Quickly summing up the whole stack in Emacs Calc

February 2, 2025

Here is a nice little improvement to calc-mode that adds up all the numbers on the stack. It’s equivalent to hitting the + key until the stack is exhausted, and it’s more handy than I would have expected.

(defun my/calc-sum-stack ()
  (interactive)
  (when-let* ((stack calc-stack)
              (additions (- (length stack) 2))
              (_ (> additions 0)))
    (dotimes (i additions) (call-interactively 'calc-plus))))

I’ve bound it to Ctrl + like this:

(define-key calc-mode-map (kbd "C-+") #'my/calc-sum-stack)