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From: jones%cs.uiowa.edu@RELAY.CS.NET (Douglas Jones)
Newsgroups: comp.unix.questions
Subject: What became of QED
Message-ID: <10512@brl-adm.ARPA>
Date: Tue, 24-Nov-87 01:35:56 EST
Article-I.D.: brl-adm.10512
Posted: Tue Nov 24 01:35:56 1987
Date-Received: Fri, 27-Nov-87 00:27:24 EST
Sender: news@brl-adm.ARPA
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As a long-time UNIX user who has used many of the predecessor systems on
which (or should I say from which) UNIX developed, I have noticed that
the ED editor (and descendants such as EX and brothers such as SED) have
not got the general regular expression facility of some of their predecessors.

In Ritchie and Thompson's version of QED, one could name a regular expression

  e(name)/expression/

and then use it in other expressions such as /regular \E(name)/ which would
match the string "regular expression".  I've recently written a grinder
for Pascal programs in LaTeX documents, and this would have made things easier
(the grinder is written in SED).

By way of history, QED was originally written by Deutsch and Lampson back
on the Berkeley Timesharing System (they published a CACM paper on it in
Dec. 1967).  Ken Thompson did a version of QED on MULTICS, (the tech report
came out before the Deutsch and Lampson's paper), and Ritchie and Thompson
did a version on the Murray Hill GCOS Timesharing System in 1970.  ED on UNIX
is a scaled back version of the GCOS QED editor, while SED puts back some of
the QED features that ED dropped, but abandons the possibility of interactive
use.  I've used QED on the Berkeley system in 1968, and on the Murray Hill
GCOS system in 1974.

Does anyone know why Ritchie and Thompson dropped the features they did when
they made QED into ED on UNIX?  If the reason was memory capacity, now that
most UNIX systems have capacity, why hasn't anyone put these features back
into text processing tools such as SED?

			Douglas W. Jones
			jones@cs.uiowa.edu (csnet)