(defface esk-paren-face
      '((((class color) (background dark))
         (:foreground "grey50"))
        (((class color) (background light))
         (:foreground "grey55")))
      "Face used to dim parentheses."
      :group 'starter-kit-faces)

    ;; Change lambda to an actual lambda symbol
    (mapc (lambda (major-mode)
            (font-lock-add-keywords
             major-mode
             `(("(\\(lambda\\)\\>"
                (0 (ignore
                    (compose-region (match-beginning 1)
                                    (match-end 1) ?λ))))
               ("(\\|)" . 'esk-paren-face))))
          '(emacs-lisp-mode
            inferior-emacs-lisp-mode
            lisp-mode
            inferior-lisp-mode
            slime-repl-mode))