Api changes for sendT (#72)

Author: devanshj

src/index.ts

@@ -1,9 +1,10 @@
 import { useEffect, useReducer } from "react";
-import { UseStateMachine, Machine, $$t } from "./types";
+import { UseStateMachine, Machine, $$t, O } from "./types";
 import { assertNever, R, useConstant } from "./extras";
 
+
 const useStateMachineImpl = (definition: Machine.Definition.Impl) => {
-  const [state, dispatch] = useReducer(createReducer(definition), createInitialState(definition));
+  const [machineInstant, dispatch] = useReducer(createReducer(definition), createInitialState(definition));
 
   const send = useConstant(() => (sendable: Machine.Sendable.Impl) => dispatch({ type: "SEND", sendable }));
 
@@ -13,30 +14,33 @@ const useStateMachineImpl = (definition: Machine.Definition.Impl) => {
   };
 
   useEffect(() => {
-    const entry = R.get(definition.states, state.value)!.effect;
+    const entry = R.get(definition.states, machineInstant.state)!.effect;
     let exit = entry?.({
       send,
       setContext,
-      event: state.event,
-      context: state.context,
+      event: machineInstant.event,
+      context: machineInstant.context,
     });
 
     return typeof exit === "function"
-      ? () => exit?.({ send, setContext, event: state.event, context: state.context })
+      ? () => exit?.({ send, setContext, event: machineInstant.event, context: machineInstant.context })
       : undefined;
     // eslint-disable-next-line react-hooks/exhaustive-deps
-  }, [state.value, state.event]);
+  }, [machineInstant.state, machineInstant.event]);
 
-  return [state, send];
+  return { ...machineInstant, send };
 };
 
-const createInitialState = (definition: Machine.Definition.Impl): Machine.State.Impl => {
+type MachineInstant =
+  O.OmitKey<Machine.Impl, "send">
+
+const createInitialState = (definition: Machine.Definition.Impl): MachineInstant => {
   let nextEvents = R.keys(R.concat(
     R.fromMaybe(R.get(definition.states, definition.initial)!.on),
     R.fromMaybe(definition.on)
   ))
   return {
-    value: definition.initial,
+    state: definition.initial,
     context: definition.context as Machine.Context.Impl,
     event: { type: "$$initial" } as Machine.Event.Impl,
     nextEvents: nextEvents,
@@ -46,56 +50,56 @@ const createInitialState = (definition: Machine.Definition.Impl): Machine.State.
 
 const createReducer = (definition: Machine.Definition.Impl) => {
   let log = createLogger(definition);
-  return (machineState: Machine.State.Impl, internalEvent: InternalEvent): Machine.State.Impl => {
+  return (machineInstant: MachineInstant, internalEvent: InternalEvent): MachineInstant => {
     if (internalEvent.type === "SET_CONTEXT") {
-      let nextContext = internalEvent.updater(machineState.context);
-      log("Context update", ["Previous Context", machineState.context], ["Next Context", nextContext]);
+      let nextContext = internalEvent.updater(machineInstant.context);
+      log("Context update", ["Previous Context", machineInstant.context], ["Next Context", nextContext]);
 
-      return { ...machineState, context: nextContext };
+      return { ...machineInstant, context: nextContext };
     }
 
     if (internalEvent.type === "SEND") {
       let sendable = internalEvent.sendable;
       let event = typeof sendable === "string" ? { type: sendable } : sendable;
-      let context = machineState.context;
-      let stateNode = R.get(definition.states, machineState.value)!;
+      let context = machineInstant.context;
+      let stateNode = R.get(definition.states, machineInstant.state)!;
       let resolvedTransition =
         R.get(R.fromMaybe(stateNode.on), event.type) ?? R.get(R.fromMaybe(definition.on), event.type);
 
       if (!resolvedTransition) {
         log(
           `Current state doesn't listen to event type "${event.type}".`,
-          ["Current State", machineState],
+          ["Current State", machineInstant],
           ["Event", event]
         );
-        return machineState;
+        return machineInstant;
       }
 
-      let [nextStateValue, didGuardDeny = false] = (() => {
+      let [nextState, didGuardDeny = false] = (() => {
         if (typeof resolvedTransition === "string") return [resolvedTransition];
         if (resolvedTransition.guard === undefined) return [resolvedTransition.target];
         if (resolvedTransition.guard({ context, event })) return [resolvedTransition.target];
         return [resolvedTransition.target, true]
-      })() as [Machine.StateValue.Impl, true?]
+      })() as [Machine.State.Impl, true?]
 
       if (didGuardDeny) {
         log(
-          `Transition from "${machineState.value}" to "${nextStateValue}" denied by guard`,
+          `Transition from "${machineInstant.state}" to "${nextState}" denied by guard`,
           ["Event", event],
           ["Context", context]
         );
-        return machineState;
+        return machineInstant;
       }
-      log(`Transition from "${machineState.value}" to "${nextStateValue}"`, ["Event", event]);
+      log(`Transition from "${machineInstant.state}" to "${nextState}"`, ["Event", event]);
 
