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Regexp notation

To: scsh@martigny.ai.mit.edu
Subject: Regexp notation
From: Alan Bawden <Alan@lcs.mit.edu>
Date: Thu, 9 Jan 1997 14:37:57 -0500
Sender: Alan@lcs.mit.edu
   Date: 09 Jan 1997 06:27:15 -0800
   From: Sean Doran <smd@cesium.clock.org>

   Alan@lcs.mit.EDU (Alan Bawden) writes:

   >    Date: 08 Jan 1997 12:55:30 -0500
   >    From: Olin Shivers <shivers@ai.mit.edu>
   >        (* <regex> ...)             0 or more matches
   > 
   > I, too, am puzzled by the "..." here (and in several of the others).

   I see this as consistent with the usual re-using tools in
   4.4BSD and other systems.  Egrep -e pattern1 -e pattern2 -e pattern3 
   in those systems will match on any of the patterns.

   Having (* <regex1> <regex2> <regex3>) match 0 or more
   matches of any of regex1, regex2 or regex3 seems natural
   to me.  Moreover, it is an obviously handy short-cut over
   something like (or (* <regex1>) (* <regex2>) (* <regex3>))
   when it comes to things like named regular expressions and
   the like....

We've seen three proposed meanings for (* <regex1> <regex2> <regex3>) so
far:

  (| (* <regex1>) (* <regex2>) (* <regex3>))
  (* (| <regex1> <regex2> <regex3>))
  (* (& <regex1> <regex2> <regex3>))

Until somebody presents a compelling reason to prefer one interpretation
over all the other possible interpretations, `*' should remain a unary
operation.

Olin, what did you have in mind?

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