spacemacs/layers/+lang/extra-langs/packages.el

(setq extra-langs-packages
  '(
    arduino-mode
    julia-mode
    matlab-mode
    qml-mode
    scad-mode
    stan-mode
    wolfram-mode
    ))

(defun extra-langs/init-arduino-mode ()
  (use-package arduino-mode :defer t))

(defun extra-langs/init-scad-mode ()
  (use-package scad-mode :defer t))

(defun extra-langs/init-qml-mode ()
  (use-package qml-mode :defer t :mode "\\.qml\\'"))

(defun extra-langs/init-julia-mode ()
  (use-package julia-mode :defer t))

(defun extra-langs/init-matlab-mode ()
  (use-package matlab-mode :defer t))

(defun extra-langs/init-stan-mode ()
  (use-package stan-mode :defer t))

;; no associated extension because conflicts with more common Objective-C, manually invoke for .m files.
(defun extra-langs/init-wolfram-mode ()
  (use-package wolfram-mode
    :defer t
    :interpreter "\\(Wolfram\\|Mathematica\\)Script\\( -script\\)?"))