txlyre
/
avram


			
				
					
						
						
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<h3 class="section">B.3 Replace</h3>

<p><a name="index-g_t_0040code_007breplace_007d-701"></a>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>((</code><var>locations</var><code>,</code><var>values</var><code>),</code><var>store</var><code>)</code> and returns the
store with the values stored at the locations indicated.

<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>
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