Hmm. What if the algorithm could be contained within the transaction's scriptsig? So, suppose I'm betting on.... who the next pope will be.
Well, then it is a bet on a fixed set of outcomes. E.g. if outcome is YES Alice gets money, if outcome is NO Bob gets money.
It is possible to associate a hash with each outcome (e.g. YES-hash, NO-hash), it needs to be done by a service which you use as a data source, then these hashes will be embedded in script.
Eventually data source service will publish either YES-unlock-hash or NO-unlock-hash and this will let Alice or Bob to get their money.
I don't think that bets which cannot be reduced to simple bet on specific outcome can be done with Bitcoin scripts anyway...
I've outlined this hash-based betting process in more detail some time ago, if you're interested I can dig it up.
So, this would require the scriptsig to:
a) match the text "the new pope is Alice"
b) verify the signature from cnn
This isn't possible Bitcoin Script now (it can only verify signature for a transaction), but it is possible to do something like HMAC verification.
It is possible to make a cryptocurrency with a more expressive scripting language, but I still don't see why it would be an improvement: all you can do with it you can do now.