Comparison of Python and Go programming.

gistfile1.go

package main

import (
	"path/filepath"
	"io/ioutil"
	"regexp"
	"fmt"
	"strings"
)

/*
 * def retrieveLatestDateSuffix(target):
 *     return max(map("".join, filter(lambda x: x, 
 *         map(lambda x: re.findall(r"_([0-9]{8})\.txt$", x), 
 *             os.listdir(target)))))
 */

var rldsPat = regexp.MustCompile(`_([0-9]{8})\.txt$`)
func retrieveLatestDateSuffix(target string) (string, error) {
	if fis, e := ioutil.ReadDir(target); e == nil {
		t := ""
		for _, fi := range fis {
			if m := rldsPat.FindStringSubmatch(fi.Name()); m != nil {
				if m[1] > t { t = m[1] }
			}
		}
		return t, nil
	} else {
		return "", e
	}
}

/*
 * def addDateSuffix(target, suffix):
 *     for fn in filter(lambda x: re.search(r"(?<!_[0-9]{8})\.txt$", x), os.listdir(target)):
 *         pref, ext = os.path.splitext(fn)
 *         gn = "{0}_{1}{2}".format(pref, suffix, ext)
 *         print(fn, " -> ", gn)
 */

var adsPat1 = regexp.MustCompile(`\.txt$`)
var adsPat2 = regexp.MustCompile(`_[0-9]{8}\.txt$`)
func addDateSuffix(target string, suffix string) error {
	if fis, e := ioutil.ReadDir(target); e == nil {
		for _, fi := range fis {
			if m1 := adsPat1.FindStringSubmatch(fi.Name()); m1 != nil {
				if m2 := adsPat2.FindStringSubmatch(fi.Name()); m2 == nil {
					ext := filepath.Ext(fi.Name())
					gn := fmt.Sprintf("%s_%s%s", strings.TrimSuffix(fi.Name(), ext), suffix, ext)
					fmt.Println(fi.Name(), "->", gn)
				}
			}
		}
		return nil
	} else {
		return e
	}
}

func main() {
	target := "."
	latest, _ := retrieveLatestDateSuffix(target)
	addDateSuffix(target, latest)

}