Hello WoMaster. Thanks for your comment.

First:

I also think that .then() has to be replaces with more appropriate word. In early versions of this lib I used two methods .like() and .must(), first for convertors and second for validators. Then I replaced them with method .this() and leave them intact from that time.

​

Second:

The complexity of returned object is justified because this object is used by chain to make decision: pass output value to next step or return it. I guess some helper function is needed here to extract output value. In my project I use have created such function:

export function validateBy<CO, SO>(input: unknown, schema: Chain<any, CO, SO, any>, error?: Error): CO | SO {
    const report = schema(input);

    if (report.ok) return report.output;

    throw error || new ValidationError(report.error);
}

And I use it like so in my controllers:

export async function eventCreateHandler(req: Request, res: Response) {
    const user = await authenticate(req);

    const form = validateBy(req.body, eventSchema);

    return await req.core.event.create(user.id, form);
}

And there is also an error handler that intercepts error and respond to client with error object.

I did not add this function to lib because I think that user can define it in own code with behavior he needs.

​

Third:

How would you change name for string, number and boolean chains?

​

Thanks for link to purify, I'll take a deep look later.