Lazy-loading Org-babel

Typically, Babel's languages are loaded all at once during initialisation. Example: 

  (org-babel-do-load-languages
   'org-babel-load-languages
   ;; Enable R
   '((R . t)
     ;; Disable Elisp
     (emacs-lisp . nil)))

Doom's lazy-loading incrementally adds to the org-babel-load-languages variable as demanded.

Notes on Doom's code

digraph {
  "+org-init-babel-lazy-loader-h"
}

+org-init-babel-lazy-loader-h

Ran as a hook after org.el is loaded via org-load-hook (it's probably best to use with-eval-after-load).

When called, several procedures are defined, most being injected into Babel via advice-add:

+org--babel-lazy-load

(+org--babel-lazy-load LANG &optional ASYNC)

If LANG is not loaded (i.e. not present and enabled in org-babel-load-languages), try

  1. Running each of +org-babel-load-functions.

  2. Importing ob-LANG.

  3. Importing LANG.

When any attempt succeeds, run with the result and mark the language as enabled in org-babel-load-languages.

If ASYNC is non-nil, load ob-async.