arktype•2mo ago

Generic & intersection

I'm looking to have a helper arkWithMetadata, which basically takes a base type and add { metadata: { id: <id> }} I wanted to write this :

export const arkWithMetadata = type(
  '<doc extends Record<string, unknown>, id extends string>',
  "{ metadata: { id: 'id' } & doc"
);

export const arkWithMetadata = type(
  '<doc extends Record<string, unknown>, id extends string>',
  "{ metadata: { id: 'id' } & doc"
);

But it doesn't work. I want to retain both types doc and id. Is there a way to do that ? I also tried to write a function :

export function arkWithMetadata<
  const Doc extends Record<string, unknown>,
  const Id extends string,
>(doc: Type<Doc>, id: Type<Id>) {
  return type(doc as any).and(id as any) as Type<
    Doc & { metadata: { id: Id; cas: string } }
  >;
}

export function arkWithMetadata<
  const Doc extends Record<string, unknown>,
  const Id extends string,
>(doc: Type<Doc>, id: Type<Id>) {
  return type(doc as any).and(id as any) as Type<
    Doc & { metadata: { id: Id; cas: string } }
  >;
}

But it doesn't work either 🤷‍♂️ PS: I'm using v2.0.0-rc.18

12 Replies

Dimava•2mo ago

Type deos have withMetadata or smth

JesusTheHunOP•2mo ago

@Dimava of course not, that's just some business name I just want a generic type that can be expressed in the form of an intersection In my case it's a validator named arkWithMetadata that takes two arguments, a Type representing some kind of record, and a Type that extends string. The TypeScript equivalent is :

type WithMetadata<T extends Record<string, unknown>, ID extends string> = T & {
  metadata: {
    id: ID;
    cas: string;
  };
};

type WithMetadata<T extends Record<string, unknown>, ID extends string> = T & {
  metadata: {
    id: ID;
    cas: string;
  };
};

Dimava•2mo ago

You are looking for .merge I guess

JesusTheHunOP•2mo ago

how does that play with a generic ?

Dimava•2mo ago

const WithMetadata = generic('T', 'M')([ 'T', '&', { metadata: 'M' } ])

const WithMetadata = generic('T', 'M')([ 'T', '&', { metadata: 'M' } ])

I mean '.and' does not work as & on objects iirc Or does it

JesusTheHunOP•2mo ago

I assumed it does too

Dimava•2mo ago

Anyways does this work?

JesusTheHunOP•2mo ago

Btw, is there an equivalent for merge ? Because an intersection is not the same, although it works for me here Let me try It works perfectly ! You are a beast 😄 do you want me to open another topic for my question about merge vs & ?

Dimava•2mo ago

Check the docs maaaaaybe its there idk Otherwise yes

JesusTheHunOP•2mo ago

are you the author of the lib ?

Dimava•2mo ago

Nah I'm contributor Has been hitting every pipe edge case bug is the last month

JesusTheHunOP•2mo ago

oh yeah, I've seen the issues on GH ^^ nope, nothing about merge

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Generic & intersection