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avram


			
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<title>avram - a virtual machine code interpreter: B.4 Transition</title>

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<a name="Transition"></a>
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<a name="Transition-1"></a>
<h2 class="section">B.4 Transition</h2>

<p>This code is relevant to the discussion of <code>transfer</code> in <a href="Transfer.html#Transfer">Transfer</a>,
where its specification is described in detail. When this code
is evaluated on a virtual code application <code><var>f</var></code>, the result is
the code for a transition function that takes one configuration to the
next in the course of evaluating a transfer function, as specified in
equations <em>E7</em> to <em>E9</em>.
<a name="index-transition-1"></a>
</p>
<table><tr><td>&nbsp;</td><td><pre class="example">
output_buffer = compose(left,argument)
input_buffer = compose(right,compose(right,argument))
active = compose(left,compose(right,argument))
state = compose(left,active)
output = compose(right,active)

transition =

bu(compose,refer) (hired bu(conditional,active))(
   (hired conditional)(
      constant input_buffer,
      bu(compose,(fan bu(hired meta,self))) (hired apply)(
         constant fan bu(couple,couple(output,output_buffer)),
         couple (fan bu(compose,couple))(
            couple(
               (hired apply)(
                  hired,
                  constant (state,compose(head,input_buffer))),
               constant compose(tail,input_buffer)),
            couple(
               (hired apply)(hired,constant(state,constant nil)),
               constant constant nil)))),
   constant compose(flat,compose(reverse,output_buffer)))
</pre></td></tr></table>

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