`as` as a no-no

asFreeWriteableSignal.ts

interface IMyWriteableSignal<T> {
  (): T;
  set: (value: T) => void;
  update: (updater: (currentValue: T) => T) => void;
}

function myWriteableSignal<T>(initialValue: T): IMyWriteableSignal<T> {
  let value = initialValue;

  function signal() {
    return value;
  }

  signal.set = (newValue: T) => {
    value = newValue;
  };

  signal.update = (updater: (v: T) => T) => {
    value = updater(value);
  };

  return signal;
}

const counter = myWriteableSignal(0);
counter.set(10);
counter.update(n => n + 2);
console.log(counter()); // 12