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<!doctype html public "-//W3C//DTD HTML 4.0 Transitional//EN" "http://www.w3.org/TR/REC-html40/loose.dtd"><html><!-- Generated from TeX source by tex2page, v 4o4, (c) Dorai Sitaram, http://www.cs.rice.edu/~dorai/tex2page --><head><title>Revised^5 Report on the Algorithmic Language Scheme</title><link rel="stylesheet" type="text/css" href="r5rs-Z-C.css" title=default><meta name=robots content="noindex,follow"></head><body><p><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><p><a name="%_chap_Temp_6"></a><h1 class=chapter><div class=chapterheading> </div><p><a href="r5rs-Z-H-2.html#%_toc_%_chap_Temp_6">Notes</a></h1><p><p><p><p><p><a name="%_sec_Temp_7"></a><h3><a href="r5rs-Z-H-2.html#%_toc_%_sec_Temp_7">Language changes</a></h3><p><p>This section enumerates the changes that have been made to Scheme sincethe ``Revised<sup>4</sup> report'' [<a href="r5rs-Z-H-14.html#%_sec_7.3">6</a>] was published.<p><p><ul><p><li>The report is now a superset of the IEEE standard for Scheme[<a href="r5rs-Z-H-14.html#%_sec_7.3">13</a>]: implementations that conform to the report willalso conform to the standard. This required the following changes:<p><ul><p><li>The empty list is now required to count as true.<p><li>The classification of features as essential or inessential has beenremoved. There are now three classes of built-in procedures: primitive,library, and optional. The optional procedures are <tt>load</tt>,<tt>with-input-from-file</tt>, <tt>with-output-to-file</tt>,<tt>transcript-on</tt>, <tt>transcript-off</tt>, and<tt>interaction-environment</tt>,and <tt>-</tt> and <tt>/</tt> with more than two arguments.None of these are in the IEEE standard.<p><li>Programs are allowed to redefine built-in procedures. Doing sowill not change the behavior of other built-in procedures.</ul><p><p><li><em>Port</em> has been added to the list of disjoint types.<p><li>The macro appendix has been removed. High-level macros are now partof the main body of the report. The rewrite rules for derived expressionshave been replaced with macro definitions. There are no reserved identifiers.<p><li><tt>Syntax-rules</tt> now allows vector patterns.<p><li>Multiple-value returns, <tt>eval</tt>, and <tt>dynamic-wind</tt> havebeen added.<p><li>The calls that are required to be implemented in a properly tail-recursivefashion are defined explicitly.<p><li>`<tt>@</tt>' can be used within identifiers. `<tt><code class=verbatim>|</code></tt>' is reservedfor possible future extensions.<p></ul><p><p><p> <p> <p><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><p></body></html>⌨️ 快捷键说明
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