> To me, all you're doing here is describing an object-based language in which functions are first-class. Obviously, Urbit didn't invent this concept. Its predecessors used normal names for these terms. Why does Urbit invent new ones?
That's a pretty (unintentionally) misleading description of it. What is an object? An Urbit function has basically nothing that an OOP object has. No class, no inheritance, no attributes, and no methods. It's just a way of encapsulating a formula (VM assembly expression) in a way that's convenient to call with formulas. It uses the the "core" pattern because it's convenient.
"Arm" is a pretty specific term that refers to the way an "element" of a core is represented in the core. When you want to map a particular use of cores to its underlying representation in the "core" pattern, you want to be able to talk about specific data structures.
In general, Urbit errs on the sides of giving names to concepts that could only otherwise be described in multiple sentences. Most projects just don't give names to those concepts. Urbit needs better human descriptions of its concepts, but using traditional names for them would be misleading.
