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Synonym streams

Is a synonym-stream a stream?  Can a stream be a synonym of a synonym-stream?

On the LMI, I tried

(defvar *describe-output* (make-synonym-stream '*standard-output*))

Because *standard-output* is by default a synonym of *terminal-io*, *describe-
output* became a synonym for a synonym.  When I tried printing to
*describe-stream*, the system hung.  It did not hang if I used *terminal-io*
in place of *standard-output*.

LMI's technical support agreed that in spirit it should work; however, CLtL
is ambiguous or at least not complete.

The problem, of course, is that if a synonym-stream is a stream but cannot
be the synonym for another stream, then there must be some function for
testing whether a stream is a synonym or a real stream. (synonym-stream-p).

Do other systems support using *standard-output* as a synonym?

Don Mitchell	  		Don@atc.bendix.com
Bendix Aero. Tech. Ctr.		Don%atc.bendix.com@relay.cs.net
9140 Old Annapolis Rd.		(301)964-4156
Columbia, MD 21045