I am new to Lisp as well, so please excuse my ignorance as I am probably missing something thats obvious to others here.
Does this mean then, that whenever we make a change to a macro definition we must also redefine every function that already depends on the original macro definition? If this is the case then I would imagine there's a lot of tricky maintenance required for a program that has lots of 'layers' when a 'base' macro is changed.
Yes. The way most Lisp hackers deal with this is to (a) define macros before functions that use them and (b) use the function load, which evaluates all the expressions in a file in order.
This breaks down on bigger projects spread across multiple source files, at which point one needs some "make" tool such as ASDF for CL where one can pile macros into earlier files and then make other files with code using those macros dependent on the macro-bearing file(s). This can make for a lot of recompilation after minor changes, so I just take my chances and (yep) recompile all when in doubt (which with today's systems goes pretty fast).
