;;; -*- lexical-binding: t -*-
;;
;; this file:
;;   https://dataswamp.org/~incal/emacs-init/sequence-string.el

(require 'cl-lib)

(defun seq-str (beg end &optional step delim suffix)
  (or step   (setq step 1))
  (or delim  (setq delim " "))
  (or suffix (setq suffix ""))
  (let ((str (format "%s%s" beg suffix)))
    (cl-loop for n from (+ beg step) to end by step do
      (setq str (format "%s%s%s%s" str delim n suffix)) )
    (string-trim str) ))

;; (seq-str 1 10)              ; 1 2 3 4 5 6 7 8 9 10
;; (seq-str 3 5 3)             ; 3
;; (seq-str 5 15 2)            ; 5 7 9 11 13 15
;; (seq-str 20 30 3 ", ")      ; 20, 23, 26, 29
;; (seq-str 1 15 2 " " ".pdf") ; 1.pdf 3.pdf ... 15.pdf
;; (seq-str 2 15 2 " " ".pdf") ; 2.pdf 4.pdf ... 14.pdf

(provide 'sequence-string)