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avram


			
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<title>avram - a virtual machine code interpreter: B.3 Replace</title>

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<a name="Replace"></a>
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<a name="Replace-1"></a>
<h2 class="section">B.3 Replace</h2>

<a name="index-replace-2"></a>
<p>This code is needed in the discussion of assignment in <a href="Assignment.html#Assignment">Assignment</a>.
where it serves as a solution to equation <em>E0</em>. The idea is that
the function takes an argument of the form
<code>((<var>locations</var>,<var>values</var>),<var>store</var>)</code> and returns the
store with the values stored at the locations indicated.
</p>

<table><tr><td>&nbsp;</td><td><pre class="example">
locations = compose(left,compose(left,argument))
values    = compose(right,compose(left,argument))
store     = compose(right,argument)

replace =

refer conditional(
   store,
   (
      conditional(
         compose(left,locations),
         (
            conditional(
               compose(right,locations),
               (
                  (hired meta)(
                     self,
                     couple(
                        (hired fan right)(locations,values),
                        (hired meta)(
                           self,
                           couple(
                              (hired fan left)(locations,values),
                              store)))),
                  couple(
                     (hired meta)(
                        self,
                        couple(
                           couple(compose(left,locations),values),
                           compose(left,store))),
                     compose(right,store)))),
            conditional(
               compose(right,locations),
               (
                  couple(
                     compose(left,store),
                     (hired meta)(
                        self,
                        couple(
                           couple(compose(right,locations),values),
                           compose(right,store)))),
                  values)))),
         (hired meta)(
            self,
            couple(couple(locations,values),constant (nil,nil)))))
</pre></td></tr></table>

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