Functions with transform in returns/args

[gbouteiller]

Hello and first of all, thank you for this great library.
I'm trying to validate a function with a schema with a returns that contains a transform. The problem occurs when the function schema is implemented : the return type is Returns['_input'] instead of Returns['_output']. Here is a simple example :

const a = z.function().args(z.string()).returns(z.number().transform((v) => `${v}`));
const b = a.implement((e) => +e); // b is (e:string) => number but should be (e:string) => string

By investigating, I guess the problem comes from https://github.com/colinhacks/zod/blob/master/src/types.ts (lines 2884-2894) where the return types of implement and strictImplement are not accurate :

implement<F extends InnerTypeOfFunction<Args, Returns>>(func: F): F {
    const validatedFunc = this.parse(func);
    return validatedFunc as any;
}

strictImplement(func: InnerTypeOfFunction<Args, Returns>): InnerTypeOfFunction<Args, Returns> {
    const validatedFunc = this.parse(func);
    return validatedFunc as any;
}

I guess they should match the OuterTypeOfFunction defined in the same file at line 2752.

[gbouteiller]

In addition, the problem is the same for the args for the same reason :

const a = z.function().args(z.string().transform((v) => +v).returns(z.number().transform((v) => `${v}`));
const b = a.implement((e) => +e); // b is (e:number) => number but should be (e:string) => string

[stale[bot]]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[colinhacks]

Fixed in 3.18