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- Subject: Re: Macros
- From: Bernard S. Greenberg <Greenberg at MIT-Multics>
- Date: Tue ,25 Nov 80 13:18:00 EDT
I have been following this over CRD's shoulder (quite literally,
and to his consternation). Having had exactly this debate
with Friedman while at the Lisp conference, I have some idea
what is going on here..
It is possible to implement "reduction languages" via meta-rules
of the form "see if this thing is reducible, if so reduce it,
and keep doing this until its not". These things are really
interesting. I have a toy implementation (dating from 1973
when I heard Backus lecture on the subject) in MacLisp on
Multics, if anybody cares, of Backus' "RED1".
I \believe/ this is the kind of thing that Friedman is hinting at:
Lisp macro processing is exactly this kind of language. From
my viewpoint, attempting to implement such a hack via
Lisp macros is "cute", but kind of like Johnson's old saw
about teaching bears to dance; If I did such a thing, I might
show, say, ALAN, but not publicize it or let anyone else
know I had done it. It is clearly WRONG, a gross misuse of
Lisp macros and their features, and in terms of showing
the power of anything, something that better not be shown.