Emacs setup for use with LaTeX, Org, and Python

• Quick start
• Introduction
• Early Init File (info)
• Init File (info) header
  • Text faces or look (info)
  • Dired: directory editor as file manager (info)
  • Processes (info)
• Install the selected packages (info)
• Info documentation
• Key bindings (info)
  • Disabling Commands (info)
• Using Emacs as a server (info)
  • Latexmk save-compile-display loop
  • Qutebrowser userscript
  • Look into: org-protocol handling with other browser on Darwin
• Completion
  • Vertico (info)
  • Orderless (info)
  • Embark (info)
  • Marginalia (info)
  • Consult (info)
  • Company: a modular complete anything framework for Emacs
  • Minibuffer history completion
• Search and replace (info)
  • Deadgrep
• Version Control (info)
  • Ediff (info)
• Reading
  • Reading DjVu files
  • Reading EPUB files
  • Reading PDF files
• Writing
  • Writing LaTeX files
    • Math-preview
    • Improve the AUCTeX configuration slowly
  • Writing Org files
    • Org activation (info)
    • Org customization
    • Citar: citing bibliography with Org Mode
    • Compare bibtex and biblatex
    • Making Org hyperlink types (info)
    • Translate capital keywords (old) to lower case (new)
    • Evaluate specific source blocks at load-time
    • Easy LaTeX preamble editing
    • #+INCLUDE: <FILE> (info)
    • Advanced LaTeX export settings
    • Worg: backend dependent execution
    • Org Syntax
• Programming
  • Common Lisp programming
    • CS 325 AI Programming
    • Quicklisp
  • Emacs Lisp Programming (info)
  • Python programming
    • Python-mode
    • Eglot
    • Anaconda
    • Jedi
    • Code-cells
    • Look into: editing facilities
• Libraries
  • Library dash.el (info)
  • Library f.el
  • Library s.el
• Minor Modes (info)
  • Synchronal multiple-region editing
  • Unobtrusive whitespace trimming
  • Structural editing
  • Electric operators
  • Smart snippets
• Display (info)
  • Narrowing
  • Text faces or styles (info)
  • Visualize color codes and names
  • Flash the line around point for visual feedback
• Applications
  • Hyperlinking and Web Navigation Features (info)
    • Browse URL (info)
    • Emacs Web Wowser
    • Goto address mode (info)
    • Mailcap
    • Webjump
  • Elfeed: Emacs web feed reader
  • Emacs Multimedia System (info)
• Init File (info) footer
• Local variables linking to Latexmk save-compile-display-loop

Quick start

Backup your user-emacs-directory (defaults often to ~/.emacs.d on Linux, Unix, or Darwin) directory and execute the commands in listing lst:prepare-user-emacs-directory. After invoking Emacs interactively (in interactive mode, neither in batch mode, nor in server mode), Emacs will ask you to install a selected set of packages. Quit Emacs and invoke Emacs again.

  cd ~
  git clone ccdr@mercury.grenoble.cnrs.fr:SERVER/emacs.d.git .emacs.d
  make --directory=.emacs.d init
  emacs &

Introduction

This Emacs setup aims to install automatically a minimal set of extension packages that allows to handle my reports and presentations. The file format of the reports is Org Mode plain text with Python source code blocks and the file format of the presentations is LaTeX.

This org file (more precisely the original org source file of this file) illustrates three methods in my work-flow:

1. How to tangle (or export) source blocks from org files. This file contains source blocks to produce the files early-init.el, init.el, latexmkrc, org-store-link, and example.py by tangling.
2. How to export org files to other formats such as HTML, LaTeX, and PDF.
3. How org hyperlinks (info) allow to link inside and outside Org Mode: hover over or click on the links to experiment.

The AUCTeX - Aalborg University Center TeX extension package provides a powerful Text-based User Interface (TUI) environment to edit the LaTeX presentations.

The citar extension package provides quick filtering and selecting of bibliographic entries, and the option to run different commands on those selections. Citar requires Org-9.5 (info), which is already part of Emacs-28.1. Citar exploits the enhancements of Emacs' builtin selection mechanism provided by the extension packages vertico, orderless, embark, marginalia, and consult. The citeproc extension package provides CSL: citation style language processing capabilities to citar and Org Mode.

The pdf-tools extension package renders PDF file with the possibility to annotate the file or to click on anchors in the PDF file that link back to the original LaTeX file of the document. An example of my work-flow are the steps to convert this org file to PDF and to see the result with pdf-tools in Emacs: execute the commands pdf-tools-install, org-babel-tangle, org-latex-export-latex-to-latex, and compile. This sets up an infinite LaTeX compilation loop to update and redisplay the PDF file after excution of the org-latex-export-latex-to-latex command in this buffer.

Here follows a list of interesting Emacs configurations:

1. Musa Al-hassy's configuration is an impressive example of producing the Emacs initialization files and other files by tangling an org file. His methodology is impressive, as his Elisp Cheat Sheet and org-special-block-extra package show. To me, this is a configuration to admire, but his methodology is way over my head.
2. Omar Antolin Camarena's configuration exploits built-in packages, Omar's own small packages, and large external packages. Omar is the author of orderless and embark. I have stolen his idea of using custom-set-variables instead of the customize interface although that is bad Emacs advice for new users.
3. Pierre Neirhardt's configuration implements lazy loading without help of external packages. I have stolen his approach of using lazy loading to silently ignore the setup stanzas of uninstalled extension packages.
4. Sacha Chua's configuration is a practical example of producing the Emacs initialization files by tangling an org file. It gives me the impression that she is a very practical person trying to achieve her goals by the most efficient means. I have stolen her idea of using quelpa to install packages from any source.
5. Steve Purcell's configuration is well organized, a showcase of readable code, as well helpful commit and issue histories. See for instance the discussion on the correctness of order of company candidates in Emacs lisp mode.

Here follows a list of links on how to use Emacs and Elisp:

1. A guided tour of Emacs is a link to a video tour pointing how buffers (info), dired (info), documentation (info), elisp (info), elisp debugging (info), eshell (info), and keyboard macros (info) turn Emacs in an powerful coding and editing environment.
2. Emergency Emacs is a link to a video on fundamental editing features and principles with focus on ediff (info), undo (info), moving point (info), erasing (info), and dynamic abbreviations (info).
3. Endless Parentheses is a blog with many mindblowing code snippets.
4. Learning Emacs and Elisp is a link to a video tutorial with a transcript on the best approach to learn Emacs and Elisp.
5. Mastering Emacs is a link to a blog with many interesting posts that promotes a book on how to become a proficient Emacs user.

Early Init File (info)

Try to load no-littering as early as possible, since it helps to keep ~/.emacs.d clean.

  ;;; early-init.el --- user early-init file        -*- lexical-binding: t -*-
  ;;; Commentary:
  ;;; Code:
  (setq load-prefer-newer t)

  (require 'no-littering nil 'noerror)

  (provide 'early-init)
  ;; Emacs looks for "Local variables:" after the last "?\n?\f".
  
  ;; Local Variables:
  ;; indent-tabs-mode: nil
  ;; End:
  ;;; earl-init.el ends here

In order to get help in understanding the code block above in a buffer showing the original Org source file, type

(eval

after moving point (or cursor) to one of the items of the list:

1. src_emacs-lisp{(describe-variable #'load-prefer-newer t)}
2. src_emacs-lisp{(apropos-library "no-littering")}
3. src_emacs-lisp{(find-function #'hack-local-variables)}

to execute the code between the curly braces for access to help. This shows that Emacs is a self-documenting editor.

Init File (info) header

The user-init-file header requires cl-lib and customizes Emacs variables. It consists of three parts in listing lst:1st-custom-set-variables-call, lst:2nd-custom-set-variables-call, and lst:3rd-custom-set-variables-call in order to limit the length of the listings for exporting to LaTeX. The quoting (info) and the backquote (info) pages explain how to understand the reader macros ' (quote), ` (backquote), , (substitute) and @, (splice) in the custom-set-variables function calls in listing lst:1st-custom-set-variables-call, lst:2nd-custom-set-variables-call, and lst:3rd-custom-set-variables-call. A tutorial of how to use those reader macros is the didactic emacs-lisp macro example. The init file (info) does not load the custom-file as saving customizations (info) recommends because of the custom-set-variables function calls.

  ;;; init.el --- user init file                    -*- lexical-binding: t -*-
  ;;; Commentary:
  ;;; Code:
  (require 'cl-lib)

  (custom-set-variables
   '(after-save-hook #'executable-make-buffer-file-executable-if-script-p)
   '(column-number-mode t)
   '(cursor-type 'box)
   `(custom-file ,(locate-user-emacs-file "custom.el"))
   '(epg-pinentry-mode 'loopback)
   '(global-hl-line-mode t)
   '(global-hl-line-sticky-flag t)
   '(history-delete-duplicates t)
   '(history-length 500)
   '(indent-tabs-mode nil)
   '(inhibit-startup-buffer-menu t)
   '(inhibit-startup-screen t)
   '(initial-buffer-choice t)
   '(initial-scratch-message "")
   `(insert-directory-program ,(or (executable-find "gls")
                                   (executable-find "ls")))
   '(kill-ring-max 300)
   '(package-archives '(("gnu" . "https://elpa.gnu.org/packages/")
                        ("nongnu" . "https://elpa.nongnu.org/nongnu/")
                        ("melpa" . "https://melpa.org/packages/")))
   ;; Pin those packages to GNU ELPA to get the info documentation.
   '(package-pinned-packages '((consult . "gnu")
                               (marginalia . "gnu")
                               (vertico . "gnu"))))

  (custom-set-variables
   `(package-selected-packages
     `(,@(when (version< emacs-version "28.0")
           '(org                  ; plain text thought organizer
             python))             ; mode to edit Python code
       anaconda-mode              ; strangles python-mode
       applescript-mode           ; mode to edit AppleScript code
       async                      ; asynchroneous processing
       auctex                     ; Aalborg University Center TeX
       blacken                    ; Black Python code formatter client
       citar                      ; bibliography handling
       citeproc                   ; bibliography handling
       code-cells                 ; lightweight notebooks in Emacs
       company                    ; complete anything
       company-anaconda           ; complete anything in anaconda-mode
       consult                    ; consult completing-read
       deadgrep                   ; use ripgrep from Emacs
       eglot                      ; Emacs polyGLOT LSP client
       electric-operator          ; automatic spacing around operators
       elfeed                     ; web feed reader
       embark                     ; act on any buffer selection
       emms                       ; Emacs Multi-Media System
       htmlize                    ; convert buffer contents to HTML
       iedit                      ; simultaneous multi-entity editing
       keycast                    ; show current command with binding
       magit                      ; Git Text-based User Interface
       marginalia                 ; minibuffer margin notes
       markdown-mode              ; markdown text mode
       math-preview               ; display LaTeX math with MathJax
       no-littering               ; keep `user-emacs-directory' clean
       nov                        ; EPUB reader
       orderless                  ; Emacs completion style
       pdf-tools                  ; interactive docview replacement
       pdf-view-restore           ; add view history to pdf-tools
       quelpa                     ; install Emacs packages from source
       rainbow-mode               ; set background color to color string
       sly                        ; Sylvester the Cat's Common Lisp IDE
       smartparens                ; smart editing of character pairs
       toml-mode                  ; Tom's Obvious Minimal Language mode
       undo-tree                  ; more advanced yet simpler undo system
       vertico                    ; VERTical Interactive Completion
       wgrep                      ; open a writable grep buffer
       wordnut                    ; WordNet lexical database
       writegood-mode             ; bullshit and weasel-word detector
       ws-butler                  ; remove trailing whitespace
       xr                         ; undo rx to grok regular expressions
       yasnippet)))               ; code or text template expansion

  (custom-set-variables
   '(recentf-mode t)
   '(save-place-mode t)
   '(scroll-bar-mode nil)
   '(tab-always-indent 'complete)
   '(tab-width 8)
   '(tool-bar-mode nil)
   '(url-cookie-trusted-urls nil)
   '(url-cookie-untrusted-urls '(".*"))
   '(use-dialog-box nil)
   '(view-read-only t))

  (when (version< "28.0" emacs-version)
    (custom-set-variables
     '(mode-line-compact 'long)
     '(next-error-message-highlight t)
     '(use-short-answers t)))

  (when (eq system-type 'darwin)
    (custom-set-variables
     '(ns-alternate-modifier nil)
     '(ns-command-modifier 'meta)
     '(ns-right-command-modifier 'super)))

  (when (eq window-system 'ns)
    (add-to-list 'initial-frame-alist '(height . 51))
    (add-to-list 'initial-frame-alist '(width . 180)))

Text faces or look (info)

Section text faces or styles tells that this setup does not use theming. However, in order to improve visibility, it relies on:

1. Tweaking faces in memory after loading as in listing lst:tweak-faces-faces-after.
2. Toggling between a dark and light background by means of src_emacs-lisp{(invert-default-face)} in listing lst:invert-default-face.
3. Shadowing the definition of faces before loading as in listing lst:tweak-org-faces-before and lst:tweak-sh-script-faces-before. The last item in the page on fontifying Org mode source code blocks describes this method.

  (with-eval-after-load 'emacs
    (defun tweak-region-face-background-color ()
      (when (featurep 'gtk)
        (set-face-attribute
         'region nil
         :background (cdr (assoc (face-attribute 'default :background)
                                 '(("white" . "LightGoldenrod2")
                                   ("black" . "blue3")))))))

    (tweak-region-face-background-color))

  (with-eval-after-load 'emacs
    (defun invert-default-face ()
      "Invert the default face."
      (interactive)
      (invert-face 'default)
      (tweak-region-face-background-color)))

  (with-eval-after-load 'emacs
    ;; Shadow the definition in org-faces.el:
    (defface org-block
      ;; https://emacs.stackexchange.com/a/9604 answers:
      ;; How to override a defined face for light and dark backgrounds?
      `((((background dark))
         :inherit (fixed-pitch)
         ,@(and (>= emacs-major-version 27) '(:extend t))
         :background "#444444")
        (t
         :inherit (fixed-pitch)
         ,@(and (>= emacs-major-version 27) '(:extend t))
         :background "#FFFFD0"))
      "My face used for text inside various blocks.

