path: root/Emacs/.config/emacs/config.org

#+title: Emacs configuration
#+author: Aryadev Chavali
#+description: My Emacs configuration
#+property: header-args:emacs-lisp :tangle config.el :comments link :results none
#+startup: noindent
#+options: toc:t num:t
#+latex_header:\usepackage[margin=1.0in]{geometry}
#+latex_class: article
#+latex_class_options: [a4paper,12pt]

* Introduction
Welcome to my Emacs configuration.  This thing is quite big, but a lot
of it has been "write and forget" i.e. I've only needed to configure
it once.  Sections tagged =WAIT= are currently unused, usually with
some reasoning given.

Some sections border on blog posts justifying why I think they're good
applications or giving some greater reasoning about my specific
configuration of a package.  If you don't really want that, you may
tangle this file, [[file:core.org][the core file]] and
[[file:app.org][the app file]] and just read their source code.
* Basics
Firstly, set full name and mail address.  This is used in encryption
and mailing.
#+begin_src emacs-lisp
(setq user-full-name "Aryadev Chavali"
      user-mail-address "aryadev@aryadevchavali.com")
#+end_src

Let's set all yes or no questions to single letter responses.
#+begin_src emacs-lisp
(fset 'yes-or-no-p 'y-or-n-p)
#+end_src

Set the encoding to UTF-8-Unix by default.
#+begin_src emacs-lisp
(use-package emacs
  :straight nil
  :init
  (setq-default buffer-file-coding-system 'utf-8-unix
                save-buffer-coding-system 'utf-8-unix))
#+end_src
** File saves and custom file
Setup automatic saving for files (in case of system failure) and
auto-revert-mode (which refreshes the buffer on changes to the
underlying file).  Along with that, set the custom-file (which holds
temporary customisation)  in the etc folder.
#+begin_src emacs-lisp
(use-package emacs
  :straight nil
  :init
  (setq backup-directory-alist `(("." . ,(no-littering-expand-var-file-name "saves/")))
        global-auto-revert-non-file-buffers t
        auto-revert-verbose nil)
  :config
  (global-auto-revert-mode 1))
#+end_src
* Custom functionality
Functions that don't require a packages to work other than Emacs,
which means I can define them early.  These are used much later in the
config.
** Toggle buffer
Like VSCode's toggling feature for just the terminal but now for
any buffer of choice, as long as I can generate it via a command.
#+begin_src emacs-lisp
(with-eval-after-load "window"
  (defmacro +oreo/create-toggle-function (func-name buf-name
                                                    buf-create
                                                    &optional accept-numeric)
    "Generate a function named FUNC-NAME that toggles the buffer with
name BUF-NAME, using BUF-CREATE to generate it if buffer BUF-NAME
does not exist already.

BUF-NAME cannot be a regexp, it must be a fixed name.

ACCEPT-NUMERIC modifies the function to allow numeric arguments
via C-u.  Mostly used in Eshell."
    (let ((interactive-arg
           (if accept-numeric '(interactive "p") '(interactive)))
          (arguments
           (if accept-numeric '(&optional arg) nil))
          (buffer-name (if accept-numeric
                           `(if (= arg 1)
                                ,buf-name
                              (concat ,buf-name "<" (int-to-string arg) ">"))
                         buf-name))
          (buffer-create (if accept-numeric
                             `(if (= arg 1)
                                  (,buf-create)
                                (,buf-create arg))
                           `(,buf-create))))
      `(defun ,func-name ,arguments
         ,interactive-arg
         (let* ((buffer (or (get-buffer ,buffer-name)
                            ,buffer-create))
                (displayed (get-buffer-window buffer)))
           (if displayed
               (delete-window displayed)
             (display-buffer buffer)
             (select-window (get-buffer-window buffer))))))))
#+end_src
** Auto-run command after-save-hook
Define a macro which creates hooks into the ~after-save-hook~.  On
certain ~conditions~ being met, ~to-run~ is evaluated.
#+begin_src emacs-lisp
(use-package simple
  :straight nil
  :config
  (defmacro +oreo/create-auto-save (conditions &rest to-run)
    "Create a hook for after saves, where (on CONDITIONS being met)
TO-RUN is evaluated. "
    `(add-hook 'after-save-hook #'(lambda ()
                                    (interactive)
                                    (when ,conditions
                                      ,@to-run)))))
#+end_src
** Procedure
A ~lambda~ which takes no arguments is a procedure.  This macro
generates procedures, with the parameters of the macro being the body
of the procedure.  It returns it in quoted form, as that is the most
common use of this macro.

(You may notice ~proc~ is used where the return value is irrelevant).
#+begin_src emacs-lisp
(defmacro proc (&rest BODY)
  "For a given list of forms BODY, return a quoted 0 argument
lambda."
  `(quote (lambda nil ,@BODY)))
#+end_src
** System specificity
A macro that acts as a switch case on ~(system-name)~ which allows the
writing of system specific code.  For me this is for my desktop and
laptop, particularly for font sizes.  Though there may be an easier
solution than this, this seems simple enough.
#+begin_src emacs-lisp
(defmacro +oreo/sys-name-cond (&rest pairs)
  "Switch case on result of function `system-name'.

Each pair in PAIRS is typed as: (string . (forms...)) where the
string represents the system name to test, and forms being the
consequence if true."
  `(cond
    ,@(mapcar #'(lambda (pair)
      ;; (str . forms..) -> ((string= str (system-name))
      ;; forms...)
      (let ((name (car pair))
      (body (cdr pair)))
        `((string= ,name (system-name)) ,@body)))
  pairs)))
#+end_src

In [[file:early-init.el][early-init.el]] I set the number of
native-workers to 4, which isn't necessarily optimal when
loading/compiling the rest of this file depending on the machine I
use:
- On my laptop (=spiderboy=) I'd prefer to have it use 2-3 threads so I
  can actually use the rest of the laptop while waiting for
  compilation
- On my desktop (=oldboy=) I'd prefer to use 4-6 threads as I can
  afford more, so I can get a faster load up.
#+begin_src emacs-lisp
(+oreo/sys-name-cond
 ("spiderboy"
  (setq native-comp-async-jobs-number 3))
 ("oldboy"
  (setq native-comp-async-jobs-number 6)))
#+end_src
** Clean buffer list
Instead of cleaning my buffer list manually, selectively preserving
some fixed set of buffers, this function does it for me.  Preserves
any buffers in ~+oreo/keep-buffer~ and kills the rest.
#+begin_src emacs-lisp
(defconst +oreo/keep-buffers
  (list "config.org" "*scratch*"
        "*dashboard*" "*Messages*"
        "*Warnings*")
  "List of buffer names to preserve.")

