[Ur] simple example about constructing rects - guarded types?

[Adam Chlipala]

Marc Weber wrote:
> In which way is this related to the
> e! guarded expression application?
>    

The points where these need to be inserted are usually inferred.  In 
particular, this happens with a normal application of any function 
defined at the top level of a module.  For instance, most uses of the 
function examples I gave would involve all guarded applications being 
inferred.