[% setvar title unified container theory %]
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<a name='TITLE'></a><h1>TITLE</h1>
<p>unified container theory</p>
<a name='VERSION'></a><h1>VERSION</h1>
<pre>  Maintainer: David Nicol &lt;<a href='mailto:perl6rfc@davidnicol.com'>perl6rfc@davidnicol.com</a>&gt;
  Date: 28 Sep 2000
  Mailing List: <a href='mailto:perl6-language-data@perl.org'>perl6-language-data@perl.org</a>
  Number: 341
  Version: 1
  Status: Developing</pre>
<a name='ABSTRACT'></a><h1>ABSTRACT</h1>
<p>Viewing Hash and Array as instances of &quot;Container&quot; leads
to easy implementation of &quot;Sparse Array&quot; and &quot;Sorted Hash&quot;
and &quot;Real Array&quot;</p>
<a name='DESCRIPTION'></a><h1>DESCRIPTION</h1>
<p>There are two big differences between Hash and Array.</p>
<ul>
<li><a name='Hash keys are string, and Array keys are Integer'></a>Hash keys are string, and Array keys are Integer</li>
<p>Hash keys are string, and Array keys are Integer</p>
<li><a name='Array semantics include listing keys which have not been assigned to yet.'></a>Array semantics include listing keys which have not been assigned to yet.</li>
<p>Array semantics include listing keys which have not been assigned to yet.
This is really an issue for the accessing functions, not the underlying data.</p>
<li><a name='Curly braces mean look up by string, and square brackets mean look up by integer.'></a>Curly braces mean look up by string, and square brackets mean look up by integer.</li>
<p>maybe square brackets as the <code>qr</code> delimiter would be a good way to
indicate RFC197 regex semantics.  Wouldn't that make for an easy way to take
a slice from a collection of data points?</p>
</ul>
<a name='IMPLEMENTATION'></a><h1>IMPLEMENTATION</h1>
<p>With this in mind, it becomes possible to consider implementing both container
types as sorted trees, possibly transparently switching to block offset arrays
when Array is sufficiently dense.</p>
<p>The one tree framework could be used for both types of trees, by switching
the comparison function.</p>
<p>Tree search may be faster than
hash function calculation for easily compared data.</p>
<a name='REFERENCES'></a><h1>REFERENCES</h1>
<p>The above is written from memory of conversation in August on perl6-internals.</p>
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