angular - Typescript, @ngrx and default store values -

i think missing obvious trying work @ngrx. trying use nested reducers, , want able return default starting child values. child

export const counter:reducer<number> =      (state:number = 0, action:action = {type:null}) => {      switch (action.type) { 

my question how use initialise counter. counters.ts looks like

export const counters:reducer<number[]> = (state:number[] = [], action:action) => {      switch (action.type) {         case add_counter:             return [counter(), ...state]; 

this works have typescript error on counter: supplied parameters not match signature of call target , i'm wondering how around this.

i'm using @ngrx, provides this:

export interface action {   type: string;   payload?: any; }  export interface reducer<t> {   (state: t, action: action): t; }  export class store<t> extends behaviorsubject<t> {     private _storesubscription: subscription<t>     constructor(private _dispatcher:dispatcher<action>, private _reducers:{[key:string]:reducer<any>}, initialstate: t) {     super(initialstate);     let rootreducer = this._mergereducers(_reducers, initialstate);     this._storesubscription = rootreducer.subscribe(this);     } 

the definition of reducer should be

export interface reducer<t> {     (state?: t, action?: action): t; } 

to allow calling without parameters.

default parameter values allowed in constructor , function implementations (like in lambda), can't specify default values in interface definition.

when call counter() typescript compiler check type (reducer<number>) , see 2 parameters required.

so either suggested above or call default parameters:

counter(0, {type: null})