[aleyan]

Nice. Assuming that the computation of each node is memoized, can we 'dirty' a single node, so that during the next computation only the needed parts of the graph are recomputed? This would make multiple computation of models where only a few parameters are changing much more efficient.

Also, has this at all been inspired by SecDB's powerful graph oriented features?

[w01fe]

We haven't had the need for that application yet, but it's certainly possible -- that's why declarative specifications are great :)

I haven't heard of SecDB, but I'll definitely check it out -- thanks!

[gajomi]

This is definitely a use case I am interested in. I have been playing around with computer algebra in Clojure for awhile where it is critical to keep track of these dependencies (I have a hacky implementation which relies on metadata so that the resulting data structure is out of site). But of course, when you actually want to evaluate something, this is when you need to get sophisticated. There can be multiple paths in the graph to arrive at the same node and you have to decide. With memoization at nodes being an important consideration. Anyway, I would be very happy to see an open source version of this!

P.S. As I understand it all the graphs are dags. In my line of work (which involves doing stuff at the interface of probability and statistics) there are quite a few recursive functions that are difficult to unroll explicitly, or are otherwise undesirable to unroll for the purposes of readability. Can we expect to see circular dependencies at some point. Well, I know, the halting problem and all, but still...