/** Invoke a test function as if it was a typeGuard for a given type */
export function typeGuard<T>(o: any, matcher: (o: any) => boolean) {
    return matcher(o);
}

export namespace typeGuard {

    /**
     * type guard that always returns true for a given type.
     * 
     * Use case: 
     * declare const x: "FOO" | "BAR";
     * assert(typeGuard.dry<"BAR">(x));
     * x; <== x is of type "BAR"
     * 
     * OR
     * 
     * assert(!typeGuard.dry<"BAR">(x,false));
     * x; <== x is of type "FOO"
     */
    export function dry<T>(o: any, isMatched: boolean = true): o is T {
        return typeGuard<T>(o, () => isMatched);
    }


}