// Real world r12

Fetch with retry

A request that can succeed, fail, or be retried — without a tangle of nested if-statements. The graph names every legal transition; the calling code stays flat.

Code

request.fsl

const req = sm`
  idle     'fetch'   → loading;
  loading  'resolve' → success;
  loading  'reject'  → error;
  error    'retry'   → loading;
  success  'reset'   → idle;
`;

run.ts

async function run() {
  req.go('fetch');
  try { const data = await api.get(); req.go('resolve', { data }); }
  catch { req.go('reject'); }
}