[plt-scheme] How to define exceptions in typed-scheme?

Richard Cobbe wrote:
> I'm using Typed Scheme, and I'm trying to define exception structures that
> inherit from the native PLT exception hierarchy.  Typed-Scheme doesn't
> provide types for these structs, so I'm having to do it myself with
> require/typed.

It looks like it includes types for a few exns but not all. In 
particular, exn:fail is typed, but exn:fail:contract seems not to be. So 
you can work around it for now if you don't mind extending exn:fail 
directly instead of exn:fail:contract.

(I tried paring down the require/typed to just grab exn:fail:contract, 
but I still got problems on provide.)

Ryan