-      let resolvedStateNode = R.get(definition.states, nextStateValue)!;
+      let resolvedStateNode = R.get(definition.states, nextState)!;
 
       let nextEvents = R.keys(R.concat(
         R.fromMaybe(resolvedStateNode.on),
         R.fromMaybe(definition.on)
       ));
       return {
-        value: nextStateValue,
+        state: nextState,
         context,
         event,
         nextEvents,

src/types.ts

@@ -3,15 +3,44 @@ import { R } from "./extras"
 
 export type UseStateMachine =
   <D extends Machine.Definition<D>>(definition: A.InferNarrowestObject<D>) =>
-    [ state: A.Instantiated<Machine.State<Machine.Definition.FromTypeParamter<D>>>
-    , send: A.Instantiated<Machine.Send<Machine.Definition.FromTypeParamter<D>>>
-    ]
+    Machine<Machine.Definition.FromTypeParameter<D>>
 
 export const $$t = Symbol("$$t");
 type $$t = typeof $$t;
 export type CreateType = <T>() => { [$$t]: T }
 
+export type Machine<D,
+  State = Machine.State<D>,
+  NextEvents =
+    ( State extends any
+        ? A.Get<Machine.ExitEventForState<D, State>, "type">
+        : never
+    )[]
+  > =
+    & { nextEvents: NextEvents
+      , send: Machine.Send<D>
+      }
+    & ( State extends any
+          ? { state: State
+            , context: Machine.Context<D>
+            , event: Machine.EntryEventForState<D, State>
+            , nextEventsT: A.Get<Machine.ExitEventForState<D, State>, "type">[]
+            }
+          : never
+      )
+
+interface MachineImpl
+  { state: Machine.State.Impl
+  , context: Machine.Context.Impl
+  , event: Machine.Event.Impl
+  , nextEvents: Machine.Event.Impl["type"][]
+  , nextEventsT: Machine.Event.Impl["type"][]
+  , send: Machine.Send.Impl
+  }
+
 export namespace Machine {
+  export type Impl = MachineImpl
+
   export type Definition<
     Self,
     States = A.Get<Self, "states">,
@@ -52,8 +81,8 @@ export namespace Machine {
       )
 
   interface DefinitionImp
-    { initial: StateValue.Impl
-    , states: R.Of<StateValue.Impl, Definition.StateNode.Impl>
+    { initial: State.Impl
+    , states: R.Of<State.Impl, Definition.StateNode.Impl>
     , on?: Definition.On.Impl
     , schema?: { context?: null, events?: R.Of<Event.Impl["type"], null> }
     , verbose?: boolean
@@ -64,7 +93,7 @@ export namespace Machine {
   export namespace Definition {
     export type Impl = DefinitionImp
 
-    export type FromTypeParamter<D> =
+    export type FromTypeParameter<D> =
       "$$internalIsConstraint" extends keyof D
         ? D extends infer X ? X extends Definition<infer X> ? X : never : never
         : D
@@ -120,7 +149,7 @@ export namespace Machine {
     }
 
     export type Transition<D, P,
-      TargetString = Machine.StateValue<D>,
+      TargetString = Machine.State<D>,
       Event = { type: L.Pop<P> }
     > =
       | TargetString
@@ -135,12 +164,12 @@ export namespace Machine {
         }
 
     type TransitionImpl =
-        | State.Impl["value"]
-        | { target: State.Impl["value"]
+        | Machine.Impl["state"]
+        | { target: Machine.Impl["state"]
           , guard?:
               ( parameter:
-                { context: State.Impl["context"]
-                , event: State.Impl["event"]
+                { context: Machine.Impl["context"]
+                , event: Machine.Impl["event"]
                 }
               ) => boolean
           }
@@ -149,10 +178,10 @@ export namespace Machine {
     }
 
 
-    export type Effect<D, P, StateValue = L.Pop<L.Popped<P>>> = 
-      (parameter: A.Instantiated<EffectParameterForStateValue<D, StateValue>>) =>
+    export type Effect<D, P, State = L.Pop<L.Popped<P>>> = 
+      (parameter: A.Instantiated<EffectParameterForState<D, State>>) =>
         | void
-        | ((parameter: A.Instantiated<EffectCleanupParameterForStateValue<D, StateValue>>) => void)
+        | ((parameter: A.Instantiated<EffectCleanupParameterForState<D, State>>) => void)
 
     type EffectImpl =
       (parameter: EffectParameter.Impl) =>
@@ -218,15 +247,15 @@ export namespace Machine {
     export type InitialEventType = "$$initial";
   }
 
-  export type StateValue<D> =
+  export type State<D> =
     keyof A.Get<D, "states">
 
-  export type InitialStateValue<D> =
+  export type InitialState<D> =
     A.Get<D, "initial">
 
