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| 4 | <title>List Generation</title> | |
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| 24 | </div> | |
| 25 | <div class="section"> | |
| 26 | <div class="titlepage"><div><div><h4 class="title"> | |
| 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> | |
| 29 | </h4></div></div></div> | |
| 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> | |
| 51 | </div> | |
| 52 | <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> | |
| 53 | <td align="left"></td> | |
| 54 | <td align="right"><div class="copyright-footer">Copyright © 2002-2005, 2010, 2014, 2015 Joel de Guzman, Dan Marsden, Thomas | |
| 55 | Heller, John Fletcher<p> | |
| 56 | Distributed under the Boost Software License, Version 1.0. (See accompanying | |
| 57 | file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>) | |
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| 64 | </div> | |
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