Ah, I see this. I think I have been thinking of macros differently than you have (and probably wrongly). I suppose lexical scoping for macros would make the most difference in the case where a macro expands to a function call, like this:
(let x 0 ; call (count) to keep a count of things
(def count () (set x (+ x 1))))
; count-ops: count how many lines of code you run.
(mac count-ops body
(if body
(cons (car body)
(cons '(count)
(count-ops (cdr body))))
'())
(def foo ()
(count-ops ; this count-ops call fails
(with (count 1 step 2)
; do some loopy stuff here
)))
If that's not a compelling example, pretend that count-ops is inserting an interrupt check between every two lines of code. Why is dynamic scoping better for cases like these?
As for real arguments to macros, yes, I meant something like the CL stuff. You're right, though, that macros modify syntax, and I wasn't thinking about them that way. Two posts up you said that macros are "expanded in place". I think that you were thinking about the effect macros have on the code they're called on, whereas I was thinking about the call to the actual macro procedure, and passing arguments to it.
