[Haskell-cafe] Categorical description of systems with dependent types

Hi, recently, I was studying how cartesian closed categories can be used to describe typed functional languages. Types are objects and morphisms are functions from one type to another. Since I'm also interested in systems with dependent types, I wonder if there is a categorical description of such systems. The problem (as I see it) is that the codomain of a function depends on a value passed to the function. I'd happy if someone could give me some pointers to some papers or other literature. Thanks, Petr