  It is always used for source blocks.  You can refine what face
  should be used depending on the source block language by setting,
  `org-src-block-faces', which takes precedence.

  When `org-fontify-quote-and-verse-blocks' is not nil, text inside
  verse and quote blocks are fontified using the `org-verse' and
  `org-quote' faces, which inherit from `org-block'."))

  (with-eval-after-load 'emacs
    ;; Shadow the definition in sh-script.el:
    (defface sh-heredoc
      '((((class color) (background dark))
         (:foreground "yellow"))
        (((class color) (background light))
         (:foreground "magenta"))
        (t
         (:weight bold)))
      "My face to show a here-document."))

Dired: directory editor as file manager (info)

Dired (info) and the ranger file manager offer similar capabilities for copying, deleting, opening, renaming, and viewing files and directories, but the integration of dired (info) in Emacs is obviously much better than the integration of ranger in Emacs.

For instance, this setup allows to insert an org-mode link to an poorly identified file containing a specific image into an org-mode buffer by means of the facilities of dired (info) as follows:

1. Type

   (eval

   to open the directory containing the pooly identified file with the specific image in a dired-mode buffer.
2. Start searching for the specific image by navigating to the name of any image file.
3. Type

   (eval

   to switch to view the file in an image-mode buffer.

4. In the image-mode buffer, continue searching for the specific image by typing:

   • (eval

     to view the next image in the dired-mode buffer,

   • (eval

     to view the previous image in the dired-mode buffer, and

   • (eval

     to quit the image-mode buffer and to go back to the dired-mode buffer.
5. After finding the specific image, use

   (eval

   in the image-mode buffer or the dired-mode buffer to store the org-link.
6. Switch to the org-mode buffer and use

   (eval

   to insert the org-link into the buffer.

Listing lst:customize-dired makes the directory editor sort entries alphabetically after grouping the directories before grouping the files by extension.

  (with-eval-after-load 'dired
    (custom-set-variables
     '(dired-dwim-target t)
     ;; | switch | action                                 |
     ;; |--------+----------------------------------------|
     ;; | -a     | also list hidden entries               |
     ;; | -l     | use a long listing format              |
     ;; | -X     | sort alphabetically by entry extension |
     ;; | -G     | skip long listing format group names   |
     ;; | -1     | list one entry per line                |
     '(dired-listing-switches "-alGX1 --group-directories-first")
     '(dired-recursive-copies 'always)
     '(dired-recursive-deletes 'always)))

  (with-eval-after-load 'files
    (custom-set-variables
     ;; Ensure the use of `GNU-ls' from `coreutils' on darwin.
     '(insert-directory-program (or (executable-find "gls")
                                    (executable-find "ls")))))

  (with-eval-after-load 'wdired
    (custom-set-variables
     '(wdired-allow-to-change-permissions t)))

Listing lst:extra-dired-key-bindings adds new key bindings to dired-mode-map to:

1. Open files with the Emacs Web Wowser inside Emacs.
2. Let rsync copy marked files outside Emacs to a local or remote directory.

The link asynchoronous execution library for Emacs Dired is the original source for the idea of using rsync and the blog articles using rsync in dired and asynchronous rsync with Emacs, dired and tramp are vivid recommendations written by experienced Emacs users.

  (with-eval-after-load 'dired
    (define-key
      dired-mode-map (kbd "E")
      (defun my-dired-eww-find-file ()
        "Visit dired file with eww."
        (interactive)
        (eww-open-file (dired-get-file-for-visit))))

    ;; https://truongtx.me/tmtxt-dired-async.html
    (define-key
      dired-mode-map (kbd "Y")
      (defun my-dired-rsync (target)
        "Copy marked files with `rsync' to TARGET directory."
        (interactive
         (list (expand-file-name
                (read-file-name "Rsync to:" (dired-dwim-target-directory)))))
        ;; Store all marked files into the `files' list and intialize
        ;; the `rsync-command'.
        (let ((files (dired-get-marked-files nil current-prefix-arg))
              (rsync-command "rsync -av --progress "))
          ;; Add all marked files as arguments to the `rsync-command'.
          (dolist (file files)
            (setq rsync-command
                  (concat rsync-command
                          (if (string-match "^/ssh:\\(.*\\)$" file)
                              (format " -e ssh %s" (match-string 1 file))
                            (shell-quote-argument file)) " ")))
          ;; Append the destination directory to the `rsync-command'.
          (setq rsync-command
                (concat rsync-command
                        (if (string-match "^/ssh:\\(.*\\)$" target)
                            (format " -e ssh %s" (match-string 1 target))
                          (shell-quote-argument target))))
          ;; Run the async shell command.
          (async-shell-command rsync-command)
          ;; Finally, switch to that window.
          (other-window 1)))))

Processes (info)

Listing lst:process-utilities defines a function to run a (command-line) program with arguments and to obtain a list with its numeric exit status as well as its output to stdout.

  ;; https://gitlab.com/howardabrams/spacemacs.d/blob/master/layers/ha-org/funcs.el#L418
  (defun shell-command-with-exit-code (program &rest args)
    "Run PROGRAM with ARGS and return exit-code and output in a list."
    (with-temp-buffer
      (list (apply 'call-process program nil (current-buffer) nil args)
            (buffer-string))))

Install the selected packages (info)

Emacs installs packages from archives on the internet. This setup uses three archives:

1. The GNU Emacs Lisp Package Archive
2. The NonGNU Emacs Lisp Package Archive.
3. The Milkypostman's Emacs Lisp Package Archive (MELPA).

In addition, the quelpa tool allows to fetch code from any source and build a package on your computer before installation. The code in listing lst:install-selected-packages assumes that the package system is in a virgin state if the package no-littering is not present:

1. It installs and loads no-littering after ensuring refreshing of the contents of available packages.
2. It ensures installation of quelpa before ensuring installation of undo-tree.
3. It calls src_emacs-lisp{(package-install-selected-packages)} to check the installation status of all packages in src_emacs-lisp{package-selected-packages} and to install the missing packages after the user has agreed to its prompt.

In case of normal Emacs usage, src_emacs-lisp{(package-list-packages)} refreshes the contents of packages and allows to update packages to the latest version.

  (unless (require 'no-littering nil 'noerror)
    (package-refresh-contents)
    (package-install 'no-littering)
    (require 'no-littering))

  (unless (package-installed-p 'quelpa)
    (package-install 'quelpa))

  (unless (package-installed-p 'undo-tree)
    ;; Neither GNU ELPA, nor MELPA have the latest version.
    (quelpa '(undo-tree :repo "tsc25/undo-tree" :fetcher gitlab)))

  (unless noninteractive
    (package-install-selected-packages))

Info documentation

Listing lst:configure-info adds a path in my home directory to the places where info looks for files.

  (with-eval-after-load 'info
    ;; Emacs should find my "python.info" file.
    (add-to-list 'Info-directory-list
                 (expand-file-name "~/.local/share/info")))

Key bindings (info)

command	keys	key map
undo	(eval	global-map
backward-kill-word	(eval	global-map
backward-char	(eval	global-map
forward-char	(eval	global-map
backward-word	(eval	global-map
forward-word	(eval	global-map
backward-sentence	(eval	global-map
forward-sentence	(eval	global-map

Disabling Commands (info)

Execute src_emacs-lisp{(find-library "novice")} to see how Emacs prevents new users from shooting themselves in the feet. Listing lst:configure-disabled-command-function enables disabled commands on the fly.

  (with-eval-after-load 'emacs
    (setq disabled-command-function
          (defun my-enable-this-command (&rest _args)
            "Called when a disabled command is executed.
  Enable it and re-execute it."
            (put this-command 'disabled nil)
            (message "You typed %s.  %s was disabled until now."
                     (key-description (this-command-keys)) this-command)
            (sit-for 0)
            (call-interactively this-command))))

Using Emacs as a server (info)

Emacs can act as a server that listens to a socket to share its state (for instance buffers and command history) with other programs by means of a shell command emacsclient. Section #sec:latexmk-save-compile-display-loop and #sec:qutebrowser-userscript show how to use emacsclient to:

1. Install an asynchronous (or background) loop of saving a LaTeX file, compiling it, and redisplaying the output in Emacs.
2. Make qutebrowser send html links with document titles to Emacs.

The code in listing lst:start-emacs-server starts the Emacs server.

  (when window-system
    (unless (or noninteractive (daemonp))
      (add-hook 'after-init-hook #'server-start)))

Latexmk save-compile-display loop

The latexmk resource file in the next source code block shows how to use emacsclient to (re)display the PDF file in Emacs after each succesful (re)compilation on condition that the settings of the compile-command local variable in section are compatible. The local variable compile-command in the local variables section (only visible in org files, but not in html and pdf files) shows how to use the latexmkrc file.

  # pdf previewer and update pdf previewer
  $pdf_previewer = "emacsclient -e '(find-file-other-window %S)'";
  $pdf_update_method = 4;  # 4 runs a command to force the update
  $pdf_update_command = "emacsclient -e '(with-current-buffer (find-buffer-visiting %S) (pdf-view-revert-buffer nil t))'";
  # see for instance glossary.latexmkrc
  add_cus_dep( 'acn', 'acr', 0, 'makeglossaries' );
  add_cus_dep( 'glo', 'gls', 0, 'makeglossaries' );
  $clean_ext .= " acr acn alg bbl glo gls glg ist lol run.xml";
  sub makeglossaries {
      my ($name, $path) = fileparse( $$Psource );
      return system "makeglossaries -d '$path' '$name'";
  }
  # Emacs looks for "Local variables:" after the last "?\n?\f".
  
  # Local Variables:
  # mode: perl
  # End:

Qutebrowser userscript

The next block contains an userscript that sends a store-link org-protocol message with the url and the title from qutebrowser to emacsclient. The function urlencode translates the url and the title for the message. The Python urllib examples show how to use urlencode. The final execvp call deals with a qutebrowser userscript requirement: the emacsclient process must get the PID of the userscript that must kill itself after the take-over. Termination of the emacsclient process hands control back to qutebrowser.

On a POSIX system, you can run the userscript from qutebrowser or from a terminal to see whether it works. In case you try to run it from Emacs, Emacs may hang or die.

  #!/usr/bin/env python
  from urllib.parse import urlencode
  from os import environ, execvp

  url = environ.get("QUTE_URL", "https://orgmode.org")
  title = environ.get("QUTE_TITLE", "Org Mode")
  parameters = urlencode({"url": url, "title": title})
  print(payload := f"org-protocol://store-link?{parameters}")
  execvp("emacsclient", ("-n", payload))

TODO Look into: org-protocol handling with other browser on Darwin

1. Patrick Goddi: macOS URI protocol handler and his URI-Handler.
2. Hammerspoon
3. Emacs Capture Anywhere

Completion

Vertico (info) provides a performant and minimalistic vertical completion UI based on the default completion system and behaves therefore correctly under all circumstances. Using Vertico, Marginalia, Consult, and Embark links to a video demonstration. Vertico integrates well with fully supported complementary packages to enrich the completion UI:

1. Orderless (info) for an advanced completion style,
2. Embark (info) for minibuffer actions with context menus,
3. Marginalia (info) for rich annotations in the minibuffer, and
4. Consult (info) for useful search and navigation commands,

where the order is that of enhancing citar's experience and the configuration steps below.

Finally, company: a modular complete-anything framework for Emacs provides completion in any buffer and minibuffer-history-completion provides completion on previous input in the minibuffer.

Vertico (info)

Listing lst:enable-vertico-mode configures and enables savehist-mode and enables vertico-mode. The documentation src_emacs-lisp{(describe-function 'savehist-mode)} why it is best to turn on savehist-mode in the Emacs init file.

  (when (fboundp 'savehist-mode)
    (savehist-mode +1)
    (custom-set-variables
     '(savehist-additional-variables
       '(eww-history
         kill-ring
         regexp-search-string
         search-ring
         search-string))))
  (when (fboundp 'vertico-mode)
    (vertico-mode +1))
  (with-eval-after-load 'vertico
    (define-key vertico-map (kbd "RET") #'vertico-directory-enter)
    (define-key vertico-map (kbd "DEL") #'vertico-directory-delete-char)
    (define-key vertico-map (kbd "M-DEL") #'vertico-directory-delete-word))

command	keys	remap
vertico-directory-delete-char	(eval
vertico-directory-delete-word	(eval
vertico-directory-enter	(eval
vertico-exit	(eval	exit-minibuffer
vertico-exit-input	(eval
vertico-first	(eval	beginning-of-buffer
vertico-first	(eval	minibuffer-beginning-of-buffer
vertico-insert	(eval
vertico-last	(eval	end-of-buffer
vertico-next-group	(eval	forward-paragraph
vertico-next	(eval	next-line-or-history-element
vertico-next	(eval	next-line
vertico-previous-group	(eval	backward-paragraph
vertico-previous	(eval	previous-line-or-history-element
vertico-previous	(eval	previous-line
vertico-save	(eval	kill-ring-save
vertico-scroll-down	(eval	scroll-down-command
vertico-scroll-up	(eval	scroll-up-command

Orderless (info)

Listing lst:configure-orderless enables orderless.

