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* Chickadee: (chickadee). Game programming toolkit for Guile.
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<span id="Live-Coding"></span><div class="header">
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Previous: <a href="Window-Manipulation.html#Window-Manipulation" accesskey="p" rel="prev">Window Manipulation</a>, Up: <a href="Kernel.html#Kernel" accesskey="u" rel="up">Kernel</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Index.html#Index" title="Index" rel="index">Index</a>]</p>
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<hr>
<span id="Live-Coding-1"></span><h4 class="subsection">2.1.4 Live Coding</h4>
<p>One of the biggest appeals of any Lisp dialect is the ability to use
the “read-eval-print loop” (REPL for short) to build programs
iteratively and interactively while the program is running. However,
programs that run in an event loop and respond to user input (such as
a video game) require special care for this workflow to be pleasant.
Chickadee provides no built-in support for live coding, but it’s
fairly easy to hook up a special kind of REPL yourself.
</p>
<p>First, create a cooperative REPL server (It’s important to use Guile’s
cooperative REPL server instead of the standard REPL server in
<code>(system repl server)</code> to avoid thread synchronization issues).
Then, in the game loop’s update procedure, call
<code>poll-coop-repl-server</code> and pass the REPL object. Here is a
template to follow:
</p>
<div class="example">
<pre class="example">(use-modules (chickadee)
(system repl coop-server))
(define repl (spawn-coop-repl-server))
(define (update dt)
(poll-coop-repl-server repl)
...)
(run-game #:update update ...)
</pre></div>
<p>To use the REPL, connect to it via port 37146. Telnet will do the
trick, but using the <a href="https://www.nongnu.org/geiser/">Geiser</a>
extension for Emacs is by far the best way to develop at the REPL with
Guile. Use <code>M-x connect-to-guile</code> to connect to the REPL server.
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