113 lines
3.4 KiB
HTML
113 lines
3.4 KiB
HTML
<!doctype html public "-//W3C//DTD HTML 4.0 Transitional//EN" "http://www.w3.org/TR/REC-html40/loose.dtd">
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<html>
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<!-- Generated from TeX source by tex2page, v 4p4,
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(c) Dorai Sitaram, http://www.cs.rice.edu/~dorai/tex2page -->
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<head>
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<title>
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Revised^5 Report on the Algorithmic Language Scheme
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</title>
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<link rel="stylesheet" type="text/css" href="r5rs-Z-C.css" title=default>
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<meta name=robots content="noindex,follow">
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</head>
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<body>
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<div class=navigation>[Go to <span><a href="r5rs.html">first</a>, <a href="r5rs-Z-H-10.html">previous</a></span><span>, <a href="r5rs-Z-H-12.html">next</a></span> page<span>; </span><span><a href="r5rs-Z-H-2.html#%_toc_start">contents</a></span><span><span>; </span><a href="r5rs-Z-H-15.html#%_index_start">index</a></span>]</div>
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<p></p>
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<a name="%_chap_Temp_6"></a>
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<h1 class=chapter>
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<div class=chapterheading> </div><br>
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<a href="r5rs-Z-H-2.html#%_toc_%_chap_Temp_6">Notes</a></h1>
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<p>
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</p>
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<p></p>
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<p></p>
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<p>
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</p>
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<p>
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</p>
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<a name="%_sec_Temp_7"></a>
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<h3><a href="r5rs-Z-H-2.html#%_toc_%_sec_Temp_7">Language changes</a></h3>
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<p></p>
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<p>
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This section enumerates the changes that have been made to Scheme since
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the ``Revised<sup>4</sup> report'' [<a href="r5rs-Z-H-14.html#cite{R4RS}">6</a>] was published.</p>
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<p>
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</p>
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<ul>
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<p>
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</p>
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<li>
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<p>The report is now a superset of the IEEE standard for Scheme
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[<a href="r5rs-Z-H-14.html#cite{IEEEScheme}">13</a>]: implementations that conform to the report will
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also conform to the standard. This required the following changes:
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</p>
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<ul>
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<p>
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</p>
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<li>
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<p>The empty list is now required to count as true.</p>
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<p>
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</p>
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<li>
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<p>The classification of features as essential or inessential has been
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removed. There are now three classes of built-in procedures: primitive,
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library, and optional. The optional procedures are <tt>load</tt>,
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<tt>with-input-from-file</tt>, <tt>with-output-to-file</tt>,
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<tt>transcript-on</tt>, <tt>transcript-off</tt>, and
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<tt>interaction-environment</tt>,
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and <tt>-</tt> and <tt>/</tt> with more than two arguments.
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None of these are in the IEEE standard.</p>
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<p>
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</p>
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<li>
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<p>Programs are allowed to redefine built-in procedures. Doing so
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will not change the behavior of other built-in procedures.
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</p>
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</ul>
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<p></p>
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<p>
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</p>
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<li>
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<p><em>Port</em> has been added to the list of disjoint types.</p>
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<p>
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</p>
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<li>
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<p>The macro appendix has been removed. High-level macros are now part
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of the main body of the report. The rewrite rules for derived expressions
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have been replaced with macro definitions. There are no reserved identifiers.</p>
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<p>
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</p>
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<li>
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<p><tt>Syntax-rules</tt> now allows vector patterns.</p>
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<p>
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</p>
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<li>
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<p>Multiple-value returns, <tt>eval</tt>, and <tt>dynamic-wind</tt> have
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been added.</p>
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<p>
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</p>
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<li>
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<p>The calls that are required to be implemented in a properly tail-recursive
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fashion are defined explicitly.</p>
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<p>
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</p>
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<li>
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<p>`<tt>@</tt>' can be used within identifiers. `<tt><code class=verbatim>|</code></tt>' is reserved
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for possible future extensions.</p>
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<p>
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</p>
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</ul>
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<p></p>
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<p>
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</p>
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<p>
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</p>
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<p>
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</p>
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<div class=navigation>[Go to <span><a href="r5rs.html">first</a>, <a href="r5rs-Z-H-10.html">previous</a></span><span>, <a href="r5rs-Z-H-12.html">next</a></span> page<span>; </span><span><a href="r5rs-Z-H-2.html#%_toc_start">contents</a></span><span><span>; </span><a href="r5rs-Z-H-15.html#%_index_start">index</a></span>]</div>
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<p></p>
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</body>
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</html>
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