Finite state modeling
Slap yourself if
You think finite state modeling is just enums with extra ceremony.
Why this exists
Finite state modeling exists because ad-hoc boolean flags and loosely coupled state variables eventually describe impossible states. FSMs force you to model reality instead of hoping your conditionals line up.
Mental model
An FSM is a contract about what can happen next. State is not a bag of values — it’s a position in a graph, and transitions are the only legal moves.
- The system is described as a finite set of mutually exclusive states.
- Transitions define which states can move to which, and why.
- Events are interpreted relative to the current state.
- Invalid transitions are rejected by construction, not by convention.
- Modeling data shape instead of behavior.
- Letting multiple flags imply state instead of encoding it explicitly.
- Adding escape hatches that bypass transitions.
- Treating FSMs as UI-only abstractions.
Finite state modeling represents application behavior as explicit states and transitions, preventing impossible combinations by encoding what can happen next instead of inferring it from flags.
- Multiple booleans describing the same lifecycle
- State transitions hidden in side effects
- Impossible UI states explained as ‘edge cases’
- FSMs dismissed as overengineering
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