-  type StateValueImpl = string & A.Tag<"Machine.StateValue">
-  export namespace StateValue {
-    export type Impl = StateValueImpl;
+  type StateImpl = string & A.Tag<"Machine.State">
+  export namespace State {
+    export type Impl = StateImpl;
   }
 
   export type Context<D> =
@@ -240,7 +269,7 @@ export namespace Machine {
   export type Event<D, EventsSchema = A.Get<D, ["schema", "events"], {}>> = 
     | O.Value<{ [T in U.Exclude<keyof EventsSchema, Definition.ExhaustiveIdentifier>]:
         A.Get<EventsSchema, [T, $$t]> extends infer P
-          ? P extends any ? O.ShallowMerge<{ type: T } & P> : never
+          ? P extends any ? O.ShallowClean<{ type: T } & P> : never
           : never
       }>
     | ( A.Get<EventsSchema, Definition.ExhaustiveIdentifier, false> extends true ? never :
@@ -271,7 +300,17 @@ export namespace Machine {
   }
 
   export namespace EffectParameter {
+    export interface EffectParameterForState<D, State>
+      extends BaseEffectParameter<D>
+      { event: Machine.EntryEventForState<D, State>
+      }
+
     export namespace Cleanup {
+      export interface ForState<D, State>
+        extends BaseEffectParameter<D>
+        { event: Machine.ExitEventForState<D, State>
+        }
+      
       export type Impl = EffectParameter.Impl
     }
 
@@ -284,14 +323,14 @@ export namespace Machine {
     , setContext: SetContext.Impl
     }
 
-  export interface EffectParameterForStateValue<D, StateValue>
+  export interface EffectParameterForState<D, State>
     extends BaseEffectParameter<D>
-    { event: A.Uninstantiated<Machine.EntryEventForStateValue<D, StateValue>>
+    { event: A.Uninstantiated<Machine.EntryEventForState<D, State>>
     }
 
-  export interface EffectCleanupParameterForStateValue<D, StateValue>
+  export interface EffectCleanupParameterForState<D, State>
     extends BaseEffectParameter<D>
-    { event: A.Uninstantiated<Machine.ExitEventForStateValue<D, StateValue>>
+    { event: A.Uninstantiated<Machine.ExitEventForState<D, State>>
     }
 
   export interface BaseEffectParameter<D>
@@ -300,8 +339,8 @@ export namespace Machine {
     , setContext: Machine.SetContext<D>
     }
 
-  export type EntryEventForStateValue<D, StateValue> =
-  | ( StateValue extends InitialStateValue<D>
+  export type EntryEventForState<D, State> =
+  | ( State extends InitialState<D>
         ? { type: Definition.InitialEventType }
         : never
     )
@@ -311,27 +350,27 @@ export namespace Machine {
           | O.Value<{ [S in keyof A.Get<D, "states">]:
               O.Value<{ [E in keyof A.Get<D, ["states", S, "on"]>]:
                 A.Get<D, ["states", S, "on", E]> extends infer T
-                  ? (T extends A.String ? T : A.Get<T, "target">) extends StateValue
+                  ? (T extends A.String ? T : A.Get<T, "target">) extends State
                       ? E
                       : never
                   : never
               }>
             }>
           | O.Value<{ [E in keyof A.Get<D, ["on"]>]:
               A.Get<D, ["on", E]> extends infer T
-                ? (T extends A.String ? T : A.Get<T, "target">) extends StateValue
+                ? (T extends A.String ? T : A.Get<T, "target">) extends State
                     ? E
                     : never
                 : never
             }>
       }
     >
 
-  export type ExitEventForStateValue<D, StateValue> =
+  export type ExitEventForState<D, State> =
     U.Extract<
       Event<D>,
       { type:
-          | keyof A.Get<D, ["states", StateValue, "on"], {}>
+          | keyof A.Get<D, ["states", State, "on"], {}>
           | keyof A.Get<D, "on", {}>
       }
     >
@@ -378,34 +417,6 @@ export namespace Machine {
   export namespace ContextUpdater {
     export type Impl = ContextUpdaterImpl;
   }
-
-  export type State<D,
-    Value = StateValue<D>,
-    NextEvents =
-      ( Value extends any
-          ? A.Get<ExitEventForStateValue<D, Value>, "type">
-          : never
-      )[]
-  > =
-    Value extends any
-      ? { value: Value
-        , context: A.Uninstantiated<Context<D>>
-        , event: A.Uninstantiated<EntryEventForStateValue<D, Value>>
-        , nextEventsT: A.Get<ExitEventForStateValue<D, Value>, "type">[]
-        , nextEvents: NextEvents
-        }
-      : never
-    
-  interface StateImpl
-    { value: StateValue.Impl
-    , context: Context.Impl
-    , event: Event.Impl
-    , nextEvents: Event.Impl["type"][]
-    , nextEventsT: Event.Impl["type"][]
-    }
-  export namespace State {
-    export type Impl = StateImpl
-  }
 }
 
 export namespace L {
@@ -439,7 +450,8 @@ export namespace U {
 
 export namespace O {
   export type Value<T> = T[keyof T];
-  export type ShallowMerge<T> = { [K in keyof T]: T[K] } & unknown
+  export type ShallowClean<T> = { [K in keyof T]: T[K] }
+  export type OmitKey<T, K extends keyof T> = { [P in U.Exclude<keyof T, K>]: T[P] }
 }
 
 export namespace A {