Emacs 24.4 ships with a new minor mode called prettify-symbols-mode . Its purpose is to replace the standard text representation of various identifiers/symbols with a (arguably) more aesthetically pleasing representation (often a single unicode character would replace several ascii characters).

A classic example would be lambda from various Lisp dialects that many people prefer to replace with the greek letter λ (small lambda). prettify-symbols-mode allows you to achieve this by relying on a simple mapping expressed in the form of an alist that each major mode must initialize ( prettify-symbols-alist ). Simply put - major modes have to provide the configuration for prettify-symbols-mode .

Lisp modes do this via lisp--prettify-symbols-alist :

( defconst lisp--prettify-symbols-alist ' (( "lambda" . ? λ )))

This means that out of the box only lambda will get replaced. You can, of course, add more mappings for different major modes:

( add-hook 'emacs-lisp-mode-hook ( lambda () ( push ' ( ">=" . ? ≥ ) prettify-symbols-alist )))

Let’s see the mode in action. Consider this bit of Emacs Lisp code:

( lambda ( x y ) ( if ( >= x y ) ( something ) ( something-else )))

After you do M-x prettify-symbols-mode you’ll end up with:

( λ ( x y ) ( if ( ≥ x y ) ( something ) ( something-else )))

To enable this for a particular mode use (add-hook 'some-mode-hook 'prettify-symbols-mode) . If you’d like to enable it globally just add the following to your config:

( global-prettify-symbols-mode +1 )