  (when (fboundp 'orderless-filter)
    (custom-set-variables
     ;; https://github.com/purcell/emacs.d/issues/778
     '(completion-styles '(basic completion-partial orderless))
     '(completion-category-defaults nil)
     '(completion-category-overrides
       '((file (styles partial-completion)))))
    (add-hook 'minibuffer-setup-hook
              (defun my-on-minibuffer-setup-hook()
                (setq-default completion-styles '(substring orderless)))))

Embark (info)

Listing lst:configure-embark configures embark key bindings: type for instance that the initialization src_emacs-lisp{(setq prefix-help-command #'embark-prefix-help-command)} enables minibuffer help after a prefix key.

  (when (cl-every #'fboundp '(embark-act embark-bindings embark-dwim))
    (global-set-key (kbd "C-,") #'embark-act)
    (global-set-key (kbd "C-:") #'embark-dwim)
    (global-set-key (kbd "C-h B") #'embark-bindings)
    (setq prefix-help-command #'embark-prefix-help-command))

Marginalia (info)

Listing lst:enable-marginalia-mode enables marginalia-mode.

  (when (fboundp 'marginalia-mode)
    (marginalia-mode +1))

Consult (info)

Listing lst:configure-consult configures consult.

command	keys	key map
consult-apropos	(eval	global-map
consult-bookmark	(eval	ctl-x-keymap
consult-buffer-other-frame	(eval	ctl-x-keymap
consult-buffer-other-window	(eval	ctl-x-keymap
consult-buffer	(eval	ctl-x-keymap
consult-compile-error	(eval	goto-map
consult-complex-command	(eval	ctl-x-keymap
consult-find	(eval	search-map
consult-focus-lines	(eval	search-map
consult-git-grep	(eval	search-map
consult-global-mark	(eval	goto-map
consult-goto-line	(eval	goto-map
consult-goto-line	(eval	goto-map
consult-history	(eval	global-map
consult-imenu-project	(eval	goto-map
consult-keep-lines	(eval	search-map
consult-line	(eval	search-map
consult-mark	(eval	goto-map
consult-mode-command	(eval	global-map
consult-multi-occur	(eval	search-map
consult-outline	(eval	goto-map
consult-register	(eval	ctl-x-keymap
consult-yank-pop	(eval	global-map
deadgrep	(eval	search-map
elfeed	(eval	global-map
embark-act	(eval	global-map
embark-bindings	(eval	global-map
embark-dwim	(eval	global-map
iedit-mode	(eval	global-map
minibuffer-complete-history	(eval	minibuffer-local-map
narrow-or-widen-dwim	(eval	ctl-x-keymap
org-agenda	(eval	global-map
org-capture	(eval	global-map
org-cite	(eval	org-mode-map
org-insert-link-global	(eval	global-map
org-narrow-to-table	(eval	ctl-x-keymap
org-store-link	(eval	global-map

  (when (fboundp 'consult-apropos)
    (custom-set-variables
     '(consult-project-root-function #'vc-root-dir))
    ;; C-c bindings (mode-specific-map)
    (global-set-key (kbd "C-c h") #'consult-history)
    (global-set-key (kbd "C-c m") #'consult-mode-command)
    ;; C-x bindings (ctl-x-map)
    (define-key ctl-x-map (kbd "M-:") #'consult-complex-command)
    (define-key ctl-x-map (kbd "b") #'consult-buffer)
    (define-key ctl-x-map (kbd "4 b") #'consult-buffer-other-window)
    (define-key ctl-x-map (kbd "5 b") #'consult-buffer-other-frame)
    (define-key ctl-x-map (kbd "r x") #'consult-register)
    (define-key ctl-x-map (kbd "r b") #'consult-bookmark)
    ;; M-g bindings (goto-map)
    (define-key goto-map (kbd "g") #'consult-goto-line)
    (define-key goto-map (kbd "M-g") #'consult-goto-line)
    (define-key goto-map (kbd "o") #'consult-outline)
    (define-key goto-map (kbd "m") #'consult-mark)
    (define-key goto-map (kbd "k") #'consult-global-mark)
    (define-key goto-map (kbd "i") #'consult-imenu-project)
    (define-key goto-map (kbd "e") #'consult-compile-error)
    ;; M-s bindings (search-map)
    (define-key search-map (kbd "g") #'consult-git-grep)
    (define-key search-map (kbd "f") #'consult-find)
    (define-key search-map (kbd "k") #'consult-keep-lines)
    (define-key search-map (kbd "l") #'consult-line)
    (define-key search-map (kbd "m") #'consult-multi-occur)
    (define-key search-map (kbd "u") #'consult-focus-lines)
    ;; Other bindings
    (global-set-key (kbd "M-y") #'consult-yank-pop)
    (global-set-key (kbd "<help> a") #'consult-apropos)
    ;; Tweak functions
    (advice-add 'completing-read-multiple
                :override #'consult-completing-read-multiple))

Company: a modular complete anything framework for Emacs

Listing lst:configure-company configures company.

  (when (fboundp 'company-mode)
    (custom-set-variables
     ;; https://github.com/purcell/emacs.d/issues/778
     '(company-transformers '(company-sort-by-occurrence)))
    (dolist (hook '(LaTeX-mode-hook
                    org-mode-hook
                    emacs-lisp-mode-hook
                    lisp-interaction-mode-hook
                    lisp-mode-hook
                    python-mode-hook
                    ielm-mode-hook
                    sly-mrepl-mode-hook))
      (add-hook hook #'company-mode)))

Minibuffer history completion

See Juri Linkov (Emacs Developer mailing list) for how to allow completion on previous input in the minibuffer. Listing lst:enable-minibuffer-history-completion enables minibuffer history completion.

  (with-eval-after-load 'emacs
    (defun minibuffer-setup-history-completions ()
      (unless (or minibuffer-completion-table minibuffer-completion-predicate)
        (setq-local minibuffer-completion-table
                    (symbol-value minibuffer-history-variable))))

    (add-hook 'minibuffer-setup-hook 'minibuffer-setup-history-completions)

    ;; Stolen from Emacs-28.1 for Emacs-27.2:
    (unless (fboundp 'minibuffer--completion-prompt-end)
      (defun minibuffer--completion-prompt-end ()
        (let ((end (minibuffer-prompt-end)))
          (if (< (point) end)
              (user-error "Can't complete in prompt")
            end))))

    ;; Adapted from ‘minibuffer-complete’:
    (defun minibuffer-complete-history ()
      "Allow minibuffer completion on previous input."
      (interactive)
      (completion-in-region (minibuffer--completion-prompt-end) (point-max)
                            (symbol-value minibuffer-history-variable)
                            nil))

    (define-key minibuffer-local-map (kbd "C-<tab>") #'minibuffer-complete-history))

Search and replace (info)

Deadgrep

Deadgrep uses ripgrep for superfast text searching in the default directory or the current VCS directory tree. Listing lst:configure-deadgrep binds deadgrep to .

  (when (autoload 'deadgrep "deadgrep" nil t)
    (define-key search-map (kbd "d") #'deadgrep))
  (with-eval-after-load 'deadgrep
    (define-key deadgrep-mode-map (kbd "C-c C-w") #'deadgrep-edit-mode))

Version Control (info)

Ediff (info)

Video links to complete the ediff (info) manual are:

1. Emergency Emacs.
2. Use smerge and ediff to resolve file conflicts.

Listing lst:configure-ediff configures ediff to display all its buffers in a single frame and to make all text visible prior to ediffing Org buffers.

  (with-eval-after-load 'emacs
    (custom-set-variables
     '(ediff-merge-split-window-function #'split-window-horizontally)
     '(ediff-split-window-function #'split-window-horizontally)
     '(ediff-window-setup-function #'ediff-setup-windows-plain)))
  (with-eval-after-load 'org
    ;; https://github.com/oantolin/emacs-config#readme
    (defun ediff-with-org-show-all ()
      "Expand all headings prior to ediffing org buffers."
      (add-hook 'ediff-prepare-buffer-hook #'org-show-all nil t))
    (add-hook 'org-mode-hook #'ediff-with-org-show-all))

Reading

Reading DjVu files

This setup relies on Document View (info) to facilitate reading DjVu files. Reading the code shown by src_emacs-lisp{(find-function 'doc-view-djvu->tiff-converter-ddjvu)} shows that reading DjVu files requires the command line DjVu decoder ddjvu from the DjVuLibre utilities.

Reading EPUB files

Listing lst:enable-nov-mode enables nov-mode.

  (when (fboundp 'nov-mode)
    (add-to-list 'auto-mode-alist `(,(rx ".epub" eos) . nov-mode)))

Reading PDF files

The pdf-tools package exploits the poppler library to render and to let you annotate PDF files. It also exploits the SyncTeX library to link anchors in PDF files produced with LaTeX to the original LaTeX sources.

In order to use pdf-tools, you have to type

(eval

after installation of pdf-tools from MELPA or after each update of poppler to build or rebuild the epdfinfo executable that serves the PDF files to Emacs.

  (when (fboundp 'pdf-loader-install)
    ;; `pdf-loader-install' is the lazy equivalent of `pdf-tools-install':
    ;; see the README file.
    (pdf-loader-install)

    (with-eval-after-load 'pdf-view
      (custom-set-variables
       '(pdf-view-display-size 'fit-page))

      (when (fboundp 'pdf-view-restore-mode)
        (add-hook 'pdf-view-mode-hook #'pdf-view-restore-mode))))

Writing

Writing LaTeX files

Loading tex.el immediately instead of lazily ensures proper initialization of AUCTeX. For instance, the TeX-master safe local variable in the tex.el elisp library file has no autoload cookie. Without prior loading of tex.el, Emacs will complain that TeX-master is no safe local variable in case it reads a LaTeX file that sets TeX-master. Listing lst:require-auctex initializes AUCTeX properly.

  ;; Use `require' to make `TeX-master' a safe local variable.
  (when (require 'tex nil 'noerror)
    (custom-set-variables
     '(TeX-auto-save t)
     '(TeX-install-font-lock #'font-latex-setup)
     '(TeX-parse-self t)))

Listing lst:configure-bibtex configures the Emacs bibtex library to use the LaTeX BiBTeX dialect for backwards compatibility.

  (with-eval-after-load 'bibtex
    (custom-set-variables '(bibtex-dialect 'BibTeX)))

Listing lst:configure-font-latex disables font scaling of section titles.

  (with-eval-after-load 'font-latex
    (custom-set-variables
     '(font-latex-fontify-sectioning 1.0)))

Listing lst:configure-latex configures latex for a full featured LaTeX-section-command. Finally, out of the box, AUCTeX does not indent text between square brackets. The code in listing lst:configure-tex corrects this by advising to override TeX-brace-count-line with my-TeX-brace-count-line.

  (with-eval-after-load 'latex
    (custom-set-variables
     '(LaTeX-section-hook '(LaTeX-section-heading
                            LaTeX-section-title
                            LaTeX-section-toc
                            LaTeX-section-section
                            LaTeX-section-label))))

  (with-eval-after-load 'tex
    (custom-set-variables
     ;; Disable `TeX-electric-math' to prevent collisions with `smartparens'.
     '(TeX-electric-math nil))

    ;; https://emacs.stackexchange.com/questions/17396/
    ;; indentation-in-square-brackets
    (defun my-TeX-brace-count-line ()
      "Count number of open/closed braces."
      (save-excursion
        (let ((count 0) (limit (line-end-position)) char)
          (while (progn
                   (skip-chars-forward "^{}[]\\\\" limit)
                   (when (and (< (point) limit) (not (TeX-in-comment)))
                     (setq char (char-after))
                     (forward-char)
                     (cond ((eq char ?\{)
                            (setq count (+ count TeX-brace-indent-level)))
                           ((eq char ?\})
                            (setq count (- count TeX-brace-indent-level)))
                           ((eq char ?\[)
                            (setq count (+ count TeX-brace-indent-level)))
                           ((eq char ?\])
                            (setq count (- count TeX-brace-indent-level)))
                           ((eq char ?\\)
                            (when (< (point) limit)
                              (forward-char) t))))))
          count)))

    (advice-add 'TeX-brace-count-line :override #'my-TeX-brace-count-line))

Math-preview

  (with-eval-after-load 'math-preview
    (let ((command (executable-find "~/node_modules/.bin/math-preview")))
      (if command
          (custom-set-variables
           `(math-preview-command ,command)
           '(math-preview-raise 0.5)
           '(math-preview-scale 1))
        ;; https://stackoverflow.com/a/17509764 answers:
        ;; How to install an npm package from github directly?
        (cl-destructuring-bind (exit-code output)
            (shell-command-with-exit-code
             "npm" "install" "git+https://gitlab.com/matsievskiysv/math-preview.git")
          (if (= 0 exit-code) (message "%s" (string-trim output))
            (error "%s" (string-trim output)))))))

TODO Improve the AUCTeX configuration slowly

AUCTeX setup of an experienced user

Writing Org files

Org activation (info)

  (when (cl-every #'fboundp '(org-agenda org-capture))
    (global-set-key (kbd "C-c a") #'org-agenda)
    (global-set-key (kbd "C-c c") #'org-capture)
    (with-eval-after-load 'ol
      (global-set-key (kbd "C-c l") #'org-store-link)
      (global-set-key (kbd "C-c C-l") #'org-insert-link-global)))

Org customization

The code in listing lst:customize-org-babel, lst:customize-org, and lst:customize-org-export does basic customization of Org-mode variables. Listing lst:customize-org-latex-classes defines org-latex-classes (info) for backward compatibility. See table tab:org-latex-class-tag-placeholder and type

(eval

for an explanation of the code in listing lst:customize-org-latex-classes.

