Void Function Error

Question

The following function is meant to call an arbitrary function at each of the immediate children of an org heading:

(defun org-map-shallow-tree (funcarg)
  ""
  (save-excursion
    (org-back-to-heading)    
    (let* ((cur-level (car (org-heading-components))))
      (org-map-tree (lambda () (when (equal (+ 1 cur-level) (car (org-heading-components)))
                                     (funcall 'funcarg)))))))

The problem is that when I call it, as in:

(defun lol () (message "lol"))
(org-map-shallow-tree 'lol)

I get the following error:

Debugger entered--Lisp error: (void-function funcarg)

Answer 1

You have a stray quote in your code:

(defun org-map-shallow-tree (funcarg)
  ""
  (save-excursion
    (org-back-to-heading)    
    (let* ((cur-level (car (org-heading-components))))
      (org-map-tree (lambda () (when (equal (+ 1 cur-level) (car (org-heading-components)))
                                     (funcall funcarg))))))) ; <= Don't quote funcarg

You passed a function symbol via funcarg, and you want funcall to call that function, i.e., the content of funcarg, not the funcarg symbol itself.