It may not be exactly what you want, but I played with <a href="https://github.com/luqui/topology-extras/blob/master/TopologyExtras/Topology.hs">https://github.com/luqui/topology-extras/blob/master/TopologyExtras/Topology.hs</a> a few months ago, it may be a good basis to start with. (no pun intended)<br>
<br><div class="gmail_quote">On Thu, Aug 11, 2011 at 5:08 PM, Grigory Sarnitskiy <span dir="ltr">&lt;<a href="mailto:sargrigory@ya.ru">sargrigory@ya.ru</a>&gt;</span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
Oh, I guess the class would look something like that:<br>
<br>
class TopologicalSpace a where<br>
    ifOpen :: (Subset a) -&gt; Bool<br>
<br>
and Subset x is a type corresponding to subsets of x.<br>
<br>
11.08.2011, 17:52, &quot;Grigory Sarnitskiy&quot; &lt;<a href="mailto:sargrigory@ya.ru">sargrigory@ya.ru</a>&gt;:<br>
<div><div></div><div class="h5">&gt; Hello! I just wonder whether it is possible to have a typeclass for topological spaces?<br>
&gt;<br>
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