From cph at zurich.ai.mit.edu  Fri Mar 15 14:45:01 2002
From: cph at zurich.ai.mit.edu (Chris Hanson)
Date: Sat Dec  3 00:52:12 2005
Subject: [info-cscheme] MIT Scheme 7.7.0 is released
Message-ID: <E16lxdN-0006Ca-00@nuwen.ai.mit.edu>

MIT Scheme 7.7.0 is released.  The release notes follow.  As usual,
this is available at

	http://www.swiss.ai.mit.edu/projects/scheme/mit/

* Release 7.7.0 provides "hygienic" macro support, as defined in R^4RS
  and R^5RS. This is a complete rewrite of the syntax engine, so any
  program that uses macros should be rewritten to use the new engine.
  A subset of the old macro-definition syntax is still supported, but
  this will eventually be removed. Note that the new syntax engine has
  no effect on the compiled-code format; most binaries compiled by
  release 7.6.x should continue to work.

  There are several user-visible consequences to this change:

      * These syntactic keywords have been eliminated: define-macro,
	in-package, macro, make-environment, scode-quote, unassigned?, and
	using-syntax.

      * The syntactic keyword the-environment has been restricted to use in
	top-level environments. It is no longer allowed in the body of any
	binding form (e.g. lambda, let).

      * Syntactic keywords are now stored in environments, rather than in a
	separate syntax-table structure. The environment abstraction has
	been enhanced to support this, as well as to make it more general.
	The changes are documented in the reference manual.

      * The syntax-table abstraction has been eliminated, and most
	procedures and arguments involving syntax tables have been removed.
	One exception is the load procedure, which still accepts a
	syntax-table argument, but ignores it.

* Although the 7.6.1 release had a workaround for problems with certain
  AMD Athlon processors, the workaround was ineffective on machines
  running Windows operating systems (and possibly OS/2 systems as well).
  This version fixes that problem.

* The hash-table abstraction is now always loaded. It's not necessary to
  call load-option prior to use of hash tables. For upwards
  compatibility, calling `(load-option 'hash-table)' is still permitted
  but does nothing.