Your mental model of directed graphs is a functional model. In the more general sense that may be true, but I was talking about Factorio specifically, where I'

Your mental model of directed graphs is a functional model. In the more general sense that may be true, but I was talking about Factorio specifically, where I'm using the graph representation to do the analysis. Or rather, just because a functional interpretation exists doesn't mean I actually reach for the toolkit filed in my memory in the box labeled "functional stuff". In practice I mostly reach for the boxes I've filed away under "linear algebra", "graph theory", and "circuit design", which aren't things I typically reach for when I'm actually doing functional programming.