Xah Talk Show 2025-03-28 Ep636 emacs lisp, change bracket type, design of function arguments

change brackets

• Emacs: Change Brackets 📜

links

• Emacs: Xah Fly Keys 📦

• Elisp: Interactive Form
• Elisp: Get User Input

• Emacs: Cycle Hyphen Lowline Space 📜
• Emacs: Open File Path Under Cursor 📜

• Linux: Manage Processes, ps, kill
• Practical git Tutorial
• Emacs: magit-mode for git
• Emacs: Version Control Commands (git)
• Richard Stallman: What's magit? (2014-09)

examples of define function

const xadd = ((x,y) => x+y);
console.log( xadd(3,4) )

def xadd(x, y):
	"""add 2 nums"""
	return x + y
print( xadd(3, 4))
# 7

;; define a function

(defun xadd (x y)
  "add 2 numbers"
  (+ x y))

;; call the function
(xadd 3 4)
;; 7

;; HHHH------------------------------

;; now in emacs lisp,
;; any function can be trivially turn into a command,
;; and user can call it by Meta-x (normally Alt+x)

;; you can do this by adding
;; (interactive)
;; right after the docstring

(defun xadd3and4 ()
  "add 2 numbers"
  (interactive)
  (insert (number-to-string (+ 3 4))))

;; HHHH------------------------------

;; there is a question, how do you pass the function argument
 ;; when you call it interactively

;; there are many ways
;; the simplest and naive way, is to simply promp user,
;; and put the args inside list inside interactive

(defun xadd (x y)
  "add 2 numbers"
  (interactive (list 3 4))
  (insert (number-to-string (+ x y))))

;; here's is how to ask user for arguments

(defun xadd (x y)
  "add 2 numbers"
  (interactive (list
                (read-number "enter first number:")
                (read-number "enter second number:")))
  (insert (number-to-string (+ x y))))

;; 10

;; fantastic

design of the semantics of function's aruments

• one thing of concern, is
• the design of the semantics of function's aruments
• this applies to any language, python perl ruby js fsharp clojure haskell java PowerShell Wolfram language etc

• this is a very broad topic
• you need to learn and think about.

• Microsoft PowerShell function argument design guide
• https://learn.microsoft.com/en-us/powershell/module/microsoft.powershell.core/about/about_functions_advanced_parameters

design of the syntax of function's aruments

• the other thing, is the
• the design of the syntax of function's aruments
• this aspect, is usually just part of the programing language syntax
• you no need to worry about much

example of unix fuckup

here are illustrations of the complete unix fuckup in both the function argument semantics and syntax

ps auwwx
ps -ef
ls -al