Emacs - “Editor MACroS”

3.1.1. From the EmacsWiki:

3.2.1. “Editor”

1. Emacs does much more than edit text
   

   • To show itself off, Emacs by default comes with a full game of tetris!

     (tetris)
     

     • Besides being a great tool to play tetris when you’re bored and your boss is looking away, Emacs can also:
       1. Write emails with the `mu4e` package
       2. Write documents with Org Mode (more on this later)
       3. Be your window manager with the exwm package
          • I’ve given this a try, but I’m gonna stick with dwm

       4. Browse the internet with eww!

          • Eww in action

          (eww "https://gnu.org")
          

3.2.2. Emacs Glossary

1. Weird key-binding notation?
   
   • “C” is control
   • “M” is alt/meta
   • “S” is shift

   When there is a “-” between two keys that means press them together.

   “C-x C-f”: Control and x and then control and f (you can also hold down control)

2. What is a “buffer”?
   

   Buffers hold a file’s text. In the example before with Tetris, `(tetris)` creates a Tetris buffer.

   You can think of buffers as “tabs” in a browser or GUI text editor

3. What is a “window”?
   

   A window hosts a buffer. When you make a split, each side is a “window”

   Cycle between windows with “C-x C-o”

   Close a window with “C-x 0”

4. What is a “frame”?
   

   A frame hosts a complete instance Emacs. They are equivalent to “windows” in a window manager. It’s common to only really ever use one.

5. Good-to-know keybindings
   
   1. Quit emacs with “C-x C-c”
   2. Open a file with “C-x C-f”
   3. Save a file with “C-x C-s”
   4. Accidentally pressed a different command and you have no idea what you’re looking at? “C-g” will probably get you out of it.
   5. “C-x u” to undo
   6. “C-space” to select a region and “C-g” to stop selecting it
   7. With a region selected, cut it with “C-w” (this is also known as “killing”)
   8. Paste with “C-y” (this is also known as “yanking”)
   9. Window/buffer keybindings:
      • “C-x C-b” changes the buffer in the current window
      • “C-x 2” splits a buffer vertically
      • “C-x 3” splits a buffer horizontally
      • “C-x o” changes the current window
      • “C-x 0” kills the current window
      • “C-x k” kills the current buffer
   10. Movement keys
       • “C-n” goes to the next line
         • Vim: “j”
       • “C-p” goes to the previous line
         • Vim: “k”
       • “C-f” goes to the next character
         • Vim: “l”
       • “C-b” goes to the previous character
         • Vim: “h”
       • “M-f” and “M-b” goes forward/back a word
         • Vim: “f” and “b”
       • “C-a” goes to beginning of a line
         • Vim: “0”
       • “C-e” goes to the end of a line
         • Vim: “$”
   11. Documentation
       • “C-h a” to find the keybindings for a command, or to search for a command
       • “C-h k” to find the name of a function tied to a keybinding

3.3.1. Lisp’s simple syntax

1. Sum of numbers
   
   1. The list way
      

      (+ . (2 . (2 . nil))) ;; 2 + 2
      

   2. The S-expression way
      

      (+ 2 2)
      

2. Difference of numbers
   

   (- 3 2) ;; 3 - 2
   

3. Printing values
   

   `princ` will take the value of a lisp object at print it:

   (princ "Hello, world!")
   

4. Multiplication
   

   (* 3 5) ;; 3 * 5
   

5. Division
   

   (Integer math)

   (princ (/ 3 5)) ;; 3 / 5
   

   (Floating-point math)

   (princ (/ 3.0 5)) ;; 3 / 5
   

6. Order of operations
   

   (setq a (/ (* 2 3) (- 6 1)))     ;; variable a = (2 * 3) / (6 - 1) = 1
   (setq b (- (* 2 (/ 3.0 6.0)) 1)) ;; variable b = (2 * (3 / 6)) - 1 = 0
   (princ (list a b)) ;; Print a linked list a -> b -> nil
   

3.3.2. Writing a simple function in Elisp

(split-window-right)
(split-window-below)

1. Definining a function to go back a window
   

   Functions in Elisp are made with the `defun` macro (macros are for a different presentation) and the syntax is:

   `(defun function-name (list-of-args) function-body)`

   The last element in the function body is what is returned

   For example, to make a function to find the hypotenuse of a right triangle with lengths a,b:

   (defun pythagoras (a b)
     (setq a-squared (* a a))
     (setq b-squared (* b b))
     (sqrt (+ a-squared b-squared)))
   (princ (pythagoras 5 12))
   

   Defining the function

   (defun go-back-window ()
     (interactive) ;; makes a function an interactively-callable command (e.g. allowing call by a keybinding)
     (other-window -1)) ;; (other-window n) goes n windows forward in the window stack
   

   (go-back-window)
   

   Let’s add a key binding for this!

   (global-set-key (kbd "C-c u") 'go-back-window) ;; We specify the name of the function by turning it into a "symbol"
   

4.1.1. “Your life, in plain text”

4.1.2. Programming in org mode

(princ "I run in a source block!")

4.1.3. Math homework in org mode

1. Inline org mode math
   
   1. A function f
      

      S = {students at USU} M = {members of FSLC} B = {cool, uncool}

      f : S → B ∋ f(x) = { cool (x ∈ M), uncool }

   2. Definition of a proper subset
      

      Let A,B be sets: A ⊂ B ⇔ ∀ x (x ∈ A ⇒ x ∈ B) ∧ A ≠ B

   3. Let’s make it pretty!
      

      Right now, it doesn’t look pretty, but watch this:

      (org-toggle-pretty-entities)
      

2. Exporting to LaTeX
   

   There’s still a lot more flexibility in completely exporting an org mode document to a LaTeX pdf. You can define equations, include diagrams, captions, etc. It’s super simple too! Just use the command `C-c C-e l o` (you need latex packages installed)

4.1.4. Export to literally any format

4.2.1. MELPA

4.2.2. SLIME

4.2.3. Magit

4.2.4. Company-mode

4.2.5. Undo-tree

4.2.6. LSP-mode