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

(defun mode-p (fun)
  (let*((sfx "-mode")
        (len (length sfx)) )
    (and (functionp fun)
         (string= sfx (substring (symbol-name fun) (- len))) )))

(defun set-mode (&optional fun)
  (interactive (list (completing-read
                      "mode: "
                      obarray
                      (lambda (e) (mode-p e))
                      t ; require-match
                      nil
                      nil
                      (symbol-name #'normal-mode) )))
  (if fun
      (let ((f (if (stringp fun)
                   (intern fun)
                 fun) ))
        (when (mode-p f)
          (apply (list f)) ))
    (normal-mode) ))

;; (set-mode #'kill-emacs)        ; safe as not a mode
;; (set-mode #'fundamental-mode)  ; mode function
;; (set-mode "emacs-lisp-mode")   ; mode function name
;; (set-mode)                     ; derive mode from extention/hashbang
;; M-x set-mode RET conf-mode RET ; interactive explicit
;; M-x set-mode RET RET           ; ditto derive

(provide 'set-mode)