Validation with TS Generics

validation.ts

function isRequired<T extends string> (prop: T, message: string = `${prop} is a required field`) {
    return [
        (model: { [name in T]: any }) => !!model[prop],
        { [prop as string]: message }
    ];
}

interface Foo {
    price: 123;
    desc: 'foo';
}

export type FooKeys = keyof Foo;

const a = isRequired<FooKeys>('price');