Ask HN: What do you use to model things?

For a long time now I've wanted a general purpose modeling tool. I looking something that's a mixture of a programming language and a visualization engine. Some features:

- create hypotheses that affect bits of state in the model. hypotheses are expressed as functions which get run on an interval

- connect hypotheses to external data sources .. web scraping / RESTFUL APIs et al

- visualize all pieces of state