Re: Historical clarification on &PROTECT

[Kent M. Pitman <KMP at MIT-MC>]

    Date: 11 November 1980 12:06-EST
    From: Jon L White <JONL>

    .. I might mention as RMS did that some "cleaner" version of DEFSUBST is
    what many users (you included) have apparently wanted, but been lacking.
    The Berkeley crowd diddled their macro definer to get some minimal 
    capability (was it "&SAFE"?), and we've had DEFSIMPLEMAC for some time...
-----
Actually, it was &PROTECT. It's in their DEFMACRO compatibility package I think
-- not a primitive part of Franz Lisp. Doesn't show up in the manual, anyway.
JKF's mail to MACSYMA-I on the subject follows for those interested in what it
did...
-----
    Date: 17 Jul 1980 14:04:06-PDT
    From: CSVAX.jkf at Berkeley
    To:   macsyma-i@mit-mc
    Re:   special defmacro

    We are converting many small functions to macros and have run into the
    problems of a macro argument being evaluated twice.  In the case of
    atoms, this does not matter, but of course is does for function calls.
    I added a special clause to our defmacro, called &protect, which 
    checks at macro expansion time if certain macro formal variables
    are bound to lists, in which case it surrounds the macro with a lambda
    expression.  I recall you doing something like this a while ago
    and I would like to see what your syntax for this is.
    An example is:
    (defmacro EVEN (&protect (A) A) `(AND (FIXP ,A) (NOT (ODDP ,A))))
-----
I presume this means that 
  (EVEN X)  =>  (AND (FIXP X) (NOT (ODDP X)))
while
  (EVEN (F)) => ((LAMBDA (G0001) (AND (FIXP G0001) (NOT (ODDP G0001)))) (F))
-kmp