Convert Filters to Where Clause

I'm trying to use a radDataFilter in my ViewModel for server-side data retrieval. Retrieving a million records to the UI before I filter them is not feasible. I saw a code example that looked like this:

     var query = mgr.INVENTORY.Where(UIForm.myFilter.FilterDescriptor)

but an hour of experimentation has produced nothing that's even syntactically correct. Do you have a complete working example of how to pass the FilterDescriptors to an E-F query?