xah talk show 2022-08-08 programing language design, walk directory, in python, golang, PowerShell, emacs lisp, WolframLang

• ease and intuitiveness ranking: PowerShell, WolframLang, emacs lisp, python, golang. demo it.
• both python and golang had to change their walk dir function to improve speed.
• emacs lisp and WolframLang, are very different from the industrial langs such as python golang. math langs focus on function aspects, input, output. Static. e.g. sin(x). The non-math langs adds a time concept. This is also the different between math and algorithm. What is, vs how to.

• PowerShell: List Files
• Elisp: Walk Directory, List File Names
• WolframLang: List Files (Walk Directory)
• Python 2: Walk Directory, List Files
• Python 3: Walk Directory, List Files
• Golang: Walk Directory, List Files

(directory-files-recursively
  "c:/Users/xah/web/xahlee_info/emacs/"
  "\.ts$\\|\.js$")

FileNames[ {"*ts", "*js"}, "c:/Users/xah/web/xahlee_info/emacs/", Infinity ]

import os
import re

input_path = "c:/Users/xah/web/xahlee_info/emacs/"

for dir_path, subdir_list, file_list in os.walk(input_path):
    for fname in file_list:
     if (re.search(r"\.ts$|\.js$", fname, re.U)):
       print(dir_path + fname)

package main

import (
	"fmt"
	"io/fs"
	"path/filepath"
	"regexp"
)

var xDir = "c:/Users/xah/web/xahlee_info/emacs/"

func main() {

	var doF = func(xpath string, xinfo fs.DirEntry, xerr error) error {

		// first thing to do, check error. and decide what to do about it
		if xerr != nil {
			fmt.Printf("error [%v] at a path [%q]\n", xerr, xpath)
			return xerr
		}

		var x, err = regexp.MatchString(`\.ts$|\.js$`, xpath)
		if err != nil {
			panic(err)
		}

		if x {
			fmt.Printf("%v\n", xpath)
		}

		return nil
	}

	err := filepath.WalkDir(xDir, doF)

	if err != nil {
		fmt.Printf("error walking the path %q: %v\n", xDir, err)
	}
}