Command to list all programming major modes know to an Emacs instance

list-prog-modes.el

(defun list-prog-modes ()
  "List all programming modes known to this Emacs."
  (interactive)
  (with-help-window "*Programming Major Modes*"
    (mapatoms (lambda (f)
                (when (provided-mode-derived-p f 'prog-mode)
                  (princ f)
                  (princ "\n"))))))

Running the above in my current instance of Emacs gets this:

slime-xref-mode
prog-mode
rust-mode
idl-mode
web-mode
java-mode
c-mode
makefile-automake-mode
makefile-makepp-mode
pike-mode
python-mode
makefile-gmake-mode
awk-mode
hy-mode
js-mode
lisp-interaction-mode
scss-mode
js2-jsx-mode
powershell-mode
makefile-imake-mode
makefile-mode
elisp-byte-code-mode
css-mode
js2-mode
lisp-mode
c++-mode
emacs-lisp-mode
objc-mode
js-jsx-mode
makefile-bsdmake-mode