#+caption[The relation tag-placeholder in listing lst:customize-org-latex-classes]:

tag	placeholder
+1	[DEFAULT-PACKAGES]
+2	[PACKAGES]
+3	[EXTRA]
-1	[NO-DEFAULT-PACKAGES]
-2	[NO-PACKAGES]
-3	[NO-EXTRA]

  (with-eval-after-load 'ob-core
    (custom-set-variables
     '(org-confirm-babel-evaluate nil)))

  (with-eval-after-load 'ob-python
    (custom-set-variables
     '(org-babel-python-command "python -E")))

  (with-eval-after-load 'ob-latex
    (custom-set-variables
     '(org-babel-latex-preamble
       (lambda (_)
         "\\documentclass[preview]{standalone}\n"))
     '(org-babel-latex-begin-env
       (lambda (_)
         "\\begin{document}\n"))
     '(org-babel-latex-end-env
       (lambda (_)
         "\\end{document}\n"))))

  (with-eval-after-load 'ob-lisp
    (with-eval-after-load 'sly
      (custom-set-variables
       '(org-babel-lisp-eval-fn #'sly-eval))))

  (with-eval-after-load 'org
    (custom-set-variables
     '(org-babel-load-languages '((C . t)
                                  (calc . t)
                                  (dot . t)
                                  (emacs-lisp . t)
                                  (eshell . t)
                                  (fortran . t)
                                  (gnuplot . t)
                                  (latex . t)
                                  (lisp . t)
                                  (maxima . t)
                                  (org . t)
                                  (perl . t)
                                  (python . t)
                                  (shell . t)))
     '(org-export-backends '(ascii beamer html icalendar latex odt texinfo))
     '(org-file-apps '((auto-mode . emacs)
                       (directory . emacs)
                       ("\\.mm\\'" . default)
                       ("\\.x?html?\\'" . default)
                       ("\\.pdf\\'" . emacs)))
     '(org-modules '(ol-bibtex
                     ol-doi
                     ol-eww
                     ol-info
                     org-id
                     org-protocol
                     org-tempo))
     '(org-structure-template-alist '(("a" . "export ascii")
                                      ("c" . "center")
                                      ("C" . "comment")
                                      ("e" . "example")
                                      ("E" . "export")
                                      ("h" . "export html")
                                      ("l" . "export latex")
                                      ("q" . "quote")
                                      ("s" . "src")
                                      ("p" . "src python :session :async")
                                      ("v" . "verse")))))

  (with-eval-after-load 'org
    ;; From: "Nicolas Richard" <theonewiththeevillook@yahoo.fr>
    ;; Date: Fri, 08 Mar 2013 16:23:02 +0100	[thread overview]
    ;; Message-ID: <87vc913oh5.fsf@yahoo.fr> (raw)
    (defun org-electric-dollar ()
      "When called once, insert \\(\\) and leave point in between.
  When called twice, replace the previously inserted \\(\\) by one $."
      (interactive)
      (if (and (looking-at "\\\\)") (looking-back "\\\\(" (- (point) 2)))
          (progn (delete-char 2)
                 (delete-char -2)
                 (insert "$"))
        (insert "\\(\\)")
        (backward-char 2)))

    (define-key org-mode-map (kbd "$") #'org-electric-dollar)
    (define-key org-mode-map (kbd "M-q") #'org-fill-paragraph))

  (with-eval-after-load 'ox-latex
    (custom-set-variables
     '(org-latex-compiler "lualatex")
     '(org-latex-hyperref-template "\\hypersetup{
    pdfauthor={%a},
    pdftitle={%t},
    pdfkeywords={%k},
    pdfsubject={%d},
    pdfcreator={%c},
    pdflang={%L},
    citecolor=blue,
    colorlinks=true,
    filecolor=blue,
    hyperfootnotes=false,
    linkcolor=blue,
    unicode=true,
    urlcolor=blue,
  }\n")
     '(org-latex-listings 'minted)
     '(org-latex-minted-langs '((cc "c++")
                                (cperl "perl")
                                (diff "diff")
                                (shell-script "bash")
                                (org "text")
                                (toml "toml")))
     '(org-latex-minted-options '(("bgcolor" "LightGoldenrodYellow")))
     `(org-latex-logfiles-extensions
       ',(cl-union '("lof" "lot") org-latex-logfiles-extensions :test #'equal))
     '(org-latex-prefer-user-labels t)
     '(org-latex-subtitle-separate t)))

  (with-eval-after-load 'ox-latex
    (mapc (function (lambda (element)
                      (add-to-list 'org-latex-classes element)))
          (nreverse
           (quote (("elsarticle-1+2+3"	; Elsevier journals
                    "\\documentclass{elsarticle}
  [NO-DEFAULT-PACKAGES]
  [PACKAGES]
  [EXTRA]"
                    ("\\section{%s}" . "\\section*{%s}")
                    ("\\subsection{%s}" . "\\subsection*{%s}")
                    ("\\subsubsection{%s}" . "\\subsubsection*{%s}")
                    ("\\paragraph{%s}" . "\\paragraph*{%s}")
                    ("\\subparagraph{%s}" . "\\subparagraph*{%s}"))
                   ("article-1+2+3"
                    "\\documentclass{article}
  [NO-DEFAULT-PACKAGES]
  [PACKAGES]
  [EXTRA]"
                    ("\\section{%s}" . "\\section*{%s}")
                    ("\\subsection{%s}" . "\\subsection*{%s}")
                    ("\\subsubsection{%s}" . "\\subsubsection*{%s}")
                    ("\\paragraph{%s}" . "\\paragraph*{%s}")
                    ("\\subparagraph{%s}" . "\\subparagraph*{%s}"))
                   ("report-1+2+3"
                    "\\documentclass[11pt]{report}
  [NO-DEFAULT-PACKAGES]
  [PACKAGES]
  [EXTRA]"
                    ("\\part{%s}" . "\\part*{%s}")
                    ("\\chapter{%s}" . "\\chapter*{%s}")
                    ("\\section{%s}" . "\\section*{%s}")
                    ("\\subsection{%s}" . "\\subsection*{%s}")
                    ("\\subsubsection{%s}" . "\\subsubsection*{%s}"))
                   ("book-1+2+3"
                    "\\documentclass[11pt]{book}
  [NO-DEFAULT-PACKAGES]
  [PACKAGES]
  [EXTRA]"
                    ("\\part{%s}" . "\\part*{%s}")
                    ("\\chapter{%s}" . "\\chapter*{%s}")
                    ("\\section{%s}" . "\\section*{%s}")
                    ("\\subsection{%s}" . "\\subsection*{%s}")
                    ("\\subsubsection{%s}" . "\\subsubsection*{%s}")))))))

Citar: citing bibliography with Org Mode

Citar is a completing-read front-end to browse and act on BibTeX, BibLaTeX, as well as CSL JSON bibliographic data with LaTeX, markdown, and org-cite editing support. In combination with vertico, orderless, embark, marginalia, and consult, Citar provides quick filtering and selecting of bibliographic entries from the minibuffer, as well as the option to run different commands on those selections. Listing lst:configure-oc-cite+citar configures org-cite, citar, and org.

  (with-eval-after-load 'oc
    (require 'oc-biblatex)
    (require 'oc-csl)

    (custom-set-variables
     '(org-cite-export-processors '((latex biblatex)
                                    (t csl)))
     '(org-cite-global-bibliography '("~/VCS/research/refs.bib")))

    (when (require 'citar nil 'noerror)
      (custom-set-variables
       '(org-cite-activate-processor 'citar)
       '(org-cite-follow-processor 'citar)
       '(org-cite-insert-processor 'citar))))

  (with-eval-after-load 'org
    (when (require 'citar nil 'noerror)
      (custom-set-variables
       '(citar-bibliography '("~/VCS/research/refs.bib"))
       '(citar-file-extensions '("djvu" "pdf"))
       '(citar-library-paths '("~/VCS/research/papers/"))))

    (define-key org-mode-map (kbd "C-c b") #'org-cite-insert))

Ref. [cite:@Schulte.MCSE.2011.41] shows that Org-mode is a simple, plain-text markup language for hierarchical documents allowing intermingling of data, code, and prose. It serves as an example link to to show how to use Citar within this setup, provided that citar-bibliography and citar-library-paths point to valid directories and files. In an Org-mode buffer this setup allows to:

1. Insert an Org-mode cite link:

   1. Type .
   2. Navigate to the bibliographic entry to insert.
   3. Select it.

2. View an electronic copy of an Org-mode cite link:

   1. Move point to the Org-mode cite link.
   2. Type .
   3. Navigate to the corresponding library file.
   4. Select it.

3. Open the DOI of an Org-mode cite link:

   1. Move point to the Org-mode cite link.
   2. Type .
   3. Navigate to the corresponding link.
   4. Select it.

TODO Compare bibtex and biblatex

1. Using bibtex: a short guide
2. The biblatex package
3. Rebiber: A tool for normalizing bibtex with official info
4. A biblatex implementation of the AIP and APS bibliography style

Making Org hyperlink types (info)

Listing lst:customize-org-link configures org-link to use relative file path links.

  (with-eval-after-load 'ol
    (custom-set-variables
     '(org-link-file-path-type 'relative)))

Listing lst:org-ref-like-org-link-types defines org-link types for backwards compatibility with org-ref. Listing lst:define-org-pdfview-link-type uses ideas from the definition of docview-org-link and doi-org-link types to define an pdfview-org-link type for use with pdf-tools. Finally, listing lst:emacs-lisp-setup-patch-ol-info patches the function org-info-export and listing lst:emacs-lisp-setup-buffer-local-ol-info sets the constants org-info-emacs-documents and org-info-other-documents as buffer local variables in order to export the info-org-link types in this document to html and LaTeX correctly.

  (with-eval-after-load 'ol
    (org-link-set-parameters
     "ac*" :export (lambda (path _desc backend _info)
                     (pcase backend
                       (`latex (format "\\gls*{%s}" path))
                       (_ path))))
    (org-link-set-parameters
     "cite" :export (lambda (path _desc backend _info)
                      (pcase backend
                        (`latex (format "\\cite{%s}" path))
                        (_ path))))
    (org-link-set-parameters
     "eqref" :export (lambda (path _desc backend _info)
                       (pcase backend
                         (`latex (format "\\eqref{%s}" path))
                         (_ path))))
    (org-link-set-parameters
     "hyperlink" :export (lambda (path desc backend _info)
                           (pcase backend
                             (`latex (format "\\hyperlink{%s}{%s}" path desc))
                             (_ path))))
    (org-link-set-parameters
     "label" :export (lambda (path _desc backend _info)
                       (pcase backend
                         (`latex (format "\\label{%s}" path))
                         (_ path))))
    (org-link-set-parameters
     "ref" :export (lambda (path _desc backend _info)
                     (pcase backend
                       (`latex (format "\\ref{%s}" path))
                       (_ path)))))

  (with-eval-after-load 'ol
    (autoload 'pdf-view-goto-page "pdf-view" nil t)
    (org-link-set-parameters "pdfview"
                             :follow #'org-pdfview-open
                             :export #'org-pdfview-export
                             :store #'org-pdfview-store-link)

    (defun org-pdfview-export (link description backend _)
      "Export a \"pdfview\" type link.
  The paths of the links export as file relative paths in order to
  facilate moving single directories or whole directory trees."
      (let ((path (if (string-match "\\(.+\\)::.+" link)
                      (match-string 1 link)
                    link))
            (desc (or description link)))
        (when (stringp path)
          (setq path (file-relative-name path))
          (pcase backend
            (`html (format "<a href=\"%s\">%s</a>" path desc))
            (`latex (format "\\href{%s}{%s}" path desc))
            (`ascii (format "%s (%s)" desc path))
            (_ path)))))

    (defun org-pdfview-open (link _)
      "Open a \"pdfview\" type link."
      (string-match "\\(.*?\\)\\(?:::\\([0-9]+\\)\\)?$" link)
      (let ((path (match-string 1 link))
            (page (and (match-beginning 2)
                       (string-to-number (match-string 2 link)))))
        ;; Let Org mode open the file (in-emacs = 1) to ensure
        ;; org-link-frame-setup is respected.
        (org-open-file path 1)
        (when page (pdf-view-goto-page page))))

    (defun org-pdfview-store-link ()
      "Store a \"pdfview\" type link."
      (when (eq major-mode 'pdf-view-mode)
        (let* ((path buffer-file-name)
               (page (pdf-view-current-page))
               (link (concat "pdfview:" path "::" (number-to-string page))))
          (org-link-store-props
           :type "pdfview"
           :link link
           :description path)))))

  (with-eval-after-load 'ol-info
    (defun org-info-export (path desc format)
      "Export an info link.
  See `org-link-parameters' for details about PATH, DESC and FORMAT."
      (let* ((parts (split-string path "#\\|::"))
             (manual (car parts))
             (node (or (nth 1 parts) "Top")))
        (pcase format
          (`html
           (format "<a href=\"%s#%s\">%s</a>"
                   (org-info-map-html-url manual)
                   (org-info--expand-node-name node)
                   (or desc path)))
          (`latex
           (format "\\href{%s\\#%s}{%s}"
                   (org-info-map-html-url manual)
                   (org-info--expand-node-name node)
                   (or desc path)))
          (`texinfo
           (let ((title (or desc "")))
             (format "@ref{%s,%s,,%s,}" node title manual)))
          (_ nil)))))

  (with-eval-after-load 'ol-info
    (make-variable-buffer-local 'org-info-emacs-documents)
    (setq org-info-emacs-documents (delete "org" org-info-emacs-documents))
    (make-variable-buffer-local 'org-info-other-documents)
    (setq org-info-other-documents
          (cl-union '(("consult" . "https://github.com/minad/consult")
                      ("embark" . "https://github.com/oantolin/embark")
                      ("marginalia" . "https://github.com/minad/marginalia")
                      ("org" . "https://orgmode.org/org.html")
                      ("orderless" . "https://github.com/oantolin/orderless")
                      ("sly" . "https://joaotavora.github.io/sly/")
                      ("vertico" . "https://github.com/minad/vertico"))
                    org-info-other-documents :test #'equal)))

Translate capital keywords (old) to lower case (new)

  (with-eval-after-load 'org
    (defun org-syntax-convert-keyword-case-to-lower ()
      "Convert all #+KEYWORDS to #+keywords."
      (interactive)
      (save-excursion
        (goto-char (point-min))
        (let ((count 0)
              (case-fold-search nil))
          (while (re-search-forward "^[ \t]*#\\+[A-Z_]+" nil t)
            (unless (s-matches-p "RESULTS" (match-string 0))
              (replace-match (downcase (match-string 0)) t)
              (setq count (1+ count))))
          (message "Replaced %d keywords" count)))))

Evaluate specific source blocks at load-time

How to do load time source block evaluation

  (defun my-org-eval-blocks-named (infix)
    "Evaluate all source blocks having INFIX in their name."
    (when (eq major-mode 'org-mode)
      (let ((blocks
             (org-element-map
                 (org-element-parse-buffer 'greater-element nil) 'src-block
               (lambda (block)
                 (let ((name (org-element-property :name block)))
                   (when (and name (string-match-p infix name))
                     block))))))
        (dolist (block blocks)
          (goto-char (org-element-property :begin block))
          (org-babel-execute-src-block)))))

  ;; Emacs looks for "Local variables:" after the last "?\n?\f".
  (add-to-list 'safe-local-eval-forms
               '(apply 'my-org-eval-blocks-named '("emacs-lisp-setup")))
  (add-to-list 'safe-local-eval-forms
               '(apply 'my-org-eval-blocks-named '("python-setup")))

Easy LaTeX preamble editing

There are at least two ways (new and old) to edit the LateX preamble latex_header and latex-extra_header export options easily in LaTeX source or export blocks. This Org (info) file uses the new way, but keeps the old way for backwards compatibility.

