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From: larus@dill.Berkeley.EDU.berkeley.edu (James Larus)
Newsgroups: comp.lang.lisp
Subject: Re: Importance of REPLACA, REPLACD, and - (nf)
Message-ID: <19747@ucbvax.BERKELEY.EDU>
Date: Fri, 17-Jul-87 13:16:50 EDT
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Posted: Fri Jul 17 13:16:50 1987
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Reply-To: larus@paris.Berkeley.EDU(James Larus)
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Luddy Harrison (of the Center for Supercomputing Research &
Development at the Univ. of Illinois) has done some very nice work on
using vector-like structures to store lists.  The purpose of this work
is to make fast, concurrent reduction operations possible on
multiprocessors.  It has other advantages in that certain common
operations, such as APPEND, become very fast and efficient.  It's main
disadvantage is that RPLACA and RPLACD are outlawed because they screw
up the structure-sharing.  Luddy argues that a lot of cases in which
these operations were previously necessary for efficiency reasons are
not as important, i.e., NCONC is unnecessary when APPEND is almost
constant-time.

There is a paper in the 1986 Parallel Processing Conf. and a couple of
tech. reports on this work.

/Jim