On Sat, 29 Mar 2003 08:39:52 -0800 (PST)
David Sankel
I'm not sure what you mean by filter? Something like an onTitleChange callback?
Given a Variable a, I think that it's a good idea to have an ability to filter the values with something like addFilter :: (Variable a) -> (a -> IO (Maybe a)) -> IO (IO ()) the IO action returned is to uninstall the filter (wich is like a callback). but this is just an idea, there might be reasons not to do it, or to do it in a simpler way. If there are no filters (like in MVar), you can always provide a set/get pair of functions wich allow filtering, but there is no way to avoid the ability to bypass the filters. Of course, I could entirely rewrite an MVar layer on top of the old one, but that sounds silly. V.