txlyre
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avram


			
				
					
						
						
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<h3 class="section">B.1 Pairwise</h3>

<p><a name="index-g_t_0040code_007bpairwise_007d-699"></a>This <code>silly</code> code fragment is mentioned in <a href="Reduce.html#Reduce">Reduce</a>, in the
discussion of <code>reduce</code>, and is provided as an example of a solution
to equations <em>E1</em> to <em>E3</em>. It is written in the style of a
higher order function, in that it takes a function <var>f</var> as an
argument and returns another function, [[<code>pairwise</code>]]
<var>f</var> as a result.

<pre class="example">     
     self     = left
     argument = right
     head     = left
     tail     = right
     
     pairwise =
     
     compose(
        refer,
        compose(
           bu(
              conditional,
              conditional(argument,compose(tail,argument),constant nil)),
           couple(
              (hired couple)(
                 (hired compose)(
                    identity,
                    constant (hired fan head)(
                       argument,
                       compose(tail,argument))),
                 constant (hired meta)(
                    self,
                    compose(tail,compose(tail,argument)))),
              constant argument)))
     
</pre>
   <p class="noindent">To see how this works, one should evaluate it symbolically with an
unknown <var>f</var>, which will result in some <code>silly</code>
pseudocode, and then evaluate that symbolically with some sample lists.

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