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<title>avram - a virtual machine code interpreter: 2.7 Virtual Code Semantics</title>

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<a name="Virtual-Code-Semantics"></a>
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<td valign="middle" align="left">[<a href="Virtual-Machine-Specification.html#Virtual-Machine-Specification" title="Beginning of this chapter or previous chapter"> &lt;&lt; </a>]</td>
<td valign="middle" align="left">[<a href="Virtual-Machine-Specification.html#Virtual-Machine-Specification" title="Up section"> Up </a>]</td>
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<td valign="middle" align="left"> &nbsp; </td>
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<td valign="middle" align="left">[<a href="avram.html#Top" title="Cover (top) of document">Top</a>]</td>
<td valign="middle" align="left">[<a href="avram_toc.html#SEC_Contents" title="Table of contents">Contents</a>]</td>
<td valign="middle" align="left">[<a href="Function-Index.html#Function-Index" title="Index">Index</a>]</td>
<td valign="middle" align="left">[<a href="avram_abt.html#SEC_About" title="About (help)"> ? </a>]</td>
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<a name="Virtual-Code-Semantics-1"></a>
<h2 class="section">2.7 Virtual Code Semantics</h2>

<p>As the previous sections explain, virtual code applications are defined
in terms of mathematical functions. Up until this point, the discussion
has focused on the interface between the function and the virtual
machine interpreter, by detailing the arguments passed to the functions under
various circumstances and the results they are expected to return in
order to achieve various effects.
</p>
<p>The purpose of this section is to complete the picture by explaining how
a given computable function can be expressed in virtual code,
considering only functions operating on the trees described in <a href="Raw-Material.html#Raw-Material">Raw Material</a>.
Functions manipulating trees of <code>nil</code> are undoubtedly a frivolous
and abstract subject in themselves. One is obliged to refer back to the
previous sections if in need of motivation.
</p>
<table class="menu" border="0" cellspacing="0">
<tr><td align="left" valign="top"><a href="A-New-Operator.html#A-New-Operator">2.7.1 A New Operator</a></td><td>&nbsp;&nbsp;</td><td align="left" valign="top">              
</td></tr>
<tr><td align="left" valign="top"><a href="On-Equality.html#On-Equality">2.7.2 On Equality</a></td><td>&nbsp;&nbsp;</td><td align="left" valign="top">                 
</td></tr>
<tr><td align="left" valign="top"><a href="A-Minimal-Set-of-Properties.html#A-Minimal-Set-of-Properties">2.7.3 A Minimal Set of Properties</a></td><td>&nbsp;&nbsp;</td><td align="left" valign="top">  
</td></tr>
<tr><td align="left" valign="top"><a href="A-Simple-Lisp-Like-Language.html#A-Simple-Lisp-Like-Language">2.7.4 A Simple Lisp Like Language</a></td><td>&nbsp;&nbsp;</td><td align="left" valign="top">  
</td></tr>
<tr><td align="left" valign="top"><a href="How-avram-Thinks.html#How-avram-Thinks">2.7.5 How <code>avram</code> Thinks</a></td><td>&nbsp;&nbsp;</td><td align="left" valign="top">     
</td></tr>
<tr><td align="left" valign="top"><a href="Variable-Freedom.html#Variable-Freedom">2.7.6 Variable Freedom</a></td><td>&nbsp;&nbsp;</td><td align="left" valign="top">            
</td></tr>
<tr><td align="left" valign="top"><a href="Metrics-and-Maintenance.html#Metrics-and-Maintenance">2.7.7 Metrics and Maintenance</a></td><td>&nbsp;&nbsp;</td><td align="left" valign="top">     
</td></tr>
<tr><td align="left" valign="top"><a href="Deconstruction.html#Deconstruction">2.7.8 Deconstruction</a></td><td>&nbsp;&nbsp;</td><td align="left" valign="top">              
</td></tr>
<tr><td align="left" valign="top"><a href="Recursion.html#Recursion">2.7.9 Recursion</a></td><td>&nbsp;&nbsp;</td><td align="left" valign="top">                   
</td></tr>
<tr><td align="left" valign="top"><a href="Assignment.html#Assignment">2.7.10 Assignment</a></td><td>&nbsp;&nbsp;</td><td align="left" valign="top">                  
</td></tr>
<tr><td align="left" valign="top"><a href="Predicates.html#Predicates">2.7.11 Predicates</a></td><td>&nbsp;&nbsp;</td><td align="left" valign="top">                  
</td></tr>
<tr><td align="left" valign="top"><a href="Iteration.html#Iteration">2.7.12 Iteration</a></td><td>&nbsp;&nbsp;</td><td align="left" valign="top">                   
</td></tr>
<tr><td align="left" valign="top"><a href="List-Combinators.html#List-Combinators">2.7.13 List Combinators</a></td><td>&nbsp;&nbsp;</td><td align="left" valign="top">            
</td></tr>
<tr><td align="left" valign="top"><a href="List-Functions.html#List-Functions">2.7.14 List Functions</a></td><td>&nbsp;&nbsp;</td><td align="left" valign="top">              
</td></tr>
<tr><td align="left" valign="top"><a href="Exception-Handling.html#Exception-Handling">2.7.15 Exception Handling</a></td><td>&nbsp;&nbsp;</td><td align="left" valign="top">          
</td></tr>
<tr><td align="left" valign="top"><a href="Interfaces-to-External-Code.html#Interfaces-to-External-Code">2.7.16 Interfaces to External Code</a></td><td>&nbsp;&nbsp;</td><td align="left" valign="top"> 
</td></tr>
<tr><td align="left" valign="top"><a href="Vacant-Address-Space.html#Vacant-Address-Space">2.7.17 Vacant Address Space</a></td><td>&nbsp;&nbsp;</td><td align="left" valign="top">        
</td></tr>
</table>

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<td valign="middle" align="left"> &nbsp; </td>
<td valign="middle" align="left">[<a href="Virtual-Machine-Specification.html#Virtual-Machine-Specification" title="Beginning of this chapter or previous chapter"> &lt;&lt; </a>]</td>
<td valign="middle" align="left">[<a href="Virtual-Machine-Specification.html#Virtual-Machine-Specification" title="Up section"> Up </a>]</td>
<td valign="middle" align="left">[<a href="Library-Reference.html#Library-Reference" title="Next chapter"> &gt;&gt; </a>]</td>
<td valign="middle" align="left"> &nbsp; </td>
<td valign="middle" align="left"> &nbsp; </td>
<td valign="middle" align="left"> &nbsp; </td>
<td valign="middle" align="left"> &nbsp; </td>
<td valign="middle" align="left">[<a href="avram.html#Top" title="Cover (top) of document">Top</a>]</td>
<td valign="middle" align="left">[<a href="avram_toc.html#SEC_Contents" title="Table of contents">Contents</a>]</td>
<td valign="middle" align="left">[<a href="Function-Index.html#Function-Index" title="Index">Index</a>]</td>
<td valign="middle" align="left">[<a href="avram_abt.html#SEC_About" title="About (help)"> ? </a>]</td>
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