Specify Option.of return type as NonNullable

[OliverJAsh]

Re. microsoft/TypeScript#19469 (comment)

In TS, we have this issue:

declare class Maybe<A> {
    static of<A>(value: A | undefined): Maybe<A>;
    map<B>(f: (a: A) => B): Maybe<B>;
}

{
    type User = { name: string };
    const logUser = (_user: User) => {};

    type State = {
        user: User | undefined;
    };

    const fn = function<Own extends {}>(p: Readonly<Own & State>) {
        const { user } = p;

        Maybe.of(user).map(
            user =>
                // Unexpected error: Object is possibly 'undefined'.
                user.name,
        );
    };
}

Annotating Option.of return type as NonNullable, as recommended in the TS issue, fixes this.

[OliverJAsh]

@alexandru Any thoughts on this?

[OliverJAsh]

Hi @alexandru, is this library still being maintained?

[alexandru]

@OliverJAsh unfortunately due to my other commitments and the fact that I'm no longer involved in TypeScript driven projects, for the last couple of months the library has been unmaintained.

It's not by intention and I'm pretty sure I'll get involved in other TypeScript projects in the future.

I'm looking for options, to share the maintenance burden with other people.

[alexandru]

@OliverJAsh fyi I'm updating the dependencies and will merge this too.