arktypea
arktype•6mo ago
Bobakanoosh

Keep type name when using generic

I'm using a custom set of branding utilities (from ts-brand iirc). 
export declare type AnyBrand = Brand<unknown, any>;

export declare type Brand<Base, Branding, ReservedName extends string = "__type__"> = Base & {
    [K in ReservedName]: Branding;
} & {
    __witness__: Base;
};


Since I'm not using arktype's branding, I've made this (maybe not so great) function:
export function customArktypeBrand<TBrand extends AnyBrand>(validation: Type<string | number>): Type<TBrand> {
    return validation as unknown as Type<TBrand>;
}

const schema = type({
   id: customArktypeBrand<MyBrand>(type.number)
})

This works well enough so its not my main question, though if theres a better way lmk.

I'm now wanting to pass a given brand to another type generically:
export const TranslationSchema = <T extends AnyBrand>(of: type.Any<T>) =>
    type({
        id: of,
        value: "string",
    });

const output = TranslationSchema(customArktypeBrand<MyBrand>(type.number));
type Output= typeof output.infer;


This works, but now the output type is inferred like:
type Test = {
    id: {
        __type__: "myBrand";
    } & {
        __witness__: number;
    };
    value: string;
}


Which isn't ideal since I'm exporting from a package this and want it to instead be:
type Test = {
    id: MyBrand;
    value: string;
}
Was this page helpful?