nix-doom-emacs-unstraightened/flake.nix

# Copyright 2024 Google LLC
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

{
  inputs = {
    # Default to reusing the system's emacs package if it has nixpkgs in the system flake registry.
    nixpkgs.url = "nixpkgs";
    systems.url = "github:nix-systems/default";
    doomemacs = {
      url = "github:doomemacs/doomemacs";
      flake = false;
    };
    emacs-overlay = {
      url = "github:nix-community/emacs-overlay";
      inputs = {
        # These should be unused, but let's unset them to make that explicit.
        nixpkgs-stable.follows = "";
        nixpkgs.follows = "";
      };
    };
  };

  outputs = { self, systems, doomemacs, nixpkgs, emacs-overlay, ... }: let
    perSystemPackages = let
      eachSystem = nixpkgs.lib.genAttrs (import systems);
    in
      f: eachSystem (system: f nixpkgs.legacyPackages.${system});

    doomFromPackages = pkgs: args: let
      # Hack to avoid pkgs.extend having to instantiate an additional nixpkgs.
      #
      # We need emacsPackagesFor from the overlay, but neither the overlay itself
      # (it only uses "super", not "self") nor us actually needs anything overlaid
      # on nixpkgs. So we can call the overlay and pass emacsPackagesFor through
      # directly instead of having pkgs.callPackage do it.
      inherit (emacs-overlay.overlays.package {} pkgs) emacsPackagesFor;
      mergedArgs = args // {
        inherit emacsPackagesFor;
        doomSource = doomemacs;
      };
    in
      pkgs.callPackages self mergedArgs;

    # Convert a Nix expression to a `doom!` block suitable for init.el.
    #
    # Input: a nested attribute set.
    # The keys of the first level are categories (like `lang`).
    # The keys of the second level are module names (like `nix`).
    # The values are lists of module flags, or `true` for no flags.
    toInit = let
      inherit (nixpkgs.lib) concatLines concatStringsSep isList mapAttrsToList toPretty;
    in
      attrs:
      concatLines (
        [ "(doom!" ]
        ++ (mapAttrsToList (
          cat: modules:
          (concatLines (
            [ (":" + cat) ]
            ++ (mapAttrsToList (
              mod: value:
              if value == true then mod
              else if isList value then "(${mod} ${concatStringsSep " " value})"
              else abort "${toPretty value} not supported"
            ))
              modules
          ))
        ) attrs)
        ++ [ ")" ]
      );

    in {
      checks = perSystemPackages (pkgs: pkgs.callPackages ./checks.nix {
        inherit toInit;
        doomSource = doomemacs;
        makeDoomPackages = doomFromPackages pkgs;
      });
      packages = perSystemPackages (pkgs: {
        doom-emacs = (doomFromPackages pkgs {
          doomDir = ./doomdir;
          doomLocalDir = "~/.local/share/nix-doom-unstraightened";
        }).doomEmacs;
        doom-emacs-without-loader = (doomFromPackages pkgs {
          doomDir = ./doomdir;
          doomLocalDir = "~/.local/share/nix-doom-unstraightened";
          profileName = "";
        }).doomEmacs;
        cachix-packages = let
          doomDirs = pkgs.callPackages ./build-helpers/doomdirs.nix {
            doomSource = doomemacs;
          };
          inherit (nixpkgs) lib;
          depBuilds = lib.mapCartesianProduct
            ({doomDir, emacs}: (
              lib.nameValuePair
                "${emacs.name}-${doomDir.name}"
                (doomFromPackages pkgs {
                  doomDir = doomDir.value;
                  emacs = emacs.value;
                  doomLocalDir = "~/.local/share/nix-doom-unstraightened";
                  experimentalFetchTree = true;
                }).doomEmacs.emacsWithPackages.deps))
            {
              doomDir = lib.attrsToList doomDirs;
              # TODO: emacs29-gtk3 and emacs29-pgtk fail to build jupyter (segfault in zmq)
              emacs = lib.attrsToList {
                inherit (pkgs) emacs29 emacs29-nox;
              };
            };
        in
          pkgs.linkFarm "unstraightened-cachix-packages" (
            { inherit doomemacs; }
            // lib.listToAttrs depBuilds
          );
      });
      overlays.default = final: prev: {
        doomEmacs = args: (doomFromPackages final args).doomEmacs;
        emacsWithDoom = args: (doomFromPackages final args).emacsWithDoom;
      };
      hmModule = import ./home-manager.nix {
        inherit doomFromPackages;
      };
    };
}