Smart contract languages look still in infancy as practical applications are audit trails with stronger guarantees and lower operating costs. What you are thinking of sounds like a far more advanced deal management system. Besides, is it even possible to invent a way to trade risk in such a way that if one party hold unbounded exposure before the trade then after the trade both parties have bounded exposure? does it even make sense to have unbounded risks in system that is inescapably formal and will hold a bounded amount of money at each time? One could argue that risks that look unbounded are usually (as in without a ledger) handled less formally (ie: state bailout, https://www.forbes.com/sites/jamesconca/2016/03/10/after-fiv...) (Disclaimer: I work for Bloomberg on DLIB BLAN that is a contract language for structuring, pricing and managing exotic derivatives, no block-chains involved)