For decades, the dominant metaphor for building software was architectural. We drew blueprints, laid foundations, and built upward. It was a linear process: Requirements → Design → Code → Test → Deploy.
Nonlin software treats state as a stream of facts. Instead of overwriting "User Status: Offline" with "User Status: Online," we append an event: UserLoggedIn . The current state is simply a derivation of the history of events. nonlin software