The Urbit operating system hews to a conceptual model wherein each expression takes place in a certain context (the subject). While sharing a lot of practicality with other programming paradigms and platforms, Urbit's model is mathematically well-defined and unambiguously specified. Every expression of Hoon is evaluated relative to its subject, a piece of data that represents the environment, or the context, of an expression.
Further reading
- Hoon School: subject-oriented programming: A guide to subject-oriented programming.