(defun +oreo/clean-buffer-list ()
  "Kill all buffers except any with names in +oreo/keep-buffers."
  (interactive)
  (mapcar #'(lambda (buf)
              (if (not (member (buffer-name buf) +oreo/keep-buffers))
                  (kill-buffer buf)))
          (buffer-list)))
#+end_src
* Aesthetics
General look and feel of Emacs (mostly disabling stuff I don't like).
** Themes
*** Dark theme
My preferred dark theme is my own "personal-primary" theme which is
stored in the Emacs lisp folder (look at
[[file:elisp/personal-primary-theme.el][this file]]).  It tries to use
the primary colours for everything, leading to a colour -> meaning
relation.

I have an older version of this theme that uses a homogeneous colour
scheme ([[file:elisp/personal-theme.el][this file]])
#+begin_src emacs-lisp
(use-package custom
  :demand t
  :straight nil
  :init
  (setq custom-theme-directory (concat user-emacs-directory "elisp/"))
  :config
  (load-theme 'personal-primary t))
#+end_src
*** Light theme
I'm not very good at designing light themes as I don't really use
them.  However they are necessary in high light situations where a
dark mode would strain the eyes too much.  So I built a custom theme
on top of the default Emacs theme, "personal-light" (look at
[[file:elisp/personal-light-theme.el][this file]]).

I don't use it by default but I may need to switch between light and
dark easily, so here's a command to switch between them.

#+begin_src emacs-lisp
(use-package custom
  :defer t
  :straight nil
  :commands +oreo/switch-theme
  :init
  (defvar +oreo/theme 'dark)
  :config
  (defun +oreo/switch-theme ()
    (interactive)
    (cond
     ((eq +oreo/theme 'dark)
      (load-theme 'personal-light t)
      (setq +oreo/theme 'light))
     ((eq +oreo/theme 'light)
      (load-theme 'personal-primary t)
      (setq +oreo/theme 'dark)))))

#+end_src
** Font size
Set font size to 140 if on my desktop (oldboy) or 175 if on my laptop
(spiderboy).
#+begin_src emacs-lisp
(use-package faces
  :straight nil
  :config
  (+oreo/sys-name-cond
   ("spiderboy" (set-face-attribute 'default nil :height 175))
   ("oldboy" (set-face-attribute 'default nil :height 140))))
#+end_src
** Startup screen
The default startup screen is quite bad in all honesty, great for
first time users who have no idea what is going on but terrible for
regular users.

The scratch buffer is an interaction buffer made when Emacs is first
started, as a way to quickly prototype Emacs Lisp code.  When startup
screen is disabled, this buffer is the first thing presented on boot
for Emacs.  So we can use it to store some useful information.

As I use [[*Org mode][org-mode]] to compile my Emacs, it is available
essentially at startup, so I use it for the scratch buffer.  That way,
I can use all the abilities of org-mode (particularly writing a system
of code using =#+RESULTS=) in an ephemeral buffer at startup!
#+begin_src emacs-lisp
(use-package emacs
  :straight nil
  :init
  (setq
   inhibit-startup-screen t
   initial-major-mode 'org-mode
   initial-scratch-message ""
   ring-bell-function 'ignore)
  (add-hook 'after-init-hook (proc
                              (with-current-buffer "*scratch*"
                                (goto-char (point-max))
                                (insert (format "#+title: Scratch buffer
,#+author: %s
,#+description: Emacs v%s

Booted in %s
" user-full-name emacs-version (emacs-init-time)))))))

#+end_src
** Blinking cursor
Turn off blinking-cursor-mode as [[*Hl-line][hl-line]] is better.
#+begin_src emacs-lisp
(use-package frame
  :straight nil
  :config
  (blink-cursor-mode 0))
#+end_src
** Fringes
Turning off borders in my window manager was a good idea, so turn off
the borders for Emacs.
#+begin_src emacs-lisp
(use-package fringe
  :after dashboard
  :straight nil
  :config
  (fringe-mode 0))
#+end_src
** Mode line
A mode line in an editor can provide a LOT of information, or very
little.  I customised the Emacs modeline to give me a bit of info,
~telephone-line~ to give me a lot.

Currently I use the default mode line with some customisation;
simplicity is above all.
*** Emacs Mode-line
#+begin_src emacs-lisp
(defun +mode-line/generate-padding ()
  (let ((wid (frame-width))
        (str ""))
    (dotimes (n (floor (/ wid 7)))
      (setq str (concat str " ")))
    str))

(setq-default
 mode-line-format
 (list
  "%l:%c    " ;; Line and column
  "%p[" ;; Where in file + Evil state
  '(:eval (upcase
           (substring
            (format "%s" (if (bound-and-true-p evil-state)
                             evil-state
                           ""))
            0 1)))
  "]    "
  "%+%b("
  '(:eval (format "%s" major-mode))
  ")    "
  "%I    "
  '(:eval (+mode-line/generate-padding))
  '(vc-mode vc-mode)
  mode-line-misc-info
  mode-line-end-spaces))
#+end_src
*** WAIT Telephone-line
:PROPERTIES:
:header-args:emacs-lisp: :tangle no
:END:
Telephone-line is a mode-line package for Emacs which prioritises
extensibility.  It also looks much nicer than the default mode line
with colouring and a ton of presentations to choose from.
#+begin_src emacs-lisp
(use-package telephone-line
  :init
  (defface +telephone/position-face '((t (:foreground "red" :background "grey10"))) "")
  (defface +telephone/mode-face '((t (:foreground "white" :background "dark green"))) "")
  (defface +telephone/file-info-face '((t (:foreground "white" :background "Dark Blue"))) "")
  :custom
  (telephone-line-faces
   '((evil      . telephone-line-modal-face)
     (modal     . telephone-line-modal-face)
     (ryo       . telephone-line-ryo-modal-face)
     (accent    . (telephone-line-accent-active . telephone-line-accent-inactive))
     (nil         . (mode-line                    . mode-line-inactive))
     (position  . (+telephone/position-face     . mode-line-inactive))
     (mode      . (+telephone/mode-face         . mode-line-inactive))
     (file-info . (+telephone/file-info-face    . mode-line-inactive))))
  (telephone-line-primary-left-separator    'telephone-line-halfcos-left)
  (telephone-line-secondary-left-separator  'telephone-line-halfcos-hollow-left)
  (telephone-line-primary-right-separator   'telephone-line-identity-right)
  (telephone-line-secondary-right-separator 'telephone-line-identity-hollow-right)
  (telephone-line-height 24)
  (telephone-line-evil-use-short-tag nil)
  :config
  (telephone-line-defsegment +telephone/buffer-or-filename ()
                             (cond
                              ((buffer-file-name)
                               (if (and (fboundp 'projectile-project-name)
                                        (fboundp 'projectile-project-p)
                                        (projectile-project-p))
                                   (list ""
                                         (funcall (telephone-line-projectile-segment) face)
                                         (propertize
                                          (concat "/"
                                                  (file-relative-name (file-truename (buffer-file-name))
                                                                      (projectile-project-root)))
                                          'help-echo (buffer-file-name)))
                                 (buffer-file-name)))
                              (t (buffer-name))))

