Typesafe getter and setter

setter.ts

type Key = string | number | symbol

const PathSymbol = Symbol('path');

function pathProxy(path: Key[] = []) {
    return new Proxy({
        get [PathSymbol]() {
            return path;
        },
    }, {
        get: (target, prop) => {
          if (prop === PathSymbol) {
            return target[prop];
          }
          return pathProxy(target[PathSymbol].concat(prop));
        }
    });
}

export function setter<T, V>(fn: (state: T) => V, value: V): (state: T) => T {
    const proxy = fn(pathProxy()) as any;
    return lodashSet(proxy[PathSymbol], value) as any;
}