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<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML//EN">
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<title>Lisp Series Package</title>
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<body>
<h1>What's New?</h1>
<dl>
<!-- one of (dd dt) -->
<dt><a href="series-19990702.tar.gz">1999-07-02</a></dt>
<dd>Some fixes from Pekka Pirinen for initializing variables and
a genuine bug in add-physical-out-interface. The package stuff
has been split out to it's own file too.
<dt><a href="series-19990415.tar.gz">1999-04-15</a></dt>
<dd>Some fixes from Arther Lemmens. make-sequence was being
called with invalid sequences. Some tests were also added to
catch for these errors. Some small changes for CLISP were also
made. See the RCS logs for more details.
</dd>
<dt>1998-06-10</dt>
<dd>Fixed a long-standing bug in scan-range: the initial values
of the loop variables were almost always initialized with
fixnums despite what :type might say. This is wrong if :type is
specified such that fixnum is not a valid subtype. This change
is a bit of a hack, but it appears to work with all systems I've
tried.</dd>
<dt>1998-06-04</dt>
<dd>Fixed some serious errors in the tests when I renamed a
macro from T (ACL complains about this) to TO. There already
was a macro named TO. Changed to TON.</dd>
</dl>
<h1>Lisp Series Package</h1>
This is my modified version of Richard Water's series package.
For more information about this package, refer to Appendix A in <a
href="http://www.cs.cmu.edu/afs/cs.cmu.edu/project/ai-repository/ai/html/cltl/cltl2.html">Common
Lisp the Language, 2nd Edition</a>. This package is also
described in two reports available. Search for the reports <cite>AI Memo
1082</cite> and <cite>AI Memo 1083</cite> on
<a
href="http://www.ai.mit.edu/publications/pubsDB/pubs-index.html">MIT AI Lab: Publications Database Search Results</a>
<p>
The introduction says
<blockquote>
Series combine aspects of sequences, streams, and loops. Like
sequences, series represent totally ordered multi-sets. In
addition, the series functions have the same flavor as the
sequence functions-namely, they operate on whole series, rather
than extracting elements to be processed by other functions. For
instance, the series expression below computes the sum of the
positive elements in a list.
<pre>
(collect-sum (choose-if #'plusp (scan '(1 -2 3 -4)))) => 4</pre>
<p>
Like streams, series can represent unbounded sets of elements
and are supported by lazy evaluation: each element of a series
is not computed until it is needed. For instance, the series
expression below returns a list of the first five even natural
numbers and their sum. The call on scan-range returns a series
of all the even natural numbers. However, since no elements
beyond the first five are ever used, no elements beyond the
first five are ever computed.
</p>
<pre>
(let ((x (subseries (scan-range :from 0 :by 2) 0 5)))
(values (collect x) (collect-sum x)))
=> (0 2 4 6 8) and 20
</pre>
<p>
Like sequences and unlike streams, a series is not altered when
its elements are accessed. For instance, both users of x above
receive the same elements.
</p>
</blockquote>
This differs from the original version. The following changes
were made:
<ul>
<li>Type declarations are generated better now, so that the
compiler can optimize the resulting series expression
better.</li>
<li>Some clean up of the code to fix a few bugs and enhance
portability. In particular, the following systems are known to
work:
<ul>
<li>CMU Common Lisp</li>
<li>Allegro Common Lisp</li>
<li>Harlequin LispWorks</li>
</ul>
</li>
</ul>
<p> To install, just untar it somewhere, compile
<code>s-package.lisp</code> and <code>s-code.lisp</code> and load
them in that order. Then run <code>(series::install)</code> to
install in the current Lisp package. Compile and load
<code>s-tests.lisp</code> and then run <code>(do-tests)</code> to
run the tests.</p>
<p>Alternatively, if you have Mark Kantrowitz's defsystem, you can
use the supplied defsystem files to compile and load the two
pieces. Be sure to change the paths in the defsystem files to
match your installation. </p>
<p>You should not get many errors. Here are the results from
different implementations:</p>
<dl>
<dt>CMUCL (post 18b)</dt>
<dd>8 out of 552 total tests failed: 294, 319, 381, 382, 383,
427, 428, 429. These failures appear to be bugs in the
byte-code interpreter, which is known to be much buggier than
the compiler.</dd>
<dt>CLISP</dt>
<dd>No tests failed, in ANSI mode (clisp -a). Otherwise tests
200, 201, and 203 fail.</dd>
<dt>ACL 5.0 (Linux)</dt>
<dd></dd>
<dt>Harlequin Lispworks (Windows Personal Edition 4.1)</dt>
<dd>No tests failed!</dd>
</dl>
<p>Hope you find this useful.</p>
<hr>
<address><a href="mailto:toy@rtp.ericsson.se">Raymond Toy</a></address>
<!-- Created: Mon Jun 1 12:31:07 EDT 1998 -->
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Last modified: Fri Jul 2 16:49:45 EDT 1999
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