/prog/ challenge

Write a macro that, given a term of code, transforms all the calls to the function FOO in that term, and only those calls, into calls to function BAR with the same arguments.
Language: Common Lisp or Scheme.

>>44
Furthermore, you cock sucking faggot, unevaluated lisp with no expanded macros may consist of forms outside the lisp spec. Lisp macros allow you to define entirely different languages and a macro that attempts to locate all function calls will not be able to do the traversal without being extended for each macro written. Thus the only way the macro can work as intended is to expand the inner macros, thereby translating all nested DSLs to lisp, and then performing the code transformation on code containing nothing other than lisp forms defined in the spec.