  (telephone-line-defsegment +telephone/get-position ()
                             `(,(concat "%lL:%cC"
                                        (if (not mark-active)
                                            ""
                                          (format " | %dc" (- (+ 1 (region-end)) (region-beginning)))))))

  (setq-default
   telephone-line-lhs '((mode telephone-line-major-mode-segment)
                        (file-info telephone-line-input-info-segment)
                        (position +telephone/get-position)
                        (accent   +telephone/buffer-or-filename
                                  telephone-line-process-segment))
   telephone-line-rhs '((accent telephone-line-flycheck-segment telephone-line-misc-info-segment
                                telephone-line-projectile-segment)
                        (file-info telephone-line-filesize-segment)
                        (evil  telephone-line-evil-tag-segment)))
  (telephone-line-mode))
#+end_src
** Mouse
Eww who uses a mouse?
#+begin_src emacs-lisp
(setq use-file-dialog nil)
#+end_src
* Core packages (loading)
For my core packages, whose configuration doesn't change much anyway,
I have a [[file:core.org][separate file]].  Here I'll load it up for
usage later on.
#+begin_src emacs-lisp
(load-file (concat user-emacs-directory "core.el"))
#+end_src
* Small packages
** ISearch
ISearch is the default incremental search application in Emacs.  I use
~evil-search-forward~ so I don't interact with isearch that much, but
I may need it occasionally.
#+begin_src emacs-lisp
(use-package isearch
  :straight nil
  :general
  (:keymaps 'isearch-mode-map
   "M-s" #'isearch-repeat-forward))
#+end_src
** Info
Info is GNU's attempt at better man pages.  Most Emacs packages have
info pages so I'd like nice navigation options.
#+begin_src emacs-lisp
(use-package info
  :straight nil
  :general
  (nmmap
    :keymaps 'Info-mode-map
    "h" #'evil-backward-char
    "k" #'evil-previous-line
    "l" #'evil-forward-char
    "H" #'Info-history-back
    "L" #'Info-history-forward
    "RET" #'Info-follow-nearest-node))
#+end_src
** Display line numbers
I don't really like line numbers, I find them similar to [[*Fringes][fringes]] as
useless space, but at least it provides some information.  Sometimes
it can help with doing repeated commands so a toggle option is
necessary.
#+begin_src emacs-lisp
(use-package display-line-numbers
  :straight nil
  :commands display-line-numbers-mode
  :general
  (mode-leader
    "l" #'display-line-numbers-mode)
  :init
  (setq-default display-line-numbers-type 'relative))
#+end_src
** WAIT esup
:PROPERTIES:
:header-args:emacs-lisp: :tangle no
:END:
I used to be able to just use
[[file:elisp/profiler-dotemacs.el][profile-dotemacs.el]], when my
Emacs config was smaller, but now it tells me very little information
about where my setup is inefficient due to the literate config.  Just
found this ~esup~ thing and it works perfectly, exactly how I would
prefer getting this kind of information.  It runs an external Emacs
instance and collects information from it, so it doesn't require
restarting Emacs to profile, and I can compile my configuration in my
current instance to test it immediately.

2023-10-16: Unless I'm doing some optimisations or tests, I don't
really need this in my config at all times.  Enable when needed.
#+begin_src emacs-lisp
(use-package esup
  :defer t)
#+end_src
** xref
Find definitions, references and general objects using tags without
external packages.  Provided by default in Emacs and just requires a
way of generating a =TAGS= file for your project.  Helps with minimal
setups for programming without heavier packages like [[*Eglot][Eglot]].

[[*Projectile][Projectile]] provides a nice way to generate tags.
#+begin_src emacs-lisp
(use-package xref
  :straight nil
  :display
  ("\\*xref\\*"
   (display-buffer-at-bottom)
   (inhibit-duplicate-buffer . t)
   (window-height . 0.25))
  :general
  (code-leader
    "t" '(nil :which-key "Tags"))
  (code-leader
    :infix "t"
    "t" #'xref-find-apropos
    "d" #'xref-find-definitions
    "r" #'xref-find-references)
  (nmmap
    :keymaps 'xref--xref-buffer-mode-map
    "RET" #'xref-goto-xref
    "J" #'xref-next-line
    "K" #'xref-prev-line
    "g" #'xref-revert-buffer
    "q" #'quit-window))
#+end_src
** Hl-line
Highlights the current line, much better than a blinking cursor.
#+begin_src emacs-lisp
(use-package hl-line
  :straight t
  :hook (text-mode-hook . hl-line-mode)
  :hook (prog-mode-hook . hl-line-mode))
#+end_src
** Recentf
Recentf provides a method of keeping track of recently opened files.
#+begin_src emacs-lisp
(use-package recentf
  :straight nil
  :hook (emacs-startup-hook . recentf-mode))
#+end_src
** Projectile
Projectile is a project management package which integrates with Emacs
very well.  It essentially provides alternative Emacs commands scoped
to the current 'project', based on differing signs that a directory is
a 'project'.
#+begin_src emacs-lisp
(use-package projectile
  :after evil
  :hook (emacs-startup-hook . projectile-mode)
  :general
  (general-def
    :keymaps 'projectile-command-map
    "t" #'projectile-test-project
    "r" #'projectile-run-project
    "q" #'projectile-replace-regexp)
  (leader "p" '(projectile-command-map :which-key "Projectile"))
  (nmap
    "<f5>" #'projectile-compile-project
    "<f6>" #'projectile-configure-project
    "<f7>" #'projectile-test-project)
  :init
  (setq projectile-tags-command "ctags -Re -f \"%s\" %s \"%s\""
        projectile-enable-caching t))
#+end_src
*** Counsel projectile
Counsel integration for projectile commands, very nice.
#+begin_src emacs-lisp
(use-package counsel-projectile
  :after (projectile counsel)
  :config
  (counsel-projectile-mode +1))
#+end_src
** Avy
Setup avy with leader.  As I use ~avy-goto-char-timer~ a lot, use the
~C-s~ bind which replaces isearch.  Switch isearch to M-s in case I
need to use it.
#+begin_src emacs-lisp
(use-package avy
  :after evil
  :general
  (nmmap
    "C-s" #'avy-goto-char-timer
    "M-s" #'isearch-forward)
  (search-leader
    "l" #'avy-goto-line))
#+end_src
** Ace window
Though evil provides a great many features in terms of window
management, ace window can provide some nicer chords for higher
management of windows (closing, switching, etc).

