Emacs 24.4 has a nice
prettify-symbols-mode. In lisp code, it displays
lambda as “λ”.
prettify-symbols-mode to activate it.
Open a emacs lisp file. (For example, call
describe-function 【F1 f】 then type
byte-compile, then click to source file.) Then, search for “lambda”. Then, call
prettify-symbols-mode to watch it change.
Note that it only DISPLAYS the function named “lambda” as λ, it doesn't really change the string.
To set it globally, put the following in your emacs init:
;; display “lambda” as “λ” (global-prettify-symbols-mode 1)
If you don't have emacs 24.4 yet, see: Web Browser Bundled in Emacs 24.4, and How to Build Emacs from git Repository.