It looks kind of similar to a dream project of my own. It's a project that I've promised myself to take up on one day. I started building a prototype in haskell, with front end in Gloss. Tried to get inspiration from functional reactive programming/modelling.

I thought about using something like a prototype called Hydra (1) as a sort of runtime for evaluating graphs. Anyway, I really want to get back to it at some point but other cool things that are slightly more low hanging tends to get in the way. :)

Another nice inspiration for these things is Ecolanguage (2), not really programming related but a diagram language for visualizing economic transactions.

(1) - https://github.com/giorgidze/Hydra (2) - https://www.youtube.com/watch?v=-QI1iuAvTKE