#+begin_src emacs-lisp
(use-package ace-window
  :after evil
  :custom
  (aw-keys '(?a ?s ?d ?f ?g ?h ?j ?k ?l))
  :general
  (nmmap
    [remap evil-window-next] #'ace-window))
#+end_src
** Helpful
Helpful provides a modernised interface for some common help
commands.  I replace ~describe-function~, ~describe-variable~ and
~describe-key~ by their helpful counterparts.
#+begin_src emacs-lisp
(use-package helpful
  :after ivy
  :commands (helpful-callable helpful-variable)
  :general
  (general-def
    [remap describe-function] #'helpful-callable
    [remap describe-variable] #'helpful-variable
    [remap describe-key]      #'helpful-key)
  :display
  ("\\*helpful.*"
   (display-buffer-at-bottom)
   (inhibit-duplicate-buffer . t)
   (window-height . 0.25))
  :config
  (evil-define-key 'normal helpful-mode-map "q" #'quit-window))
#+end_src
** Which-key
Which key uses the minibuffer when performing a keybind to provide
possible options for the next key.
#+begin_src emacs-lisp
(use-package which-key
  :config
  (which-key-mode))
#+end_src
** Keychord
Keychord is only really here for this one chord I wish to define: "jk"
for exiting insert state.
#+begin_src emacs-lisp
(use-package key-chord
  :after evil
  :config
  (key-chord-define evil-insert-state-map "jk" #'evil-normal-state)
  (key-chord-mode))
#+end_src
** (Rip)grep
Grep is a great piece of software, a necessary tool in any Linux
user's inventory.  By default Emacs has a family of functions to use
grep, presenting results in a ~compilation~ style.  ~grep~ searches
files, ~rgrep~ searches in a directory using the ~find~ program and
~zgrep~ searches archives.  This is a great solution for a general
computer environment; essentially all Linux installs will have ~grep~
and ~find~ installed.

Ripgrep is a Rust program that attempts to perform better than grep,
and it actually does.  This is because of a set of optimisations, such
as checking the =.gitignore= to exclude certain files from being
searched.  The ripgrep package provides utilities to ripgrep projects
and files for strings.  Though [[file:core.org::*Ivy][ivy]] comes with
~counsel-rg~, it uses Ivy's completion framework rather than the
~compilation~ style buffers, which sometimes proves very useful.

Of course, this requires installing the rg binary which is available
in most repositories nowadays.
*** Grep
I have no use for standard 'grep'; ~counsel-swiper~ does the same
thing faster and within Emacs lisp.  ~rgrep~ is useful though.
#+begin_src emacs-lisp
(use-package grep
  :straight nil
  :display
  ("^\\*grep.*"
   (display-buffer-at-bottom display-buffer-reuse-window)
   (window-height . 0.25)
   (reusable-frames . t))
  :general
  (search-leader
    "d" #'rgrep)
  (nmmap
    :keymaps 'grep-mode-map
    "0" #'evil-digit-argument-or-evil-beginning-of-line
    "W" #'wgrep-change-to-wgrep-mode))
#+end_src
*** rg
#+begin_src emacs-lisp
(use-package rg
  :after grep
  :general
  (search-leader
    "R" #'rg)
  (:keymaps 'rg-mode-map
   "]]" #'rg-next-file
   "[[" #'rg-prev-file
   "q"  #'quit-window)
  :init
  (setq rg-group-result t
        rg-hide-command t
        rg-show-columns nil
        rg-show-header t
        rg-custom-type-aliases nil
        rg-default-alias-fallback "all"
        rg-buffer-name "*ripgrep*"))
#+end_src
** Olivetti
Olivetti provides a focus mode for Emacs, which makes it look a bit
nicer with fringes.  I also define ~+olivetti-mode~ which will
remember and clear up any window configurations on the frame, then
when turned off will reinsert them - provides a nice way to quickly
focus on a buffer.
#+begin_src emacs-lisp
(use-package olivetti
  :commands (+olivetti-mode)
  :general
  (mode-leader
    "o" #'+olivetti-mode)
  :init
  (setq-default olivetti-body-width 0.7)
  (setq olivetti-style nil)
  (add-hook 'olivetti-mode-on-hook  (proc (interactive) (text-scale-increase 1)))
  (add-hook 'olivetti-mode-off-hook (proc (interactive) (text-scale-decrease 1)))
  :config
  (defun +olivetti-mode ()
    (interactive)
    (if (not olivetti-mode)
        (progn
          (window-configuration-to-register 1)
          (delete-other-windows)
          (olivetti-mode t))
      (jump-to-register 1)
      (olivetti-mode 0))))
#+end_src
** All the Icons
Nice set of icons with a great user interface to manage them.
#+begin_src emacs-lisp
(use-package all-the-icons
  :straight t
  :defer t
  :commands (all-the-icons-insert)
  :general
  (insert-leader
    "e" #'all-the-icons-insert))
#+end_src
** Hide mode line
Custom minor mode to toggle the mode line.  Check it out at
[[file:elisp/hide-mode-line.el][elisp/hide-mode-line.el]].
#+begin_src emacs-lisp
(use-package hide-mode-line
  :straight nil
  :load-path "elisp/"
  :defer t
  :general
  (mode-leader
    "m" #'hide-mode-line-mode))
#+end_src
** Save place
Saves current place in a buffer permanently, so on revisiting the file
(even in a different Emacs instance) you go back to the place you were
at last.
#+begin_src emacs-lisp
(use-package saveplace
  :straight nil
  :config
  (save-place-mode))
#+end_src
** Rot13
ROT13 encoding is a pretty simple cipher; fun to make decoders and
encoders for.  Emacs has default support for it, to the point where it
can display files with the encoding without changing the underlying
text.  That's what this is mainly for.

