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POHow should FRP work at the top level?
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copied!<p>I have been experimenting with creating a <a href="http://www.github.com/oetzi/echo" rel="nofollow">Functional Reactive Programming framework for Scala</a>. One thing at the moment I am confused about is how current implementations have dealt with representing behaviours at the top level. To explain what I mean I'll give an example. Say I have a JPanel and I want to do this:</p> <pre><code> JPanel panel = new Panel() panel.setBackground(new Behaviour(time => Color.red)) </code></pre> <p>Although the color is static here we want the panel background to update when the value of the Behaviour updates. The way I have done it so far is to essentially create a discretized Behaviour using Events (accessible via a <code>changes</code> function on Behaviours). This is basically just an event source that occurs whenever the Behaviour changes. Using this the implementation of setBackground here would be:</p> <pre><code>def setBackground(color : Behaviour[Color]) { super.setBackground(color.now) color.changes.each(change => super.setBackground(change)) } </code></pre> <p>This feels kind of messy. Does anyone have any suggestions of whether this is a bad approach or not? I have been looking at Elliott's <a href="http://conal.net/papers/push-pull-frp/" rel="nofollow">Push-Pull FRP</a> today and it feels like I might be going in the right direction but getting lost somewhere.</p> <p>EDIT: If no one has a definite clear cut solution then ideas/thoughts would be great!</p>

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