R^3RS

[RKIRCHNE%carleton.edu@RELAY.CS.NET]

R^3RS is also included with the documentation for TI's PC Scheme version 3.
I just upgraded to it.  Also included as one of several sample files is
Kent Dybvig's extend-syntax, which is described in his book and included
as a standard feature in Chez Scheme v 2.  extend-syntax is incredibly
powerful for defining special forms -- all one has to do is describe
patterns.

Someone was looking for Scheme for a VAX.  I highly recommend Chez Scheme
by Kent Dybvig (dybvig@indiana.csnet, I think) distributed by Cadence
Associates (or something like that).  Academic pricing for VMS, other
versions is very reasonable.  Someone with accurate info should respond.

Someone else was looking for a Scheme compiler for a Tandy 1000.  I should
think TI's PC Scheme would work.  It is really excellent.

PC Scheme v 3.0 uses #T and #F instead of #!TRUE and #!FALSE, the same as
Chez Scheme.  That is much cleaner.

Quasiquote expressions can be nested, and UNQUOTE, UNQUOTE-SPLICING key
words have been added.

Graphics now supports EGA 640 x 350 resolution.  That is the improvement
I was looking for.  New graphics functions are GET-PEN-COLOR, GET-PEN-
POSITION, POINT-COLOR, and SET-CLIPPING-RECTANGLE.  EGA 640 x 200 is also
supported.  Also, GRAPHICS-WINDOW for creating graphics windows is
described in the release notes, but undocumented.

Transcendental functions are computed using a new feature which allows
programs compiled from C or Turbo Pascal to be called from Scheme.  An
8087 (80287) is used if present.

READ-LINE now echos to the screen when used to read from the console or
a window.

There are lots of other improvements.  There is a one change from conforming
to nonconforming with the Report. The form (DEFINE ( ... ) ...) no
longer expands to a NAMED-LAMBDA.  But this can still be forced by setting
PCS-INTEGRATE-DEFINE to ().

Roger Kirchner  rkirchne@carleton.edu.csnet