#+begin_src emacs-lisp
(use-package rot13
  :straight nil
  :general
  (mode-leader
    "r" #'toggle-rot13-mode))
#+end_src
** Licensing
Loads [[file:elisp/license.el][license.el]] for inserting licenses.
Licenses are important for distribution and attribution to be defined
clearly.
#+begin_src emacs-lisp
(use-package license
  :straight nil
  :load-path "elisp/"
  :demand t
  :general
  (insert-leader
    "l" #'+license/insert-copyright-notice
    "L" #'+license/insert-complete-license))
#+end_src
** Memory-report
New feature of Emacs-29, gives a rough report of memory usage with
some details.  Useful to know on a long Emacs instance what could be
eating up memory.
#+begin_src emacs-lisp
(use-package memory-report
  :straight nil
  :general
  (leader
    "qm" #'memory-report))
#+end_src
** Save minibuffer history
#+begin_src emacs-lisp
(use-package savehist
  :straight nil
  :config
  (savehist-mode t))
#+end_src
* Applications (loading)
Emacs is basically an operating system whose primary datatype is text.
Applications are interfaces/environments which serve a variety of
purposes, but provide a lot of capability.  I have a
[[file:app.org][separate file]] for such configuration (2023-09-29:
mainly because it was so goddamn huge).

#+begin_src emacs-lisp
(load-file (concat user-emacs-directory "app.el"))
#+end_src
* Text modes
Standard packages and configurations for text-mode and its derived
modes.
** Flyspell
Flyspell allows me to quickly spell check text documents.  I use
flyspell primarily in org mode, as that is my preferred prose writing
software, but I also need it in commit messages and so on.  So
flyspell-mode should be hooked to text-mode.
#+begin_src emacs-lisp
(use-package flyspell
  :hook (text-mode-hook . flyspell-mode)
  :general
  (nmmap
    :keymaps 'text-mode-map
    (kbd "M-C") #'flyspell-correct-word-before-point
    (kbd "M-c") #'flyspell-auto-correct-word)
  (mode-leader
    "s" #'flyspell-mode))
#+end_src
** Undo tree
Undo tree sits on top of the incredible Emacs undo capabilities.
Provides a nice visual for edits and a great way to produce branches
of edits.  Also allows saving of undo trees, which makes Emacs a quasi
version control system in and of itself!  The only extra necessary
would be describing changes...
#+begin_src emacs-lisp
(use-package undo-tree
  :straight t
  :hook (after-init-hook . global-undo-tree-mode)
  :init
  (setq undo-tree-auto-save-history t
        undo-tree-history-directory-alist backup-directory-alist)
  :general
  (leader
    "u" #'undo-tree-visualize))
#+end_src
** Whitespace
Deleting whitespace, highlighting when going beyond the 80th character
limit, all good stuff.  I don't want to highlight whitespace for
general mode categories (Lisp shouldn't really have an 80 character
limit), so set it for specific modes need the help.
#+begin_src emacs-lisp
(use-package whitespace
  :straight nil
  :general
  (nmmap
    "M--"   #'whitespace-cleanup)
  (mode-leader
    "w" #'whitespace-mode)
  :hook
  (before-save-hook  . whitespace-cleanup)
  (c-mode-hook       . whitespace-mode)
  (c++-mode-hook     . whitespace-mode)
  (haskell-mode-hook . whitespace-mode)
  (python-mode-hook  . whitespace-mode)
  (org-mode-hook     . whitespace-mode)
  (text-mode-hook    . whitespace-mode)
  :init
  (setq whitespace-style '(face lines-tail spaces tabs tab-mark trailing newline)
        whitespace-line-column 80))
#+end_src
** Set auto-fill-mode for all text-modes
Auto fill mode automatically newlines text on 80 characters, which
looks nice and integrates well with Evil's sentence and paragraph text
objects.
#+begin_src emacs-lisp
(add-hook 'text-mode-hook #'auto-fill-mode)
#+end_src
** Show-paren-mode
Show parenthesis for Emacs
#+begin_src emacs-lisp
(add-hook 'prog-mode-hook #'show-paren-mode)
#+end_src
** Smartparens
Smartparens is a smarter electric-parens, it's much more aware of
context and easier to use.
#+begin_src emacs-lisp
(use-package smartparens
  :hook
  (prog-mode-hook . smartparens-mode)
  (text-mode-hook . smartparens-mode)
  :after evil
  :config
  (setq sp-highlight-pair-overlay nil
        sp-highlight-wrap-overlay t
        sp-highlight-wrap-tag-overlay t)

  (let ((unless-list '(sp-point-before-word-p
                       sp-point-after-word-p
                       sp-point-before-same-p)))
    (sp-pair "'"  nil :unless unless-list)
    (sp-pair "\"" nil :unless unless-list))
  (sp-local-pair sp-lisp-modes "(" ")" :unless '(:rem sp-point-before-same-p))
  (require 'smartparens-config))
#+end_src
** Thesaurus
=le-thesaurus= is a great extension for quickly searching up words for
synonyms or antonyms.  I may need it anywhere so I bind it to all
keymaps.  Same with dictionary searching.
#+begin_src emacs-lisp
(use-package le-thesaurus
  :straight t
  :display
  ("\\*Dictionary\\*"
   (display-buffer-reuse-window display-buffer-same-window)
   (reusable-frames . t))
  :general
  (local-leader
    :keymaps 'override
    "[" #'le-thesaurus-get-synonyms
    "]" #'le-thesaurus-get-antonyms
    "#" #'dictionary-search))
#+end_src
* Programming packages
Packages that help with programming in general, providing IDE like
capabilities.
** Eldoc
Eldoc presents documentation to the user upon placing ones cursor upon
any symbol.  This is very useful when programming as it:
- presents the arguments of functions while writing calls for them
- presents typing and documentation of variables

Eldoc box makes the help buffer a hovering box instead of printing it
in the minibuffer.  A lot cleaner.
#+begin_src emacs-lisp
(use-package eldoc
  :straight nil
  :hook (prog-mode-hook . eldoc-mode)
  :init
  (global-eldoc-mode 1))

(use-package eldoc-box
  :hook (eldoc-mode-hook . eldoc-box-hover-mode)
  :init
  (setq eldoc-box-position-function #'eldoc-box--default-upper-corner-position-function
        eldoc-box-clear-with-C-g t))
#+end_src
** Eglot
Eglot is package to communicate with LSP servers for better
programming capabilities.  Interactions with a server provide results
to the client, done through JSON.

NOTE: Emacs 28.1 comes with better JSON parsing, which makes Eglot
much faster.