The new way – exploiting an idea of Omar Antolin Camarena – is to code new <LANGUAGE>-modes allowing to edit in LaTeX mode and to export to LaTeX code with correct LaTeX preamble export setting prefixes. Here, are links to three posts exposing his idea:

1. Export LaTeX macros to LaTeX and HTML/MathJax preambles (reddit),
2. Export JavaScript source blocks to script tags in HTML (reddit),
3. Export JavaScript source blocks to script tags in HTML (SX).

Listing lst:emacs-lisp-setup-latex-header implements this way by means of two new <LANGUAGE>-modes: latex-header and latex-extra-header.

  (with-eval-after-load 'org-src
    (defun prefix-all-lines (prefix body)
      (with-temp-buffer
        (insert body)
        (string-insert-rectangle (point-min) (point-max) prefix)
        (buffer-string)))

    (add-to-list 'org-src-lang-modes '("latex-header" . latex))

    (defvar org-babel-default-header-args:latex-header
      '((:exports . "results") (:results . "raw")))

    (defun org-babel-execute:latex-header (body _params)
      "Execute a block of LaTeX preamble lines with org-babel.
  This function is called by `org-babel-execute-src-block' and
  prefixes all lines with \"#+latex_header: \"."
      (prefix-all-lines "#+latex_header: " body))

    (add-to-list 'org-src-lang-modes '("latex-extra-header" . latex))

    (defvar org-babel-default-header-args:latex-extra-header
      '((:exports . "results") (:results . "raw")))

    (defun org-babel-execute:latex-extra-header (body _params)
      "Execute a block of LaTeX preamble lines with org-babel.
  This function is called by `org-babel-execute-src-block' and
  prefixes all lines with \"#+latex_extra_header: \"."
      (prefix-all-lines "#+latex_extra_header: " body)))

The old way is to use a special export attribute as in the function org-latex-header-blocks-filter in ox-extra.el. Apparently, nobody is using this broken function (broken, since it relies on support only in org-mode before 2014-11-11). Listing lst:org-latex-header-blocks-filter proposes a fix for org-latex-header-blocks-filter.

  (with-eval-after-load 'ox
    (defun org-latex-header-blocks-filter (backend)
      "Convert marked LaTeX export blocks to \"#+latex_header: \" lines.
  The marker is a line \"#+header: :header yes\" preceding the block.

  For instance, the LaTeX export block

  ,#+header: :header yes
  ,#+begin_export latex
  % This line converts to a LaTeX header line.
  ,#+end_export

  converts to

  \"#+latex_header: % This line converts to a LaTeX header line.\"."
      (when (org-export-derived-backend-p backend 'latex)
        (let ((blocks
               (org-element-map
                   (org-element-parse-buffer 'greater-element nil) 'export-block
                 (lambda (block)
                   (let ((type (org-element-property :type block))
                         (header (org-export-read-attribute :header block :header)))
                     (when (and (string= type "LATEX") (string= header "yes"))
                       block))))))
          (mapc (lambda (block)
                  ;; Set point to where to insert LaTeX header lines
                  ;; after deleting the block.
                  (goto-char (org-element-property :post-affiliated block))
                  (let ((lines
                         (split-string (org-element-property :value block) "\n")))
                    (delete-region (org-element-property :begin block)
                                   (org-element-property :end block))
                    (dolist (line lines)
                      (insert (concat "#+latex_header: "
                                      (replace-regexp-in-string "\\` *" "" line)
                                      "\n")))))
                ;; Reverse to go upwards to avoid wrecking the list of
                ;; block positions in the file that would occur in case
                ;; of going downwards.
                (reverse blocks)))))

    ;; Push the filter on the hook.
    (cl-pushnew #'org-latex-header-blocks-filter
                org-export-before-parsing-hook))

This file uses the new way, while keeping the old way for backwards compatibility, because the new way feels less hackish than the old way. A practical difference is that new way source blocks (contrary to old way export blocks) do not work in #+SETUPFILE: <FILE>, but only in #+INCLUDE: <FILE> files.

#+INCLUDE: <FILE> (info)

Evaluation of the source block in listing lst:make-source-block-with-export-keyword-settings produces the source block that exports to listing lst:source-file-export-keyword-settings in order to show the first nine lines of this /gav451/emacs.d/src/commit/cd455d635364c0c077c0f2622583be55d6d21123/README.org file. The last line shows that include.org is the argument for #+INCLUDE: <FILE>.

  echo "#+caption[Source file export keyword settings]:"
  echo "#+caption: The first nine lines of README.org containing the export"
  echo "#+caption: keyword settings."
  echo "#+name: lst:source-file-export-keyword-settings"
  echo "#+begin_src org :tangle no"
  head -n 9 README.org
  echo -n "#+end_src"

#+title: Emacs setup for use with LaTeX, Org, and Python
#+author: Gerard Vermeulen
#+babel: :cache no
#+latex_class: article-local
#+latex_class_options: [11pt,a4paper,english,svgnames,tables]
#+macro: kbd (eval (by-backend-kbd-org-macro $1))
#+property: header-args:emacs-lisp :exports code :results silent :tangle init.el
#+property: header-args:org :tangle include.org
#+startup: content

Listing lst:by-backend-kbd-org-macro defines the tools for the definition of the Org mode kbd macro on the fifth line of listing lst:source-file-export-keyword-settings.

  (with-eval-after-load 'ox
    (autoload 'htmlize-protect-string "htmlize" nil t)

    (defmacro by-backend (&rest body)
      `(cl-case org-export-current-backend ,@body))

    (defun by-backend-kbd-org-macro (keys)
      (by-backend
       (html (format "@@html:<kbd>%s</kbd>@@" (htmlize-protect-string keys)))
       (latex (format "@@latex:\\colorbox{PowderBlue}{\\texttt{%s}}@@" keys)))))

Listing lst:use-latex-header-1, lst:use-latex-header-2, lst:use-latex-header-3, lst:use-latex-header-4, and lst:use-latex-header-5 tangle into the include.org file in order to create the LaTeX preamble.

  #+begin_src latex-header
    % LuaLaTeX-, PdfLaTeX-, or XeTeX-COMPILER COMPATIBILITY:
    % Prevent collisions by using font packages before compiler specific packages.
    \usepackage{ifthen,ifluatex,ifxetex}
    \usepackage{amsmath}
    \usepackage{amssymb}
    \usepackage{pifont}          % check mark (\ding{52}) and cross mark (\ding{56})
    \usepackage{textcomp}        % \texttimes
    \usepackage{wasysym}         % \diameter
    \ifthenelse{\boolean{luatex}}{
      \usepackage{fontspec}        % lualatex
      \usepackage{unicode-math}    % lualatex
    }{\ifthenelse{\boolean{xetex}}{
        \usepackage{mathspec}        % xetex
      }{
        \usepackage[T1]{fontenc}     % pdflatex
        \usepackage[utf8]{inputenc}  % pdflatex
      }
    }

    % Org-mode REQUIREMENTS:
    \usepackage{graphicx}
    \usepackage{longtable}
    \usepackage{wrapfig}
    \usepackage{rotating}
    \usepackage[normalem]{ulem}
    \usepackage{capt-of}
    \usepackage{hyperref}

  #+end_src

  #+begin_src latex-header
    % LANGUAGE:
    \usepackage{babel}
    \usepackage{fvextra}
    \usepackage{csquotes}

    % LISTS:
    \usepackage{enumitem}
    \setlist{noitemsep}

    % LISTINGS:
    % Section 2.6 of caption-eng.pdf (texdoc caption) explains that the sign
    % of "skip" depends on the assumption "position=above" or "position=below".
    % The assumption should match the real caption position in the LaTeX code.
    \usepackage{caption}
    \usepackage[newfloat]{minted}
    \captionsetup[listing]{position=below,skip=0em}
    \usemintedstyle{xcode}

    % TABLES:
    % https://tex.stackexchange.com/questions/341205/
    % what-is-the-difference-between-tabular-tabular-and-tabularx-environments
    % https://emacs.stackexchange.com/questions/26179/
    % change-org-mode-table-style-just-for-latex-export
    % https://tex.stackexchange.com/questions/468585/
    % table-formatting-using-siunitx
    \usepackage{booktabs}
    \usepackage{colortbl}
    \usepackage{tabularx}  % DANGER: beware of Org table :width and :align options!

  #+end_src

  #+begin_src latex-header
    % PAGE LAYOUT:
    \usepackage{fancyhdr}
    \usepackage{lastpage}
    \usepackage[
      headheight=20mm,
      top=40mm,
      bottom=20mm,
      left=60pt,
      right=60pt,
      heightrounded,
      verbose,
    ]{geometry}

    % TECHNICS:
    \usepackage{siunitx}
    \usepackage{tikz}

  #+end_src

  #+begin_src latex-header
    % FLOAT BARRIERS:
    % https://tex.stackexchange.com/questions/118662/use-placeins-for-subsections
    % Make section an implicit float barrier:
    \usepackage[section]{placeins}
    % Make subsection an implicit float barrier:
    \makeatletter
    \AtBeginDocument{%
      \expandafter\renewcommand\expandafter\subsection\expandafter{%
        \expandafter\@fb@secFB\subsection
      }%
    }
    \makeatother
    % Make subsubsection an implicit float barrier:
    \makeatletter
    \AtBeginDocument{%
      \expandafter\renewcommand\expandafter\subsubsection\expandafter{%
        \expandafter\@fb@secFB\subsubsection
      }%
    }
    \makeatother

  #+end_src

  #+begin_src latex-header
    % FANCY HEADERS AND FOOTERS:
    % Add fancy headers and footers to normal pages.
    \pagestyle{fancy}
    \fancyhf{}
    \renewcommand{\footrulewidth}{0.4pt}
    \fancyfoot[C]{\emph{
        Emacs setup for use with \LaTeX{}, Org, and Python -- Gerard Vermeulen}}
    \renewcommand{\headrulewidth}{0.4pt}
    \fancyhead[L]{\includegraphics[height=1.8cm]{Org-mode-unicorn.png}}
    \fancyhead[C]{
      Page: \thepage/\pageref{LastPage} \\
      \text{ } \\
      \text{ } \\
      DRAFT
    }
    \fancyhead[R]{\includegraphics[height=1.8cm]{Emacs-logo.png}}

    % Add fancy header and footer to custom titlepage.
    % https://tex.stackexchange.com/questions/506102/
    % adding-header-and-footer-to-custom-titlepage
    \fancypagestyle{titlepage}{%
      \fancyhf{}
      \renewcommand{\footrulewidth}{0.4pt}
      \fancyfoot[C]{\emph{
          Emacs setup for use with \LaTeX{}, Org, and Python -- Gerard Vermeulen}}
      \renewcommand{\headrulewidth}{0.4pt}
      \fancyhead[L]{\includegraphics[height=1.8cm]{Org-mode-unicorn.png}}
      \fancyhead[C]{
        \pageref{LastPage} pages \\
        \text{ } \\
        \text{ } \\
        DRAFT
      }
      \fancyhead[R]{\includegraphics[height=1.8cm]{Emacs-logo.png}}
    }
    % #+latex_header: END.
  #+end_src

Advanced LaTeX export settings

Listing lst:ox-latex-emacs-lisp-setup initializes the buffer local variables org-latex-classes, org-latex-title-command, org-latex-toc-command, and org-latex-subtitle-format. Listing /gav451/emacs.d/src/commit/cd455d635364c0c077c0f2622583be55d6d21123/lst/title-page is a template to initialize org-latex-title-command. Type

(eval

,

(eval

}},

(eval

, and

(eval

to read how those variables control exporting from Org-mode to LaTeX.

