It could theoretically be a graph. For example I can make a circular list being a part of the source and the macro may process it. Get the first two items fro

It could theoretically be a graph. For example I can make a circular list being a part of the source and the macro may process it. Get the first two items from a list and add them: CL-USER 21 > (defmacro add-2 (a) (list '+ (first a) (second a))) ADD-2 Now we construct a circular list and use the macro: CL-USER 22 > (add-2 #1=(1 2 3 . #1#)) 3 The circular list is really a part of the source code: CL-USER 23 > '(add-2 #1=(1 2 3 . #1#)) (ADD-2 #1=(1 2 3 . #1#)) Another example: One could pass in a string and have the macro parse the string...