2023-03-26: I've found Eglot to be useful sometimes, but many of the
projects I work on don't require a heavy server setup to efficiently
edit and check for errors; Emacs provides a lot of functionality.  So
by default I've disabled it, using =M-x eglot= to startup the LSP
server when I need it.
#+begin_src emacs-lisp
(use-package eglot
  :after project
  :defer t
  :general
  (code-leader
    :keymaps 'eglot-mode-map
    "f" #'eglot-format
    "a" #'eglot-code-actions
    "r" #'eglot-rename
    "R" #'eglot-reconnect)
  ;; :init
  ;; (setq eglot-stay-out-of '(flymake))
  :config
  (add-to-list 'eglot-server-programs '((c++-mode c-mode) "clangd")))
#+end_src
** Flycheck
Flycheck is the checking system for Emacs.  I don't necessarily like
having all my code checked all the time, so I haven't added a hook to
prog-mode as it would be better for me to decide when I want checking
and when I don't.
#+begin_src emacs-lisp
(use-package flycheck
  :commands (flycheck-mode flycheck-list-errors)
  :hook
  (c-mode-hook   . flycheck-mode)
  (c++-mode-hook . flycheck-mode)
  :general
  (mode-leader
    "f" #'flycheck-mode)
  (code-leader
    "x" #'flycheck-list-errors
    "J" #'flycheck-next-error
    "K" #'flycheck-previous-error)
  :display
  ("\\*Flycheck.*"
   (display-buffer-at-bottom)
   (window-height . 0.25))
  :config
  (with-eval-after-load "evil-collection"
    (evil-collection-flycheck-setup)))
#+end_src
** Tabs and spaces
By default, turn off tabs and set the tab width to two.
#+begin_src emacs-lisp
(setq-default indent-tabs-mode nil
              tab-width 2)
#+end_src

However, if necessary later, define a function that may activate tabs locally.
#+begin_src emacs-lisp
(defun +oreo/activate-tabs ()
  (interactive)
  (setq-local indent-tabs-mode t))
#+end_src
** Highlight todo items
TODO items are highlighted in org-mode, but not necessarily in every
mode.  This minor mode highlights all TODO like items via a list of
strings to match.  It also configures faces to use when highlighting.
I hook it to prog-mode.

#+begin_src emacs-lisp
(use-package hl-todo
  :after prog-mode
  :hook (prog-mode-hook . hl-todo-mode)
  :init
  (setq hl-todo-keyword-faces
        '(("TODO"  . "#E50000")
          ("WIP"   . "#ffa500")
          ("NOTE"  . "#00CC00")
          ("FIXME" . "#d02090"))))
#+end_src
** Hide-show mode
Turn on ~hs-minor-mode~ for all prog-mode.  This provides folds for
free.
#+begin_src emacs-lisp
(use-package hideshow
  :straight nil
  :hook (prog-mode-hook . hs-minor-mode))
#+end_src
** Aggressive indenting
Essentially my dream editing experience: when I type stuff in, try and
indent it for me on the fly.  Just checkout the
[[https://github.com/Malabarba/aggressive-indent-mode][page]], any
description I give won't do it justice.

#+begin_src emacs-lisp
(use-package aggressive-indent
  :straight t
  :demand t
  :config
  (add-to-list 'aggressive-indent-excluded-modes
               'c-mode)
  (add-to-list 'aggressive-indent-excluded-modes
               'c++-mode)
  (add-to-list 'aggressive-indent-excluded-modes
               'cc-mode)
  (global-aggressive-indent-mode))
#+end_src
** Compilation
Colourising the compilation buffer so ANSI colour codes get computed.
#+begin_src emacs-lisp
(use-package compile
  :straight nil
  :general
  (code-leader
    "j" #'next-error
    "k" #'previous-error
    "c" #'compile
    "C" #'recompile)
  (nmmap
    :keymaps 'compilation-mode-map
    "c" #'recompile)
  (general-def
    :keymaps 'compilation-mode-map
    "g" nil) ;; by default this is recompile
  :display
  ("\\*compilation\\*"
   (display-buffer-reuse-window display-buffer-at-bottom)
   (reusable-frames . t)
   (window-height . 0.25))
  :config
  (defun +compile/colourise ()
    "Colourise the emacs compilation buffer."
    (interactive)
    (let ((inhibit-read-only t))
      (ansi-color-apply-on-region (point-min) (point-max))))
  (add-hook 'compilation-filter-hook #'+compile/colourise))
#+end_src
* Org mode
2023-03-30: finally decided to give org mode its own section.

Org is, at its most basic, a markup language.  Files use the ".org"
extension and use =org-mode= to write text, with the ability to export
to a few formats, all within Emacs.  Some other features include:
+ A complete spreadsheet system, with formulas (including
  [[file:app.org::*Calculator][calc-mode]] integration)
+ Evaluation of code blocks, even using the results of them in exports
  (to, say, a $\LaTeX$ or HTML document)
  + This includes exporting code blocks to a code file.  All the
    emacs-lisp code blocks in this file are compiled to =config.el=
    ([[file:elisp/literate.el][literate]])
+ Complete calendar/todo system with deadlines, scheduling and
  repeaters
+ Export to a variety of formats or make your own export engine using
  the org AST!
+ Writing $\LaTeX$ inline, with the ability to render the fragments on
  demand
** Org Essentials
Org has a ton of settings to tweak, which change your experience quite
a bit.  My setup should be as portable as possible and (/sometimes/) I
need to access org mode files in other editors, so org files should be
as close to clear text as possible.  This is the guiding philosophy
that essentially makes most of my options pretty immediate.

Some arbitrary notes:
+ By default =~/Text= is my directory for text files.  I actually have
  a repository that manages this directory for agenda files and other
  documents
+ Indentation in file should not be allowed, i.e. text indentation,
  as that forces other editors to read it a certain way as well.  It
  obtrusive hence it's off.
+ Org startup indented is on by default as most documents do benefit
  from the indentation, but I do turn it off for some files via
  ~#+startup:noindent~
+ When opening an org document there can be a lot of headings, so I
  set folding to just content
+ Org documents can also have a lot of latex previews, which make
  opening some after a while a massive hassle.  If I want to see the
  preview, I'll do it myself, so turn it off.
+ Org manages windowing itself, to some extent, so I set those options
  to be as unobtrusive as possible

