RWalkling

import { MapDeltaStream } from '../delta-streams/streams/map'
import { Point } from './Points'
import { mapValues } from 'lodash'
import { deltaNone, deltaUnknown } from '../delta-streams/deltas/collection'
import mapDeltaStream from '../delta-streams/mapDeltaStream'

export default (points: MapDeltaStream<Point>): MapDeltaStream<number> => {
    const outSubject = mapDeltaStream<number>({})

    points.stream.subscribe(({ data, delta }) => {

RWalkling

import { get } from 'lodash'

export interface EqualByProperties<TObject extends object> {
    (): (object1: TObject, object2: TObject) => boolean
    <TKey extends keyof TObject>(key: TKey): EqualByProperties<TObject>
    <TKey1 extends keyof TObject, TKey2 extends keyof TObject[TKey1]>(
        ...key: readonly [TKey1, TKey2]
    ): EqualByProperties<TObject>
    <TKey1 extends keyof TObject, TKey2 extends keyof TObject[TKey1], TKey3 extends keyof TObject[TKey1][TKey2]>(
        ...key: readonly [TKey1, TKey2, TKey3]

RWalkling

import { Observable, Subject } from 'rxjs'
import { distinctUntilChanged, map, withLatestFrom } from 'rxjs/operators'
import { apply, assocPath, path } from 'ramda'

type StreamLens<TObject, TOriginal> = <TKey extends keyof TObject | undefined = undefined>(
    key?: TKey,
) => TKey extends keyof TObject
    ? StreamLens<TObject[TKey], TOriginal>
    : {
          readonly stream: Observable<TObject>

RWalkling

function useObserved<TObject>(observable: Observable<TObject>) {
    const [state, setState] = useState<TObject>()

    useEffect(() => {
        const subscription = observable.subscribe(setState)
        return () => subscription.unsubscribe()
    }, [])

    return state
}