lucy typescript notes

notes.ts

import { EventObject, Guard, InvokeCreator, StateMachine } from 'xstate'

type EventNames = 'GO_BACK' | 'GO_FORWARD' | 'GO_SIDEWAYS';

type KnownContextKeys = 'user';

type LucyKnownContext<Keys extends string> = Record<Keys, any>

function createMachine<TContext extends LucyKnownContext<KnownContextKeys>, TEvent extends { type: EventNames } = any>() {
  return {} as any
}

createMachine<{
  otherThing: {},
  user: {}
}>()

type MyEventShape = {
  type: 'GO_BACK'

} | {
  type: 'GO_FORWARD'
  y: number
} | {
  type: 'GO_SIDEWAYS';
  x: number
} | {
  type: 'done.invoke.fetchUsers';
  data: {
    user: {
      name: string;
    }
  }
}

interface CreateMachineOptions<TContext, TEvent extends EventObject> {
  guards: {
    checkAfterGoBack: Guard<
      TContext,
      TEvent extends Extract<TEvent, { type: 'GO_BACK' }> ? Extract<TEvent, { type: 'GO_BACK' }> : TEvent
    >;
  }
  services: {
    fetchUsers: InvokeCreator<
      TContext,
      Extract<TEvent,
        | { type: 'SUBMIT' }
      >
      ,
      Extract<
        TEvent,
        { type: 'done.invoke.fetchUsers' }> extends { 'data': infer T } ? T : any
    > | StateMachine<any, any, any>
  }
}