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POFP: Reflecting state in absence of actual state change?
 

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  1. POFP: Reflecting state in absence of actual state change?
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    <p>I am new to some of the advanced functional programming ideas, in particular: how to work with immutable data. Data structures are often composites, composed of smaller data structures. For instance, if we have a Family collection which is made up all of the Members of a household. We might construct the family:</p> <pre><code>var flintstones = new Family(). add(new Member({name: 'Fred'})). //returns new instance of family add(new Member({name: 'Wilma'}). // " add(new Member({name: 'Pebbles'})); // " var fred = flintstones.get({name: 'Fred'}).set({lname: 'Flintstone'}); flintstones = fred.family(); //new instance of family with latest fred. </code></pre> <p>Notice how changing <code>fred</code> did not actually change <code>flintstones</code>. I can grab a fresh reference to <code>flintstones</code> but for what purpose? As all objects are mere snapshots I can't see the point of retaining a reference. State changes have been abstracted away, so we're not going to use the Observer pattern. Thus, how are dependent things like GUIs that care about state changes handled? What is the functional alternative to observation for keeping things in sync? I don't see the objects themselves as having any business in rendering themselves. How might a functional program handle keeping the state of a single-page webapp GUI in sync? </p> <p>For what it's worth <a href="http://qconlondon.com/dl/qcon-london-2009/slides/RichHickey_PersistentDataStructuresAndManagedReferences.pdf" rel="nofollow">Rich Hickey's talks</a> inspired me to explore functional programming. I get his concepts, but I struggle with leaping to a practical implementation (in JavaScript).</p>
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    1. CONot sure I got your question: this is an OOP approach, not a functional programming one. Are you asking how to convert that in a more functional way?
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    2. COFrom what I've been reading (especially the links provided by Matthew Strawbridge on his comments), this is more about *reactive* than *functional* programming.
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