  (when (require 'ox-latex nil 'noerror)
    ;; https://emacs.stackexchange.com/questions/47347/
    ;; customizing-org-latex-title-command-to-edit-title-page
    (make-variable-buffer-local 'org-latex-classes)
    (cl-pushnew '("article-local"
                  "\\documentclass[11pt]{article}
  [NO-DEFAULT-PACKAGES]
  [PACKAGES]
  [EXTRA]"
                  ("\\section{%s}" . "\\section*{%s}")
                  ("\\subsection{%s}" . "\\subsection*{%s}")
                  ("\\subsubsection{%s}" . "\\subsubsection*{%s}")
                  ("\\paragraph{%s}" . "\\paragraph*{%s}")
                  ("\\subparagraph{%s}" . "\\subparagraph*{%s}"))
                org-latex-classes :key #'car :test #'equal)

    (make-variable-buffer-local 'org-latex-title-command)
    (setq org-latex-title-command (concat title-page))

    (make-variable-buffer-local 'org-latex-toc-command)
    (setq org-latex-toc-command "
  \\tableofcontents\\label{toc}
  \\listoftables
  \\listoffigures
  \\newpage
  ")

    (make-variable-buffer-local 'org-latex-subtitle-format)
    (setq org-latex-subtitle-format ""))

  \begin{titlepage}
    %% https://tex.stackexchange.com/questions/506102/
    %% adding-header-and-footer-to-custom-titlepage
    \thispagestyle{titlepage}
    \begin{center}
      %% Title
      \begin{Huge}
        {\bf %t} \\
        \vspace{1em}
      \end{Huge}
      %% Author
      \begin{Large}
        {\bf %a} \\
        \vspace{1em}
      \end{Large}
    \end{center}
  \end{titlepage}

Worg: backend dependent execution

  #+latex_header: \usepackage{tikz}

  #+header: :file (by-backend (html "tree.svg") (latex nil))
  #+header: :results (by-backend (html "raw file") (latex "latex replace"))
  #+header: :headers '("\\usepackage{tikz}\n")
  #+begin_src latex
    \usetikzlibrary{trees}
    \begin{tikzpicture}
      \node [circle, draw, fill=red!20] at (0,0) {1}
      child { node [circle, draw, fill=blue!30] {2}
        child { node [circle, draw, fill=green!30] {3} }
        child { node [circle, draw, fill=yellow!30] {4} }};
    \end{tikzpicture}
  #+end_src

  # Setup
  #+begin_src emacs-lisp :exports none
    (with-eval-after-load 'ox
      (setq org-babel-latex-htlatex "htlatex")
      (defmacro by-backend (&rest body)
        `(cl-case org-export-current-backend ,@body)))
  #+end_src

This section updates the outdated Worg: backend dependent execution example to Emacs-27.2 and Org-9.5.2. It shows how to export PGF/TikZ images to:

1. PDF by embedding in LaTeX.
2. HTML by passing from LaTeX by PDF and to SVG.

Listing lst:backend-dependent-execution-update tangles to worg-backend-dependent-execution-update.org as either a standalone example or an example for inclusion. Finally, inclusion of worg-backend-dependent-execution-update.org produces here the figure with the nodes 1, 2, 3, and 4:\\

How to include such figures as floats remains an open question.

Org Syntax

Two tools to grok how Org mode parsing works are the Org Syntax specification and the Org mode parser tutorial. The Org element parsing API boils down to three functions:

1. The function org-element-parse-buffer implements a fully recursive buffer parser that returns an abstract syntax tree.
2. The functions org-element-at-point and org-element-context return information on the document structure around point either at the element level or at the object level in case of org-element-context.

Listing lst:grok-org-element-tree improves the Org mode parser tutorial by defining interactive wrappers that pretty print the results of those non-interactive org-element functions to an Emacs-lisp buffer.

  (with-eval-after-load 'org-element
    (when (autoload 'pp-display-expression "pp")
      (defconst grok-org-output
        "*Grok Org Element Output*"
        "Grok Org output buffer name.")

      (defun grok-org-element-at-point ()
        (interactive)
        (pp-display-expression
         (org-element-at-point) grok-org-output))

      (defun grok-org-element-context ()
        (interactive)
        (pp-display-expression
         (org-element-context) grok-org-output))

      (defun grok-org-element-parse-buffer ()
        (interactive)
        (let ((what (completing-read
                     "granularity: "
                     '(headline element greater-element object)
                     nil 'require-match)))
          (pp-display-expression
           (org-element-parse-buffer what) grok-org-output)))

      (defun grok-org-heading-components ()
        (interactive)
        (pp-display-expression
         (org-heading-components) grok-org-output))))

Programming

Common Lisp programming

Listing lst:configure-sly configures the Sly (info) Common Lisp IDE for Emacs for use with Steel Bank Common Lisp (sbcl):

1. It configures sly-default-lisp and sly-lisp-implementations as in the sly documentation string instead of in the multiple lisps (info) manual.
2. It ensures the automatic connection to the lisp server (info) when opening a Common Lisp file.
3. It configures searching documentation in the Common Lisp HyperSpec according to the basic customization (info) manual.

Finally, listing lst:configure-sly uses a technique to load Slynk faster (info) by means of a custom core file in src_emacs-lisp{no-littering-var-directory}. Listing lst:sbcl-core-for-sly tangles to a script to dump such a SBCL core.

  (with-eval-after-load 'sly
    (custom-set-variables
     ;; Customize `sly-default-lisp' instead of `inferior-lisp-program',
     ;; because `sly' uses `inferior-lisp-program' only as a backwards
     ;; compatibility fallback option.
     '(sly-default-lisp 'sbcl)
     `(sly-lisp-implementations
       '((sbcl (,(executable-find "sbcl")
                "--core"
                ,(no-littering-expand-var-file-name "sbcl.core-for-sly"))))))

    (add-hook 'sly-mode-hook
              (defun on-sly-mode-hook ()
                (unless (sly-connected-p)
                  (save-excursion (sly)))))

    (cond
     ((eq system-type 'darwin)
      (setq common-lisp-hyperspec-root
            "file:///usr/local/share/doc/hyperspec/HyperSpec/")
      (setq common-lisp-hyperspec-symbol-table
            (concat common-lisp-hyperspec-root "Data/Map_Sym.txt")))
     ((eq system-type 'gnu/linux)
      (setq common-lisp-hyperspec-root
            "file:///usr/share/doc/hyperspec-7.0/HyperSpec/"))
     (t (message "Default Common Lisp HyperSpec access")))

    (define-key sly-prefix-map (kbd "M-h") #'sly-documentation-lookup))

  #!/bin/sh

  sbcl <<EOF
  (mapc 'require '(sb-bsd-sockets sb-posix sb-introspect sb-cltl2 asdf))
  (save-lisp-and-die "sbcl.core-for-sly")
  EOF

  # Local Variables:
  # mode: shell-script
  # sh-indentation: 2
  # sh-basic-offset: 2
  # End:

CS 325 AI Programming

The CS 325 AI Programming course allows to learn Common Lisp by self-study and the page CS 325: Setting up Lisp gives instructions how to:

1. Download and install common lisp.
2. Install Quicklisp.
3. Install the CS325 library.

Quicklisp

Quicklisp is a library manager for Common Lisp. Listing lst:download+verify-quicklisp downloads the Quicklisp file and verifies its signature to prevent tampering. Listing lst:bootstrap-quicklisp tangles to a shell script allowing to bootstrap Quicklisp with SBCL. Listing lst:quicklisp-sbclrc-file tangles to the a SBCL resource file with Quicklisp support.

  curl -sS -O https://beta.quicklisp.org/quicklisp.lisp
  curl -sS -O https://beta.quicklisp.org/quicklisp.lisp.asc
  curl -sS -O https://beta.quicklisp.org/release-key.txt
  gpg --import release-key.txt
  gpg --verify quicklisp.lisp.asc quicklisp.lisp

  #!/bin/sh

  sbcl --load ~/quicklisp.lisp <<EOF
  (quicklisp-quickstart:install)
  (quit)
  EOF

  # Local Variables:
  # mode: shell-script
  # sh-indentation: 2
  # sh-basic-offset: 2
  # End:

  ;;; Hey Emacs, this is my -*- lisp -*- .sbclrc file.
  #-quicklisp
  (let ((quicklisp-init (merge-pathnames "quicklisp/setup.lisp"
                                         (user-homedir-pathname))))
    (when (probe-file quicklisp-init)
      (load quicklisp-init)))

Emacs Lisp Programming (info)

1. Evaluating Elisp in Emacs
2. Debugging Elisp Part 1: Earn your independence
3. Debugging Elisp Part 2: Advanced topics
4. Xah talk show: Elisp coding: xah-add-space-after-comma
5. Xah talk show: Elisp coding: narrow-to-region, sort-lines, hilight-unicode

Python programming

The Python Programming in Emacs wiki page lists options to enhance Emacs's built-in python-mode. Here, the focus is on two packages:

1. Eglot - Emacs polyGLOT: an Emacs LSP client that stays out of your way. The maintainer also contributes to Emacs itself and has a deep understanding of the Way of Emacs. He refuses to add new features without seeing how they fit into the Way of Emacs as this discussion on org-mode source code blocks shows.
2. Anaconda - code navigation, documentation lookup, and completion for Python.

In my opinion, eglot has more potential than anaconda, but anaconda is compatible with source code block editing while eglot is not.

Here are a few links covering how to integrate Emacs, Python and a Python LSP server, before plunging into the configuring steps:

1. Building Your Own Emacs IDE with LSP
2. Doom Emacs and Language Servers
3. Eglot based Emacs Python IDE
4. Getting started with lsp-mode for Python
5. Python & Emacs, Take 3
6. Python with Emacs: py(v)env and lsp-mode

Python-mode

Listing lst:configure-python tells the Python shell to disregard its environment variables (in particular PYTHONSTARTUPFILE). The pythonic and pyvenv packages provide support to handle Python virtual environments within Emacs. The pyenv package provides support to work with pyenv (eventually with pyenv-virtualenv) to select between different python versions (eventually each with different environments). In the end, all those packages do is to set python-shell-virtualenv-root (in case of pyenv and pythonic) and tweak the environment variables and restart the relevant Python child processes (in case of pyvenv). Therefore, this setup replaces those packages with listing lst:manage-pyenv to manage pyenv from within Emacs and listing lst:setting-python-shell-virtualenv-root to set python-shell-virtualenv-root.

  (with-eval-after-load 'python
    (custom-set-variables
     '(python-indent-guess-indent-offset nil)
     '(python-shell-interpreter-args "-i -E")))

  (when (executable-find "pyenv")
    (defun pyenv-full-path (version)
      "Return the full path for VERSION."
      (unless (string= version "system")
        (concat (pyenv-root) (file-name-as-directory "versions") version)))

    (defun pyenv-root ()
      "Return \"pyenv root\" as a directory."
      (cl-destructuring-bind (exit-code output)
          (shell-command-with-exit-code "pyenv" "root")
        (if (= 0 exit-code) (file-name-as-directory (string-trim output))
          (error "%s" (string-trim output)))))

    (defun pyenv-version-name ()
      "Return \"pyenv version-name\"."
      (cl-destructuring-bind (exit-code output)
          (shell-command-with-exit-code "pyenv" "version-name")
        (if (= 0 exit-code) (string-trim output)
          (error "%s" (string-trim output)))))

    (defun pyenv-versions ()
      "Return \"pyenv versions --bare --skip-aliases\" as a list.
  Complete the result with \"system\"."
      (cl-destructuring-bind (exit-code output)
          (shell-command-with-exit-code
           "pyenv" "versions" "--bare" "--skip-aliases")
        (if (= 0 exit-code) (cons "system" (split-string output))
          (error "%s" (string-trim output)))))

    (defun pyenv-virtualenvs ()
      "Return \"pyenv virtualenvs --bare --skip-aliases\" as a list."
      (cl-destructuring-bind (exit-code output)
          (shell-command-with-exit-code
           "pyenv" "virtualenvs" "--bare" "--skip-aliases")
        (if (= 0 exit-code) (split-string output)
          (error "%s" (string-trim output))))))

  (with-eval-after-load 'python
    (when (cl-every #'fboundp '(pyenv-full-path
                                pyenv-version-name
                                pyenv-versions
                                pyenv-virtualenvs))
      (setq python-shell-virtualenv-root
            (pyenv-full-path (or (car (pyenv-virtualenvs))
                                 (car (pyenv-versions)))))
      (message "Now `python-shell-virtualenv-root' equals \"%s\""
               python-shell-virtualenv-root)

      (defun set-python-shell-virtualenv-root-to-pyenv-version ()
        "Set `python-shell-virtual-env-root' to a pyenv version."
        (interactive)
        (let* ((version-name (pyenv-version-name))
               (prompt (format "pyenv version (%s): " version-name))
               (choices (pyenv-versions))
               (version (completing-read prompt choices nil 'require-match)))
          (unless (string= version-name version)
            (setq python-shell-virtualenv-root (pyenv-full-path version))
            (setenv "PYENV_VERSION" version))
          (message "Now `python-shell-virtualenv-root' equals \"%s\""
                   python-shell-virtualenv-root)))

      (defun set-python-shell-virtualenv-root-to-pyenv-virtualenv ()
        "Set `python-shell-virtual-env-root' to a pyenv virtualenv."
        (interactive)
        (let* ((version-name (pyenv-version-name))
               (prompt (format "pyenv virtualenv (%s): " version-name))
               (choices (pyenv-virtualenvs))
               (version (completing-read prompt choices nil 'require-match)))
          (unless (string= version-name version)
            (setq python-shell-virtualenv-root (pyenv-full-path version))
            (setenv "PYENV_VERSION" version))
          (message "Now `python-shell-virtualenv-root' equals \"%s\""
                   python-shell-virtualenv-root)))))

Eglot

Listing lst:configure-eglot+python-lsp-server-for-python tangles to user-init-file and configures eglot for Python using the python-lsp-server. In order to enable all builtin python-lsp-server capabilities, ensure installation of the Python packages autopep8, flake8, pydocstyle, pylint, rope, and yapf. In addition, install the pyls-flake8 plugin to let python-lsp-server use flake8.