#+begin_src emacs-lisp
(use-package org
  :defer t
  :straight t
  :init
  (setq
   org-directory "~/Text"
   org-adapt-indentation nil
   org-indent-mode nil
   org-startup-indented t
   org-startup-folded 'content
   org-startup-with-latex-preview nil
   org-imenu-depth 10
   org-src-window-setup 'current-window
   org-indirect-buffer-display 'current-window
   org-link-frame-setup '((vm . vm-visit-folder-other-frame)
                          (vm-imap . vm-visit-imap-folder-other-frame)
                          (file . find-file))))
#+end_src
** Org Latex
Org mode has deep integration with latex, can export to PDF and even
display latex fragments in the document directly.  I setup the
pdf-process, code listing options via minted and the format options
for latex fragments.
#+begin_src emacs-lisp
(use-package org
  :defer t
  :init
  (setq org-format-latex-options '(:foreground default :background default :scale 2
                                   :html-foreground "Black" :html-background "Transparent"
                                   :html-scale 1.0 :matchers ("begin" "$1" "$" "$$" "\\(" "\\["))
        org-latex-src-block-backend 'minted
        org-latex-minted-langs '((emacs-lisp "common-lisp")
                                 (ledger "text")
                                 (cc "c++")
                                 (cperl "perl")
                                 (shell-script "bash")
                                 (caml "ocaml"))
        org-latex-packages-alist '(("" "minted"))
        org-latex-pdf-process
        '("latexmk -f -bibtex -pdf -shell-escape -%latex -interaction=nonstopmode -output-directory=%o %f")
        org-latex-minted-options '(("style" "colorful")
                                   ("linenos")
                                   ("frame" "single")
                                   ("mathescape")
                                   ("fontfamily" "courier")
                                   ("samepage" "false")
                                   ("breaklines" "true")
                                   ("breakanywhere" "true"))))
#+end_src
** Org Core Variables
Tons of variables for org-mode, including a ton of latex ones.  Can't
really explain because it sets up quite a lot of local stuff.  Also I
copy pasted the majority of this, tweaking it till it felt good.  Doom
Emacs was very helpful here.
#+begin_src emacs-lisp
(use-package org
  :defer t
  :init
  (setq org-edit-src-content-indentation 0
        org-goto-interface 'outline
        org-imenu-depth 10
        org-export-backends '(ascii html latex odt icalendar)
        org-eldoc-breadcrumb-separator " → "
        org-enforce-todo-dependencies t
        org-fontify-quote-and-verse-blocks t
        org-fontify-whole-heading-line t
        org-footnote-auto-label t
        org-hide-leading-stars t
        org-hide-emphasis-markers nil
        org-image-actual-width nil
        org-priority-faces '((?A . error) (?B . warning) (?C . success))
        org-link-descriptive nil
        org-tags-column 0
        org-todo-keywords
        '((sequence "TODO" "WIP" "DONE")
          (sequence "PROJ" "WAIT" "COMPLETE"))
        org-use-sub-superscripts '{}
        org-babel-load-languages '((emacs-lisp . t)
                                   (lisp . t)
                                   (shell . t))))
#+end_src
** Org Core Functionality
Hooks, prettify-symbols and records for auto insertion.
#+begin_src emacs-lisp
(use-package org
  :hook
  (org-mode-hook . prettify-symbols-mode)
  :display
  ("\\*Org Src.*"
   (display-buffer-same-window))
  :pretty
  (org-mode-hook
   ("#+begin_src" . "≫")
   ("#+end_src"   . "≪"))
  :init
  (with-eval-after-load "autoinsert"
    (define-auto-insert '("\\.org\\'" . "Org skeleton")
      '("Enter title: "
        "#+title: " str | (buffer-file-name) "\n"
        "#+author: " (read-string "Enter author: ") | user-full-name "\n"
        "#+description: " (read-string "Enter description: ") | "Description" "\n"
        "#+date: " (format-time-string "%Y-%m-%d" (current-time)) "\n"
        "* " _))))
#+end_src
** Org Core Bindings
Some bindings for org mode.
#+begin_src emacs-lisp
(use-package org
  :after counsel
  :config
  (defun +org/swiper-goto ()
    (interactive)
    (swiper "^\\* "))
  (defun +org/search-headings ()
    "Searches directory (of buffer) for org headings via counsel-rg"
    (interactive)
    (counsel-rg "^\\* " (file-name-directory (buffer-file-name))))
  (defun +org/search-config-headings ()
    "Searches USER-EMACS-DIRECTORY for org headings via counsel-rg"
    (interactive)
    (counsel-rg "^\\* "
                (cl-subseq user-emacs-directory 0 (- (length user-emacs-directory) 1))))
  :general
  (file-leader
    "l" #'org-store-link
    "i" #'org-insert-last-stored-link)
  (code-leader
    "D" #'org-babel-detangle)
  (search-leader
    "c" #'+org/search-config-headings)
  (search-leader
    :keymaps 'org-mode-map
    "I" #'+org/search-headings)
  (nmmap
    :keymaps 'org-mode-map
    [remap imenu] #'+org/swiper-goto)
  (local-leader
    :keymaps 'org-mode-map
    "l" '(nil :which-key "Links")
    "'" '(nil :which-key "Tables")
    "c" '(nil :which-key "Clocks")
    "r" #'org-refile
    "d" #'org-date-from-calendar
    "t" #'org-todo
    "," #'org-priority
    "T" #'org-babel-tangle
    "i" #'org-insert-structure-template
    "p" #'org-latex-preview
    "s" #'org-property-action
    "e" #'org-export-dispatch
    "o" #'org-edit-special)
  (local-leader
    :keymaps 'org-mode-map
    :infix "l"
    "i" #'org-insert-link
    "l" #'org-open-at-point
    "f" #'org-footnote-action)
  (local-leader
    :keymaps 'org-mode-map
    :infix "'"
    "a" #'org-table-align
    "c" #'org-table-create
    "f" #'org-table-edit-formulas
    "t" #'org-table-toggle-coordinate-overlays
    "s" #'org-table-sum
    "e" #'org-table-calc-current-TBLFM
    "E" #'org-table-eval-formula)
  (local-leader
    :keymaps 'org-mode-map
    :infix "c"
    "i" #'org-clock-clock-in
    "o" #'org-clock-clock-out
    "c" #'org-clock-in-last
    "d" #'org-clock-display))
#+end_src
** Org Agenda
Org agenda provides a nice viewing for schedules.  With org mode it's
a very tidy way to manage your time.
#+begin_src emacs-lisp
(use-package org-agenda
  :after org
  :straight nil
  :init
  (defconst +org/agenda-root "~/Text"
    "Root directory for all agenda files")
  (setq org-agenda-files (list (expand-file-name +org/agenda-root))
        org-agenda-window-setup 'current-window
        org-agenda-skip-deadline-prewarning-if-scheduled t
        org-agenda-skip-scheduled-if-done t
        org-agenda-skip-deadline-if-done t
        org-agenda-start-with-entry-text-mode nil)
  :config
  (evil-set-initial-state 'org-agenda-mode 'normal)
  :general
  (file-leader
    "a" `(,(proc (interactive)
                 (find-file (completing-read "Enter directory: " org-agenda-files nil t)))
          :which-key "Open agenda directory"))

