I think to express "A depends on B and C; B depends on D, and C depends on D and E" in haskell, you do something like:

A = f B C where
B = g D
C = h D E

Yesterday I saw a talk called "XML Stream Processing Using a Lazy Concurrent Language". That guy presented an extension to haskell that allows you to explicitly process some of your mutually independent arguments in parallel, using the syntax:

let B = g D
C = h D E
in
A = f B C

So, I guess you might like that :)