Listing lst:on-hack-local-variables-hook-eglot-maybe defines a hook function to launch eglot in presence of a proper .dir-locals.el file in the root directory of any Python project. Listing lst:eglot-directory-variables-for-python shows such a proper .dir-locals.el file.

  (with-eval-after-load 'eglot
    ;; (setq eglot-server-programs '((python-mode "pylsp")))
    (add-to-list 'eglot-server-programs '(python-mode "pylsp"))

    (setq-default
     eglot-workspace-configuration
     '(;; Disable the `:pyls_flake8' plugin to fall back to pycodestyle.
       (:pylsp . (:plugins (:pyls_flake8 (:enabled t))))
       (:pylsp . (:plugins (:jedi_completion (:cache_for ["astropy"]))))
       (:pylsp . (:plugins (:jedi (:auto_import_modules ["numpy"]))))))

    (define-key eglot-mode-map (kbd "C-c n") #'flymake-goto-next-error)
    (define-key eglot-mode-map (kbd "C-c p") #'flymake-goto-prev-error)
    (define-key eglot-mode-map (kbd "C-c r") 'eglot-rename))

  (when (fboundp 'eglot-ensure)
    ;; The two hooks `after-change-major-mode-hook' and
    ;; `hack-local-variables-hook' are OK, but language mode hooks like
    ;; `python-mode-hook' are not.
    (add-hook 'hack-local-variables-hook
              (defun on-hack-local-variables-hook-eglot-maybe ()
                (when (and (derived-mode-p 'python-mode)
                           (assoc 'eglot-workspace-configuration
                                  dir-local-variables-alist))
                  (eglot-ensure)))))

  ;; Proposal for a .dir-locals.el file in the root of any Python project.
  ((python-mode
    . ((eglot-workspace-configuration
        . (;; Disable the `:pyls_flake8' plugin to fall back to pycodestyle.
           (:pylsp . (:plugins (:pyls_flake8 (:enabled t))))
           (:pylsp . (:plugins (:jedi (:auto_import_modules ["numpy"]))))
           (:pylsp . (:plugins (:jedi_completion (:cache_for ["astropy"])))))))))

command	keys	key map
xref-find-definition	(eval	global-map
xref-pop	(eval	global-map
flymake-goto-next-error	(eval	eglot-mode-map
flymake-goto-prev-error	(eval	eglot-mode-map
eglot-rename	(eval	eglot-mode-map
eldoc-doc-buffer	(eval	eglot-mode-map

Allthough the configuration of blacken is not explicit, I use it to format all new Python code with the Python Black code formatter. Listing lst:pyproject-toml-kick-off and lst:setup-cfg-kick-off implement the rules in using black with other tools in order to make flake8 or pycodestyle agree with black's uncompromising style.

  [build-system]
  requires = ["setuptools", "wheel"]
  build-backend = "setuptools.build_meta"

  [tool.black]
  line-length = 88

  [flake8]
  max-line-length = 88
  extend-ignore = E203

  [pycodestyle]
  ignore = E203
  max-line-length = 88

Jedi provides grammar checking and completion candidates to python-lsp-server. Only jedi-0.18.1 works with for instance numpy-1.22.0 in the sense that it does not choke on universal functions provided that jedi does not parse but imports numpy-1.22.0 (see jedi issue #1744, #1745, and #1746). Since the universal functions are neither builtin methods nor data instances but a kind of "callable instances", the Python inspect module also fails to handle the universal functions properly.

Listing lst:make-pylsp-server-patch generates and listing lst:echo-pylsp-server-patch echos the patch in listing lst:show-pylsp-server-patch to make jedi import numpy-1.22.2 in order to serve the information to python-lsp-server allowing it to handle universal functions.

  git -C $HOME/VCS/python-lsp-server diff >pylsp-auto-import-modules.patch

  echo "#+attr_latex: :options breaklines"
  echo "#+caption[Show =pylsp-auto-import-modules.patch=]:"
  echo "#+caption: Show =pylsp-auto-import-modules.patch=."
  echo "#+name: lst:show-pylsp-server-patch"
  echo "#+begin_src diff :tangle no"
  cat pylsp-auto-import-modules.patch
  echo -n "#+end_src"

diff --git a/pylsp/config/schema.json b/pylsp/config/schema.json
index c29d78b..4f30101 100644
--- a/pylsp/config/schema.json
+++ b/pylsp/config/schema.json
@@ -69,6 +69,14 @@
       "default": null,
       "description": "List of errors and warnings to enable."
     },
+    "pylsp.plugins.jedi.auto_import_modules": {
+      "type": "array",
+        "default": ["numpy", "gi"],
+      "items": {
+        "type": "string"
+      },
+      "description": "List of module names for jedi to import (jedi.settings.auto_import_modules)."
+    },
     "pylsp.plugins.jedi.extra_paths": {
       "type": "array",
       "default": [],
diff --git a/pylsp/workspace.py b/pylsp/workspace.py
index bf312f6..4758b53 100644
--- a/pylsp/workspace.py
+++ b/pylsp/workspace.py
@@ -14,6 +14,8 @@ from . import lsp, uris, _utils

 log = logging.getLogger(__name__)

+DEFAULT_AUTO_IMPORT_MODULES = ["numpy", "gi"]
+
 # TODO: this is not the best e.g. we capture numbers
 RE_START_WORD = re.compile('[A-Za-z_0-9]*$')
 RE_END_WORD = re.compile('^[A-Za-z_0-9]*')
@@ -252,6 +254,8 @@ class Document:

         if self._config:
             jedi_settings = self._config.plugin_settings('jedi', document_path=self.path)
+            jedi.settings.auto_import_modules = jedi_settings.get('auto_import_modules',
+                                                                  DEFAULT_AUTO_IMPORT_MODULES)
             environment_path = jedi_settings.get('environment')
             extra_paths = jedi_settings.get('extra_paths') or []
             env_vars = jedi_settings.get('env_vars')

Anaconda

Listing lst:configure-anaconda+company-for-python and lst:define-my-toggle-anaconda-mode configure anaconda. See elpy-module-company for how to handle company-backends as a local variable in listing lst:configure-anaconda+company-for-python. The call to advice-add in listing lst:define-my-toggle-anaconda-mode opens Python org-edit-src-code buffers in anaconda-mode.

  (with-eval-after-load 'python
    (with-eval-after-load 'company
      (when (and (fboundp 'anaconda-mode)
                 (fboundp 'company-anaconda))
        (defun my-disable-anaconda-mode ()
          (when (derived-mode-p 'python-mode)
            (anaconda-mode -1)
            (make-variable-buffer-local 'company-backends)
            (setq company-backends
                  (delq 'company-anaconda
                        (mapcar #'identity company-backends)))
            (anaconda-eldoc-mode -1)))
        (defun my-enable-anaconda-mode ()
          (when (derived-mode-p 'python-mode)
            (anaconda-mode +1)
            (make-variable-buffer-local 'company-backends)
            (setq company-backends
                  (cons 'company-anaconda
                        (delq 'company-semantic
                              (delq 'company-capf
                                    (mapcar #'identity company-backends)))))
            (anaconda-eldoc-mode
             (if (file-remote-p default-directory) -1 1)))))))

  (with-eval-after-load 'python
    (unless (and (fboundp 'my-disable-anaconda-mode)
                 (fboundp 'my-enable-anaconda-mode))
      (when (fboundp 'anaconda-mode)
        (defun my-disable-anaconda-mode ()
          (when (derived-mode-p 'python-mode)
            (anaconda-mode -1)
            (anaconda-eldoc-mode -1)))
        (defun my-enable-anaconda-mode ()
          (when (derived-mode-p 'python-mode)
            (anaconda-mode +1)
            (anaconda-eldoc-mode
             (if (file-remote-p default-directory) -1 1))))))

    (when (fboundp 'my-enable-anaconda-mode)
      (advice-add 'org-edit-src-code :after #'my-enable-anaconda-mode))
    (when (and (fboundp 'my-disable-anaconda-mode)
               (fboundp 'my-enable-anaconda-mode))
      (defun my-toggle-anaconda-mode ()
        "Toggle anaconda-mode with bells and whistles."
        (interactive)
        (if (bound-and-true-p anaconda-mode)
            (my-disable-anaconda-mode)
          (my-enable-anaconda-mode)))))

Jedi

Listing lst:example-py is a Python example to test whether jedi in combination with and either anaconda or eglot works when coding certain functions of for instance numpy and scipy.

  import numpy
  import astropy.units as apu

  a = numpy.arange(0, 11)
  a = numpy.linspace(0, 10, num=11)
  a = numpy.arccos(a)
  q = apu.Quantity(a, apu.meter)
  print(q)

Code-cells

Code-cells allows to edit IPython or Jupyter notebooks in Emacs with help from either Jupytext or Pandoc to translate between the ipynb format and different plain text formats. Sofar, I have used code-cells to open ipynb notebooks with

(eval

in Emacs for viewing.

TODO Look into: editing facilities

1. Emacs extension to insert numpy style docstrings in function definitions

Libraries

Library dash.el (info)

The library dash.el (info)positions itself as a modern alternative for the list processing API of cl. It is a requirement of several important packages in this Emacs setup (for instance anaconda, citeproc, magit, and smartparens). Listing lst:configure-dash enables fontification of dash macros and makes info-lookup-symbol take into account the dash macros.

  (when (fboundp #'global-dash-fontify-mode)
    (global-dash-fontify-mode))

  (when (fboundp #'dash-register-info-lookup)
    (with-eval-after-load 'info-look
      (dash-register-info-lookup)))

Library f.el

The library f.el positions itself as a modern API for working with files and directories in Emacs. It is a requirement of several packages in this Emacs setup (anaconda, citeproc, pythonic) and requires no configuration.

Library s.el

The library s.el positions itself as the long lost Emacs string manipulation library. It is a requirement of several packages in this Emacs setup (anaconda, citeproc, citar, and company-anaconda) and requires no configuration.

Minor Modes (info)

Synchronal multiple-region editing

  (with-eval-after-load 'emacs
    (require 'iedit nil 'noerror))

Unobtrusive whitespace trimming

  (when (require 'ws-butler nil 'noerror)
    (custom-set-variables
     '(ws-butler-keep-whitespace-before-point nil))
    (add-hook 'prog-mode-hook #'ws-butler-mode)
    (add-hook 'text-mode-hook #'ws-butler-mode))

Structural editing

Structural editing keeps character pairs (for instance parentheses, curly and square brackets as well as single and double quotes) balanced to leave code (for instance Lisp and Python) and text (for instance LaTeX and Org) structure intact. I use smartparens which offers a normal mode (smartparens-mode) and a a strict mode (smartparens-strict-mode). Although both modes insert character pairs, the normal mode allows to delete one of the paired characters easily while the strict mode does not. Therefore, the strict mode is more for code editing since it never breaks programming language rules and the normal mode is more for text editing where structure is a matter of convention instead of programming language rules.

For instance, the strict mode in Python allows to delete entire lists, tuples, or the arguments after the cursor (what Emacs calls point) in a function call without breaking the character pair balance. In order to repair a broken character pair balance, insert a single character by prefixing it with "C-q" bound to quoted-insert.

The smartparens documentation targets experienced Emacs users. The following links show how to put the documentation to practical use:

1. Omar Antolin's gist "my-smartparens-config.el" is the first place to look for how to tweak smartparens. However, the gist may be partially obsolete, since it is not part of his current Emacs configuration.
2. How to enable smartparens in the minibuffer after eval-expression explains how the machinery after the first and after later usages of eval-expression differ and discusses options how to handle those differences.

Listing lst:configure-smartparens aims to configure smartparens for Elisp, LaTeX, Org, and Python.

Despite the provocative post "What if structural editing was a mistake?", smartparens is one of my favorite packages. In particular, smartparens handles matching pairs in Org-mode files with export and source blocks for multiple formats and languages correctly. Therefore, show-smartparens-mode highlights matching pairs immediately in front or after point in such files correctly, contrary to for instance rainbow-delimiters.

  (with-eval-after-load 'emacs
    ;; To disables pairing of the quote character for lisp modes,
    ;; require smartparens-config instead of smartparens.
    (when (require 'smartparens-config nil 'noerror)
      (custom-set-variables
       '(sp-base-key-bindings 'sp)
       '(sp-override-key-bindings '(("C-(" . sp-backward-barf-sexp)
                                    ("C-)" . sp-forward-slurp-sexp))))

      (dolist (hook '(prog-mode-hook text-mode-hook))
        (add-hook hook #'smartparens-mode))

      ;; Hook on the specific `eval-expression-minibuffer-setup-hook'
      ;; and not on the general `minibuffer-setup-hook'.
      (dolist (hook '(emacs-lisp-mode-hook
                      eval-expression-minibuffer-setup-hook
                      ielm-mode-hook
                      lisp-mode-hook
                      python-mode-hook
                      sly-mrepl-mode-hook))
        (add-hook hook #'smartparens-strict-mode))

      ;; Tweak for the call to `smartparens-strict-mode' hooked on
      ;; `eval-expression-minibuffer-setup-hook'.
      (sp-with-modes '(fundamental-mode           ; first usage.
                       minibuffer-inactive-mode)  ; later usage.
        (sp-local-pair "'" nil :actions nil))

      ;; https://xenodium.com/emacs-smartparens-auto-indent/index.html
      (defun indent-between-pair (&rest _ignored)
        (newline)
        (indent-according-to-mode)
        (forward-line -1)
        (indent-according-to-mode))

      (dolist (left '("(" "[" "{"))
        (sp-local-pair 'prog-mode left
                       nil :post-handlers '((indent-between-pair "RET"))))

      (show-smartparens-global-mode +1)))

Electric operators

Listing lst:configure-electric-operator-mode configures electric-operator-mode to add spaces around operators for compatibility with for instance the Black code formatter for Python.

