Type instantiation is excessively deep and possibly infinitely deep

Hello, I have some TRPC endpoint definition which contain some complex type

type VeryComplexType = ... // (discriminated union of 40 options that comes from some library)

// error: Type instantiation is excessively deep and possibly infinitely deep
const FooPayload = type({
  bar: 'object' as type.cast<VeryComplexType>
})

const router = {
  get(): procedure().output(FooPayload).query(() => {...})
}

type VeryComplexType = ... // (discriminated union of 40 options that comes from some library)

// error: Type instantiation is excessively deep and possibly infinitely deep
const FooPayload = type({
  bar: 'object' as type.cast<VeryComplexType>
})

const router = {
  get(): procedure().output(FooPayload).query(() => {...})
}

For this matter I am not even checking the schema of VeryComplexType, I just want to contain the type in the schema definition and get end-to-end type safety. Is there a way to work around the issue?

4 Replies

ssalbdivad•2w ago

Yes, just add it to a prototypes config! https://arktype.io/docs/configuration#prototypes

knthmnOP•2w ago

Thanks, just to clarify, does this work for raw types (no classes)? What about if I want to do this for multiple types? Do I use a union?

type VeryComplexType1 = ...
type VeryComplexType2 = ...

declare global {
  interface ArkEnv {
    meta(): {
      prototypes(): VeryComplexType1 | VeryComplexType2;
    };
  }
}

type VeryComplexType1 = ...
type VeryComplexType2 = ...

declare global {
  interface ArkEnv {
    meta(): {
      prototypes(): VeryComplexType1 | VeryComplexType2;
    };
  }
}

ssalbdivad•2w ago

Yes and yes

knthmnOP•2w ago

Thanks for the instant response!

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Type instantiation is excessively deep and possibly infinitely deep

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