How to create the Typescript type from a generic?

const document = type({
  id: "string",
  coll: type.instanceOf(Module),
  ts: TimeStub as type.cast<TimeStub>,
  "ttl?": TimeStub as type.cast<TimeStub>,
});

const namedDocument = type("<t>",["t", "&",{
  coll: type.instanceOf(Module),
  name: "string",
  ts: TimeStub as type.cast<TimeStub>,
  "data?": "object",
}]);

const test = namedDocument(document) // This works as expected

type Document = typeof document;
type NamedDocument = typeof namedDocument;
const test: NamedDocument<Function> // This  throws the error Type 'NamedDocument' is not generic.ts(2315)

const document = type({
  id: "string",
  coll: type.instanceOf(Module),
  ts: TimeStub as type.cast<TimeStub>,
  "ttl?": TimeStub as type.cast<TimeStub>,
});

const namedDocument = type("<t>",["t", "&",{
  coll: type.instanceOf(Module),
  name: "string",
  ts: TimeStub as type.cast<TimeStub>,
  "data?": "object",
}]);

const test = namedDocument(document) // This works as expected

type Document = typeof document;
type NamedDocument = typeof namedDocument;
const test: NamedDocument<Function> // This  throws the error Type 'NamedDocument' is not generic.ts(2315)

5 Replies

ssalbdivad•3mo ago

It's not possible in TypeScript to dynamically create a generic name like that. You will have to pass the param to the AT generic like you did in the other example and infer that

MichaOP•3mo ago

ah ok, good to know, so this seems working:

const test = namedDocument(func).infer;
const test4: typeof test

const test = namedDocument(func).infer;
const test4: typeof test

Is it also possible to write that shorter? Something like this? (In this case he seems not liking the function call)

const test3: typeof namedDocument(func).infer = {
    body: "string",
    role: "string"
}

const test3: typeof namedDocument(func).infer = {
    body: "string",
    role: "string"
}

ssalbdivad•3mo ago

No, TS doesn't let you do much directly within a typeof expression

MichaOP•3mo ago

All right - thanks a lot for your help! 🙂

ssalbdivad•3mo ago

Sorry about that! Good luck

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How to create the Typescript type from a generic?

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