  (when (fboundp 'electric-operator-mode)
    (add-hook 'c-mode-common #'electric-operator-mode)
    (add-hook 'python-mode-hook #'electric-operator-mode))

Smart snippets

  (when (require 'yasnippet nil 'noerror)
    (custom-set-variables
     '(yas-alias-to-yas/prefix-p nil))
    (yas-global-mode +1))

Display (info)

Narrowing

Narrowing means focusing in on some portion of the buffer and widening means focussing out on the whole buffer. This allows to concentrate temporarily on for instance a particular function or paragraph by removing clutter. The "Do What I Mean" narrow-or-widen-dwim function allows to toggle between narrowed and widened buffer states. Here, the function narrow-or-widen-dwim operates also on tables by means of org-narrow-to-table.

  (defun org-narrow-to-table ()
    "Narrow buffer to current table."
    (interactive)
    (if (org-table-p)
        (narrow-to-region (org-table-begin) (org-table-end))
      (user-error "Not in a table")))

  (defun narrow-or-widen-dwim (p)
    "Widen if buffer is narrowed, narrow-dwim otherwise.
  Dwim means: region, org-src-block, org-subtree, or defun,
  whichever applies first. Narrowing to org-src-block actually
  calls `org-edit-src-code'.
  With prefix P, don't widen, just narrow even if buffer is
  already narrowed."
    (interactive "P")
    (declare (interactive-only))
    (cond ((and (buffer-narrowed-p) (not p)) (widen))
          ((and (bound-and-true-p org-src-mode) (not p))
           (org-edit-src-exit))
          ((region-active-p)
           (narrow-to-region (region-beginning) (region-end)))
          ((derived-mode-p 'org-mode)
           (or (ignore-errors (org-edit-src-code))
               (ignore-errors (org-narrow-to-block))
               (ignore-errors (org-narrow-to-table))
               (org-narrow-to-subtree)))
          ((derived-mode-p 'latex-mode)
           (LaTeX-narrow-to-environment))
          ((derived-mode-p 'tex-mode)
           (TeX-narrow-to-group))
          (t (narrow-to-defun))))

  (define-key ctl-x-map (kbd "n t") #'org-narrow-to-table)
  (define-key ctl-x-map (kbd "C-n") #'narrow-or-widen-dwim)

Text faces or styles (info)

This setup does not configure custom themes (info) in order to prevent endless useless tweaking. See the note on mixed font heights in Emacs for how to setup fonts properly. It boils down to two rules:

1. The height of the default face must be an integer number to make the height a physical quantity.
2. The heights of all other faces must be real numbers to scale those heights with respect to the height of the face (those heights default to 1.0 for no scaling).

The code in listing lst:configure-face-attributes source implements those rules. In case of proper initialization of all face heigths, font scaling is easy as listing lst:set-default-face-height shows.

  (with-eval-after-load 'emacs
    ;; Set face attributes.
    (cond
     ((eq system-type 'darwin)
      (set-face-attribute 'default nil :family "Hack" :height 120)
      (set-face-attribute 'fixed-pitch nil :family "Hack")
      (set-face-attribute 'variable-pitch nil :family "FiraGo"))
     ((eq system-type 'gnu/linux)
      (set-face-attribute 'default nil :family "Hack" :height 110)
      (set-face-attribute 'fixed-pitch nil :family "Hack")
      (set-face-attribute 'variable-pitch nil :family "FiraGo"))
     (t
      (set-face-attribute 'default nil :family "Hack" :height 110)
      (set-face-attribute 'fixed-pitch nil :family "Hack")
      (set-face-attribute 'variable-pitch nil :family "DejaVu Sans"))))

  (with-eval-after-load 'emacs
    (defun set-default-face-height ()
      "Set the default face height in all current and future frames.

  Scale all other faces with a height that is a real number."
      (interactive)
      (let* ((prompt (format "face heigth (%s): "
                             (face-attribute 'default :height)))
             (choices (mapcar #'number-to-string
                              (number-sequence 50 200 10)))
             (height (string-to-number
                      (completing-read prompt choices nil 'require-match))))
        (message "Setting the height of the default face to %s" height)
        (set-face-attribute 'default nil :height height))))

Visualize color codes and names

Listing lst:enable-rainbow-mode enables rainbow-mode to colorize color codes and names in buffers for debugging.

  (when (fboundp 'rainbow-mode)
    (custom-set-variables
     '(rainbow-x-colors-major-mode-list
       '(c++-mode
         c-mode
         emacs-lisp-mode
         inferior-emacs-lisp-mode
         java-mode
         lisp-interaction-mode
         org-mode
         python-mode)))
    (rainbow-mode +1))

Flash the line around point for visual feedback

  (with-eval-after-load 'emacs
    ;; https://karthinks.com/software/batteries-included-with-emacs/
    ;; https://www.reddit.com/r/emacs/comments/jwhr6g/batteries_included_with_emacs/
    (defun my-pulse-one-line (&rest _)
      "Pulse the current line."
      (let ((pulse-iterations 16)
            (pulse-delay 0.1))
        (pulse-momentary-highlight-one-line (point))))
    (dolist (command '(scroll-up-command
                       scroll-down-command
                       recenter-top-bottom
                       other-window))
      (advice-add command :after #'my-pulse-one-line)))

Applications

Hyperlinking and Web Navigation Features (info)

Browse URL (info)

Listing lst:configure-browse-url configures browse-url.

  (with-eval-after-load 'browse-url
    (defun browse-url-mpv (url &optional _)
      (start-process "mpv" nil "mpv" url))
    (if (version< emacs-version "28.0")
        (custom-set-variables
         '(browse-url-browser-function
           `((,(rx (or "https://www.youtube.com/" "https://youtu.be/")) . browse-url-mpv)
             ("https://soundcloud.com/" . browse-url-mpv)
             ("." . eww-browse-url)))
         `(browse-url-generic-program ,(or (when (eq system-type 'darwin) "open")
                                           (executable-find "firefox"))))
        (custom-set-variables
         '(browse-url-handlers
           `((,(rx (or "https://www.youtube.com/" "https://youtu.be/")) . browse-url-mpv)
             ("https://soundcloud.com/" . browse-url-mpv)
             ("." . eww-browse-url)))
         `(browse-url-generic-program ,(or (when (eq system-type 'darwin) "open")
                                           (executable-find "firefox"))))))

Emacs Web Wowser

  (when (fboundp 'eww-browse-url)
    (defmacro defun-dictionary (name where how)
      `(defun ,name (word)
         ,(format "Look up WORD at '%s' in Emacs." where)
         (interactive
          (list (if (use-region-p)
                    (buffer-substring (region-beginning) (region-end))
                  (read-string ,(format "Search '%s' for: " where)
                               (thing-at-point 'word)))))
         (eww-browse-url (concat ,(format "%s%s" where how) word))))

    (defun-dictionary eww-dict-en "www.thefreedictionary.com" "/")
    (defun-dictionary eww-dict-fr "www.cntrl.fr" "/definition/")
    (defun-dictionary eww-dict-nl "www.woorden.org" "/woord/")
    (defun-dictionary eww-webster "webster-dictionary.org" "/definition/")

    (defun eww-subreddit ()
      "Read a subreddit in Emacs."
      (interactive)
      (eww-browse-url (format "www.reddit.com/r/%s/.mobile"
                              (completing-read "subreddit: "
                                               '("emacs"
                                                 "i3wm"
                                                 "orgmode")
                                               nil t)))))

  (with-eval-after-load 'eww
    (defun eww-rename-buffer ()
      "Rename the buffer using title or url."
      (let* ((title (plist-get eww-data :title))
             (name (or (and (eq "" title) (plist-get eww-data :url)) title)))
        (rename-buffer (format "*%s # eww*" name) t)))

    (add-hook 'eww-after-render-hook #'eww-rename-buffer)
    (advice-add 'eww-back-url :after #'eww-rename-buffer)
    (advice-add 'eww-forward-url :after #'eww-rename-buffer))

Goto address mode (info)

Listing lst:configure-goto-address-mode:

1. Enables goto-address-prog-mode for programming modes and goto-address-mode for a selection of other modes.
2. Defines a function to toggle goto-address-prog-mode for programming modes and goto-address-mode for other modes.
3. Binds

   (eval

   to goto-address-at-point in goto-address-highlight-keymap.

  (when (cl-every #'fboundp '(goto-address-mode goto-address-prog-mode))
    (defun toggle-goto-address-dwim-mode ()
      "Toggle `goto-address-mode' or `goto-address-prog-mode' smartly.
  In case of `prog-mode', toggle the latter, else the former."
      (interactive)
      (if (derived-mode-p 'prog-mode)
          (call-interactively #'goto-address-prog-mode)
        (call-interactively #'goto-address-mode)))

    (dolist (hook '(eshell-mode-hook shell-mode-hook org-mode-hook))
      (add-hook hook #'goto-address-mode))

    (add-hook 'prog-mode-hook #'goto-address-prog-mode)

    (with-eval-after-load 'goto-addr
      (define-key goto-address-highlight-keymap
        (kbd "C-c C-o") #'goto-address-at-point)))

Mailcap

Extension packages as EWW (info), Gnus (info), and Org (info) rely on a mailcap file to know what application should open a specific media file type. Listing lst:tangle-mailcap-file specifies emacsclient as the application to open PDF files.

  # https://emacs.stackexchange.com/a/24502 answers the question:
  # How to use pdf-tools (pdf-view-mode) in emacs?
  application/pdf; emacsclient %s

Webjump

Listing lst:configure-webjump binds

(eval

to webjump and initializes a list of webjump-sites.

  (when (fboundp 'webjump)
    (global-set-key (kbd "C-c j") 'webjump)
    (with-eval-after-load 'webjump
      (custom-set-variables
       '(webjump-sites
         '(("Emacs Git Repositories" . "savannah.gnu.org/git/?group=emacs")
           ("Emacs News" . "sachachua.com/blog/category/emacs-news")
           ("Org Mode List" . "list.orgmode.org")
           ("Planet Emacs Life" . "planet.emacslife.com")
           ("Asian Pacific Journal Japan Focus" . "apjjf.org")
           ("Counterpunch" . "www.counterpunch.org")
           ("Dictionary EN" . [simple-query "thefreedictionary.com"
                                            "thefreedictionary.com/" ""])
           ("Dictionary FR" . [simple-query "www.cntrl.fr"
                                            "www.cntrl.fr/definition/" ""])
           ("Dictionary NL" . [simple-query "www.woorden.org"
                                            "www.woorden.org/woord/" ""])
           ("Dictionary Webster" . [simple-query
                                    "www.webster-dictionary.org"
                                    "www.webster-dictionary.org/definition/" ""])
           ("NRC". "www.nrc.nl")
           ("Trouw" . "www.trouw.nl")
           ("Volkskrant" . "www.volkskrant.nl"))))))

Elfeed: Emacs web feed reader

  (autoload 'elfeed "elfeed" nil t)
  (global-set-key (kbd "C-x w") #'elfeed)

  (with-eval-after-load 'elfeed
    (custom-set-variables
     '(elfeed-feeds
       '(("http://www.howardism.org/index.xml" h-abrams)
         ("https://ambrevar.xyz/atom.xml" p-neirhardt)
         ("https://emacshorrors.com/feed.atom" v-schneidermann)
         ("https://emacsninja.com/emacs.atom" v-schneidermann)
         ("https://feeds.feedburner.com/InterceptedWithJeremyScahill" j-scahill)
         ("https://nullprogram.com/feed/" c-wellons)
         ("https://oremacs.com/atom.xml" o-krehel)
         ("https://planet.emacslife.com/atom.xml" planet-emacs)
         ("https://protesilaos.com/codelog.xml" p-stavrou)
         ("https://sachachua.com/blog/category/emacs/feed" s-chua)
         ("https://sciencescitoyennes.org/feed/" sciences)
         ("https://updates.orgmode.org/feed/updates" org-updates)
         ("https://www.aclu.org/taxonomy/feed-term/2152/feed" aclu)
         ("https://www.bof.nl/rss/" bof)
         ("https://www.democracynow.org/podcast-video.xml" dn)
         ("https://www.laquadrature.net/fr/rss.xml" lqdn)
         ("https://www.lemonde.fr/blog/huet/feed/" sciences)))))

Emacs Multimedia System (info)

  (custom-set-variables
   '(emms-mode-line-format "")
   '(emms-player-list '(emms-player-mpd emms-player-mpv))
   `(emms-player-mpd-music-directory ,(expand-file-name "~/Music"))
   '(emms-player-mpd-server-name "localhost")
   '(emms-player-mpd-server-port "6600")
   '(emms-player-mpd-verbose t)
   '(emms-playing-time-display-format " %s ")
   '(emms-playlist-mode-center-when-go t))

  (with-eval-after-load 'elfeed-show
    (when (require 'emms-setup nil 'noerror)
      (emms-all)))

  (autoload 'emms-streams "emms-streams" nil 'interactive)
  (with-eval-after-load 'emms-streams (emms-all))

Init File (info) footer

  (provide 'init)

  ;; Emacs looks for "Local variables:" after the last "?\n?\f".
  
  ;; Local Variables:
  ;; indent-tabs-mode: nil
  ;; End:
  ;;; init.el ends here

Local variables linking to Latexmk save-compile-display-loop

Only the Org source file shows the local variables footer.

\printbibliography