macro barriers are a hack to say "this form does its own macroexpansion
internally" so that we can have state-smart macros that expand to
different values depending on if they are being used in code or in a
function definition. This seems like a real bad design choice but I
can't think of a better one right now!
(not quite true: the better design choice is to allow forms to return
opgens, and then define a :bytes form that returns the address of the
generated thing. :bytes could be understood by :buffer directly.
But that's... complicated.)
Jeremy Penner