ceph/src/boost/libs/phoenix/doc/html/phoenix/lazy_list/tutorial_with_examples/list_generation.html

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  27 <a name="phoenix.lazy_list.tutorial_with_examples.list_generation"></a><a class="link" href="list_generation.html" title="List Generation">List
  28         Generation</a>
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  30 <p>
  31           One of the most interesting capabilities of <a href="http://cgi.di.uoa.gr/~smaragd/fc++/" target="_top">FC++</a>
  32           is the generation of infinite lazy lists which are evaluated only at need.
  33           The most simple example of this is
  34         </p>
  35 <pre class="programlisting"><span class="identifier">enum_from</span><span class="special">(</span><span class="number">1</span><span class="special">)</span>
  36 </pre>
  37 <p>
  38           which returns the generator for integers 1,2,3,..... infinity.
  39         </p>
  40 <pre class="programlisting"><span class="identifier">take</span><span class="special">(</span><span class="number">4</span><span class="special">,</span><span class="identifier">enum_from</span><span class="special">(</span><span class="number">1</span><span class="special">))</span>
  41 </pre>
  42 <p>
  43           returns a list of the first 4 of the list.
  44         </p>
  45 <pre class="programlisting"><span class="identifier">at</span><span class="special">(</span><span class="identifier">enum_from</span><span class="special">(</span><span class="number">1</span><span class="special">),</span><span class="number">3</span><span class="special">)</span>
  46 </pre>
  47 <p>
  48           returns the fourth member using zero indexed access. Both of the lists
  49           returned are lazy and only evaluated when the list members are accessed.
  50         </p>
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