Re: lisp v. scheme macros

[Michael Vanier <mvanier@bbb.caltech.edu>]

> Date: Thu, 28 Jun 2001 11:47:14 -0400 (EDT)
> From: Shriram Krishnamurthi <sk@cs.brown.edu>
> 
> David,
> 
> Scheme has for long had the most sophisticated macro system of any
> language.  Norvig's book is technically correct, but the hidden
> subtext is that this is the usual (unfortunate) sniping that goes on
> between the Lisp and Scheme communities.  The latest Scheme standard
> (R5RS) finally rectified this standardization problem by adding a
> formal macro system to the document, but historically, Scheme systems
> have offered slightly differing versions of the same macro system
> ("different" sometimes meaning "much more powerful" for nearly two
> decades now).  And indeed, many of the most important research on
> macro systems has come from the Scheme community.
> 

As far as I know, virtually all scheme implementations support lisp style
macros (with some minor name changes e.g. defmacro -> define-macro), but
the only scheme implementation I know of that supports full hygienic R5RS
scheme macros is Chez Scheme.  Mzscheme has nearly full support as an
add-on library, and I believe a similar situation exists in Guile.  I don't
think MIT scheme has R5RS macros at all.  This leads me to wonder if there
is some major difficulty involved in their implementation, or else if
people simply don't need hygienic macros for anything they can't do with
traditional (non-hygienic macros).  Any thoughts on this from our local
macro wizards?

Mike