statesfrom

Statesfrom, often written as statesFrom in codebases, is a concept in software engineering describing a method to derive a sequence of system states from an initial state and a stream of input events. It is closely related to state-machine modeling and event-sourced architectures, where system behavior is defined by transitions triggered by events rather than by implicit time progression. Statesfrom formalizes the idea of computing successive states by applying a transition function to each incoming event, producing a trace of states that can be inspected for verification, testing, or visualization.

In practice, statesFrom is implemented as a fold or scan over an event stream: start with the initial state, for each event apply delta(state, event) to obtain the next state, and emit it. If a given event has no valid transition from the current state, the result may be discarded, logged, or handled by a defined error policy.

A concrete example: with a simple door sensor, initial state closed, delta maps (closed, open) and (open, closed) on received events open and close, producing a sequence [closed, open, closed].

Statesfrom is used in modeling user interfaces, protocol analysis, workflow engines, and simulation tools, where reproducing or validating state trajectories is important. Performance considerations include potential state-space growth and the need for abstractions to manage complexity. See also state machine, event sourcing, model checking, and functional folds or scans.