84 lines
3.4 KiB
HTML
84 lines
3.4 KiB
HTML
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<title>Conditionals - Enigma</title>
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<!--
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This manual is for Enigma, version 0.1.
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Copyright (C) 2010 Niels Serup
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Permission is granted to copy, distribute and/or modify this
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document under the terms of the GNU Free Documentation License,
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Version 1.3 or any later version published by the Free Software
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Foundation; with no Invariant Sections, no Front-Cover Texts, and
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no Back-Cover Texts. A copy of the license is included in the
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section entitled "GNU Free Documentation License".
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This document is also available under the terms of the Creative
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Commons Attribution-Share Alike 3.0 (or any later version)
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Unported license. A copy of the license is available at
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<div class="node">
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<a name="Conditionals"></a>
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<p>
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Next: <a rel="next" accesskey="n" href="Loops.html#Loops">Loops</a>,
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Previous: <a rel="previous" accesskey="p" href="Functions.html#Functions">Functions</a>,
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Up: <a rel="up" accesskey="u" href="Language.html#Language">Language</a>
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<hr>
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</div>
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<h3 class="section">2.8 Conditionals</h3>
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<p>Any value can be related to another value. 78 is less than 85. 2 equals
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2. "Hi" is not "Bye". Enigma comes with a basic set of functions that
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can be used to test these relations. The functions <code>greater</code>,
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<code>lesser</code>, <code>equal</code>, <code>not</code>, <code>or</code> and <code>and</code> are
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available. These functions return either true or false. To run a
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function on the condition that a relational function has returned true,
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use the function <code>act</code>.
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<p>While <code>lesser</code> and <code>greater</code> are aimed at numbers only,
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and <code>and</code>, <code>or</code> and <code>not</code> are aimed at booleans only,
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<code>equal</code> can be used on all objects. It tests for all equalities.
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<pre class="verbatim">2 = a;
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4 = b;
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a 2 ! add | temp b ! equal = cond1;
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"47" ! num | temp 48 ! greater = cond2;
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cond1 cond2 ! and | temp write stdout "4 = 4 and 47 > 48\n" ! act;
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cond1 cond2 ! or | temp write stdout "4 = 4 or 47 > 48\n" ! act;
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cond2 ! not | cond1 temp ! and | temp write stdout "4 = 4 and !(47 >
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48)\n" ! act;
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</pre>
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<p>Even simpler, one can do this (though there's no real need for it):
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<pre class="verbatim"># Instead of stdout "Hello" !write;
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true write stdout "Hello" !act;
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</pre>
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</body></html>
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