This sounds like a scenario where you'd be using or extending an existing stdlib generic type such as Set, no?<br><div class="gmail_quote"><div dir="ltr">On Fri, Jul 8, 2016 at 15:53 Tino Heth via swift-evolution <<a href="mailto:swift-evolution@swift.org">swift-evolution@swift.org</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Right now I'm working on a lib for charts/plots, and I choose to create a custom interval-type that has no comparable requirement.<br>
Of course, as soon as I leave the completely abstract and generic world, I need to bring things into an order — but if this order has to be defined by a global function "<", there is a loss in flexibility.<br>
My plan is to use "<" as a default wherever possible to define my ranges, with the option to change it to a custom alternative; maybe similar reasoning can be applied to the index-problem.<br>
<br>
Tino<br>
<br>
Real world example:<br>
Let's assume I want to create a bar-chart to compare the population of several countries.<br>
There is no natural order for countries (I hope we can agree on that ;-), so no matter how I'd model them, it would feel wrong to define "<":<br>
Sort by name might be the most obvious choice, but it could also be the size, the timezone, average income, the peak hight of its highest mountain...<br>
Additionally, I might want to use different orders for different charts, which is only possible when I can change the function which dictates the order.<br>
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