Simplification of Inngest Event Definitions

[khill-fbmc]

Hello 👋🏻

I wanted to stop by and sing a little praise on how your library solved a problem for me.

Background

I am using Inngest, an event framework, and you can see in this small example that the event string is repeated 3 times!

I don't like that at all.

My Solution

I tried making my own utility type that could help with the name...

type InngestNamedEventRecord<T extends { name: string }> = Record<T["name"], T>;

That worked fine, defining the event like so:

export type SendEmailEvent = InngestNamedEventRecord<{
  name: "app/email.send";
  data: {
    mailTo: string;
    subject: string;
    message: string;
  };
}>;

which enabled me to export the type to the module with the client and merge them all together. I still don't like that I can't really use the type at all, it just type hints the params for me, which is nice, but I wanted more...

Enter ArkType

With your beautiful library I was able to replicate the type, and de-duplicate the event name into one variable!

YES!

[ssalbdivad]

Wow, that looks awesome! I hadn't really even considered the possibilities of creating "higher-order types" manually. As long as whatever variables you're using are inferred as narrowed strings/objects, you could totally abstract this out to something like:

const data = type({
    mailTo: "string",
    subject: "string",
    message: "string"
})

const defineEvent = <name extends string>(name: name) =>
    ({
        name: `'${name}'`,
        data
    } as const)

const emailSend = type(defineEvent("app/email.send"))
// Inferred as:
// 
// Type<{
//     name: "app/email.send";
//     data: {
//         mailTo: string;
//         subject: string;
//         message: string;
//     };
// }>

Unfortunately, TS does not seem to want to cooperate with narrowing dynamic key syntax like [name], but there's a huge amount you can already do with this approach, and it will be even more powerful once we support mapped/generic types!

Really nice to see it being applied so creatively so early on. Great work! 🔥

[khill-fbmc]

Thank you for applying your time to making such a neat library!

[khill-fbmc]

That is close, but for Inngest, they want the event name to be the key of the whole type, it needs one more layer I saw what you said after the fact. 😢