  (app-leader
    "a" #'org-agenda)

  (nmmap
    :keymaps 'org-agenda-mode-map
    "zd" #'org-agenda-day-view
    "zw" #'org-agenda-week-view
    "zm" #'org-agenda-month-view
    "gd" #'org-agenda-goto-date
    "RET" #'org-agenda-switch-to
    "J" #'org-agenda-later
    "K" #'org-agenda-earlier
    "t" #'org-agenda-todo
    "." #'org-agenda-goto-today
    "," #'org-agenda-goto-date
    "q" #'org-agenda-quit
    "r" #'org-agenda-redo))
#+end_src
** Org capture
#+begin_src emacs-lisp
(use-package org-capture
  :straight nil
  :init
  (setq
   org-capture-templates
   '(("t" "A todo" entry
      (file "")
      "* TODO %?
%T
%a"))
   org-default-notes-file (concat org-directory "/todo.org"))
  :general
  (file-leader
    "w" #'org-capture))
#+end_src
** Org clock-in
Org provides a nice timekeeping system that allows for managing how
much time is taken per task.  It even has an extensive reporting
system to see how much time you spend on specific tasks or overall.
#+begin_src emacs-lisp
(use-package org-clock
  :after org
  :straight nil
  :init
  (defvar +org/clock-out-toggle-report nil
    "Non-nil means update the first clock report in the file every
time a clock out occurs.")
  :config
  (advice-add #'org-clock-out
              :after
              (proc (interactive)
                    (if +org/clock-out-toggle-report
                        (org-clock-report t))))
  :general
  (local-leader
    :keymaps 'org-mode-map
    :infix "c"
    "c" #'org-clock-in
    "o" #'org-clock-out
    "r" #'org-clock-report
    "t" (proc (interactive)
              (setq-local +org/clock-out-toggle-report
                          (not +org/clock-out-toggle-report)))))
#+end_src
** Org on save
If ~+org/compile-to-pdf-on-save-p~ is non-nil, then compile to
\(\LaTeX\) and run an async process to compile it to a PDF.  Doesn't
make Emacs hang (like ~org-latex-export-to-pdf~) and doesn't randomly
crash (like the async handler for org-export).  Works really well with
~pdf-view-mode~.
#+begin_src emacs-lisp
(use-package org
  :defer t
  :init
  (defvar +org/compile-to-pdf-on-save-p
    nil
    "Non-nil to activate compile functionality.")
  :general
  (local-leader
    :keymaps 'org-mode-map
    "C" (proc (interactive)
              (if (+org/compile-to-pdf-on-save-f)
                  (setq-local +org/compile-to-pdf-on-save-p nil)
                (setq-local +org/compile-to-pdf-on-save-p t))))
  :config
  (+oreo/create-auto-save
   (and (eq major-mode 'org-mode) +org/compile-to-pdf-on-save-p)
   (start-process-shell-command "" "*pdflatex*" (concat "pdflatex -shell-escape "
                                                        (org-latex-export-to-latex)))))
#+end_src
** Org ref
For bibliographic stuff in $\LaTeX$ export.
#+begin_src emacs-lisp
(use-package org-ref
  :straight t
  :defer t
  :init
  (setq bibtex-files '("~/Text/bibliography.bib")
        bibtex-completion-bibliography '("~/Text/bibliography.bib")
        bibtex-completion-additional-search-fields '(keywords)))
#+end_src
*** Org ref ivy integration
Org ref requires ivy-bibtex to work properly with ivy, so we need to
set that up as well
#+begin_src emacs-lisp
(use-package ivy-bibtex
  :straight t
  :after org-ref
  :config
  (require 'org-ref-ivy))
#+end_src
** Org message
Org message allows for the use of org mode when composing mails,
generating HTML multipart emails.  This integrates the WYSIWYG
experience with mail in Emacs while also providing powerful text
features with basically no learning curve (as long as you've already
learnt the basics of org).

#+begin_src emacs-lisp
(use-package org-msg
  :hook (message-mode-hook . org-msg-mode)
  :hook (notmuch-message-mode-hook . org-msg-mode)
  :config
  (setq org-msg-options "html-postamble:nil H:5 num:nil ^:{} toc:nil author:nil email:nil \\n:t tex:dvipng"
        org-msg-greeting-name-limit 3)

  (add-to-list 'org-msg-enforce-css
               '(img latex-fragment-inline
                     ((transform . ,(format "translateY(-1px) scale(%.3f)"
                                            (/ 1.0 (if (boundp 'preview-scale)
                                                       preview-scale 1.4))))
                      (margin . "0 -0.35em")))))
#+end_src
** Org for evil
Evil org for some nice bindings.
#+begin_src emacs-lisp
(use-package evil-org
  :hook (org-mode-hook . evil-org-mode))
#+end_src
** Org reveal
Org reveal allows one to export org files as HTML presentations via
reveal.js.  Pretty nifty and it's easy to use.
#+begin_src emacs-lisp
(use-package ox-reveal
  :defer t
  :init
  (setq org-reveal-root "https://cdn.jsdelivr.net/npm/reveal.js"
        org-reveal-theme "sky"))
#+end_src
** WAIT Org fragtog
:PROPERTIES:
:header-args:emacs-lisp: :tangle no
:END:
Toggle latex fragments in org mode so you get fancy maths symbols.  I
use latex a bit in org mode as it is the premier way of getting
mathematical symbols rendered, but org mode > latex.

Delimited environments are aplenty, escaped brackets and dollar signs
are my favourite.  Here's a snippet:
$\int_{-\infty}^{\infty}e^{-x^2}dx = \sqrt{\pi}$.

[2023-09-10 Sun] Emacs 29 complains constantly about this, probably
because this isn't implemented that well.  Regardless it wasn't that
necessary anyway, just a nice feature to have.
#+begin_src emacs-lisp
(use-package org-fragtog
  :hook (org-mode-hook . org-fragtog-mode))
#+end_src
** Org superstar
Org superstar adds unicode symbols for headers, much better than the
default asterisks.
#+begin_src emacs-lisp
(use-package org-superstar
  :hook (org-mode-hook . org-superstar-mode))
#+end_src
* Languages (loading)
For a variety of (programming) languages Emacs comes with default
modes but this configures them as well as pulls any modes Emacs
doesn't come with.  I have a [[file:lang.org][separate file]] for this
configuration as it's quite large.
#+begin_src emacs-lisp
(load-file (concat user-emacs-directory "lang.el"))
#+end_src