// Patterns r09

Cycle

A linear loop with one shared verb. Every state is reachable from every other state, in order, by repeatedly firing the same action.

Code

light.fsl

const light = sm`
  red    'next' → green;
  green  'next' → yellow;
  yellow 'next' → red;
`;

Graph

Notes

Cycles fall apart when you reach for an enum and a counter. Modeled this way, the machine guarantees you can't skip a state — and adding a fourth phase is a one-line edit.