Circular type aliases | TypeScript Community | Page 1

winter steppeBOT Jul 17, 2025, 7:43 PM

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piscopancer#0

Playground Link

Preview:```ts
interface Humans {
inna: typeof inna
bob: typeof bob
}

type Human = Humans[keyof Humans]
type HumanName = Human["name"]

type HumanBase = {
name: string
parent: HumanName
}

function createHuman<H extends HumanBase>(human: H) {
return human
...```

quaint nymph Jul 17, 2025, 7:44 PM

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I want to human inna to reference inna, the logic is - if a person inna was ever created, it means such name exists, so her mother or a child can be called inna too

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it lays normally in my head, but TS does not let types reference themselves, how is it different from self-referencing?

grand gull Jul 17, 2025, 7:45 PM

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this doesn't really make sense to have in type-space

quaint nymph Jul 17, 2025, 7:46 PM

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i tried to reproduce my complicated error from my project using humans

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or wdym

grand gull Jul 17, 2025, 7:46 PM

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you're trying to have a kind of stateful registration, but types are kinda stateless

quaint nymph Jul 17, 2025, 7:47 PM

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i am making a lib and i wanted to do it the way Tiptap devs do it

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somehow they don't have such an error

grand gull Jul 17, 2025, 7:47 PM

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right, that's with declaration merging

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you don't have declaration merging

quaint nymph Jul 17, 2025, 7:48 PM

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:[

grand gull Jul 17, 2025, 7:48 PM

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i don't think that's exactly the issue though

quaint nymph Jul 17, 2025, 7:48 PM

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yes, i removed declaration merging from the humans example

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it's not the issue

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the issue is circular types

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which i almost understand

grand gull Jul 17, 2025, 7:49 PM

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we can reduce the example further

winter steppeBOT Jul 17, 2025, 7:50 PM

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that_guy977#0

Playground Link

Preview:```ts
interface Humans {
inna: typeof inna;
}

type HumanBase = {
name: string;
parent: Humans[keyof Humans];
};

const inna = {
name: "inna",
parent: null,
// ^?
} satisfies HumanBase```

grand gull Jul 17, 2025, 7:51 PM

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inna is a HumanBase.
HumanBase.parent is a value of Humans, aka typeof inna
inna needs to know about typeof inna before it can type parent

quaint nymph Jul 17, 2025, 7:51 PM

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damn that's deep

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though that's exactly the behavior i wanted

grand gull Jul 17, 2025, 7:52 PM

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we can get even simpler

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i shouldve named those better one sec

winter steppeBOT Jul 17, 2025, 7:53 PM

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that_guy977#0

Playground Link

Preview:ts type X = { k: typeof x } const x = { k: null //^? } satisfies X

grand gull Jul 17, 2025, 7:53 PM

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x needs to know about X.k
X.k needs to know about x

quaint nymph Jul 17, 2025, 7:53 PM

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i see

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i have to change my approach

grand gull Jul 17, 2025, 7:54 PM

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i don't think the tiptap example you brought up has any circular references, does it?

quaint nymph Jul 17, 2025, 7:54 PM

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it does not

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I can think of some ways to solve this but they all seem to have circular deps issue bcs that's exactly how i want it

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gosh i might be able to split something to help TS

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my current approach is to do it manually, type here is alternative to the name from humans example

declare module '@repo/studio' {
  interface CustomDocumentDefinitions {
    shop: { type: 'shop' }
    employee: { type: 'employee' }
  }
}

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so i am going with some manual labor

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this way i can reference document by its type from within its own definition

export const shopDefinition = defineDocument({
  type: 'shop',
  fields: {
    director: defineReference({
      to: ['employee'],
    }),
    closestShop: defineReference({
      to: ['shop'],
    }),

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basically I just helped TS by hand

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gonna mark it with resolved bcs i think TS will not let me have circular dependencies anyways

#Circular type aliases