type S<T> = { response: T }

type E = { error: string }

typeValue={value:number}

exporttype Value = { value: number }

({type:'LOAD_COUNT_REQUEST'}&Q<{}>)

|({type:'LOAD_COUNT_SUCCESS'}&Q<{}>&S<Value>)

|({type:'LOAD_COUNT_ERROR'}&Q<{}>&E)

typeThunkAction<TQ, TS, TE, _Q, _S> =

({ type:TQ }& Q<_Q>)

| ({ type:TS }& Q<_Q>& S<_S>)

| ({ type:TE}& Q<_Q>& E)

({type:'SAVE_COUNT_REQUEST'}&Q<Value>)

|({type:'SAVE_COUNT_SUCCESS'}&Q<Value>&S<{}>)

|({type:'SAVE_COUNT_ERROR'}&Q<Value>&E)

export type LoadCount = ThunkAction<

'LOAD_COUNT_REQUEST',

'LOAD_COUNT_SUCCESS',

'LOAD_COUNT_ERROR',

{},

Value

>

export type SaveCount = ThunkAction<

'SAVE_COUNT_REQUEST',

'SAVE_COUNT_SUCCESS',

'SAVE_COUNT_ERROR',

Value,

{}

>

export type Action =

|SaveCount

| { type: 'INCREMENT_COUNTER', delta: number }

| { type: 'RESET_COUNTER' }

type _T = Action['type']

({type:TQ}&Q<_Q>)

|({type:TS}&Q<_Q>&S<_S>)

|({type:TE}&Q<_Q>&E)

// TypeScript won't narrow a `ThunkAction` union directly, but

// we can help it out by tagging the three permutations.

export const asReq = <TQ extends _T>(type: TQ) =>

<_Q>(request: _Q) =>

({ type, request })

export const asRes = <TS extends _T>(type: TS) =>

<_Q, _S>(request: _Q, response: _S) =>

({ type, request, response })

export const asErr = <TE extends _T>(type: TE) =>

<_Q>(request: _Q, error: string) =>

({ type, request, error })

type Dispatch<A> = (a: A) => A

type Thunk<Q, S> = (request: Q) => Promise<S>

(fn:Thunk<Q,S>,tq:TQ,ts:TS,te:TE)=>

(request:Q)=>

(dispatch:Dispatch<ThunkActionGroup<TQ,TS,TE,Q,S>>)=>{

dispatch({type:tq, request})

type ReqCreator<A, _Q> = (q: _Q) => A

type ResCreator<A, _Q, _S> = (q: _Q, s: _S) => A

type ErrCreator<A, _Q> = (q: _Q, e: string) => A

export const dispatcher = <_Q, _S>(fn: Thunk<_Q, _S>) =>

<A extends Action>(tq: ReqCreator<A, _Q>, ts: ResCreator<A, _Q, _S>, te: ErrCreator<A, _Q>) =>

(request: _Q) =>

(dispatch: Dispatch<A>) => {

dispatch(tq(request))

fn(request)

.then(response=>dispatch({type:ts,request, response}))

.catch(err=>dispatch({type:te,request,error:err.message}))

.then(response => dispatch(ts(request, response)))

.catch(err => dispatch(te(request, err.message)))

}

type:'RESET_COUNTER',