Here, adding a 'unless' statement: (defmacro unless [expr & body] `(if ~expr nil (do ~@body))) Taken from: http://stackoverflow.com/questions/2977882/defi

Here, adding a 'unless' statement: (defmacro unless [expr & body] `(if ~expr nil (do ~@body))) Taken from: http://stackoverflow.com/questions/2977882/defining-clojure-macro-syntax http://stackoverflow.com/questions/2977882/defining-clojure-... Macro in Lisp are essentially functions taking code as argument and returning code, but they are executed at compile-time. Edit: replaced with the correct version, sorry for the error.