From: Sharon Goodall
Subject: How are Common Lisp structures allocated?
Date: 
Message-ID: <23930@mimsy.umd.edu>
Are structures typically efficiently represented in Common Lisp?

I need to create some data structures in CL for which I would like
to have the advantage of contiguous memory (i.e., efficient) found
with vectors while also having the advantages of structures: creation
of a data type for each structure, access functions, constructor 
function, etc.  Will we be losing a lot in efficiency in our
memory allocation if we choose to go with structures for these
data structures, rather than vectors?


Thanks,
  Sharon Goodall
  Dept. of Computer Science
  University of Maryland, College Park
  internet: ·······@cs.umd.edu
  uucp: uunet!mimsy!goodall
From: Barry Margolin
Subject: Re: How are Common Lisp structures allocated?
Date: 
Message-ID: <35828@think.Think.COM>
In article <·····@mimsy.umd.edu> ·······@cs.umd.edu (Sharon Goodall) writes:
>Are structures typically efficiently represented in Common Lisp?

Yes.  The reason CLtL doesn't specify the representation of structures is
to permit the implementor to choose the best representation for the
architecture.  In most Lisps these days structures are implemented as
vectors, with perhaps a few extra elements at the front to allow the
structure type to be identified.
--
Barry Margolin, Thinking Machines Corp.

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