Prettify my Emacs symbols

Emacs Redux made me aware of a new nifty feature of Emacs 24.4 (the upcoming release; I am currently using one of the nightlies). Emacs 24.4 includes a new mode called prettify-symbols-mode, which replaces tokens within code with more compact symbols (typically unicode characters like λ).

I am using the mode to replace the “function” token in JavaScript — which is used all over the place, since it is the syntax to create functions, modules and closures — with the single character λ. This results in significantly more lightweight expressions:

    
initialize: λ() {
    this.listenTo(this, "planet:drag planet:dragvelocity", 
        λ() { this.elements(true); });
}

The mode is smart enough to only replace tokens (it doesn’t replace function within a string, e.g., var a = "This is a function"; will appear unmodified). To activate the mode, use (global-prettify-symbols-mode 1) in one of your init files, and add new symbols to the mode hooks:

(add-hook 'js2-mode-hook
            (lambda ()
              (push '("function" . ?λ) prettify-symbols-alist)))

Ever been annoyed with the Emacs bell? Aside from disabling it, you can make it slightly less annoying by using a visual error indicator in place of an audible bell. There’s a Visible Bell setting included by default, but I find it quite aesthetically displeasing (at least on my nightly Mac build). I like this snipped a lot better (from EmacsWiki):

 (defun my-terminal-visible-bell ()
   "A friendlier visual bell effect."
   (invert-face 'mode-line)
   (run-with-timer 0.1 nil 'invert-face 'mode-line))
 
 (setq visible-bell nil
       ring-bell-function 'my-terminal-visible-bell)

This snippet will flash your mode line instead.

One thought on “Prettify my Emacs symbols”

Leave a Reply

Your email address will not be published.

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong>