Question

I’ve got this snippet of code:

(define-key lisp-interaction-mode-map (kbd "C-c C-e")
  (lambda ()
    (let ((result (eval (read (buffer-substring 
                               (point-at-bol) (point-at-eol)))))
          (goto-char (point-at-eol))))
    (insert (format " ; => %s" result))))

but it doesn’t work, as in

Wrong type argument: commandp, (lambda nil (let ((result (eval (read (buffer-substring (point-at-bol) (point-at-eol))))) (goto-char (point-at-eol)))) (insert (format " ; => %s" result)))

Answer 1

This command shouldn’t function on a per-line basis. Move point by sexp instead.

Here is a library I made that does basically this, but works with mult-line
results, and is reentrant. So you can change some stuff, and re-run the
command to update results.

EDIT: correct link to package mentioned.