Moving to Doom Emacs!

.emacs.d/modules/tools/direnv/README.org

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+#+TITLE:   tools/direnv
+#+DATE:    July 10, 2019
+#+SINCE:   v2.1.0
+#+STARTUP: inlineimages
+
+* Table of Contents :TOC_3:noexport:
+- [[#description][Description]]
+  - [[#module-flags][Module Flags]]
+  - [[#plugins][Plugins]]
+  - [[#hacks][Hacks]]
+- [[#prerequisites][Prerequisites]]
+  - [[#macos][MacOS]]
+  - [[#arch-linux][Arch Linux]]
+  - [[#nixos][NixOS]]
+- [[#troubleshooting][Troubleshooting]]
+  - [[#direnv--nix-is-slow][direnv + nix is slow]]
+
+* Description
+This module integrates direnv into Emacs.
+
+#+begin_quote
+direnv is an environment switcher for the shell. It knows how to hook into bash,
+zsh, tcsh, fish shell and elvish to load or unload environment variables
+depending on the current directory. This allows project-specific environment
+variables without cluttering the ~/.profile file.
+
+Before each prompt, direnv checks for the existence of a ".envrc" file in the
+current and parent directories. If the file exists (and is authorized), it is
+loaded into a bash sub-shell and all exported variables are then captured by
+direnv and then made available to the current shell.
+#+end_quote
+
+** Module Flags
+This module provides no flags.
+
+** Plugins
++ [[https://github.com/wbolster/emacs-direnv][direnv]]
+
+** Hacks
++ Normally, the direnv environment is updated on ~post-command-hook~. We've
+  changed it to update on ~doom-switch-buffer-hook~, ~doom-switch-window-hook~
+  and ~doom-switch-frame-hook~ instead.
++ Special direnv keywords/commands are highlighted in direnv-envrc-mode.
++ A fix has been applied to ensure flycheck searches for executables from within
+  the direnv environment, if any.
+
+* Prerequisites
+This module requires the ~direnv~ utility.
+
+** MacOS
+#+BEGIN_SRC bash
+brew install direnv
+#+END_SRC
+
+** Arch Linux
+#+BEGIN_SRC bash
+sudo pacman -S direnv
+#+END_SRC
+
+** NixOS
+#+BEGIN_SRC nix
+environment.systemPackages = [ pkgs.direnv ];
+#+END_SRC
+
+Or ~nix-env -i direnv~
+
+* Troubleshooting
+** direnv + nix is slow
+Consider augmenting direnv with [[https://github.com/target/lorri][lorri]], which will cache nix builds and speed up
+direnv tremendously.
+
+At the time of writing, the lorri package in nixpkgs simply emits an error
+message, telling you to install it manually. You can get around this with:
+
+#+BEGIN_SRC nix
+nixpkgs.overlays = [
+  (self: super: {
+    lorri =
+      let src = (super.fetchFromGitHub {
+            owner = "target";
+            repo = "lorri";
+            rev = "38eae3d487526ece9d1b8c9bb0d27fb45cf60816";
+            sha256 = "11k9lxg9cv6dlxj4haydvw4dhcfyszwvx7jx9p24jadqsy9jmbj4";
+          });
+      in import src { inherit src; };
+  })
+];
+
+environment.systemPackages = [ pkgs.lorri ];
+#+END_SRC
+
+Otherwise, follow [[https://github.com/target/lorri#installing-lorri][the instructions in lorri's README]] on how to install it
+manually.

.emacs.d/modules/tools/direnv/config.el

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+;;; tools/direnv/config.el -*- lexical-binding: t; -*-
+
+(defvar +direnv--keywords
+  '("direnv_layout_dir" "PATH_add" "path_add" "log_status" "log_error" "has"
+    "join_args" "expand_path" "dotenv" "user_rel_path" "find_up" "source_env"
+    "watch_file" "source_up" "direnv_load" "MANPATH_add" "load_prefix" "layout"
+    "use" "rvm" "use_nix" "use_guix")
+  "TODO")
+
+(use-package! direnv
+  :after-call after-find-file dired-initial-position-hook
+  :config
+  (add-hook! 'direnv-mode-hook
+    (defun +direnv-init-h ()
+      "Instead of checking for direnv on `post-command-hook', check only once,
+when the file is first opened/major mode is activated. This is significantly
+less expensive, but is less sensitive to changes to .envrc done outside of
+Emacs."
+      (direnv--disable)
+      (when direnv-mode
+        (add-hook 'after-change-major-mode-hook
+                  #'direnv--maybe-update-environment))))
+
+  (defadvice! +direnv--make-process-environment-buffer-local-a (items)
+    :filter-return #'direnv--export
+    (when items
+      (mapc 'kill-local-variable '(process-environment exec-path))
+      (mapc 'make-local-variable '(process-environment exec-path)))
+    items)
+
+  ;; Fontify special .envrc keywords; it's a good indication of whether or not
+  ;; we've typed them correctly.
+  (add-hook! 'direnv-envrc-mode-hook
+    (defun +direnv-envrc-fontify-keywords-h ()
+      (font-lock-add-keywords
+       nil `((,(regexp-opt +direnv--keywords 'symbols)
+              (0 font-lock-keyword-face)))))
+    (defun +direnv-update-on-save-h ()
+      (add-hook 'after-save-hook #'direnv--maybe-update-environment
+                nil 'local)))
+
+  (defadvice! +direnv-update-a (&rest _)
+    "Update direnv. Useful to advise functions that may run
+environment-sensitive logic like `flycheck-default-executable-find'. This fixes
+flycheck issues with direnv and on nix."
+    :before #'flycheck-default-executable-find
+    (direnv--maybe-update-environment))
+
+  (defadvice! +direnv--fail-gracefully-a (orig-fn)
+    "Don't try to update direnv if the executable isn't present."
+    :around #'direnv--maybe-update-environment
+    (if (executable-find "direnv")
+        (when (file-readable-p (or buffer-file-name default-directory))
+          (funcall orig-fn))
+      (doom-log "Couldn't find direnv executable")))
+
+  (defadvice! +direnv-update-async-shell-command-a (command &optional output-buffer _error-buffer)
+    :before #'shell-command
+    (when (string-match "[ \t]*&[ \t]*\\'" command)
+      (let ((environment process-environment)
+            (path exec-path)
+            (shell shell-file-name))
+        (with-current-buffer
+            (get-buffer-create (or output-buffer "*Async Shell Command*"))
+          (setq-local process-environment environment)
+          (setq-local exec-path path)
+          (setq-local shell-file-name shell)))))
+
+  (direnv-mode +1))

.emacs.d/modules/tools/direnv/doctor.el

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+;;; tools/direnv/doctor.el -*- lexical-binding: t; -*-
+
+(unless (executable-find "direnv")
+  (warn! "Couldn't find direnv executable"))

.emacs.d/modules/tools/direnv/packages.el

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+;; -*- no-byte-compile: t; -*-
+;;; tools/direnv/packages.el
+
+(package! direnv)