initial value of createStorage mandatory?

[simonihmig]

According to the RFC, the initial value of createStorage() should be optional:

declare function createStorage<T>(
  initialValue?: T,
  isEqual?: (oldValue: T, newValue: T) => boolean
): Storage<T>;

But here it is mandatory! Intentionally, or by accident?

[wycats]

I think it makes sense for it to be mandatory. If you want to create storage that is allowed to be undefined, then your T includes undefined 😄

[simonihmig]

Sure, I just wanted to clarify this as the RFC is supposed to be normative, and it explicitly specifies the signature slightly different than implemented.

AFAICT under the RFC this would have been valid, while it is not in this implementation:

const storage = createStorage<string>(undefined, (a, b) => a.toLowerCase() === b.toLowerCase());

And with T=string|undefined a and b could be undefined, so still invalid...

This is just a contrived example. I am fine either way. But if we stick with what we have now, I think the final implementation of the RFC should then also follow this, and not the RFC, to not create subtle breaking changes (at least for the types), right?