Xstate: Typestates not working as expected with xstate

[schpet]

Description

not able to narrow typestate types when subscribing to a state machine service

Expected Result

within a state.maches("foo") { ... } condition, types to be narrowed to the appropriate State type

Actual Result

types are not narrowed, you get the Context type

Reproduction

https://codesandbox.io/s/awesome-tree-qom29 (see src/index.ts L62)

Additional context

• https://github.com/davidkpiano/xstate/issues/819#issuecomment-558201650
• this problem is specific to xstate, works as expected with @xstate/fsm

[RafalFilipek]

Example: https://github.com/RafalFilipek/xstate-typestates-bug

[davidkpiano]

Fix for this coming 🔜 but for now, this should be general a workaround:

if (state.matches<any>('something')) {
  // ...
}

[RafalFilipek]

https://github.com/RafalFilipek/xstate-typestates-bug I've just updated my example. Still no luck. I think I'll wait for fix. I can live with that since we have optional chaining and nullish coalescing :)

[LookRain]

Having same issue with useMachine from @xstate/react

[davidkpiano]

Fix being released soon-ish: #868