If you are arguing defmacro vs. syntax-rules you are indeed correct. The lowest common denominator of the scheme macro world is indeed a pattern substitution on

If you are arguing defmacro vs. syntax-rules you are indeed correct. The lowest common denominator of the scheme macro world is indeed a pattern substitution one (with hygiene). No procedure application at expansion time allowed. However, all schemes include a lower level macro system that allows you to break hygiene when you want to, most of them by asking explicitly (explicit renaming macro systems being an exception). r6rs, a standard that was disliked by some, standardises a lower level macro system called syntax-case that superficially looks the same as syntax-rules but gives you all the power of unhygienic macro systems (in guile for example, the old unhygienic defmacro is implemented using syntax-case. A very trivial thing to do, I might add). So, to re-hash: syntax-case macros are procedural. They allow for the full power of scheme at expansion time, and allows you to introduce bindings unhygienically using datum->syntax.