Flow & type-safety

[arcanis]

There's a known issue with TypeScript and Generator-based APIs in that the yield expressions are typed any (#2556). I just wanted to let you know that I've submitted a proposal (and a candidate implementation) for a fix, which you can find tin the following thread: microsoft/TypeScript#43632

Under this proposal, you'd be able to annotate the yield expression results using the special YieldType marker, which would instruct TypeScript that, when passed through a yield expression, the returned value is the generic parameter:

declare function fetchGithubProjectsSomehow(): Promise<Project[]> & YieldType<Project[]>;

class Store {
    *fetchProjects() {
        this.githubProjects = yield fetchGithubProjectsSomehow();
    }
}

At the moment the current blocker requires to show the TypeScript team that this feature would have a positive practical impact, so if that's something you're interested to ever see fixed I'd appreciate any feedback you could share! 🙂

[iChenLei]

Cool, thanks for your work.