[Freebsd-haskell] Howto deal with Cabal dependencies?

Hi guys As you probably know Cabal packages sometimes have some very complicated dependencies including dependencies to older versions of a library or module. What's the best way to deal with this from the perspective of FreeBSD's ports? Can we have different versions of a port in the portstree so that a you can specify a suitable version in the *DEPENDS? I'm working on such a Cabal package at the moment. It has dependencies to an old version of the network and time module, respectively. regards, dave