
               (let ((path (expand-file-name path "~/arroyo-nix")))
                 (with-current-buffer (find-file-noselect path)
                   (let ((bs (buffer-string)))
       (s-join "\n")))
(add-to-list 'arroyo-db-keywords "ARROYO_HOME_EPKGS" nil #'equal)

arroyo-emacs-epkgs can be used to insert any overridden elisp package in to the registry for use-package to install, including things with patches or personal forks. yummy. apply a ARROYO_HOME_EPKGS keyword to the page to include it here.


arroyo-emacs-init-location above is simply the Arroyo Emacs-managed init.el:

; arroyo-emacs-init-location

NEXT how to automate epkg tangling, etc.

can use org-roam's Arcology.Roam.File to know whether a file has been updated and tangle it as part of the dynamic-home-manager dynamic-nixops etc… those things will check a cache to see if the files have changed, and tangle them and then this file if so?

DONE need a reverse of ARROYO_MODULE_WANTS for specifying "wanted-by"s


(provide 'arroyo-emacs)

  1. that is, by pressing Alt-x / M-x and then typing the name of the command; Modern Interface Terms↩︎