cycle.ts

import {Observable, Subject} from 'rxjs';

export const INCREMENT = 'INCREMENT';
export const DECREMENT = 'DECREMENT';

interface Model{
    value: number
}

interface Intent{
    type: string
}

interface ISinks{
    
}

export function intent(resources: ISinks){
    // resources.DOM.select magic to call INCREMENT and DECREMENT
}

export function model(intent$: Observable<Intent>): Observable<Model>{
    const valueStream$ = intent$
        .map(intent => {
            if(intent.type == INCREMENT){
                return 1;
            }else if(intent.type == DECREMENT){
                return -1
            }
            return 0;
        })
        .reduce((x, y) => x + y, 0);
        
    return Observable.combineLatest(
        valueStream$,
        (valueStream$) => ({
            value: valueStream$
        })
    );
}

export function view(model$: Observable<Model>): ISinks{
    return {
        DOM: model$
        .map(({value}) => 'Hey! value is ' + value)
    };
}