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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. | |
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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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