Extending built-in keywords

import { scope, type } from "arktype";
import { number } from "arktype/internal/keywords/number.ts";
import { string } from "arktype/internal/keywords/string.ts";

export const extensionToStringScope = scope({
    host: "string.ip | 'localhost'",
});

export const extensionToNumberScope = scope({
    port: type("string", "=>", (data, ctx) => {
        const asNumber = Number.parseInt(data);
        const isInteger = Number.isInteger(asNumber);
        const isBetween = 0 <= asNumber && asNumber <= 65535;
        if (!isInteger || !isBetween) {
            ctx.mustBe("an integer between 0 and 65535");
        }
        return asNumber;
    }),
});

const extendedStringModule = type.module({
    ...string,
    ...extensionToStringScope.export(),
});

const extendedNumberModule = type.module({
    ...number,
    ...extensionToNumberScope.export(),
});

export const rootScope = scope({
    string: extendedStringModule,
    number: extendedNumberModule,
});

const CoolHost = rootScope.type("string.host");