Even in C, always remember the rules of Macro Club[1]:

1) You do not write macros.

2) You do not write macros that violate expectations of normal code behavior.

3) If this is your first time, you must write a macro.

4) Don't think object-oriented.

5) No shirt, No shoes, No dynamic scope.

6) Don't create new scoping rules.

[1] http://stuartsierra.com/download/2010-10-23-clojure-conj-mac...