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<title>Teachpack : Elevator</title>
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<a href="index.html">Teachpacks for How to Design Programs</a>
<h1>Elevator</h1>
<hr> <h3><a name="elevator.ss">elevator.ss</a></h3> <!-- DOCNOTE="teach=elevator.ss" -->
<p>The teachpack <code>elevator.ss</code> implements an elevator simulator.
It displays an eight-floor elevator and accepts mouse clicks from the user,
which are translated into service demands for the elevator. The teachpack
provides a single operation:
<br>
<menu>
<li><code><a name="run">run</a> : NextFloor -> void</code>
<br>that is, it consumes an elevator controller and returns nothing .
</menu>
<br>
Sample session: First define a function that consumes the current state of
the elevator (three arguments) and returns a number between 1 and 8. Here
is a non-sensical definition:
<br> <code> (define (controller x y z) 7) </code>
<br>It moves the elevator once, to the 7th floor.
<br>
<br>Second, set the teachpack to <code>elevator.ss</code> execute and
run:
<pre>
> (run controller)
>
</pre>
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